JPH0336846A - Packet generator including carrier language - Google Patents

Abstract

PURPOSE: To prevent erroneous transmission, and to attain miniaturization by using a first prescribed parity check, at least a second parity check, and packet length indicating part for setting the range of packets. CONSTITUTION: Any packet of information control, or staff is supplied with an enable signal and a packet start sop signal to a parity unit 107 in a byte system base. The unit 107 generated first and second parity checks is response to the enable and sop signal. A generated first parity check bit in inserted into a first parity check field, and a generated second parity check bit is inserted into a second parity check field. The first and second parity checks are used cooperatively with a packet length indicator for limiting the packets, and synchronizing this system.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a packet transmission system and/or switching system, and particularly to a packet format.

BACKGROUND OF THE INVENTION In packet transmission and/or switching systems, it is important to delimit individual packets, i.e. to identify the beginning and end of the packet, and to examine the ladder data fields in the packet. . Appropriately setting the packet range is especially important in systems that use variable length packets. In conventional devices, packets are processed by bit stuffing by using flags or specific code sequences placed at the beginning and end of the packet and by the use of bit stuffing to ensure that the information being transmitted does not emulate the flags. ) was used to set the range. In prior art systems, the ladder data fields into packets were checked by using a separate cyclic redundancy check (CRC).

Such conventional range setting and testing devices require bit-by-bit sequential processing. Therefore, it is difficult, if possible, for these devices to perform processing for high bit rate transmission and/or switching systems, such as bit rates of 45 Mb/s and above. In fact, even if such conventional scoping and testing equipment were capable of operating at high bit rates, it would be expensive and therefore undesirable from an economic point of view.

It is also possible that the header or carrier word of the packet is emulated with user information. Furthermore, the carrier words used within the private network may be similar to the carrier words used within the public network. In this case, such a local network carrier word may be mistaken for a carrier word used within the public network.

The occurrence of such a phenomenon is extremely undesirable and must be avoided. If this is not avoided, errors in transmission and/or exchange will occur. That is, packets are lost or, even worse, mistransmitted.

(Eighth Point of the Invention) The problems and drawbacks of conventional packet scoping and/or inspection devices are addressed by embodiments of the present invention, which include a packet length or size indicator as well as at least one predetermined parity check. Angle 1 (is determined by using the carrier word or header of

To this end, the packet carrier word includes a plurality of bit positions each having a predetermined number of bit positions. At least one predetermined parity check! The two parity check bits are generated by calculating parity from the bits within predetermined bit positions of the carrier word.

Parity check bits resulting from forming the at least one predetermined parity check are pushed into predetermined bit positions forming at least one predetermined parity check field within the carrier word. Similarly, bits representing the packet length indicator are also pushed into predetermined bit positions forming the packet length indicator within the carrier word.

In accordance with another aspect of the invention, the use of a plurality of predetermined parity checks in conjunction with a packet length indicator in the packet carrier word provides a single degree of robustness to errors in scoping and/or checking. Realized. For this purpose, each bit from a predetermined bit position within the carrier word is used to calculate at least two different parity check bits. The number of parity check bits calculated depends on the desired degree of robustness desired.

In a particular embodiment of the invention, the parity check bits forming at least the first predetermined parity check determine the parity from the bits in the bit positions of one or more predetermined ones of the bit 1 position group in the carrier word. Generated by calculation.

The parity check bits forming the at least first predetermined parity check are the at least first predetermined parity check bits in the carrier word.
into predetermined bit positions forming the parity check field of. The parity check bits forming the at least second predetermined parity check are generated by calculating parity from bits in predetermined similar bit positions within a predetermined set of bit positions within the carrier word. The parity check bits forming this second predetermined parity check are at least the second parity check bits in the carrier word.
is inserted into predetermined bit positions forming a predetermined parity check field of.

In an exemplary embodiment of the invention, each group of bit positions forms a byte having a predetermined number of bit positions. The data is serial bytes with parallel bits: 1. This forms a carrier word having a predetermined number of column bit positions and a predetermined number of row bit positions.

At least a first predetermined parity check bit is generated by calculating parity from bits in bit positions of one or more predetermined ones of the columns, and at least a second predetermined parity check bit is generated by calculating parity from bits in bit positions of one or more predetermined ones of the columns. is generated by calculating parity from a predetermined bit position within the parity.

Further, the individual parity check bits forming the at least second predetermined parity check are
is generated from bits in predetermined bit positions of rows within the carrier word containing the parity check bits forming a predetermined parity check of the carrier word.

At least the first and second predetermined parity checks include:
It is advantageously used to examine the data in the carrier word field and, together with the packet length indicator, to set the range of individual packets.

Furthermore, the possibility of using a specific carrier word for each specific network, be it a local area network, a public network or other networks, is provided in accordance with another aspect of the invention. Minimized by using unique reference codewords when calculating parity checks.

(Margin below) (Explanation of Embodiment) FIG. 1 shows the details of a packet network node]-○○ for interconnecting a plurality of input ports to a plurality of output ports in a simplified block diagram format. Such packet network nodes can be advantageously used in networks such as those shown in FIG. 16 and described below. As a result, signals from multiple sources are supplied to packet network node 100 via terminals 100-1 to 101-(X+Y). The source may be, for example, a broadband packet transmission facility, digital data, R3232, DSOLDSI, DS3, other digital signals, such as other packet signals such as LAPD (Link Access Protocol D Channel), as disclosed herein. and similar types of broadband packets. These signals may be analog or digital at any desired transmission rate. For example, the incoming signal bit rate is 64 bits/sec DSO rate, 1. 5
It may be a 44 Mb/s DSI rate, or a 150 Mb/s transmission rate including packet formatting information, or any desired rate higher or lower.

If the incoming connection signal is being transmitted via a digital facility and contains packets in a broadband packet format of the type used within packet network node 100, it is
02-X. In this embodiment, the human facility interface 1.2 transfers packet information one byte at a time to a packet interconnect (cross-connect;
oss connect) 10B and to a corresponding one of the input boats 104-1 through 104-X therein. Such facility interfaces are well known to those skilled in the art and are Such a facility interface typically includes a phase-closed group for recovering the incoming clock signal, a framer, a bipolar-to-unipolar converter if necessary, and a gain and/or delay distortion converter. an equalizer for equalization, a performance monitoring device, and an incoming digital signal for reformatting the incoming digital signal from the incoming digital format to the broadband packet format used by the interconnect 103;
1 to 104-X, one byte at a time.

In this embodiment, packet network node 100 also includes each of packetizers 105-1 through 105-Y. Each of the bucketizers 105-1 to 105-Y includes a manual local packet interface 106 and a parity unit 107. The operation of one exemplary bucketizer 105 to generate packet carrier words or headers and packet formats in accordance with aspects of the present invention is described below. however,
It should be noted that the particular construction of bucketizer 105 may vary depending on the type of signal source to which the interface is formed. However, the broadband packet format generated is the same for all bucketizers 105. Such a bucketizer also has a transmission facility and a corresponding human power facility interface 1
02 to the packet network node 100 or, if necessary, directly to the bucketizers 105-1 to 105-1 for the following reasons.
05-Y may be included in other remotely located equipment piles that provide signals to one of the 05-Ys. It is noted that one of the packetizers 105-1 through 105-Y is designated as control manual.

The broadband packet format substitution connection signal is transmitted from the bucketizers 105-1 to 105-Y to the manual port 10.
4-(X+1) to 104-(X+y), respectively. The reference code word Xref is sent from the XrQr unit 108 to the bucketizers 105-1 to 105-Y.
to each of the human power ports 1-104-1 to 104- (X
+Y) and to the stuff port 109. Xref unit 10g may include registers or other storage for storing desired reference code words.

Standard code word X. r is specific to each network layer in the system hierarchy and sets the so-called transmission transparency range for all users.
arency: ability to pass through).

In addition, each local area network that uses the same broadband packet format is assigned a unique standard code word that is used to limit local area network packets, and the local area networks also provide trans-bearing range in the system hierarchy. .

Each of the input ports 104-1 through 104- (X+Y) is used for packet qualification and synchronization to the incoming broadband packet format, and for output ports 110-1 through 110-, in accordance with aspects of the present invention.
It is used to store the packet that would be obtained by an appropriate one of (X0Y). To this end, each of the human ports 104 interfaces with the data bus (DBUS) and address bus (ABUS) and transport bus (TBUS) of the packet interconnect 103 on a synchronized basis. These buses operate on a time division multiplexed basis. Details of each of the manpower ports 104 are shown in FIG. 5 and described below.

The stuff port 109 generates so-called stuff packets that are transmitted when there are no other packets to transmit. The stuff port 109 is used by the bucketizer 105. The stuff packets are generated in a manner substantially similar to the method and described below. The stuff packets are stored in a buffer memory for use when needed. The stuff packets are output as described below. port 11
Called when needed by one of 0-1 to 110- (X+Y). For this purpose, the stuff port 109 uses the packet interconnect 103 address bus (
ABUS) and data bus (DBUS).

Each of the output ports 110-1 to 110-(X+Y) transfers the packets obtained from the manual ports 104-1 to 104-(x+y) and the staff boat 109 to the output interfaces 111-1 to 111-X and output local packets. It is used to feed the appropriate one of interfaces 112-1 through 112-Y. For example, if a packet is to be transmitted to a remote packet network node, the packet is sent to output facility interface 1.
11-1 through 111-X and then to output terminals 115-1 through 115-X, respectively. If the destination of the packet is the same as packet network node 1
00, the packet is provided to the appropriate one of the output local packet interfaces 112-1 through 112-Y and then output to the output terminals 115-(X+1) through 11-Y.
5-(X0Y) respectively. As in the case of packetizer 105, output local packet interface 112 will also require different structures depending on the type of equipment being interfaced.

Output facility interfaces 111-1 through 111-X typically include devices for interfacing each of output ports 110-1 through 110-X to a predetermined transmission facility. To this end, each of the output facility interfaces 111 includes suitable equipment for formatting the transmitted broadband packets into the specific signal format of the corresponding transmission facility. Such output facility interfaces will be familiar to those skilled in the art.

For this purpose, the output boats 1lO-1 to 110-
Each of (X0Y) is a scheduler (5chedulc
r) Operates in conjunction with 113 to schedule transmission of packets in accordance with aspects of the present invention. To achieve these functions, each of the output ports 110 is connected to the data bus (DBUS), address bus (ABUS), scheduler bus (SBUS), and full quantum bus (SBUS) of the packet interconnect 103 on a synchronization basis. TQBUS
) and interface binding. Similarly, each of the interconnect buses operates on a time division multiplexed basis. Details of each of the output ports 110 are shown in FIG. 7 and described below.

Scheduler 113 cooperates with processor 114 to control the routing of packets from human port 104 to output port 110 and statistics port 116 and for packet 1 at output port 110 in accordance with aspects of the present invention.
04 to control the output scheduling of packets at the output port 110.

The processor 114 is provided with information regarding the state of the output port 110 and the assigned destination (DEST) for the particular packet scheduled for transmission.
) to - the value of the delay difference (DD) between the next and alternate paths. Furthermore, the statistics port 116 is the human power port 1.
Information regarding the status of 04 is provided to processor 114.

On the other hand, the proset 114 transfers this information to the scheduler 11.
Supply to 3.

The operation of packet network node 100 and the operation of packet interconnect 103 therein will be understood by those skilled in the art from the detailed description thereof below. Input port 10
It is noted that the input to 4 and the output from output port 110 are asynchronous. However, the internal interface consistency with the human ports 104 within the packet interconnect 103 is determined by the clock speed determined as a function of the number of human ports X+Y-N and the maximum transmission rate of the signals provided to the packet network node 100. are synchronized. In this embodiment, specific time slots of the timing sequence or polling cycle of interconnect 103 are used to write certain information in input port 104, as described below. Polling cycles are completed within an interval less than the packet word interval at the maximum incoming connection rate. Therefore, in this example,
If the maximum incoming connection transmission rate is e.g. 150 Mb/S, there are N-8 ports and the word length is 8 bytes, then there are 8+1-9 time slots per polling cycle and the packet The synchronous clock speed at interconnect 103 is approximately 24 Mb/s.

Each of the human ports 104-1 through 104-(X1Y) is identified by the number of time slots within the scheduler 113's synchronous polling cycle. In particular, the first time slot that passes through the Nth time slot identifies each of the input ports 104-1 to 104-(X+Y) to the scheduler 113.

During timeslot N+1+Y, output port 110-1
11O-(X1Y) have access to the storage device within the human port 104, and time slots N+1-0 are the time slots for writing input word data to the device within the input port 104. The packet network node 100 can be used in numerous applications, for example as a switching node, an access node or a so-called gateway node.

However, the configuration of interconnect 103 is different from the network configuration in which interconnect 103 is used, whether the network configuration is link, star, mesh, etc. It is important to note that independence. The switching node typically has a number of each of N-X-1 human facility interfaces 102 and N-X-1 output facility interfaces 111, and at least one bucketizer 105 and a corresponding output local packet. interface 112. The access node or gateway node is typically Y-N.
- X input ports and Y-N-X output ports and at least one input facility interface 102 and at least one corresponding output facility interface 111;
, ie, X-1, and would preferably include Y-N-1 packets 104 and Y-N-1 output local packet interfaces 112. In another application example, the packet network node 100 has multiple manpower and output facility interfaces (X) and multiple manpower and output facility interfaces (
(X) and a number of packetizers and output local packet interfaces (Y) (here X-Y). However, any number of manpower facility interfaces and output facility interfaces, and any number of bucketizers and output local packet interfaces may be used to meet the system requirements of a particular application. However, it should be noted that for each type of human interface there is a corresponding output interface. For example, if a digital signal is being received at this packet network node from a particular remote switching node via a single human power facility interface 102, then a digital signal is being received via a corresponding single output facility interface 111 to that remote switching node. Similar digital signals are being transmitted. Similarly, if a data signal is being received from a local area network at one bucketizer 105, a similar data signal is being provided to that local area network by one output local packet interface 112. That is, there is bidirectional communication between the sources of signals provided to packet network node 100.

[Bucketizer] As described above, each bucketizer 105-1 through 105Y includes a local packet interface 106 and a parity unit 107, and is configured to generate a packet format according to an aspect of the present invention as shown in FIG. used. To this end, the manual local packet interface 106 is configured to interface to a particular incoming connection signal in order to qualify that particular incoming connection signal so that a broadband packet word can be formatted according to the present invention. including equipment. Additionally, a formatted packet and a carrier word generator;
an apparatus for counting the number of packet bytes and a number of packet words; an apparatus for padding the last packet information word to configure it into an appropriate number of bytes; and Buffer storage is required for the multiplexing device and for combining the packet information words and carrier words to form the desired packet. The carrier word generator may be a register or a read/write (RAM) storage device into which the desired information can be inserted. Such devices are well known to those skilled in the art.

Accordingly, a packet format is shown in FIG. 2 that includes a carrier word (header) 201 and a number of information quantum or information words 202-1 through 202-M. Details of the carrier word are described below in conjunction with FIGS. 3 and 4. This packet format comprising M information words 202, each having a relatively short fixed length, is particularly advantageous for efficient packet transmission and/or exchange. Previous devices used either fully variable length information fields or fixed length information fields defined by flags. Devices that use fully variable length + i'7 information fields are undesirable because they use so-called bit-level processing, and devices that use fixed length information fields are undesirable because the length of the information field is too long or I don't like it because it's too short. The use of fixed length information fields also requires that the entire information field be transmitted or exchanged even when only one byte of information is present.

In the device of the invention, only M relatively short information words are transmitted or exchanged, as determined by the number of bytes of information to be included in the packet. At this time, in order to configure the final word in the packet to its proper length, only the final word in the packet is padded to include bytes that are not used for information.
tng). As shown in FIG. 2, in this embodiment, the information word 202-M contains 5 bytes of USER information and a so-called FI, which is used for padding.
3 bytes including LL (fill). In this example, the number M of packet information words ranges from zero (0) to 25
5, each packet information word containing 8 bytes and each byte containing 8 bits, but these should not be construed as limiting the scope of the invention. Although the bytes of information are shown as being in parallel, it will be apparent that they could also be arranged in series. The packet format shown in FIG. 2 is formed by packetizer 105 in a manner that will be apparent to those skilled in the art.

The human powered local packet interface 106 also generates a carrier word 201 as shown in FIG.

In this example, carrier word 201 also includes 8 bytes, each byte having 8 bits. Again, the carrier word bytes are shown as being in parallel, but they could be placed in series as well. Therefore, since the carrier word is the same size as each of the packet information words, if it were manually fed into one bucketizer 105, it would appear as is. BYTE (0:~BYTE
TE (3) is used for system address purposes and is therefore called the system address field. In this embodiment, the locations designated DEST (0) through DEST (11) form destination fields, which are used to indicate packet network node addresses. As is clear to those skilled in the art, VCID(0) to VCID(
The bit positions designated 19) can be used to further indicate the final destination of the corresponding packet; these represent so-called virtual circuit identification. In this example, bit position VCID(1
6) to VCID (19) are destination extensions (DES EX
T) specified as a field. If the destination of the packet is the same packet network node. DEST
The EXT field indicates to which output port of output ports 110-(X+1) to 110-(X+Y) the packet is to be supplied. The remaining VCID bits identify the final destination of the packet and
ling (posting).

BYTE (4) is TYPE (0) to TYPE (4
) and bit positions designated as BKG (0) through BKG (2). Bit position TYPE (0) to TY
PE (4) indicates the class or grade of service assigned to the corresponding packet and is called the type of packet field.

Bit position TYPE (0) indicates whether a packet alternative route can be selected. Therefore, the bit position TYPE
A logic 1 in (0) indicates that the packet can choose an alternative route, and a logic O indicates that it cannot. In this embodiment, normally only statistical packets can select an alternative route. The only case in which a periodic packet would choose an alternate route is if there is a failure in the primary route assigned to the destination for the packet, or if the packet was assigned a class of service that requires a minimum delay for some reason. It's time. Bit position TYP
E (1) indicates whether the type of packet is statistical or periodic. That is, if the information word of a packet contains burst information, the packet is called a statistical packet;
Also, if the information word of a packet contains circuit type information, such as PCM encoded audio, the packet is called a periodic packet. Therefore, bit position TYPE(1
) indicates a periodic packet, while a logic 0 indicates a statistical packet. Bit position TYPE
(2) and TYPE (3) are used to select the thresholds used in scheduler 113 as described below. Bit position TYPE (4) indicates whether the packet is assigned the minimum delay class of service. Bit position BKG (0) to BKG
(2) are called breakage fields and indicate the number of padded bytes since they do not contain user information to be transmitted in the final information word M of the packet. Bit position BKG (0) to B
It will be clear that KG (2) can also be used to indicate the number of bytes containing user information in the final information word.

BYTE (5) is bit position 5IZE (0) to 5I
ZE (7), these are called the SIZE field. The bits placed in the size field indicate the information word M (ie, the number of quanta) in the corresponding packet. That is, a bit representing a packet length indicator is placed in the size field. Similarly, in this example, M
can have values from zero (0) to 255.

BYTE (6) contains six blank bit positions for the first predetermined parity check bit to be populated by parity unit 107 and bit positions SGZ and EX.
Including G. The six blank bit positions are called the first parity check field. In this example, bit position SGZ indicates whether the packet contains zero (0) or more information words. If the packet length is not greater than zero, the packet length indicator field is not needed and the information can be transmitted in the BYTE (5) size field of the carrier word. Therefore, if only one byte of information is to be transmitted, SGZ is set to logic 0 and the byte of information is placed in the bit position of the size field in BYTE(5) instead of the packet length indicator bit. is forced into. In such packets, BYTE (5) can be used since a packet length indicator is not required since one packet word is accepted. It will be appreciated by those skilled in the art that this method can be extended to transmit 2 or even 3 bytes of information within the carrier word, eliminating the need to transmit additional information in this case. should be obvious. It should also be noted that additional fields in the carrier word field may be used to convey user information. The use of additional fields within the carrier word will also increase transmission efficiency by reducing the number of information words needed to be transmitted. One example where additional carrier word fields can be used to convey information is in control packets. BYTE
Bit position EXC in (6) is used to indicate whether the packet is a control packet or not.

BYTE (7) contains eight blank bit positions for the second predetermined parity check pattern to be populated by parity unit 107. BYTE (7) no 8
The blank bit positions are called the second parity check field.

Human local packet interface 106 provides packet information to parity unit 107 on a byte basis. Parity unit 107 also has ENABLE
(enabling) signal and packet star) (SOP)
A signal is provided. The ENABI, E signal indicates that a valid byte of information is available, and the SOP signal indicates the beginning of the carrier word according to the beginning of the packet.

In each bucketizer 105, the parity unit 107 inputs BYTE (6) and BY of the carrier word as shown in FIG.
Generate predetermined parity check bits forming a plurality of predetermined parity check patterns to be inserted into the blank bit positions of TE (7). FIG. 4 also shows a reference code word, Xrer, shown within a dashed box, which is used in this embodiment to generate the predetermined parity check bits forming the plurality of predetermined parity checks. It will be apparent to those skilled in the art that the use of the reference code word Xr8f is not necessary to implement certain aspects of the invention. In fact, when generating a predetermined parity check bit, even (EVEN) or odd (OD) bits are generated.
D) Either parity is available. The use of Xr8f and the number of bits contained within Xrer is determined by the number of network layers, including the local area network, in a particular system. Furthermore, the number of predetermined parity checks and the bit pattern used to calculate the parity check bits used in the implementation of the present invention determine the desired robustness (
It will also be clear that it depends on the degree of robustness. In this embodiment of the invention, two predetermined parity checks containing 14 parity check bits are used to obtain the desired level of robustness. That is, each bit from bit positions BYTE (0) through BYTE (6) of the carrier word is used to calculate at least two different parity check bits.

Therefore, the parity unit 107 receives the packet start signal and (SOP), and the ENABLE signal.
Signals and packet information BYTE are provided from the ingress local packet interface 106. The SOP signal indicates the beginning of the carrier word according to the beginning of the corresponding packet. The ENABLE signal indicates that the packet information is valid.
(packet information) is available. In this embodiment, a first predetermined parity check is generated in well-known manner for the bits in each of the vertical columns or groups of bit positions of BYTE (0) through BYTE (5) and as desired or as indicated below. When using the reference code word Xref, it is possible to set it to either even parity or odd parity.

That is, the separate parity check bits are BYTE (
0) through BYTE(5). The first predetermined parity check bits generated for BYTE (0) through BYTE (5) are PBYT (0) through PBYT (5), respectively, which are associated with the carrier word BYTE as shown in FIG. (6) The first parity check field inserted into the first parity check field in
A predetermined parity pattern is formed.

It will be appreciated that parity for generating individual parity check bits need not be limited to one byte, but can be computed from bits in any number of bit positions or groups of bit positions within one or more bytes. Will.

For example, parity can be computed from bits in particular fields of the carrier word's functional fields. In this embodiment, the second predetermined parity check is performed in a well-known manner for predetermined bits of the bits in each of the horizontal columns designated BIT(0) through BIT(7), ie, for each bit position. generated from predetermined similar bit positions within the group. The parity generated for each column can also be either even or odd parity, as desired. In this example, the parity check bits are in the horizontal column BYTE (0) through BYTE (7) containing the bits in BYTE (0) through BYTE (6).
It is noted that this is generated for each of the following. Therefore,
During the calculation of the parity check bits forming the second predetermined parity check, bit positions PBYT(0) to PBYT(0) to P
Includes parity check bits in BYT(5). This also increases the robustness of the system so that the possibility of packet information words emulating carrier words is significantly reduced. Therefore, horizontal column BIT
Separate parity check bits are generated for each of BIT(0) through BIT(7). The second predetermined parity check bits generated for horizontal columns BIT(0) to BIT(7) are PBIT(0) to PBI, respectively.
T(7) and these form a second predetermined parity check pattern which is inserted into the second parity check field within the BYTE(7) of the carrier word as shown in FIG.

However, it is noted that the parity check bits may be computed from bits in any desired pattern of carrier word internal bit positions. Indeed, any desired number of parity checks may be used when implementing aspects of the invention to achieve any desired level of robustness.

As mentioned above, the use of the reference code word Xrer guarantees transbearing range for a very large number of user networks. Furthermore, the use of the reference code word XrOc reduces the probability to zero that the local network carrier word can emulate the public system carrier word. In this example, the reference code word X is bit Xrer (0)
to Xrerref' (11). X ref (0) to X ref
(7) are attached to the horizontal rows of bits designated BIT(0) to BIT(7), respectively, and
ef' to X(11) are attached to BITE(0) to ef(3), respectively. It should be noted that the number of bit positions in Xraf' can be increased or decreased, respectively, as desired.

Additionally, the Xref' bits can be added to any desired bit position within the carrier word. For example, Xr
Individual bits of er can be attached to specific functional fields of the carrier word. BYTE (4
) and BYTE (5) bits may be either even or odd parity, as desired. A logic signal in the bit position of A logic O specifies odd parity. Therefore, Xref can be set to any desired combination of logic 1s and logic 0s.

However, it should be noted that XrOf is the same for a given network or community of nodes. Similarly, a unique predetermined parity check is used in conjunction with a packet length indicator in accordance with aspects of the present invention to qualify packets and provide packet synchronization. Additionally, the use of a unique specific parity check provides for checking of the carrier word field. Additionally, as described below, a unique reference code word be.

Similarly, each of the bucketizers 105 formats the packet as shown in FIG. 2 in a manner well known to those skilled in the art by accumulating the number M of information words 202 in the packet and adding carrier words 201 to them. Occur. To this end, each of the input local packet interfaces 106 stores an information word and inserts appropriate information about the packet into the field of the carrier word as shown in FIG.

This information is stored in bit positions DBST (0) to DEST
(11) In the address field containing the network destination in (Figure 3) and the destination extension (DEST EXT) in bit positions VCID(16) through VCID(19) and the final destination in the remaining VCID bits. Contains address information to be placed in. Bit position TYPE (0
) to TYPE(4), type information is inserted. Whether a packet type is statistical or periodic is usually provided at call set-up or otherwise known by the originating packetizer. Missing information is inserted in bit positions BKG (0) to BKG (2), which can be easily determined by knowing the number of bytes of information in the packet being formatted or the number of bytes of information in the last information word of the packet. can get. Similarly, packet size information is inserted into bit positions 5IZE(0) and 5IZE(7). This is easily obtained by knowing the number of information words stored for the packet being formatted. A packet size larger than zero information is inserted in bit position SGZ. If the packet information is in only one byte, a logical O is inserted in SGZ and the byte of information is inserted in the 5IZE (size) field of the information word. Similarly, this information is easily obtained from the number of bytes of information stored for the packet being formatted. Finally, bit position E
Information indicating whether the packet is a special packet is inserted into the XC.

When no information is stored to be formatted into either an information packet or a control packet, the manual local interface 106
It should be noted that in cooperation with 7, a so-called stuff packet is generated.

Stuff packets are generated in the same manner as the information and control packets described above. The difference is that the number of information words in the stuff packet is zero as dictated by the size field and SGZ, and the destination field is for scheduler 113, the stuff packet is scheduled for statistics collection and is sent to the statistics port. 116. A stuff packet consists of only one carrier word.

Either information, control or stuff packets are ENABLED on a parity unit 107 basis.
(Possible) signal and Start of Packet (SOP) signal. Parity unit 107 is ENA
In response to the BLE and SOPO signals, it is operative to generate the first and second parity checks as described above.

The first parity check bit generated PBYT (
0) to PBYT(5) are inserted into the first parity check field and the generated second parity check bits PBYT(0) to PBYT(7) are inserted into the second parity check field. The first and second parity checks are used in conjunction with a packet length indicator in accordance with aspects of the present invention to qualify packets and synchronize the system. As mentioned above, parity unit 107 is also provided with a reference code word
and used to generate a second parity check. Furthermore, the use of the reference code word Xref provides a unique identification for the network and simultaneously ensures that network users' packets are transparent within the public system hierarchy. The resulting formatted packet carrier word is shown in FIG.

A particular transport user can use a bucketizer that is essentially the same as packetizer 105 to generate packets, or can use a packet network node that is essentially the same as packet network node 100 in the local area network. At this time,
A particular transport user is assigned a unique reference code word Xr8r to provide a unique network identification.

Packets generated using unique reference codewords are guaranteed to be transparent in the public system hierarchy. The broadband generated within the local area network is the same as the broadband packet described above. Therefore, the local network packet containing those carrier words is sent to the packet network node 1.
00 is considered information to the packetizer 105 and is therefore transparent. Packet network node 100 simply adds a carrier word to the supplied information to form a packet. When a local network packet reaches the carrying user's local network, the public network carrier word is removed and its unique reference code word, X, is removed. , is recognized and the local area network packet is transmitted within the local area network. Packets are sent from the packetizers 105-1 to 105-Y to the manual boat 10 on a byte basis.
4-(X+1) to 104-(X+Y), respectively. Similarly, bucketizers 105-1 to 105-
A corresponding ENABLE IN signal is also provided from Y. The ENABLE IN signal indicates to the corresponding input port that a valid byte of packet information is available for delivery.

It is important to note that in this embodiment, the use of the first and second parity checks is powerful enough to check the data fields within the carrier word. This eliminates the need for additional separate checks on the carrier word as required in prior art systems. Furthermore, while so-called group processing is advantageously used when implementing aspects of the invention, it will be clear that other types of processing may be used.

[Input Port] FIG. 5 shows details of the human-powered boat 104 in a simplified block diagram format. Therefore, the shift byte unit 501 has
The ENABLE IN signal, the reference code word Xr, and the packet byte are provided in parallel via BYTE IN. ENA
BLE IN enters and ENs at the speed of the incoming connection clock.
ABLE IN indicates that valid packet bytes are available for this input port. ENABL
E_IN is also provided to byte counter 502.

Shift byte unit 501 includes a word-wide shift register, a parity generator, and a comparator (not shown). In this example, a word includes 8 serial bytes and each byte includes 8 parallel bits.

The shift bite unit 501 is originally as described above.
parity unit 107 on a byte-by-byte basis in connection with parity unit 107 (FIG. 1) in a well-known manner.
operates to generate first and second parity checks for each of the 8 bytes provided to the 8 bytes. The first and second predetermined parity checks generated and the predetermined fields of the packet word, namely PBYT (0) to PBYT (5) and PBYT (0) to PBYT (
If a match is obtained between the expected first and second parity patterns in 7), Tok-1 is generated. The output from shift byte unit 501 is a packet word (WORD) and a packet length field (S
IZE) and the packet length (S
GZ) and a carrier word candidate indicator (Tok). The shift byte unit 501 outputs 5IZE,
SGZ and T. kG, while these are controlled by the control unit 506.
is supplied to Packet WORD is word latch 503
where packet WORD remains in word latch 5031 until write time slot O occurs within the polling cycle of packet interconnect 103 and RAM 504 is then enabled to write WORD.
I am remembered. The appropriate field of packet WORD is T, if it is T. If it is a carrier word candidate, as indicated by rd=1, it is also written into scheduler data storage 505. Packet WORD is RAM
is written into the memory location within RAM 504 identified by the address generated by address generator 509 . RAM address generator 509 is byte counter 5
The write address counter is advanced during the write time slot in response to the word complete (WC) signal from 02. R
AM address generation 2A 509 is also address bus AB
It also operates to pass an address signal from US to read the packet WORD from RAM 504 and provide it to one of the output ports 110 (FIG. 1) requesting the corresponding WORD according to data bus DBUS. It is noted that any of the output ports 110 can read a word from any given input port 104 during a polling cycle. In this example, RAM50
4 has a storage capacity of 4 words.

Byte counter 502 counts the number of packet bytes provided to human port 104 in response to ENABLE IN. The word complete output (WC) from byte counter 502 indicates that the packet word, which in this example is 8 bytes, has been completed and this output is output from word counter 502.
07, word latch 503, scheduler data storage 505, status latch 508, and RAM address generator 509.

In response to a word complete (WC) signal, word latch 50
3 latches WORD from the shift byte unit 501; status latch 508 latches WORD C0UNT from the word counter 507 and TVo from the control unit 506.
rd and 1pkTok from the control unit 506,
RAM address generator 509 is enabled and advanced by one address; and scheduler data storage 505
is enabled to humanize data. It is noted that the WC signal is also generated when byte counter 502 is reset.

Word counter 507 receives W from byte counter 502.
The number of packet words provided to input port 104 in response to the C output. Packet word count (WORD COUNT) is status latch 5
08 and the control unit 506.

Scheduler interface 510 is human port 104
Connect the interface to TBUS.

The control unit 506 controls the supplied 5IZE field and the SG
Controls the human power port 104 to synchronize on incoming connection packets in response to the Z field, Tok, and WORDCOUNT. For this purpose, the control unit 506
generates a signal Two, which indicates whether the packet word is a possible carrier word candidate, and a signal 'pkToK, which indicates whether the last packet is valid or OK. Tword and 'pkToK are provided to status latch 508.

The operation of controller 506 in obtaining frame synchronization of input port 104 for incoming connection packets can be explained with reference to the flowchart shown in FIG. Therefore,
The control routine enters step 601
It is ethered from. Thereafter, work block 602 initializes byte counter 502 and word counter 507 by resetting them, thereby setting stored packet 5IZE to zero packet word, M-0. Human power port 104 is OUT-OF-FRAM
It is defined as being in E mode. Working block 603 indicates that packet bytes have been provided to shift byte unit 501. As mentioned above, the shift bite unit 5
01 generates the predetermined first and second parity unit bits and assigns them to the first and second parity check bits in the predetermined field of the packet word, i.e., BY
PBYT (0) to PBYT (5) in TE (6)
) and PBYT (0) to P in BYTE (7)
Compare with BYT (7) (Figure 4). If a match is obtained, Tok-1 is generated. If not, T. k=0 is generated. Conditional branching point 604 is when WORDCOUNT in word counter 507 is 5IZE.
+1 or the number of packet words indicated by M+1. In the first run of the process, step 604 includes YE after the first word has been provided to the shift byte unit (FIG. 5).
Obtain the result of S. In the next progression, the expected 5 IZE and SGZ fields in the packet word, i.e. BYTE (5) and SG in BYTE (6)
A packet length instruction faM is obtained from the Z bit position.

If the test result in step 604 is No, conditional branch point 6°5 or T is reached. Test whether it is k-1. If the test result in step 605 is NO
If so, control is returned to work block 603. Steps 603, 604 and 605 are then repeated until either step 604 gives a YES result or step 605 gives a YES result. If step 604 yields a YES result, then
Conditional branch point 606 is T. .

A test is performed to determine whether or not =1. If the test in step 606 is No, work block 607 sets Twoword=1 and 1pkTok=0, and byte counter 502 and word counter 50
7 and store the expected number of information words (M) in the packet from the 5IZE field. Signal 1pkTok indicates whether the final packet carrier word candidate is valid or not. Therefore, l, kTok"" 0 indicates that the final packet carrier word candidate sleeve is not valid, and 1p
kTok=1 indicates it is valid. Resetting byte counter 502 generates a WC signal. Therefore, the current WORD from shift byte unit 501
is latched in word latch 503; WORD COUNT from word counter 507 and control unit 506
T1゜1. and 'pkTo from the control unit 506
k is latched in the status latch 508 and stored in the RAM.
Stress generator 509 is enabled to advance one address; and scheduler data storage device 505 is enabled to store the data. Packet interconnect 103
The address in RAM address generator 509 is advanced in response to write time slot 0 occurring within the synchronized polling cycle of written into position. Similarly, write timeslots occurring within the polling cycle of packet interconnect 103 and status latch 5
Tw from 08.

1. -1, DEST, DEST E from packet WORD stored in word latch 503
The XT and TYPE fields are written to scheduler data storage 505. Additionally, a corresponding address identifying the packet starting address (SAD) from RAM address generator 509 for the packet word is also written into scheduler data storage 505. Thereafter, the appropriate ones of steps 603-607 are repeated until either step 605 or step 606 yields a YES result. Either of these YES results indicates that possible carrier word candidates have already been identified and the so-called ALMO3TIN-FRAME (almost intraframe) mode of operation is entered. To this end, work block 608 sets T-1 and 1, kTok-Oord, resets byte counter 502 and word counter 507, and stores the number M of information words from the 5IZE field. Similarly, a pre-reset C signal of the counter 502 is generated, and a pre-reset WC signal is generated in step 607.
Have them perform the above-mentioned work at the location. work block 6
09 indicates that the other packet bytes are in shift byte unit 5.
01. Next, conditional branch point 610
is WORD COUNT in word counter 507
is equal to 5IZE+1. 5IZE+1 is the total length of the packet and indicates the next bucket IIQ2 transmission to be interpreted. If step 6
If the test result at 10 is NO, conditional branch point 611 is T. 11. Test to determine 111. If the test result in step 611 is No, then the current packet WORD in shift byte unit 501 is not a valid path candidate and step 6
Steps 609-611 are repeated until either 10 or 611 gives a YES result. If step 610 yields a YES result, conditional branch point 612 is T. Do a test to determine if it is 11.

If the test result in step 612 is NO, the packet WOR currently in word latch 503
D is not a valid transport route candidate. Control is at step 607
, and appropriate steps 603-612 are repeated. If step 611 gives a YES result, the current packet WOR in word latch 503
D is not a valid carrier word and step 6 is not executed until step 610 gives a YES result and step 612 is reached.
08 to 611 are repeated. If a NO result is again given in step 612, then this is the current packet WORD or n as indicated by the previous packet length indicator.
reframing (rerrarQing) by returning control to step 607 instead of a valid carrier word.
The process repeats again. If step 612 yields a YES result, then the WORD latched in word latch 503 is a valid carrier word and input port 104 is synchronized with the incoming broadband packet. The IN-FRAME mode of operation has been entered.

In summary, steps 603-607 operate on incoming packets on a byte-by-byte basis to identify a first path candidate. Steps 608-612 then operate on the incoming packet similarly on a byte-by-byte basis to identify the next transport path candidate indicated by the packet length indicator from the previous transport candidate capture. When the next carrier word capture indicated by the packet length indicator from the previous carrier candidate is detected, the previous carrier candidate is identified as a valid carrier word in accordance with aspects of the present invention.

Once a valid carrier word is identified, the input port 104 operation enters the IN-FRAME mode. IN-FR
In AME mode, testing for transport path candidates is performed on a word basis in this embodiment. For this purpose, work block 613 includes T −1 and 1p
Set kTok-1, byte counter 502 and word counter 507
and store the number of information words in the packet from the 5IZE field. This indicates that the GOOD packet has been identified according to the GOOD carrier word. That is, the last packet received was identified as a GOOD packet. Thereafter, work block 614 indicates that the packet word has been provided to shift byte unit 501. Conditional branch point 615 then tests to determine if WOR5C0UNT in word counter 507 is equal to 5JZE+1.

If step 615 yields a YES result, steps 614 and 615 are repeated.

After that, the conditional branch point 616 is T. , -1. If the test result in step 616 is YES, another GOOD packet has been identified again. Again, in response to the word complete (WC) signal, WORD COUNT is output from word counter 507 and controller 506
The T1°rd and 1pkTok signals from T1° are written into status latch 508. On the other hand, the memorized WORD
The C0UNT and 'pkTok signals are interconnected 103
is written into the scheduler interface 510 during the write time slot of the polling cycle. 1p
When kTok"", the packet transport data and 1pkTok stored in the scheduler data storage device 505 for the packet immediately before the final one are stored in the scheduler 11.
Transport bus TBUS of interconnect 103 via scheduler interface 510 to be utilized by
supplied to That is, the packet transport information field DE
ST, DEST EXT, WORD COUNT and TYPE, and the packet starting address (SA
D) and the final packet "pkTok" are provided to the TBUS. The packet source (SCR) or human port is informed to the scheduler 1]3 by the time slot within the polling cycle in which the transport information is provided to the TBUS. If the test result in step 616 is NO, the operation of input port 104 is OUT-OF-
Re-enter FRAME mode and control returns to step 60
7 and the reframing process is restarted.

[Stuff Port] Stuff port 109 is used to fill output ports 110-1 through 11 when no other packets are available for transmission.
0-(X+Y) generates a so-called stuff packet which is stored in a buffer memory for use. Each stuff packet contains only a carrier word, which is generated in the same manner as described above with respect to bucketizer 105. However, the DEST field contains a predetermined destination, which indicates that the packet is a stuff packet and will subsequently be used to determine the facility activity ((['acllllty activity). For this purpose, stuff port 109 interfaces with address bus ABUS and data bus DBUS.

[Output Port] FIG. 7 shows details of the output port 110 in a simplified block diagram format. As mentioned above, each of the output ports is connected to the address bus ABUS of interconnect 103.

It interfaces with the scheduler path 5BUS, data bus DBUS, and all-quantum bus TQBUS. As explained below, scheduler 113 provides packet output information regarding packets to be transmitted by output port 110 via SBUS. This information includes output port identification, input port identification (SCR), starting address (SAD) of the packet stored in the corresponding manual port, and WORD C0 of the packet.
It includes the UNT (total length) and the TYPE of the packet (ie periodic or statistical). Output port 110 operates on this information in accordance with aspects of the present invention to schedule the transmission of statistical packets and reserve intervals for the transmission of periodic packets.

Packet output information is obtained by a queue controller (QCON) 701 at an appropriate output port 110 from the 5BUS. QCON 701 determines from TYPE whether the packet is a periodic packet or a statistical packet.

If it is a periodic packet, the manual port identification (SRC) of the packet, the packet starting address (SAD) and the wO in the word interval of the packet.
RD COUNT (M+1) is stored in periodic wait 702 and REAL QSUM counter 70
a count of 4 is incremented by WORDCOUNT;
and RE S ERVE (reservation) QSUM counter 70
A count of 4 is decremented by WORD COUNT. It should be noted that the value RESQSUM in RESERVE QSUM counter 704 must not be less than zero (0). RESQSUM is adder 70
9 and TQBUS. If the packet is statistical, the input port identification (SR
C) The packet starting address (SAD) and WORD COUNT are stored in the statistical wait 705; the counter of REAL QSUM counter 70B is incremented by WORD COUNT; and the RE
The count of SERVEQSUM counter 704 is a value representing the packet word reservation interval (R1), that is, R1-
It is increased by (k/1-k)(M+1).

In this embodiment, the reservation percentage represents the percentage of periodic packets that are expected to be transmitted from the corresponding output port. The value for reservation percentage can be a predetermined fixed value, a value provided by the processor based on call setup, or a value dynamically calculated by reservation percentage calculator 716. The reservation rate calculator 716 receives the word completion signal WC and the output port 11 during predetermined intervals.
Generates a value for the reservation rate in response to the number of periodic or TYPEI packet words transmitted by zero. Details of reservation rate calculator 716 are shown in FIG. 10 and described below.

Both periodic wait 702 and statistical wait 705 are first-first-out (FIFO) registers in this embodiment and interface with next packet unit 706 . REAL 050M counter 703 is decremented by one packet word in response to a word complete (WC) signal from byte counter 707. This is done when one packet word is transmitted. time unit 7
08 generates a reference time T, but the reference time T may be any arbitrary time, for example, the present time. time unit 7
08 is also incremented by the packet word interval in response to the WC signal. This is a smooth process because at this bucket network node the packets are contiguous and contiguous within the byte interval specified by ENABLE.

Adder 709 has REAL QSUM and RESQSUM
and obtain TQSUM. That is, TQSUM
-REAL QSUM +RESQSUM (1) where the individual values are within the packet word interval and TQSUM represents the latency delay in the output port. Meanwhile, TQSUM is supplied to adder 710 and TQBUS. Adder 710 is enabled in response to an arriving statistical packet in statistical wait 705, thereby causing TQS
UM and time T are combined to obtain a scheduled service time value 5TO8 for each corresponding statistical packet. That is, SrO2-TQSUM+T (2). This operation will become clearer from the description of FIGS. 8 and 9 below.

The 5TO3 value for the arriving statistical packet is stored in the Scheduled Service Time (SrO2) queue 711, which is also a FIFO register in this embodiment. 5
The next scheduled service time (NSTO5) at the beginning of the FIFO in TO8 wait 711 is provided to next packet unit 706. The next packet unit is also provided with a time T and a packet complete (PC) signal from word counter 712.

Next packet unit 706 sends the starting address (SAR) and manual boat identification (BRC) of the packet to be transmitted to address counter 713 and the total packet length M+1 as indicated by WORD COUNT to word counter 712. It operates to supply. If the next packet to be transmitted is a statistical packet, the provision of this information is delayed at least until the Scheduled Service Time (S To S) has occurred or the transmission of a periodic or stuff packet thereafter. is delayed until it is completed.

If there is no information about a periodic packet to be transmitted in periodic wait 702 and the next scheduled service time (NSTO3) for a statistical packet has not occurred, the stuff packet in stuff boat 109 is addressed. Stuff packets are requested by feeding counter 713. When the stuff packet is being transmitted, the next packet unit 7
06 provides a logic 1 5TUFF signal as an output.

The 5TUFF signal is connected to the corresponding output local packet interface 112 (FIG. 1) and the REAL 050M
counter 703 and RESERVE 030M counter 704. It should be noted that the 5TUFF signal is not required to be provided to the output facility interface 111. REAL
The 050M counter 703 responds to the logic 1 5TUFF signal by cutting off its decrement input (-), thereby causing the REAL
The QSUM counter is not decremented in response to word complete signal WC. This is similar to the REALQSUM counter not being incremented in response to stuff packet requests. 5TUFF signal is also RESERVE Q
SUM counter 704 is also supplied with reduced manpower and RE
The SQSUM counter is decremented by one packet word in response to a logic one 5TUFF signal. The address counter 713 supplies the address of the requested packet word to the address bus ABUS and supplies the address of the requested packet word to the address bus ABUS.
The identified word in RAM memory or stuff board 109 of 4 is read onto data bus DBUS and provided to word latch 714 . Byte converter 715 outputs ENABLE 0 from the corresponding output interface.
Provides packet words one byte at a time in response to UT (enable output). ENABLE OUT also indicates word completion (W) when the appropriate number of bytes have been transmitted.
C) Also supplied to byte counter 707 which generates a signal. In this embodiment, the packet word includes 8 bytes in series and each byte includes 8 bits in parallel. The Wc signal is used by the word counter 712, address counter 713, word latch 714, and byte converter 715.
and reservation rate,? is also supplied to calculator 716. Word counter 712 generates a packet complete (PC) in response to WC and the total length of the packet, or WORD COUNT, when the number of packet words transmitted is equal to WORD COUNT. Packet completion signal PC is provided to next packet unit 706 to initiate transmission of the next packet. Word counter 712 also provides a first packet word signal to byte counter 707, which in response provides a start of packet (SOP) signal.

Address counter 713 advances the address by one word in response to the Wc signal, thereby causing the address counter 713 to move into the appropriate manual port RAM storing the next packet word to be provided via DBUS to word latch 714. identify the memory location of. The 5TUFF and SOP signals are provided to one of the output local packet interfaces 112-1 through 112-Y. Since the 5TUFF and SOP signals are not required at the output facility interfaces 111-1 through 111-X, the 5TUFF and SOP signals are not provided to the output facility interfaces 111-X through 111-X. Through this process, aspects of the invention:
Any one of the output ports 110 is connected to any one of the RAM memories of the human boat 104 during a synchronized polling cycle.
It is Hashirama that any packet can be addressed within one. Furthermore, this feature is characterized by the so-called broadcast of work within the interconnect 103.
t) enable mode. That is, any number of output ports 1
10 can address the same packet within a particular input port 104 during a polling cycle, so that their output ports 110 can simultaneously provide the same packet as output. Therefore, any problems of conventional packet transmission and/or switching devices caused by the so-called head of the line blockage are eliminated. This results in high throughput within any network in which interconnect 103 is used. Output port status unit 717 provides an indication of the status, ie, whether or not the output port is functioning properly to processor 114 of FIG.

The operation of output port 110 in accordance with aspects of the present invention may be best understood by way of example. Accordingly, FIG. 8 depicts a sequence of timing diagrams (a) through (e) illustrating the operation of output port 110 for arriving statistical, periodic, and stuff packets. Here, FIG. 8(a) is
The arrival times for statistical packets S1, S2, S3, S4 and S5 and periodic packet completions P2, P3, P4 and P5 are shown. The arrival of stuff packets is not shown here because they do not directly affect the calculation of scheduled service times for statistical packets. When statistical packet S1 arrives, transmission has just been completed for either periodic or stuff packets, there are no other packets to be transmitted and the reserved interval for transmitting periodic packets is Assume that it does not exist. Therefore, statistical packet S1 is scheduled to be serviced immediately. REAL QSUM is zero (0) and R
Since ESQSUM is zero (0), TQSU is obtained from equation (2).
This scheduling is done with M being zero (0). Therefore, the scheduled service time for packet S1 is time T, ie, the current point in time, as shown in FIG. 8(b). REAL QSUM counter 703 is S
The count is increased by WORD COUNT of Sl written as l, and the RESERVE 030M counter 704 is increased by (k/1-k) Sl as shown in FIG. 8(C).
The count is increased by (k/1-k)CM+1) times Sl expressed as . When statistical packet S2 arrives, TQSUM is REAL QSUM i.e. packet S1
minus the number of packet words transmitted plus RESQSUM, or (k/1-k)Sl. Therefore, from equation (2), 5 for packet S2
TO5 becomes T+TQSUM. T is the time when S2 arrived and REAL QSUM is therefore TQSUM
is reduced by the number of packet words transmitted for packet S1 as shown in FIG. 8(b). R
The EAL QSUM counter 703 is incremented by the WORD COUNT count for S2, denoted S2, and the RESERVE QSUM count 704 is similarly increased by (k/1-k)·S2 as shown in FIG. 8(C).
(k/1-k)(M
+1). This procedure follows the statistical packet S3. When periodic packet S1 arrives, REAL 050M count 703 is P
The count is incremented by WORD COUNT for l, and the RESERVEQSUM counter 704 is decremented by the total length of Pl. According to aspects of the present invention, intervals or times are reserved for the transmission of periodic packets and typically the net change in TQSUM should be zero for service time scheduling for the next arriving statistical packet. Therefore, this is done. However, RESQSU
periodic packet(s) when M is zero (0), i.e. no time is reserved for the transmission of periodic packets and there are no statistical packets to be transmitted.
It is noted that the total length of , partially determines the calculated scheduling time of the service for any arriving statistical packet. See equations (1) and (2). Upon arrival of statistical packets S4 and S5, their respective scheduled service times (SrO2) are determined as described above.

Periodic packets S1, P3, P4 and P5 are placed in a periodic queue upon their arrival and REAL QS
Appropriate increase in UM counter 703 and RESERVE
030M counter 704 is decremented.

The actual service time for the packet is shown in FIG. 8(d), and the actual time of service and departure of the packet is shown in FIG. 8(e). As mentioned above, the statistical packet S1 is scheduled for service immediately after its arrival, and in order to service periodic packets, according to aspects of the invention, a predetermined relationship to the total length of the statistical packet is maintained. The interval will be reserved. Therefore, the periodic packet P1 currently in the periodic queue is serviced only after the transmission of the statistical packet S1 is completed. Since the transmission of periodic packet P1 was completed before the occurrence of 5TO8 for the next statistical packet S2 and there are currently no other periodic packets in the periodic queue, one or more stuff packets (S P ) is transmitted. This is important so synchronization is maintained and information flow is smooth. As mentioned above, continuous synchronization requires that packets exist consecutively and contiguously within the network. If there was another periodic packet in the periodic queue, it would have been serviced immediately. However, periodic packet P
2 arrived before 5TO3 for statistical packet S2 (FIG. 8(b)), so it will be serviced upon completing transmission of the current stuff packet. Since the total length of the stuff packet is only one packet word,
The delay in service of packet S1 is at most only one packet word interval. Since the total length of the periodic bucket) P2 is greater than the remainder of the reservation interval (k/1-k) Sl, the actual time of service of the statistical packet S2 is equal to the eighth (d
) and FIG. 8(e), the periodic packet P2
transmission is delayed until it is completed. Upon completing the transmission of packet S2, periodic packet P3 is serviced. Similarly, the periodic packet P3 is transmitted by the statistical packet S.
Since the stuff packet is completed before the 5TO5 for packet S3 occurs, the stuff packet is transmitted until the 5TO5 for packet S3 occurs.

Upon completion of the transmission of statistical packet S3, periodic packet P4 is serviced. Since the transmission of periodic packet P4 was completed before the occurrence of 5TO8 for statistical packet S4 and periodic packet P5 is present in the periodic wait, periodic packet P5 will be sent as soon as it completes the transmission of periodic packet P4. will be served. The service of statistical packet S4 is delayed until the transmission of periodic packet P5 is completed. Next, statistical packet S4
is transmitted. Then, 5 for statistical packet S5.
Stuff packets are transmitted until TO8 occurs and statistical packet S5 is transmitted at that time. The stuff packets are then transmitted until additional statistical and/or periodic packets arrive at the output port. By using this unique multi-queue output scheduling system according to the present invention, statistical packets are serviced without undue delay. In fact, the longest interval over which a statistical packet can have its scheduled service time delayed is equal to the interval required for the transmission of the longest periodic packet, which in this example is 2
There are 56 packet words. By using this unique multi-waiting scheme according to aspects of the present invention, periodic bucket-soto delays are reduced, making it possible to obtain accurate information for the scheduler 113 regarding the delays experienced by statistical packets, and Smoothing of bursty statistical packet-soto streams is achieved.

FIG. 9 shows another sequence of timing diagrams (a) to e) illustrating the operation of output port 110 for other sequences of arriving statistical and periodic packets. Similarly, FIG. 9(a) shows statistical packets S1, S2,
The arrival times for S3, S4 and S5 and periodic packets P1, P2 and P3 are shown. Similarly, assume initially that the periodic and statistical waits are empty and that there are no reservation intervals for periodic packet soto transmissions. Therefore, from equations (1) and (2) it can be seen that statistical packet S1 is immediately serviced as described above with respect to FIG. The remaining statistical packet nodes S2 to S5 services are scheduled as described above with respect to Figure 8, and their respective 5TO3 are scheduled as shown in Figure 9(b).
As shown in the figure. A corresponding calculated service time indicating the interval reserved for the transmission of periodic and/or stuff packets is shown in FIG. 9(C). Similarly, the spacing shown in FIG. 9(c) is generated as described above with respect to FIG. The actual times of service for packets and departure for packets are shown in Figures 9(d) and (e). Therefore, as shown in this embodiment, statistical packet S1 is transmitted first as described above with respect to FIG. Upon completion of transmission of packet S1, periodic packet P1 is transmitted as described above with respect to FIG.

Since periodic packet P2 exists in the periodic wait and 5TO3 for statistical S2 has not yet occurred, upon completion of transmission of periodic packet P1, periodic packet P
2 is served. However, as shown in FIG. 9(d), the periodic packet P2 is long and RESERV
The reserved interval RESQSUM for periodic packets in the E QSUM counter 704 has all been exceeded. Therefore, upon completion of transmission of periodic packet P2, statistical buckets S2 to S5 are continuously transmitted. The statistical packets are transmitted as shown in Figure 9(d) as their corresponding 5TO8 have been passed.

There is no reserved interval RESQSUM for the transmission of periodic or stuff packets. The time at which each statistical packet should be transmitted is determined within next packet unit 706 in response to time T and N5TOS. In particular, if 5TO5 for the next statistical packet has been passed, the corresponding statistical packet will be transmitted upon completing the transmission of periodic bucket) P2-. Therefore, in this embodiment, from FIG. 9, 5TO3 for statistical packets S2 to S3 are passed before completing the transmission of periodic packet S3, and statistical packet S4 is passed through before completing the transmission of periodic packet S3.
It can be seen that 5TO3 is passed before completing the transmission of packet S3. Therefore, packet S4 is transmitted after completing the transmission of packet S3. Similarly,
5TO8 for statistical packet S5 is passed before completing the transmission of statistical packet S4, so statistical packet S5 is transmitted immediately after completing the transmission of statistical packet S4. Periodic packet P3 is RESREVE
The reservation interval RESQSU is stored in the QSUM counter 704.
It is not transmitted until M exists or there are no statistical packets to be transmitted. Therefore, the transmission of periodic packet P3 is started upon completion of the transmission of statistical packet S5. In this way, the statistical packets will be reliably transmitted within the proper delay interval. Similarly,
It is noted that the delay in the transmission of statistical packets is at most the interval required to transmit the longest periodic packet. However, in this embodiment, statistical and periodic packets may encounter unexpected delay intervals and thus the desired smoothness may not be achieved. This means that
This emphasizes the importance of accurately estimating the value of the reservation rate, ie, the percentage of available bandwidth allocated for the transmission of periodic packets.

FIG. 10 shows details of reservation rate calculator 716 (FIG. 7) in simplified block diagram form. Here, the word completion signal WC
is supplied to word counter 1001. Word counter 1001 generates an output pulse I after a predetermined number of packet words representing a predetermined interval has been counted. The type ■ counter 1002 is reset by the output signal I from the word counter 1001, and the signal TYPE
I is incremented by I to give a count of the number of type 1 packet words, ie, periodic packet words transmitted during a given interval. The output pulse I is an index map past (
EMP) Enables the average generator 1004 and updates its output value with -, where ' represents the smooth average of the number of periodic numbers transmitted within a predetermined interval. Similarly, output pulse I enables comparator 1003 to create a new E
Compare the MP average ' with the current reservation rate and adjust the up-down counter 1005 accordingly if there is a difference. The output from up-down counter 1005 is at the reservation rate. The EMP average generator 1004 generates an exponentially mapped past average of the TYPEI packets transmitted in the final packet word by k−−Wj+(1−W)k (3), where j is a predetermined value. The interval TI ie! A value representing the proportion of periodic packets transmitted at an output port within the interval required to transmit a packet word, where k is the reservation rate of periodic packets expected to be transmitted from the output port. and W is a weighting coefficient having a value between 0 and 1. Predetermined interval T within a packet word
The values of I and the weighting factor W depend on the packet transmission rate and the desired averaging time constant, τ-Tl/W.

11, 12, 13, 14, and 15 are A-A%B-B, C-C5D-D.

When -K and L-L are connected to E-E, F-F, G-G, H-H, I-I, J-J,
form a flowchart showing the operations performed by the m1 diagram). For this purpose, scheduler 113 uses processor 114, TBUS.

Interface connection with TQBUS and 5BUS.

TBUS supplies packet transport information from human ports 104-1 to 104-(X+Y) to scheduler 113 on a synchronized basis. In this embodiment, the synchronization timing sequence or manual port polling cycle has N+1 timing slots and is completed in less than the packet word interval of the packets provided at the maximum packet transmission rate to the packet network node. Ru. Similarly, it is noted that XYY-N and that time slot 0 is used to write certain information into the input port 104 unit. Scheduler 1
The packet carrier information obtained from TBUS by 13 includes the packet destination extension (DEST EXT), WORDCOUNT for the packet, and the final packet carrier word 0K (
lpkTok), the type of packet (TYPE) and the starting address in RAM of the corresponding manual port (
SAD). The source of transport information (SCR), i.e., the human port, is the source of the transport information (SCR), during which transport information is transferred from the corresponding human port to T
It is known by the time slot of the boring cycle which is supplied to the BUS.

Processor 114 provides information regarding the power and output port status and the differential delay (DD) between the primary and secondary paths respectively assigned to the packet destination (DEST). Port status can be obtained in a well-known manner, for example by transmitting test packets or observing whether "good" packets are being received. This information is obtained in part from statistics port 116.

The delay difference can be easily obtained by performing delay measurements.

IIVj constants are obtained by using so-called loop messages, which may allow A111 to define round-trip delays on paths between packet network nodes.

The scheduler 113 also has a so-called route selection memory (R
AM), which stores information regarding the possible routing options for the packet, ie, the primary and secondary routes assigned to the packet node destination. The path selection RAM also includes delay difference values between the primary and secondary paths. Route selection RA
Also stored in M is information indicating the so-called route selection status, whether or not an alternative route was previously selected for the packet. . For some control packets, alternate routing fields are used to indicate the status of some human ports. It is noted that the primary output port assigned to a packet destination may be a so-called "true" output port or a so-called "logical" output port. In this example, there are N-8 true output ports, denoted as 1-8. The logical output ports are represented as O and 9-15, and in this example are: 0-stuffed, 9-unassigned, 10-conditional source (CSRC), 11-conditional extend ( CEXT), 12-Destination Extension (DEST EX
T), 13-Control (CTL), 14-No Assignment and 15-Stuff. Therefore, if a blowout port is identified as 1 through 8, it is the "true" output port, i.e. the actual output port 110 in this node to which traffic is directed; If it is identified as 13, for example, it is one of the output ports 110 assigned to control. The route selection RAM is indexed by the packet's DEST to provide stored information.

Furthermore, the scheduler 113 includes a so-called threshold memory unit (RAM) (not shown), which stores information regarding possible threshold values used when determining the route of a packet.

In particular, the threshold RAM stores the waiting delay TD, the alternative route selection delay TA and the reroute delay TRR. The threshold RAM is indexed by the TYPE field as described above to set predetermined threshold values TD, T for a particular packet.
Select A and TRR. In this embodiment, the selection of the threshold is based on the type of packet, the degree of service assigned to the packet and the so-called droppability of the packet.

Therefore, the process of scheduler 113 is entered from start block 1101. Thereafter, work block 1102 sets one of the input ports 104 to be polled to one. Next, the conditional branch point 1103 is
Human-powered boats 104-1 to 104- to be polled
A test is performed to determine whether the condition is good for a particular one of (X+Y). If the test result in step 1103 is No, the boat is bad or not functioning properly, and work block 1104 causes packet output information to be provided to statistics boat 116.

This is accomplished by work block 1105, which writes the appropriate packet output information on 5BUS identifying the statistics boat 116 as the output port. The packet output information written on the 5BUS typically includes the output port address, packet/soto source (SRC), and SR.
WORD C which is the starting address and TYPE field of the packet in the RAM of the corresponding human powered boat identified by C and the total length (M+1) of the packet.
0UNT. Then, the conditional branch point 1106 is
Test to determine if human port 104-(X+Y) has been polled. If step 1106
If the test result in is NO, work block 1107
causes the next input port to be polled to be set to the next input port, i.e., input port - person port +1. Control then returns to step 1103. If the test result in step 1106 is YES, the last human port X+Y-N in the polling cycle is serviced, which causes work block 1108 to cause the polling sequence to wait one time slot. As mentioned above, this is time slot 0 within the polling cycle used to write information into several units within each of the human ports 104. Control is returned to step 1102. Returning to step 1103,
If the test result is YES, then the polled input port is good and conditional branch 1109 tests to determine whether the packet being serviced within the particular one of input ports 104 is a new packet. do. If the test result in step 1109 is No, control is returned to step 1106 and step 1
The appropriate ones of steps 1102-1109 are repeated until 109 gives a YES result. Next, work block 1110 causes the new packet's transport information to be obtained from the TBUS. Similarly, the route selection RAM is indexed by the DEST field, which assigns packet destinations according to primary and secondary routes. - information about the next and secondary output ports, the delay difference between the paths, and path selection information or, if the output port is a logical output port, an indication of the appropriate one of the input ports 104 designated for a particular control function; It is noteworthy to provide

Similarly, the threshold RAM is indexed by the TYPE field, thereby providing thresholds TD, TA and TRR. Conditional branch point 1111 then tests to determine if the packet is good or if it is a stuffed packet. If 1,,Tok-1, the packet is good. If the primary output port for a packet is identified as 0 or 15 from the routing RAM, then the packet is a stuff packet. If step 1
If the test result at 111 is NO, then the packet is not good and is either 1pkTok-0 or a stuff packet, and work block 1104 causes the appropriate packet output information to be provided to statistics boat 1106 via step 1105 and 5BUS.

After that 1. lJ l is returned to step 1106 until step 1111 gives a YES result.
The appropriate ones from 02 to 1111 are repeated.

If the test result in step 1111 is YES, the packet is good, and work block 1112 calculates the delay difference between the primary and secondary paths assigned to the packet destination (DEST) and the -next and secondary paths. (DD) and
Obtain the thresholds TD, TA and TRR and the reroute status for the packet, ie whether an alternative route was previously selected for the packet. It is noted that although typically the primary path has a fixed transmission delay that is less than the secondary path, there are cases where the delays are approximately equal. work block 111
3 is from TQBUS - the waiting delay or TQ at any of the output ports 110 assigned to the next and secondary paths.
SUM (P) and TQSUM (S), respectively, and the interval reserved for the transmission of periodic packets, i.e. R
ESQSUM (P) and RESQSUM (S), respectively. 5TATUS (P) and 5TATUS (S) indicating the status, i.e. pass or fail, for the primary and secondary output ports assigned to the packet destination.
are obtained from processor 114.

Conditional branch point 1114 tests to determine whether the primary output port for the packet is one of the control ports 110 designated as a control port. This is obtained from the route selection RAM.

Especially in this length example, if the blowout port is 13
If specified, it is designated as a control output port. If the test result in step 1114 is YE
If S, conditional branch point 1115 (FIG. 13) tests to determine whether the output port designated as control (CTL) is in good condition. If the test result in step 1115 is No, control is returned to step 1104 where the appropriate steps of the process are performed until either step 1114 provides a No result or step 1115 provides a YES result. repeated. If step 1115 yields a YES result, conditional branch 1116 determines whether the waiting delay or number of packet words waiting to be transmitted at the control output port exceeds a predetermined threshold, i.e., T
QSUM (CTL)>TD (4
), where the value TD is set such that if the packet experiences more than an acceptable amount of waiting delay, its transmission is terminated at the statistics port 116. For example, the value of the threshold TD may be set such that packet transmission will be terminated if the packet is overwritten in the RAM in one of the corresponding manual ports 104 before being transmitted from the assigned output port. is set to Therefore, if the test result in step 1116 is YES, control is returned to step 1104 and the statistics port is designated as the output port. Step 1105 (FIG. 15) causes the appropriate packet output information to be written to 5BUS, which in turn provides it to statistics port 116.

Control then returns to step 1106 (Figure 11). If the test result in step 1116 is NO
If so, work block 1117 designates the output port to be one of the output ports 110 assigned to be the control (GL) output port. Step 1
105 causes appropriate packet output information to be supplied to the control output port via 5BUS. Control is then returned to step 1106 and the appropriate steps of the process are repeated.

Returning to step 1114 (FIG. 12), if the test result is No, the primary output port is not the control output, and conditional branch point 1118 indicates that the -output port is the source of the packet (SRC), that is, the conditional source ( C3RC) to determine whether it is identified as an assigned output port.

This specification essentially loops the packet back to its source. For this purpose, the conditional branch point 111
9 tests to determine if the condition source (C3RC) intends this packet to be routed to it. This is accomplished by evaluating the Routing Status field to determine if the input port (SRC) supplying the packet is authorized for this function. If the test result in step 1119 is No, then the appropriate ones of steps 1115-1117 are repeated to determine whether the output port is a control output port or a statistics output port. If the test result in step 1119 is YES, conditional branch point 1120 tests to determine the state of the output port 0PSRC assigned to the particular human power port (SRC). If the test result in step 1120 is YES, the condition (OPSRC) is good and the conditional branch point 1121
A test is performed to determine whether the waiting delay at i11 exceeds a predetermined threshold, ie, TQSUM (OPSRC)>TD (5). The value of the threshold TD and the conditions set for the threshold TD are essentially the same as those used in equation (4). If the test result in step 1121 is YES, the wait delay is too long and step 1104 (FIG. 11) causes the output port to be the statistical port 116. Step 110
5 causes the appropriate packet output information to be written to 5BUS, which in turn feeds it to statistics port 116. 5B
The packet output information written on the US typically includes the output port address, the packet source (SRC),
The starting address (SAD) of the packet in the RAM of the corresponding human boat identified by the SRC and the T
YPE field and WORD COUNT. Upon completion of step 1105, control transfers to step 1
106 (FIG. 11). If step 1121
If the test result in
Select the output port that was assigned to the SRC.

Step 1105 then causes the appropriate packet information to be written while the 5BUS provides it to the output port assigned to 0PSRC. This process may include so-called indirect addressing to determine which of the output ports 110 is assigned to a particular one of the human power ports 104 that is interfaced to a particular signal source (SRC). It is important to pay attention to This is important because the remote node from which the signal may be transmitted has no information regarding such output port assignments at this particular node. The use of direct addressing is important to achieve loop transmissions, etc. to form a table of nearest nodes (neighbors), etc.

Returning to step 1118 (Figure 12), if the test result is No, the primary output port is not C3RC, and conditional branch point 1123 indicates that the primary output port assigned to DEST of the packet is a so-called conditional extension (CEXT). Test to determine if the output port is assigned to This is another use of indirect addressing, where a determination is made that if the packet is
If the packet is from T, the packet is sent to the control output port, and if the packet is from the control input,
The packet is condition extension (CXET) or DEST EX.
is sent to the output port assigned to T. Therefore, if the test result in step 1123 is YES, then conditional branch point 1124 indicates that the human boat is in control (CTL
) is assigned. If the test result in step 1124 is NO, the output port is not DEST EXT and control is returned to step 1115. Step 1115-1
117 is repeated to determine whether the output port assigned to control (CTL) is good or whether the packet should be provided to statistics port 6, as described above. If the test result in step 1124 is YE
If S, the conditional branch point 1125 is DEST EX
Test to determine if the output port assigned to T is "true", ie, one of the N (N-1-8) actual output ports within this node. If step 11
If the test result in 25 is No, step 1104
(FIG. 11) and the packet is provided to statistics port 116 as described above. If the test result in step 1125 is YES, the attached output port is DR9.
T EXT and conditional branch point 1126 tests that condition. If the test result in step 1126 is No, the condition (DEST EXT) is not good and control is returned to step 1104 (FIG. 11) and the packet is provided to statistics port 116 as described above. The test result in step 1126 is YES.
If the condition (DEST EXT) is good, conditional branch point 1127 determines whether the waiting delay at the output port assigned to DEST EXT exceeds a predetermined threshold, i.e., TQSUM (DEST EXT)>
Test to determine TD (6). T.D.
For , the same conditions as above for equation (4) apply.

If the test result in step 1127 is YES, the wait delay is too long and control passes to step 112.
4 (FIG. 11) and the packet is provided to statistics port 116 as described above. If step 1127
If the test result is No, the waiting delay is the threshold T
D, and work block 1128 sets the output port to bit position VCI D (16) − in the packet transport path.
DEST as specified by VCI D (19)
Select EXT. Then step 1105
(FIG. 15) writes packet output information onto 5BUS, which in turn provides the information to the appropriate output port assigned to DEST EXT.

Control then returns to step 1106. Similarly, 5B
The packet output information written on the US typically includes the output port address, the packet source (SRC),
The starting address (SAD) of the packet in the RAM of the corresponding human port identified by the SRC and the T
It includes a YPE field and a WORDCOUNT which is the total length of the packet (M+1).

Returning to step 1123 (Figure 12), if the test result is No, the primary output port is not CEXT, and conditional branch point 1129 indicates that the primary output port is DEST E.
Test to determine if it is XT. If the test result in step 1129 is YES, then
Conditional branch point 1130 tests to determine if the output port assigned to DEST EXT is a control gll (CTL). Similarly, this is another example of indirect addressing. If the test result in step 1130 is YES, the output port is assigned to control and the process returns to step 1115. Step 1115-11 as described above to determine whether the packet is coupled to the control output port or the statistics port 116.
17 appropriate ones are repeated. Return to Step 1130 and if the test result is No, DEST EX
The output port assigned to T is not a control, and conditional branch point 1131 (FIG. 13) tests to determine if the output port assigned to DEST EXT is assigned to the conditional source (C3RC). Similarly, indirect addressing is used to locate the appropriate output port within this node for packets transmitted from remote nodes that do not know the port assignments within this node. If the test result in step 1131 is No, then the output port assigned to DEST EXT is not a C3RC and control is returned to step 1125 and the packet is returned to the output port assigned to DEST EXT or statistics port 116 as described above. Step 1125 to determine which should be supplied.
-1128 as appropriate are repeated. If step 1
If the test result at 131 is YES, it is determined whether the packet should be delivered to the output port assigned to the conditional source, i.e. 0PSRC, to the control (CTL) output port or to the statistics output port 116, as described above. t
, l+, as appropriate of steps 1119-1122 and 1115-1117 are repeated.

Returning to step 1129, if the test result is No, the primary output port is not the DEST EXT port;
Conditional branching point 1132 (Figure 14) has a −next output “true”
That is, it tests to determine if it is one of the N (N-1-8) actual output ports within this node.

If the test result in step 1132 is NO, control is returned to step 1104 and the packet is provided to statistics port 116 as described above. Step 1132
If the test result at
P) is tested. If the condition of the blowout output port is not good, the test result in step 1133 is No;
Conditional branch point 1134 tests the state of the output port assigned to the secondary path, 5TATUS(S). If the test result in step 1134 is No, control is returned to step 1104 (FIG. 11) and the packet is provided to statistics port 116 as described above. If the test result in step 1134 is YES, conditional branch 1135 determines whether the waiting delay, i.e. the number of packet words to be transmitted from the secondary output port, exceeds a threshold TD, i.e. TQSUM(S)>TD (7) Test to determine. Similarly, the value of TD is set such that if a packet experiences more than an acceptable amount of delay during transmission, its transmission is terminated at statistics port 116. For example, the value of the threshold TD is set such that packet transmission is terminated if the packet is overwritten in the RAM in one of the corresponding input ports 104 before being transmitted from the output port. Therefore, the delay threshold TD takes a relatively high value H. Therefore,
If the test result in step 1135 is YES, control is returned to step 104 (FIG. 11) and the packet is provided to statistics port 116 as described above. If the test result in step 1135 is NO, the delay is tolerated and conditional branch 1136 tests to determine if an alternate route was previously selected for the packet.

This is easily determined from the packet's destination (DEST), which is the manual port (SRC) at which the packet is received and is a well-known system topology.

Similarly, if excessive delays are experienced during transmission, it is important not to change the route, but to terminate the transmission of packets that were previously routed if necessary. Termination of the transmission of such packets reduces the possibility of the so-called "runeraerl'ecL" occurring.As is well known, the "runeraerl'ecL" is a phenomenon that occurs as the load on the system increases. The amount of processing within the system will be further reduced. Therefore, terminating the transmission of a packet for which an alternate route was previously selected when the delay in the secondary output port exceeds a predetermined minimum acceptable reroute threshold TRR is a "good" throughput of the system. Increase total volume. Therefore, if the test result in step 1136 is No, then no alternate route has been previously selected for the packet, and the controller 113 selects the second output port to transmit the packet. Step 11
05 writes the packet output information to S B U S +, and then control is returned to step 1106 (FIG. 11). If the test result in Ste Seop 1136 is Y
If ES, then an alternative route has previously been selected for Kerato, and conditional branch point 1138 determines whether the waiting delay TQSUM (S) at the secondary output port exceeds the predetermined reroute threshold TRR, i.e. Test to determine TQSUM(S)>TRR(8). Note that the threshold TRR represents a certain minimum transmission delay interval at a secondary output port, so if a packet is provided to a secondary output port, the packet will only experience a minimum delay before being transmitted. be done.

Therefore, if the test result in step 1138 is Y
If ES, the delay is too long and control is returned to step 1104 (FIG. 11) and the packet is returned to statistics port 116 as described above. If the test result in step 1138 is No, the delay is acceptable and step 11
37 selects a secondary output port for transmitting the packet, then step 1105 outputs the packet output information to 5.
is written on the BUS, and control then returns to step 1106 (FIG. 11).

Returning to step 1133 (FIG. 14), if the 5TATUS of the blowout port is good, a YES result is obtained, and the conditional branch point 1139 indicates whether the waiting delay threshold TD at the primary output port has been exceeded, i.e. Test to determine TQSUM (P)>TD (9). Similarly, the conditions regarding TD are the same as above. If the test result in step 1139 is YES, control is transferred to conditional branch point 1141. The test result in step 1139 is N
If o, control is transferred to conditional branch point 1140 (Figure 15).

Conditional branch point 1141 (FIG. 14) tests to determine 111 whether the packet is a so-called TYPEI or periodic packet. This is the bit position TYPE (
This is achieved by determining whether 1) contains a logical 1. If so, this packet is periodic. This test is important because it is undesirable to terminate the transmission of periodic packets. Step 11
If the test result at 41 is NO, the packet is statistical, and steps 1134-1138 and 1104, as described above, are performed as appropriate. If step 11
If the test result at 41 is YES, then the packet is periodic, and conditional branch point 1142 indicates that the packet DEST
RESQSUN (P)>O(10). If the test result in step 1142 is YES, task block 1143 (Figure 15) selects the primary output port to transmit the packet. Therefore, work block 1105 causes the packet output information to be written on 5BUS as described above, and control then returns to step 1106 (FIG. 11).

If the test result in step 1142 is No, then
Conditional branch point 1144 tests the state of the secondary output port assigned to packet DEST, namely 5TATUS(S). If the test result in step 1144 is No, the 5TATUS is not good and control is returned to step 1104 (FIG. 11) and the packet is provided to statistics boat 116 as described above. If step 1
If the test result in 144 is YES, 5 TATUS
(S) is good, and conditional branch 1145 tests to determine if the packet is of the minimum delay type. This test is accomplished by interrogating bit position TYPE (4) to determine if it is a logic one. A logic 1 indicates that the packet has the minimum delay class of the service assigned to it. It is noted that periodic and statistical packets can be assigned a class of service that requires minimum delay.

If the test result in step 1145 is No, the packet is of the minimum delay type and control is passed to step 1104.
(Figure 11) and the packet is unified as above.
1 port. If the test result in step 1145 is YES, then the packet is of minimum delay type, and conditional branch 1146 determines whether the secondary output port assigned to packet DEST has a reserved interval for transmission of periodic packets. That is, RESQSUM (S)>0 (1
1) A test is performed to determine il+. If the test result in step 1146 is YES, then there is a reserved interval for transmitting periodic packets, and control is returned to step 1136 (FIG. 15) and provided to the secondary output port 116 for transmitting the packet. Appropriate ones of steps 1136-1138 (FIG. 15) and 1104 (FIG. 11) are repeated as described above to determine if the current value is the same. On the other hand, step 1105 causes the packet output information to be written on the 5BUS as described above. Control then returns to step 1106 (FIG. 11). If step 1
If the test result at 146 is No, then there is no reservation period for transmitting periodic packets and control is returned to step 1135 and a secondary output port is selected to transmit the packet or the packet is boat 1
Steps 1135-1138 and 1104, as described above, are repeated as appropriate to determine if 16 is provided. On the other hand, step 1105 causes the packet output information to be written on the 5BUS. Control then proceeds to step 1106
(FIG. 11).

Conditional branch point 1140 (Figure 15) also tests to determine if the packet is a TYPEI or periodic packet as described above. If the test result in step 1140 is YES, then the packet is periodic, and conditional branch point 1147 indicates that the primary output port assigned to packet DEST sets the reserved interval for transmission of periodic packets according to equation (10). Test to determine if you have it. If the test result in step 1147 is YES, step 1143 selects the assigned primary output port before transmitting the packet, and step 1105 transfers the packet output information to 5BUS as described above.
and control is returned to step 1106 (FIG. 11). If the test result in step 1147 is N
If O, conditional branch 1148 tests to determine if the packet is of the minimum delay type as described above. If the test result in step 1148 is NO, steps 1135 and 1105 are aborted as described above, and control is returned to step 1106 (FIG. 11). If the test result in step 1148 is YES, conditional branch point 1149 determines the state of the secondary output port assigned to packet DEST, i.e. 5TATUS (S
) to test. If the test result in step 1149 is NO, then steps 1143 and 1 are performed as described above.
105 is executed and control is returned to step 1106 (FIG. 11). If the test result in step 1149 is YES, conditional branch 1150 determines whether the secondary output port assigned to packet DEST has a reserved interval for transmission of periodic packets according to equation (11). test for. If step 115
If the test result at 0 is YES, step 1137
selects the secondary output port to transmit the packet,
Step 1105 writes the packet output information to 5BUS and control returns to step 1106 (FIG. 11). This is done because the secondary output port has the least delay in transmitting the packet. If the test result in step 1100 is No, conditional branch point 1151 determines, in accordance with the 'aspects of the present invention, - the actual waiting delay at each of the next and secondary output ports, i.e. the amount of packet information to be transmitted; Test to determine which of the -next and secondary output ports has the lesser delay by comparing the delay difference DD between the primary and secondary paths assigned to the threshold TA and the packet DEST. do. This relationship is TQSUM (P) - TQSUM (S)〉
TA+DD (12). The value of threshold TA is chosen to be significantly lower than delay threshold TD and so that packets are not unnecessarily routed to secondary paths. This reduces the possibility of the so-called "runeral effect" occurring.

Similarly, "funeral effect" refers to a condition that results in increasingly lower network throughput due to the selection of an alternative route for a packet. Therefore, the network load increases and the system's "good" location PJ! m decreases. If the test result in step 1151 is No, the primary output port 1143 selects the primary output port to transmit the packet, step 1105 writes the packet output information to 5BUS, and control returns to step 110.
6 (Figure ↓1). If the test result in step 1151 is YES, the secondary output port has less delay, control is returned to step 1136 and the secondary output port is selected to transmit the packet or the packet is sent to the statistics port. Step 1136-1 as described above to determine whether the
The appropriate ones of 138 and 1104 are repeated. Control then returns to step 1106 (FIG. 11).

Returning to step 1140, if the test result is NO, the packet is statistical, and conditional branch 1152 tests to determine if the packet is of the minimum delay type, as described above. If the test result in step 1152 is No, then the packet is not of the minimum delay type. Step 1143 selects the primary output port to transmit the packet, then step 1105 writes the packet output information to 5BUS and control returns to step 1106 (FIG. 11). If the test result in step 1152 is YES, then the statistical packet has been assigned the minimum delay grade of service, and conditional branch point 1153 tests the state of the secondary output port, 5TATUS(S). If step 1
If the test result in 153 is No, 5 TATUS
(S) is not good, step 1143 selects the primary output port to transmit the packet. This is done because the secondary output ports are not available so the primary path will have the least delay. Similarly, step 1105 writes the packet output information to 5BUS, after which control is returned to step 1106. Step 11
If the test result at 53 is YES, conditional branch 1154 tests to determine which of the primary and secondary output ports has the less delay according to equation (12) as described above. If the test result in step 1154 is No, then the primary output port has less delay, and step 1143 selects the primary output port to transmit the packet.

Similarly, step 1165 outputs 5BU of packet output information.
S, and then control returns to step 1106. If the test result in step 1154 is YES, the secondary output port has less delay, control is transferred to step 1136 and the secondary output port is selected to transmit the packet or the packet is Appropriate steps 1136-1138 and 1104 are repeated as described above to determine whether boat 116 is to be supplied. Thereafter, step 1105 writes the packet output information to 5BUS, and then control is returned to step 1106.

[Output local packet interface] The output local packet interfaces 112-1 to 112-Y (Fig. 1) are the output ports 11Q-(X+1) to 110-
(X+Y), output terminal 115-(X+1
) through 115 (X0Y) are used to interface to the specific device and/or communication link desired. As mentioned above, the interface-coupled devices and/or communication links may include:
This corresponds to the bucketizers 105-1 to 105-Y that are interface-coupled by the input local packet interface 106. This is done because there is a need for bidirectional communication between the interfacing devices and/or communication links. To this end, each of the output ports 110~(X+1) through 110-(X+Y) transmits packet information one byte at a time along with the start of packet (SOP) signal and the 5TUFF signal to the attached output local packet interface. 112. Each of the output packet interfaces 112 is EN
An ABLE 0UT (enable output) signal is provided to one of its associated output ports 110. ENABLE
The OUT signal is the packet byte rate and indicates to the attached output port that the output local packet interface is ready to receive packet bytes. Output local packet interface 112
Each of d
epacketlzing: equipment for returning packets) and providing depacketized information in a signal format appropriate to the interfaced equipment and/or communication link. The SOP signal indicates the beginning of a packet so that it can be properly packetized.

The 5TUFF signal indicates whether the packet is ignorable.

The devices to be included within a particular one of the output local packet interfaces 112 will depend on the particular devices or communication links to be interfaced and will be well known to those skilled in the art.

[Network Figure 16 shows in simplified form a network that can be used to advantage of aspects of the present invention. It is noted that there is two-way communication between the elements forming the network. Therefore, local networks 1601 and 1602, so-called regional networks (local networks) 1603 and 1604, and a higher layer network 1605 are shown. Although only two hierarchies are shown in the public system hierarchy, it will be apparent to those skilled in the art that any number of hierarchies can be used within the overall network as needed and desired. Local network 1
Each of 601 and 1602 may include multiple switching and access packet network nodes that include aspects of the present invention. For example, local area networks 1601 and 1602 may belong to particular carrier network users and may be located at geographically dispersed locations.

Broadband packets generated within the private network are the same as those used within the network described with respect to packet network node 100 and used within the public system. A particular local area network is assigned a fixed standard code word to identify the packet and provide a transbearing range for all other information being transmitted. Broadband packets that are delivered to or from local area network 1601 and other devices and/or communication links are accessed by access packet word nodes (A
N) 1606. On the other hand, access node 160
6 is a switched packet network node (SN) in the regional network 1603
and switching packet network nodes (S
receive packets from N). As mentioned above, packets from local area network 1601 and signals from other interface coupling devices appear as information and are transmitted to access node 1.
The packetizer in 606 formats it into broadband packets. These broadband packets are generated using a unique reference code word Xref' assigned to the regional network 1603.

Packets within the regional network 1603 are sent to several switching nodes (S
N) or via access node 1606 or some other access node (not shown) to some other device, network or transmission facility that interfaces with regional network 1603. may be done. If the packet is destined for some other regional network, such as network 1604, the packet will be routed via gateway node 1607 to higher layer network 1605 and to a switching node (SN) therein. At gateway 1607, each packet is appended with a new carrier word generated using a unique reference word assigned to the higher layer network.

This addition can be accomplished by simply adding another carrier word to the packet or by adding a new carrier word generated within the gateway node 1607 that has stripped off the previous carrier word. Similarly, if a packet is being fed from higher layer network 1605 to regional network 1603, gateway node 1607 may strip the attached higher layer network carrier word, or if the carrier word is replaced. If so, the reference code word X is assigned to the regional network 1603 by dropping the higher-level network carrier word. We would add the carrier word generated using f.

If a packet transmitted within higher layer network 1605 is destined for regional network 1604, the packet is provided to regional network 1604 via gateway node 16o8. Gateway node 1608 performs the same functions as gateway node 16o7. Regional network 1604
Therein, packets are provided to access node 1609 via one or more switching nodes. Access node 1609 serves the packet. A specific device, transmission facility, or local area network 1602 is provided. Similarly, the local area network 16
Packets destined for 02 contain a carrier word generated by using the unique reference code word Xred' assigned to the local area network carrier user. Therefore, the packet will be recognized within the local area network 1602. It can therefore be seen that the local network packets are easily identifiable using unique reference code words and that the local network packets are further transmitted within the broadband packet network architecture on a transparent basis.

The above description relates to one embodiment of the present invention, and those skilled in this technical field will be able to conceive of various modifications of the present invention, but all of them are within the technical scope of the present invention. Ru.

[Brief explanation of drawings]

FIG. 1 is a detailed diagram in simplified block diagram form of a packet network node that includes aspects of the present invention; FIG. FIG. 4 is a graphical illustration of nocturnal conveyances or headers useful in describing aspects of the present invention; FIG. 6 shows a detailed view in simplified block diagram form of the manpower port 104 used within the packet interconnect 103 of FIG. 1; FIG. FIG. 7 is a detailed diagram in simplified block diagram form of the output port 110 used within the packet interconnect 103 of FIG. 1; FIG. A sequence of timing diagrams useful in explaining the operation of the packet interconnect 103 of FIG. 1 and the output port 110 of FIG.
FIG. 10 illustrates another sequence of timing diagrams that are also useful in explaining the operation of the packet interconnect 103 of FIG. 7 and the output port 110 of FIG. 7; FIG. 11, FIG. 12, FIG. 13, FIG. 14, and FIG. 15.
The diagrams are A-A, B-B, C-C, and D-D. E-E, F-F, G-G, H-H,! -1. A flow diagram illustrating the operations performed by scheduler 113 in packet interconnect 103 of FIG. 1 when connecting J-J, N-, and L-L; and FIG. 1 shows packet network equipment that can be advantageously used by node 100; 1, 1.1-1 to 111-X to 112-Y...
- Means 701 for interface coupling of information packets as output...Output information acquisition means 702...First waiting means 705...Second waiting means 706...Packet controllable supply means 711.・・・
Scheduled service time generation means 716...Reservation rate generation means 1-IO, I+ Snow In C Takashi 12CE! ;＞-Salary+37b”c) 1st≦Go to Kuzu 11 figure

Claims (14)

[Claims] (1) In a packet generating device including a carrier word: The carrier word includes a predetermined number of bit position groups each including a predetermined number of bit positions, and the predetermined carrier word bit positions are specified by a packet length indication. a predetermined parity check field, a predetermined number of said carrier word bit positions forming a first predetermined parity check field, and a predetermined number of said carrier word bit positions forming at least a second predetermined parity check field. means for generating the carrier word to form; means for obtaining the length of the packet; means for inserting a bit representing the packet length into a bit position of the packet length indicator field; means for generating a first predetermined parity check from bits within predetermined bit positions; and means for generating at least a second predetermined parity check from bits within predetermined bit positions of the carrier word; means for inserting a number of bits representing a first predetermined parity check into the plurality of bit positions of the at least one predetermined parity check field; means for inserting a plurality of bits representing the first predetermined parity check into the plurality of bit positions of the at least second predetermined parity check field; A packet generating device including a carrier word, wherein the predetermined parity check and the packet length instruction section are used to set a range of the packet. (2) the means for generating the first predetermined parity check comprises calculating parity from bits in bit positions of one or more predetermined ones of the group of bit positions in the carrier word; Apparatus according to claim 1, characterized in that it includes means for generating a predetermined number of individual parity checks forming one predetermined parity check. (3) said means for generating said first predetermined parity check comprises calculating parity from bits within a predetermined similar bit position of a predetermined one of said set of bit positions in said carrier word; 2. The apparatus of claim 1, further comprising first means for generating a predetermined number of individual parity check bits forming one predetermined parity check. (4) said means for generating said at least second parity check by calculating parity from bits within a predetermined similar bit position of a predetermined one of said set of bit positions within said carrier word; 4. Apparatus as claimed in claim 3, including second means for generating a predetermined number of individual parity check bits forming a second predetermined parity check. (5) said means for generating said first predetermined parity check comprises calculating parity from bits in bit positions of one or more predetermined ones of bit positions in said carrier word; 5. The apparatus of claim 4, further comprising means for generating a predetermined number of individual parity check bits forming one predetermined parity check. (6) the similar bits in the predetermined bit positions in the bit group used to generate the parity check bits forming the at least second predetermined parity check are 6. The apparatus of claim 5, including said parity check bits forming a predetermined parity check. 7. The apparatus of claim 1, further comprising means for interfacing to a device for providing information to be formatted into the packet. 8. The apparatus of claim 7, wherein said means for interfacing to the apparatus includes means for interfacing with a transmission facility that supplies the information to be formatted into said packets. 9. The apparatus according to claim 1, wherein said means for interfacing said packet as an output includes means for interfacing said packet to a packet network node. 10. The apparatus of claim 1, wherein said means for interfacing said packet as an output includes means for interfacing to a packet interconnect switch. 11. The apparatus of claim 4, wherein said means for interfacing said packets as output includes means for interfacing said packets to a transmission facility for transmission to a remote location. (12) further comprising a source of a reference codeword having a predetermined number of bits, wherein the first generating means generates the first predetermined parity by calculating the parity together with a predetermined one of the reference codeword bits; computing parity check bits; said at least second generating means computing parity together with a predetermined one of said reference codeword bits;
computing said at least second predetermined parity check bits, each of said reference codeword bits being an odd number of said parity being computed to obtain a corresponding one of said parity check bits being computed; The device according to claim 1, characterized in that it defines whether the number is even. (13) A packet generating device including a carrier word, wherein the carrier word includes a predetermined number of bit position groups each including a predetermined number of bit positions, and the predetermined carrier word bit positions include a plurality of predetermined carrier word bit positions. means for generating said carrier word forming a parity check field of said carrier word and predetermined others of said carrier word bit positions forming a data field; means for generating a plurality of predetermined parity checks, wherein each of said bits from said predetermined bit position in said carrier word forms said plurality of predetermined parity checks; means for generating said plurality of predetermined parity checks, which are used to calculate said parity check bits, said calculated parity check bits within said plurality of parity check fields within said carrier word; means for inserting the calculated parity check bits, where the plurality of predetermined parity checks are used to verify the carrier word data field; A packet generator containing a carrier word containing. (14) further comprising a source of a reference code word having a predetermined number of bits, wherein said means for generating a plurality of predetermined parity checks selects a first parity check bit from a predetermined number of said reference code word bits; first means for calculating a first parity check from bits in predetermined bit positions of said carrier word with a predetermined one of said reference code word bits; and at least a second parity check bit with a predetermined one of said reference code word bits at least a second means for calculating from bits within predetermined bit positions of the carrier word to form at least a second parity check, wherein each of the reference codeword bits is calculated from bits within predetermined bit positions of the carrier word; that is, obtaining a corresponding one of said parity check bits calculated by defining an odd or even number, and said inserting means inserting said first parity check bit into a first parity check field; 14. Apparatus according to claim 13, characterized in that at least a second parity check bit is inserted into at least a second parity check field.