JP2586397B2 - Address screening circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an address screening circuit, and more particularly to a message to which a destination address and a source address, which are upper protocol data units, are divided into a plurality of segmentation units, each of which can be distinguished from other messages. A plurality of multiplexed subscriber lines of a network system that communicate as a packet, which is a plurality of lower-order protocol data units to which a header including the same message identification number and segment type information indicating a position on the message are added. And an address screening circuit that performs destination address screening on an incoming line or source address screening on an outgoing line to determine whether or not to forward the message.

[0002]

2. Description of the Related Art As a network system for segmenting an upper protocol data unit including a destination address and a source address of an entity and communicating as a plurality of lower protocol data units each having the same message identification number and segment type information added thereto, SMDS (Switched Multi-Meg)
There is a system that provides an abit data service.

[0003] The SMDS referred to here is Bell in the United States.
core (Telecommunications Research Laboratory jointly funded by Bell-affiliated local telephone companies) and standardized in technical specifications (TR-TSV-0
0077 (May, 1991) for high-speed data communication. The protocol data unit of level 3 (L3-PDU) is a destination address (DA: Destination Address).
ss) and source address (SA: Source Ad)
address), which is a message of up to about 9000 bytes, and which is a level 2 protocol data unit (L2
-PDU) is divided into 53-byte packets and transferred. The header of each packet has a field called a message identifier (MID: Message Identifier), and all packets created from one message are assigned the same message identification number. The packet containing the head of the original message is B
OM (Beginning of Message), a packet including an intermediate portion is sent to COM (Continuity)
A packet including an end of message (on of Message) and an end portion is called an EOM (End of Message).
The destination address and the source address are included in the BOM packet.

A conventional address screening circuit used in an exchange of this type of system has a destination address which has been permitted in advance on the ingress side of the subscriber line and a transmission address which has been permitted in advance on the outgoing line (Egress) side. It selectively passes (address screening) only the BOM packet having the original address and the subsequent COM packet and EOM packet, and has a database in which all destination addresses or source addresses for which connection is permitted are registered in a memory or the like. , CPU of the exchange that performs the exchange processing by software
(Central control unit) repeatedly searches the database and compares it with the destination address or the source address extracted from the received BOM packet, and if a match is obtained, determines that the destination address or the source address is a normal address. Was.

[0005]

In the above-described conventional address screening circuit, it is necessary to repeatedly search and compare the destination address or the source address by software processing by a CPU or the like. It takes time to decide whether to discard,
There is a disadvantage that the network throughput cannot be improved. If the destination address or the source address is registered as the address of the database memory as it is as to whether the connection is permitted or not, it is possible to determine whether the packet can be transferred by one memory access.
The destination address and the source address used in the DS system have a length of 64 bits and require a huge memory space. In addition, if a plurality of subscriber lines are accommodated and the destination address or the source address to which connection is permitted is different for each line, the number of lines of memory is required, and the amount of memory is further increased. Not a target.

Accordingly, an object of the present invention is to operate a destination address or a source address having a long bit length such as 64 bits by using an associative memory so that the destination address or the source address operates independently of the software of the exchange. An object of the present invention is to provide an address screening circuit capable of performing address screening at high speed without increasing the amount of memory.

[0007]

SUMMARY OF THE INVENTION The present invention divides a message to which a destination address and a source address, which are higher-order protocol data units, are added into a plurality of segmentation units, each of which is identical to each other and can be distinguished from other messages. A plurality of multiplexed subscriber lines of a network system for communicating as a packet which is a plurality of lower-order protocol data units to which a header including a message identification number and a segment type information indicating a position on the message are added. Address screening circuit that performs destination address screening on the side or source address screening on the outgoing line side and determines whether or not to forward the message; one of the destination address and the source address specified in advance. Screening An associative memory for registering each address of the elephant side in advance as data, providing comparison data, performing comparison and collation with all registered data, and outputting a registration number of the data when they match; An address screening provided in correspondence with the subscriber line, and preliminarily registering connection enable / disable information indicating whether to permit connection to each address of the screening target side at the same address as the registration number in the associative memory. A memory; a screening reference memory for temporarily storing the connection availability information read from the address screening memory in correspondence with the message identification number; and analyzing the header of the received packet and analyzing the received packet based on the segment type information. The packet is a segment at the beginning of the message Identification means for identifying a BOM packet including a unit, a COM packet including a middle segmentation unit, and an EOM packet including a tail segmentation unit; and the message from the header of the received packet. Extracting means for reading an identification number and, when the packet is the BOM packet, further reading the line number of the subscriber line from the header thereof and reading the address of the screening target from the segmenting unit; Obtaining the registration number from the associative memory using the address of the screening target from the extraction means as the collation data, and using the registration number as an address corresponding to the line number from the extraction means for the address screening. The connection availability information is obtained from the memory and the BOM packet is passed or discarded, and the connection availability information is written to the screening reference memory using the message identification number from the extraction means as an address, and the COM packet and the When an EOM packet is received, a control means is provided for searching the screening reference memory based on the message identification number from the extracting means, reading the connection availability information, and passing or discarding the COM packet and the EOM packet.

In the above-mentioned configuration, the destination address is provided between an input side of the plurality of multiplexed subscriber lines and an input port of a switch unit of the exchange, and is screened; The message identification number for each subscriber line written in the header of the packet received from each is converted into the message identification number for all subscriber lines according to the line number, and the packet after the message identification number conversion is sent to the identification means. An identification number converting means for outputting; and a port number assigning means for writing an input port number of the switch unit in a header of a packet passed through the control means.

[0009] Alternatively, provided between the output port of the switch unit of the exchange and the outgoing line side of the multiplexed subscriber lines, the source address is to be screened; the output port of the switch unit ID conversion means for converting a message identification number in units of one input port written in a header of a packet received from a device into a message identification number in units of all input ports in accordance with the input port number, and outputting a packet after the conversion of the message identification number A valid destination address is registered in advance for each subscriber line, a header of the packet from the identification number conversion means is analyzed, and in the case of the BOM packet, a registration is performed according to the destination address read from the segmenting unit. Read out the line number of the subscriber line The line number is temporarily stored in correspondence with the message identification number, and in the case of the COM packet and the EOM packet, the line number stored in accordance with the message identification number is read out and written in its header. Line number assigning means for outputting to the identification means.

[0010]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, an address screening circuit 100 according to the present embodiment includes a registration number (EN) as data, which is one of a destination address (DA) and a transmission source address (SA), which are specified in advance and which are on a screening target side. An associative storage memory 150 registered in advance in correspondence with the connection availability information (AD: connectable) for each address of the screening target side (DA / SA) having memory surfaces for the number of subscriber lines to be accommodated, respectively. "1" if not, "0" if connection is not possible)
And an address screening memory 160 which is registered in advance at the same address as the registration number in the associative memory 150;
ID) a screening reference memory 170 temporarily stored in correspondence with the packet; a packet identification unit 110 that analyzes a received packet header to identify any of a BOM packet, a COM packet, and an EOM packet; The message identification number is read from the packet, and if this packet is a BOM packet, the line number (LN) of the subscriber line and the address screening target (DA) specified in advance
/ SA) when the BOM packet is received by the packet identification unit 110; a registration number is obtained from the associative storage memory 150 using the address (DA / SA) from the extraction unit 120 as collation data; 12
The connection number is obtained from the address screening memory 160 using the registration number as an address in correspondence with the line number from 0, and the message identification number from the extraction unit 120 is written into the screening reference memory 170 as the address, and the COM packet and the EOM packet are used. At the time of reception, a control unit 130 is provided which searches the screening reference memory 170 based on the message identification number from the extraction unit 120 to read the connection availability information, and sends it to the screening unit 140 to pass or discard the packet.

FIG. 2 is a diagram showing an SMDS network system to which the address screening circuit of the present invention is applied. The subscriber interface device (SNI) 420 of the SMDS exchange (SS) 400 accommodates a plurality of customer premises equipment (CPE) 600 through a plurality of subscriber lines (incoming line 610, outgoing line 620), respectively, and a switch device. (SW) 410. Switch 400 also
It is connected to another switch 400 through an inter-switch interface device (ISSI) 500. The subscriber interface device 420 performs an address screening device (ADS) 200 that performs destination address screening of the multiplexed packet from each incoming line 610 and transfers the packet to the switch device 410, and a source address screening of the packet from the switch device 410. And each outgoing line 62
Address screening device (AD
S) 300. FIG. 3 shows a detailed configuration of the address screening device 200 on the incoming line, and FIG. 4 shows a detailed configuration of the address screening device 300 on the outgoing line.

In FIG. 3, different line numbers (# 0 to #
A plurality of incoming lines 610 to which n) is assigned are accommodated in line corresponding devices 431 that terminate at the physical level. Each line corresponding device 431 writes its own line number in the first byte (access control area) of the header of the received packet, and the line multiplexer (MUX) 430 multiplexes these packets. The address screening device 200 includes a MID conversion circuit 210 for converting the message identification number of each incoming line written in the header of the packet from the line multiplexer 430 into a message identification number of every incoming line according to the line number, and an MID conversion circuit. Circuit 21
An address screening circuit 100 of the embodiment of FIG. 1 which performs destination address screening of packets from 0;
A port number assigning circuit 220 for writing an input port number of the switch device 410 into a header of a packet passed through the address screening circuit 100; In addition,
The line number can be written in the packet header by the line multiplexer 430 instead of each line corresponding device 431, and the address screening device 200 can be configured to include the line multiplexer 430.

In FIG. 4, the address screening apparatus 300 converts a message identification number for each input port written in a header of a packet received from an output port of the switch apparatus 410 into a message identification for every input port in accordance with the input port number. MID to be converted to number
In the case of a BOM packet, a valid destination address is registered in advance for each conversion line 310 and each outgoing line 620 to which different line numbers (# 0 to #n) are assigned, and the header of the packet from the MID conversion circuit 310 is analyzed. In the case of a COM packet or an EOM packet, the line number stored in accordance with the message identification number is read out and written in the header. It comprises a line number assigning circuit 320 and the address screening circuit 100 of the embodiment of FIG. 1 for screening the source address of a packet from the line number assigning circuit 320. Line separation equipment (DE
MUX) 440 receives the packets that have passed through the address screening device 300 according to the line numbers.
41, and the line corresponding device 441 sends outgoing line 6
20 is processed at the physical level and a packet is transmitted. Note that the address screening device 300 can be configured to include the line separation device 440.

Next, the operation will be described with reference to FIG. 5 showing the structure of the packet in addition to FIGS. 1 to 4 and FIG. 6 showing the operation flow of the address screening circuit 100.

Each subscriber premises device 600 is assigned a communication address on the network system in advance, and transmits information (service data unit 8) to other subscriber premises devices in a level 3 protocol.
30), a data unit (message 800) is created by adding a header 810 including the destination address (DA) 811 of the other party and its own source address (SA) 812 and a trailer 820, and a lower level. In the second protocol, the message 800 is divided into a plurality of segmented data units 850 to 870, each having a message identification number (MID) 913 having the same number that can be distinguished from other messages, and segment type information indicating a position on the message. (ST) A plurality of packets (BOM packet 950, COM packet 960, E) to which a header 910 including 912 and a trailer 920 are added.
OM packet 970) to the exchange 400.
The value of ST 912 is “10” in binary in the case of the BOM packet 950, indicating that the value includes the header 810 of the message 800, “00” in the case of the COM packet 960, and “01” in the case of the EOM packet 970. ".

In the packet input to the exchange 400, a line number (LN) 914 corresponding to an access control area (hereinafter referred to as ACF) 911 of the header 910 is written by the line corresponding device 431, and multiplexed by the line multiplexer 430. Are input to the address screening device 200. The MID conversion circuit 210 rewrites the message identification number 913 of the header 910 so that each of the multiplexed packets belongs to which message 800, and outputs the message to the address screening circuit 100.

In the address screening circuit 100 on the incoming line 610 side, all the communication addresses of the transmission destinations which are packet destination addresses are registered in the associative memory 150 in advance. Connection availability information for each destination address is registered for each memory surface corresponding to each incoming line 610, and the extraction unit 120 is specified to extract the destination address 811 from the BOM packet 950.

When the packet identification unit 110 receives a packet, it determines whether the packet is a BOM packet 950 or a COM packet 9.
60 or the EOM packet 970, and notifies the extraction unit 120 and the control unit 130 (step S10 in FIG. 6).
In the case of the BOM packet 950, the extraction unit 120 reads the line number (for example, #i), the destination address (for example, #x), and the message identification number (for example, #a), and reads the control unit 13
Send to 0. The control unit 130 sends the destination address #x to the associative memory 150 as collation data (step S1).
1). The associative memory 150 checks at a high speed whether this data is registered (step S12), and if it is registered, returns the registration number (for example, #m) to the control unit 130. The control unit 130 sends the line number #i and the registration number #m to the address screening memory 160 to read the corresponding connection availability information (step S13), and uses the connection availability information as the address of the message identification number #a as the screening reference memory. The data is written into the data 170 and sent to the screening unit 140 (step S14). The screening unit 140 determines the value of the connection availability information (step S15). If “1”, the connection is permitted and the packet is passed (step S16). If “0”, the connection is disabled and the packet is discarded (step S16). S30). If the destination address #x is not registered in the associative storage memory 150 (NO in step S12), the control unit 130 performs the same processing as above with the connection disabled, that is, the connection availability information set to “0”. Screening section 140 discards the BOM packet (step S30). On the other hand, if the received packet is a COM packet 960 or E
In the case of the OM packet 970 (NO in step S10)
Side), the extraction unit 120 reads only the message identification number and sends it to the control unit 130. At this time, if this packet belongs to the same message 800 as the previous BOM packet 950, the message identification number has the same value #a. The control unit 130 reads out the corresponding connection availability information from the screening reference memory 170 using the message identification number #a as an address and sends it to the screening unit 140 (step S20). Screening unit 140 is BO
As in the case of the M packet, the value of the connection propriety information is determined (step S15). If "1", the connection is permitted and this packet is passed (step S16). Discard (Step S3
0). In the case of the EOM packet (step S17), the control unit 130 determines whether the screening reference memory 17
The address #a of 0 is cleared (step S18) to prepare for reception of a packet belonging to the next message that may be given the same message identification number #a.

The packet passing through the address screening circuit 100 is sent to the port 91 by a port number assigning circuit 220.
0 is assigned to the input port number of the ACF 911 and input to the switch device 410. The address screening device on the outgoing line 620 side of the subscriber interface device 420 accommodating the subscriber premises device 600 according to the destination address by the processing of the exchange 400. Output to 300.

The address screening apparatus 300 has
The message identification number 91 of the header 910 is used to identify which message 800 each packet received by the ID conversion circuit 310 belongs to over all input ports.
3 in the ACF 911 according to the destination address 811 in the line number assignment circuit 320.
And input it to the address screening circuit 100.

In the address screening circuit 100 on the outgoing line 620 side, all the communication addresses of the receiving destinations, which are the source addresses of the packets, are registered in the associative memory 150 in advance. Is registered with the connection availability information for each source address for each memory surface corresponding to each of the outgoing lines 620, and the extraction unit 120 stores the BOM packet 95
It is specified to extract the source address 812 from 0. The operation of the address screening circuit 100 on the outgoing line 620 is the same as the operation of the address screening circuit 100 on the incoming line 610, except that the destination address is replaced with the source address.

The packet passing through the address screening device 300 is separated by the line separating device 440 corresponding to each line corresponding device 441, and the designated subscriber premises device 60 is designated.
Output to 0. Each subscriber premises device 600 transmits a series of BOM packets 9 having the same message identification number 913.
50, COM packet 960 and EOM packet 970
Into one message 800. As described above, the message communication between the subscriber premises devices 600 to which the connection is permitted is completed.

[0024]

As described above, the address screening circuit of the present invention comprises an associative storage memory in which a screening target address of a destination or a transmission source is registered and an associative storage memory in which connection availability information for the screening target address is registered for each subscriber line. Address screening memory registered at the same address as the registration number, a screening reference memory for temporarily storing connection availability information corresponding to the message identification number, identification means for identifying the type of the received packet, and message identification from the received packet. Extracting means for reading the number, line number and screening target address, and connection availability information from the address screening memory based on the registration number and line number of the associative memory obtained by the screening target address when the BOM packet is received. Written into the memory for screening in conjunction with the disposal or passing OM packet, C
Control means for passing or discarding the packet based on the connection availability information read from the screening reference memory based on the extracted message identification number when the OM packet and the EOM packet are received, wherein the destination address or the source address to be screened is For example, 64
Even in the case of having a long bit length of bits, the content is compressed using the associative memory and the screening result obtained at the time of BOM reception is stored until the EOM reception, so that the capacity of the address screening memory for registering the connection availability information is increased. Address screening can be performed at a high speed independently of the software of the exchange.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an SMDS network system to which the address screening circuit of the present invention is applied.

FIG. 3 is a block diagram showing a detailed configuration of an address screening device on the incoming line side in FIG. 2;

FIG. 4 is a block diagram showing a detailed configuration of an outgoing line side address screening apparatus of FIG. 2;

FIG. 5 is a diagram showing a configuration of a packet.

FIG. 6 is a diagram showing an operation flow of the address screening circuit of FIG. 1;

[Explanation of symbols]

Reference Signs List 100 address screening circuit 110 packet identification unit 120 extraction unit 130 control unit 140 screening unit 150 associative memory 160 address screening memory 170 screening reference memory 200, 300 address screening device (AD
S) 210, 310 MID conversion circuit 220 Port number assignment circuit 320 Line number assignment circuit 400 SMDS exchange (SS) 410 Switching device (SW) 420 Subscriber interface device (SNI) 600 Customer premises equipment (CPE) 610 Incoming line 620 outgoing line

Claims (3)

(57) [Claims] 1. A message to which a destination address and a source address which are upper protocol data units are added is divided into a plurality of segmentation units, and the same message identification number and the position on the message, each of which can be distinguished from other messages. Accommodates a plurality of multiplexed subscriber lines of a network system that communicates as packets, which are a plurality of lower-order protocol data units to which a header including segment type information indicating is added, and a destination address screening at an incoming line side, or An address screening circuit that performs a source address screening on an outgoing line to determine whether or not to forward the message, wherein each of the destination address and the source address is a predetermined address of a screening target. The Associative storage memory that registers in advance as a data, performs comparison and collation with all registered data when given collation data, and outputs a registration number of the data when they match, and is provided for the subscriber line. An address screening memory in which connection enable / disable information indicating whether connection to each of the addresses to be screened is permitted or not is registered in advance at the same address as the registration number in the associative memory; A screening reference memory for temporarily storing the connection availability information read from the memory corresponding to the message identification number; and analyzing the header of the received packet, and based on the segment type information, this packet is used as a leading part of the message. BOM containing a segmentation unit of Packet, COM packet with middle segmentation unit, and EO with tail segmentation unit
Identification means for identifying any one of the M packets; reading the message identification number from the header of the received packet;
In the case of an M packet, furthermore, an extracting means for reading the line number of the subscriber line from the header thereof and reading the address of the screening target from the segmenting unit, and, upon receiving the BOM packet, the screening target from the extracting means. The BOM packet is obtained by obtaining the registration number from the associative memory as the collation data, obtaining the connection availability information from the address screening memory using the registration number as an address corresponding to the line number from the extracting means. Is passed or discarded, and the connection availability information is written into the screening reference memory using the message identification number from the extracting means as an address, and the message from the extracting means is received when the COM packet and the EOM packet are received. Control means for retrieving said connection availability information by searching said screening reference memory using a message identification number and passing or discarding said COM packet and EOM packet. 2. A method according to claim 1, wherein the destination address is a screening target provided between an input line of the plurality of multiplexed subscriber lines and an input port of a switch unit of the exchange, and received from each of the subscriber lines. The message identification number for each subscriber line written in the header of the converted packet is converted into the message identification number for all subscriber lines according to the line number, and the packet after the message identification number conversion is output to the identification means. 2. The address screening circuit according to claim 1, further comprising: a number conversion unit; and a port number assignment unit that writes an input port number of the switch unit into a header of a packet that has passed through the control unit. 3. A switching device provided between an output port of a switch unit of an exchange and an outgoing line side of the multiplexed plurality of subscriber lines. Identification number conversion means for converting a message identification number for each input port written in a header of a received packet into a message identification number for all input ports in accordance with the input port number, and outputting a packet after the message identification number conversion; A valid destination address is registered in advance for each subscriber line, a header of a packet from the identification number conversion means is analyzed, and in the case of the BOM packet, a registration is performed according to the destination address read from the segmenting unit. Read the line number of the subscriber line, write it in its header, and Over di identification number corresponding to temporarily store the line number, the COM packet and the EO
A line number assigning means for reading a line number stored according to the message identification number in the case of an M packet, writing the line number in a header thereof, and outputting the packet after writing the line number to the identification means. 2. The address screening circuit according to claim 1.