JPH09205455A - Inter-lan connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize a memory effectively by making bridge connection of one or plural conventional LANs to an ELAN in the MAC layer to store multiplexed information of plural LAN groups or the like to one queue. SOLUTION: Upon the receipt of a packet stored temporarily to be sent to an ELAN, an inter-LAN connector has a queue 1 that stores temporarily the packet regardless of difference from destination MAC addresses denoted by the information of the packet and has a comparison means 2 that compares MAC addresses stored in the queue 1 one by one with a destination MAC address when packets relating to the destination MAC address are sent among packets stored temporarily. As the result, packets whose MAC addresses are coincident are sent by a relay means 3. The relay means 3 is connected to the ELAN through a port Pe and to conventional LANs through ports Pr(s), and has a filtering database, in which MAC addresses and their ports are stored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asynchro
LAN (Emulat Transfer Mode) simulated on the network
ed LAN; referred to as "ELAN") as one connection destination, and I
A conventional LAN such as EEE 802 is used as another connection destination,
In a MAC (Media Access Control) layer, a LAN-to-LAN connecting device (LAN) that bridges between these LANs
EmulationClient; "LEC").

[0002]

2. Description of the Related Art Each element for executing a LAN emulation service connecting an access function of a conventional LAN on an ATM network to another MAC on the ATM network is shown in FIG.
It is shown in FIG. LEC ₁ and LEC ₂ indicate the bridges connected to the ATM network and related to the LAN emulation service, and T ₁ and T ₂ indicate the terminals connected to the conventional LAN under the bridges.

Hereinafter, it is assumed that the terminal T ₁ transmits to the terminal T ₂ . When LEC ₁ receives a packet from the conventional LAN, LEC ₁ receives its own filtering database FD.
It searches for B (IEEE802.1d) and tries to know the relay destination corresponding to the destination MAC address (T ₂ ). However, when the packet is not registered in the filtering database FDB, the packet is held in the queue (which is a first-in first-out buffer) and the LES
AT to (LAN Emulation Server) from MAC address
Request to inquire M address LE-ARP (LE
Send Address Resolution Protocol). When the ATM address is obtained from the response from LES, LEC ₁
Leads to LEC ₂ Data Direct VCC (VCC; Vir
tual Channel Connection). And LEC
₁ transmits a packet addressed to the terminal T ₂ temporarily held in the queue to the established data direct VCC,
The relationship between ₂ and the data direct VCC is registered in the filtering database FDB. In this specification, a procedure of holding a packet and transmitting it until a data direct VCC is established by using this LE-ARP is referred to as "A-procedure".

If the destination MAC address is not registered in the filtering database FDB, the packet is not held in the queue immediately and BUS (Broadcast / Unknow)
n Server). Even in this case, L
It sends a request LE-ARP to the ES and tries to establish a data direct VCC. When the data direct VCC is established, the subsequent packet is transmitted using the data direct VCC. However, when the data direct VCC is established, in order to prevent the packet via the data direct VCC from overtaking the packet via the BUS, the packet addressed to the terminal T ₁ is temporarily held in the queue and the packet via the BUS arrives. Is confirmed by the flash protocol. After that, the packet addressed to the terminal T ₁ temporarily held in the queue is transmitted to the data direct VCC. Subsequent packets addressed to the terminal T ₁ are immediately transmitted to the data direct VCC. In this specification, the procedure for transmitting the packet whose destination is unknown to the BUS is referred to as "B-
Procedure ”.

The above items are "LAN Emulation on an ATM".
Network ”IEEE Communications Magazine, pp.70-85 M
It is described in detail in ay 1995.

[0006]

[Problems to be Solved by the Invention]
It shows a method and interface specifications for realizing interconnection between different models on the ATM network, and does not refer to the data storage structure in the LEC. A-
According to the procedure, the LEC needs to hold the received packet with the destination unknown until the data direct VCC is established. It is conventional to queue the packets to be held in order to proceed with the relaying of subsequent packets. In this case, since the address is searched in MAC units, it is necessary to configure a queue for each MAC.

Also in the B-procedure, the LEC needs to hold the received packet of the same MAC address before issuing the flush protocol and obtaining a response. Also in this case, it is necessary to configure a queue for each MAC. L
The round-trip time from requesting E-ARP or flash protocol to getting a response, and the time required to establish a connection have a guideline. Since the communication speed of the actual LAN is also fixed, the upper limit maxpn of the number of packets that can be received within the queuing time can be predicted to some extent. But,
It is unpredictable whether all of the packets will have the same or different destinations.

If software processing is performed on an OS that supports virtual memory, a storage area may be secured as necessary, but if a system in which queues are fixed is provided, the maximum case is set in anticipation of the worst case. You have to reserve a limited queue capacity. Therefore, there is a problem that the use efficiency of the memory deteriorates. Therefore, the present invention
LAN simulated on M network and one or more conventional L
It is an object of the present invention to realize an inter-LAN connection device capable of executing a LAN emulation service with a minimum memory capacity in an inter-LAN connection device configured to bridge-connect with an AN in a MAC layer.

[0009]

[Means for Solving the Problems]

(1) The LAN-to-LAN connecting device of the present invention stores information indicating a packet to be transmitted through a simulated LAN and information indicating a destination MAC address of the packet in common temporarily regardless of the difference of the destination MAC addresses. Type storage means and a destination MAC address to be transmitted when a packet relating to one destination MAC address is transmitted through the data direct VCC established on the simulated LAN, and the storage means stored in the storage means. It has a comparison means for comparing the destination MAC address and a relay means for transmitting a packet having a matching MAC address as a result of the comparison by the comparison means (claim 1).

According to the LAN-to-LAN connecting device of the first aspect, information is stored in the first-in first-out type (hereinafter referred to as "queue") regardless of the difference in destination MAC address.
When temporarily transmitting and storing the same, the information corresponding to the destination MAC address to be transmitted is searched. Therefore, since information corresponding to a plurality of MAC addresses can be multiplexed and stored in one queue, the memory can be effectively used.

FIG. 1 is a conceptual diagram of an inter-LAN connecting device of the present invention. A LAN (ELAN) simulated on an ATM network and a plurality of conventional LANs are connected to the inter-LAN connecting device. ing. When the LAN-to-LAN connecting device receives a packet to be temporarily held when transmitting to the ELAN, the information indicating the packet and the destination M of the packet are received.
A queue 1 that temporarily stores information indicating an AC address in common regardless of whether the destination MAC address is the same, and a destination to be transmitted when a packet related to one destination MAC address is transmitted from the temporarily held packets. MA
C address and destination MAC stored in the queue 1
It has a comparison means 2 for comparing the addresses one by one and a relay means 3 for transmitting a packet having a matching MAC address as a result of the comparison by the comparison means 2.

The relay means 3 is connected to the ELA through the port pe.
It is connected to N and is connected to at least one conventional LAN (such as Ethernet) through the port pr. The relay unit 3 has a filtering database FDB defined by IEEE802.1d. The filtering database FDB holds the MAC address and the port to which it is connected. But,
When the port is pe, it is different from the normal filtering database FDB in that it also holds a value DVCI that indicates a specific direct connection, and that learning by a packet received from the port pe is basically not performed.

As shown in FIG. 2, the queue 1 is of a first-in first-out type, in which the oldest stored area is indicated by a read pointer, and the area to be stored next is indicated by a write pointer. The queue 1 constitutes a ring buffer in which the start address is continuous after the end address. Queue 1
Is a packet area for storing information indicating a packet to be transmitted to the ELAN, for example, a pointer PDI indicating an area storing the packet, and information indicating a destination MAC address, for example, a pointer MA indicating an area storing the MAC address.
It is separated from the MAC area that stores C.

As shown in FIG. 1, the queue 1 is connected to the relay means 3 and is read and written by the relay means 3.
The destination MAC address output from queue 1 is
It is also supplied to the comparison means 2. The comparing means 2 compares the destination MAC addresses to be transmitted with the destination MAC addresses stored in the queue 1 one by one, and when they match, sends a match signal to the relay means 3.

The procedure for executing the A-procedure will be described below. The relay unit 3 sends the packet to be transmitted to the port pr.
Filtering database FDB if received from
To determine the relay destination. Here, if the destination MAC address is not registered in the filtering database FDB, the data direct VCC connected to the destination MAC address cannot be set, and therefore the relay unit 3 transmits LE-ARP to the LES and The packet and the destination MAC _a are sent to the queue 1 and stored therein, and the relay operation thereafter is continued.

The relay means 3 is a MAC_aLE-A for
Receives RP response and sends data direct VCC_aEstablished
After the MAC_aIs registered in the comparison means 2. Comparison means 2
Checks the entries (stored contents) of queue 1 in order and stores
The retrieved MAC is the MAC to be searched._aMatches
If the packet is a data direct VCC _a
Send to Finish checking all entries in queue 1
And the relevant MAC_a, Port pe and data direct VC
C_aIs registered in the filtering database FDB.
Here, register in the filtering database FDB
The destination is MAC_aPacket to queue 1
Process exclusively so that it is not left behind. After that, the destination
MAC_aPacket is a data direct VCC
_aSent directly to.

Here, a method (referred to as dequeue process) of sequentially checking the entries of the queue 1 will be described. As shown in Fig. 2 (a), the MAC area that stores the MAC address is
MAC address MAC _a , MAC _b , MAC _c , ..., M
It is assumed that AC _a and MAC _e are stored. MAC
_If it is desired to transmit the packet of _a , the comparison means 2 starts scanning from the read pointer. The entry being scanned at that time is indicated by the scan pointer, and the location where the entry is refilled is indicated by the relocate pointer. Initially, both the scan pointer and the relocate pointer show the same location as the read pointer. First, since MAC _a hits, it is transmitted. Next, the read pointer, the scan pointer, and the relocate pointer are moved down by one step to check whether the destination MAC addresses match. Since the MAC _b does not match, the read pointer is not updated (same in subsequent scans). Move the scan pointer and relocate pointer one step further down. Thus, 1
Step by step, when MAC _a hits, it is sent, the relocate pointer is left in its place, and only the scan pointer is shifted downward. If the entry is not sent at the position indicated by the scan pointer,
The entries are refilled to the position where the relocate pointer is located, and the scan pointer and the relocate pointer are shifted again by one. When the entry is transmitted at the position indicated by the scan pointer, the relocate pointer remains and only the scan pointer is shifted. When the scan pointer reaches the write pointer in this way, the scan is ended and the write pointer is returned to the position designated by the relocate pointer (see FIG. 2 (b)).

However, the method of sequentially checking the entries of the queue 1 is not limited to the above. For example, MAC
Does not refill the entry even if is hit and is transmitted, a flag indicating data empty "0" is set. The next time data is scanned, the flag indicating "0" is skipped. When the number of "0" s increases and the memory becomes full, the data may be refilled. According to this method, as compared with the case where the entries are refilled for almost every scan as described above, the time for refilling can be gathered together, so that the time is saved as a whole.

Next, the procedure for executing the B-procedure will be described later. The relay unit 3 sends the packet to be transmitted to the port p.
Filtering database FD when received from r
B is searched to determine the relay destination. Here, if the destination MAC address is not registered in the filtering database FDB, the LE-ARP is transmitted to the LES, the packet is transmitted to the BUS, and the relay operation thereafter is continued.

The relay unit 3 receives the LE-ARP response from the LES, after establishing the data direct VCC _a is adapted to transmit on the basis of the MAC address flush protocol BUS for the response, the MAC address subsequent destination The packet pointer to be the destination MAC
_It is stored in the queue 1 together with the pointer of a. When the relay unit 3 receives the flush response, the MA for the response is received.
The C address is registered in the comparison means 2. After that, the queue 1 entry that is being held is sequentially checked to perform the same dequeue process as that described above. (2) Further, the inter-LAN connecting device of the present invention is configured such that a plurality of conventional LANs and a plurality of simulated LANs are vertically grouped and packets to be transmitted through any one of the simulated LANs. First-in first-out storage means for temporarily storing the information indicating the destination MAC address of the packet and the information indicating the corresponding group identifier regardless of the difference of the destination MAC address or the difference of the group identifier, and one destination MAC address. And a packet related to the group identifier is transmitted through the data direct VCC established on the simulated LAN,
A comparison unit that compares the destination MAC address and the group identifier to be transmitted with the destination MAC address and the group identifier stored in the storage unit, and a packet in which the MAC address and the group identifier match as a result of the comparison by the comparison unit. It has a relay means for transmitting (Claim 2).

A LAN-to-LAN connecting device according to claim 2 is
The difference from the LAN connection device according to claim 1 is that
There are a plurality of conventional LANs connected to the LEC and a plurality of simulated LANs, which are grouped vertically and stored in common regardless of whether the destination MAC address is the same or the group identifier is the same 1 That is, there are two cues. Therefore, since information corresponding to a plurality of MAC addresses and a plurality of group identifiers can be multiplexed and stored in one queue,
The memory can be used effectively.

FIG. 3 shows an LA in which a plurality of ELANs and a plurality of conventional LANs are bridge-connected at the MAC layer.
It is a figure which shows the connection device between N concretely. In this way, LAs that are divided into multiple LAN groups and belong to the same group
The bridge connection only between N is significant in that security is improved and unnecessary traffic is blocked.

In this case, a plurality of logical bridges are realized by one LAN connecting device. Unlike the single LAN-compatible configuration (claim 1) described above, the port pr connected to the conventional LAN is associated with any logical bridge, and the filtering database FDB is also associated with each logical bridge. It is divided into The logical bridge is either EL through port pe
Connected individually to AN, each ELAN has LES, BU
S exists individually.

As a queue storage item, as shown in FIG. 4, a bridge identifier (group identifier) BD.
I is added, and the comparison unit 2 determines whether the destination MAC address is different or the group identifier is different. The procedure for executing the A-procedure will be described below. When receiving the packet from the port pr, the relay unit 3 specifies the bridge to which the port pr belongs. Now, let the identifier of the identified bridge be BDI ₁ .

The relay means 3 checks whether or not the destination MAC address is registered in the filtering database FDB of the identifier BDI ₁ , and when it is not registered, the LE-ARP is transmitted to the LES and the packet thereof is sent. Of the destination MAC address, the pointer indicating the destination MAC address, and BDI ₁ are stored in the queue 1, and the subsequent relay operation is continued.

The relay means 3 receives the LE-ARP response.
(Corresponding block depends on which LES
Can be identified. The bridge identifier is B
DI ₁And ), Data Direct VCC_aEstablished
After that, the identifier BDI₁And MAC_aComparing means 2
Register with. The comparison means 2 sequentially enters the entries of the queue 1.
Checked and stored MAC and BDI are registered
MAC_aAnd BDI₁Whether or not it matches the above
Check by queue processing.

If they match, the packet is transmitted to the data direct VCC _a . When all the entries in the queue 1 have been checked, the MAC _a , the port pe, and the data direct VCC _a are registered in the filtering database FDB corresponding to BDI ₁ and the dequeue process ends. Here, exclusive processing is performed so that packets of MAC _a and BDI ₁ are not left in the queue 1 before being registered in the filtering database FDB. After that, the packet of BDI ₁ having the destination as MAC _a is directly transmitted to the data direct VCC _a .

Although the above is the procedure for executing the A-procedure, the description thereof will be omitted because it can be easily inferred when the B-procedure using BUS is executed. (3) Further, the inter-LAN connection device of the present invention is an LE that performs connection management of the ATM network and interpretation of the protocol, and requests dequeuing processing to the forwarding means.
The destination MAC of the service means and the packet to be transmitted to the simulated LAN and the destination MAC address of the packet
First-in first-out storage means commonly stored regardless of different addresses, destination MAC address to be transmitted through a data direct VCC established on a simulated LAN, and destination MAC stored in said storage means
When a packet is received from a simulated LAN or a conventional LAN, the forwarding means comprises a comparing means for comparing with an address and a forwarding means, judges a relay destination from the destination MAC address of the packet, and performs the simulation. A packet that should be relayed to a LAN but must be temporarily held is stored in the first-in first-out storage means, and when a request for dequeue processing is received from the LE service means, the storage means is opened and an attempt is made to transmit. The destination MAC address to be compared with the destination MAC address stored in the storage means by the comparison means,
As a result of the comparison, the packet corresponding to the destination MAC address is transmitted to the simulated LAN (claim 3).

According to a third aspect of the present invention, the relay means 3 of the inter-LAN connecting device according to the first or second aspect of the invention is provided with an L function for each function.
It is divided into E service means and forwarding means. The LE service means performs processing of protocols such as LE-ARP and establishment / disconnection of ATM connection E
Responsible for LAN-specific processing. Since these processes are complicated, it is appropriate to implement them by software by the CPU.

On the other hand, the forwarding means shares simple processing such as relay destination determination, packet transmission, queue management, and update, but requires high speed, so it is optimal to implement it by hard-wired logic. . FIG.
FIG. 4 is a diagram showing a specific configuration of an inter-LAN connecting device, which has an LE service means 3b, a forwarding means 3a, a queue 1, and a comparing means 2.

A conventional LAN or ATM network is connected to the forwarding means 3a, and an EL is connected to the ATM network.
AN is configured. The forwarding means 3a
Has a filtering database FDB, ATM
It has a judging means for judging whether it is an ELAN packet or a packet other than the ELAN depending on the connection received from the network. However, this determination means may be realized as a table (VC table) indexed by the connection identifier on the memory shared by the forwarding means 3a and the LE service means 3b.

The packet on the ELAN has a LE header for identifying whether it is a data packet to be relayed or a control packet (eg LE-ARP, flash protocol) for operating the ELAN. When the forwarding means 3a receives a packet from the ELAN, the forwarding means 3a includes an identification means for identifying a data packet or a control packet by the LE header, and a transfer means for transferring the received control packet or non-LAN packet to the LE service means 3b. Have

The structures of the queue 1 and the comparison means 2 are the same as those already described. The queue 1 can be read and written by the forwarding means 3a, and the LE service means 3
At least you can read from b. The read pointer and the write pointer of the queue 1 are included in the forwarding means 3a, but can be referenced from the LE service means 3b. The comparison means 2 notifies the forwarding means 3a of the result of the comparison determination.

The LE service means 3b has an interface for requesting processing to the forwarding means 3a. This process, MAC, BDI, the aforementioned dequeuing specifying the data direct VCC _a to the destination, repacking process queue 1, packet and ELAN for connection management LE service means 3b created
The process of transmitting the control packet to the ATM network is included.

The procedure for executing the A-procedure will be described below. When the forwarding means 3a receives the packet from the port pr, the filtering database F
The DB is searched to determine the relay destination. Here, if the destination MAC address is not registered in the filtering database FDB, the data direct VCC connected to the destination MAC cannot be established, so the forwarding means 3a puts the packet and the MAC in the queue 1 and continues the relay. To do.

When the LE service means 3b polls the queue 1 or knows the non-empty state of the queue 1 by an interrupt from the forwarding means 3a, the stored contents of the queue 1 are read out and a corresponding LE-ARP packet is created, Send to the LES via the interface to the forwarding means 3a. When the forwarding means 3a receives the LE-ARP response from the LES, it knows that it is a control packet depending on the type of connection, and delivers it to the LE service means 3b. After that, the relay is continued.

[0037] LE service means 3b receives the LE-ARP reply, to establish a data direct VCC _a. The ATM connection used for this is VC
Describe in the table that it is a non-ELAN connection. Thereby, the packet for the establishment of data direct VCC _a is, ATM network and LE service means 3
It is possible to exchange with b through forwarding means 3a. After the data direct VCC is established, the LE service means 3b requests the forwarding means 3a for the above-described dequeue process by designating MAC _a and VCC _a for the response.

The forwarding means 3a uses the MAC
_a is registered in the comparing means 2, and the comparing means 2 sequentially checks the entries of the queue 1, checks whether or not the stored MAC matches the registered MAC _a, and when they match,
The matched packet is sent to the data direct VCC _a . The forwarding means 3a registers the MAC _a , the port pr and the data direct VCC _a in the filtering database FDB. After that, the destination is MAC _a
Packet is transmitted directly to the data direct VCC _a .

Although the above is the procedure for executing the A-procedure, the description thereof will be omitted because it can be easily analogized when the B-procedure using BUS is executed.

[0040]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 6 is a diagram showing the hardware configuration of the LAN-to-LAN connecting device of the present invention. The LAN-to-LAN connecting device is an ATM receiving controller 11 for receiving cells from an ATM network and reassembling into packets. Segmentation and AT
ATM transmission controller 12 for transmitting cells to the M network,
Twelve ports RP1-RP1 connecting to Ethernet
2, an Ethernet controller 13 that sends and receives packets to and from each Ethernet, a control memory 14 that holds packet sending and receiving management information and interface information between modules, a data memory 15 that holds the packet body, and a LAN group for each MAC address and FD
A forward controller 16 that controls a CAM (content addressable memory) that correlates the offset FDB OFS of B, and relays a packet within the same LAN group that includes an ELAN simulated on an ATM network;
The CPU 17 manages the TM connection, interprets a protocol unique to the ELAN, and manages and operates the ELAN.

FIG. 7 shows the configuration of the control memory 14.
It is a figure showing the data structure which interfaces between each controller and CPU17. With the forward controller 16 as the center, an ATM transmission queue 12a for requesting transmission to the ATM transmission controller 12, an ATM transmission completion queue 12b for notifying the completion of transmission in the opposite direction, an ATM reception queue 11a for which reception is notified from the ATM reception controller 11, ATM free queue 11b that pools buffers that can be used for reverse reception, E transmission queue 13a that requests transmission with the Ethernet controller 13,
E transmission completion queue 13b that notifies the completion of transmission, E free queue 13c that pools a buffer that can be used for reception,
E The reception queue 13d for notifying the reception and the CPU 17 are requested to be transmitted from the SC queue 17a and the SC queue 17a for notifying the transmission request to ATM or Ethernet and the release request of the received packet delivered to the SR queue 17b. SR queue 17 for delivering packet transmission completion notifications and receiving packets other than ELAN data packets
b, an AR queue 17c for requesting address resolution and holding an address resolution waiting packet, an FR queue 17e for requesting connection flushing, a CW queue 17d for holding a flush waiting packet,
CR queue 1 requesting the establishment of a direct connection
7f is connected.

AR queue 17c, CW queue 17d, F
The entries of each queue except the R queue 17e and CR queue 17f are basically identifiers for identifying packets PDI
However, the status or instruction code that should be originally described in the descriptor may be included in the entry. The attributes of the packet are ATM reception descriptor 11c, ATM transmission descriptor 12c, and E transmission / reception descriptor 13.
e, described in the CPU communication descriptor 17g. AT
The M connection interfaces with the ATM transmission controller 12 and the ATM reception controller 11 by the identifier VCI. The contents of the ATM transmission descriptor 12c include VCI, packet length, pointer to data memory 15, transmission completion status, etc., and the contents of ATM reception descriptor 11c include VCI, packet length, pointer to data memory 15, reception status, etc. . The contents of the E transmission / reception descriptor 13e include a transmission port number, a reception port number, a packet length, a pointer to the data memory 15, a transmission / reception completion status, and the like. The CPU communication descriptor 17g sends a transmission request, a release request, a transmission completion,
Type to distinguish delivery, packet length, data memory 1
Includes a pointer to 5, and also includes the VCI or transmission port number at the time of transmission request, the status of transmission completion and delivery.

8 and 9 show the AR queue 17 respectively.
c, showing the contents of the entry of the CW queue 17d, and FIG.
Indicates the contents of the entries of the FR queue 17e and the CR queue 17f. 10, 11, and 12 are ATMs, respectively.
The contents of entries in the table 17h, the VC table 17i, and the FDB are shown. MA between LANs that belong to the same group
Since it is the bridge that connects at the C layer, it can be considered that there is a logical bridge for each group.
If the identifier of this bridge is BDI, VC table 1
7i and FDB are configured for each BDI. Further, each bridge is connected to one ELAN.

The entry of the AR queue 17c is a valid flag
V, BDI, PDI and destination MAC address DA, CW
Queue 17d contains valid flags V, BDI, PDI and FDB offset FDB OFS. The entries of the FR queue 17e and CR queue 17f are the same, and BDI and FDB OF
S, the time when queued is TIME. The ATM table 17h is indexed by VCI and has a flag V indicating the validity of the entry, a flag T indicating that the connection carries a packet to be relayed at the MAC layer (in the case of negative, indicating delivery to the CPU 17), It consists of flags D and BDI that represent direct connection, ATM address index AAI, and reception time RX TIME. The VC table 17i is indexed by AAI for each BDI, and comprises flags V, VCI indicating the validity of the entry, and the transmission time TX TIME. FDB is indexed by FDBOFS for each BDI, flag S indicating a static entry (if not, it indicates a dynamic entry), flag E indicating that it is an entry on the ELAN side (Ethernet port if negative), pending flag Q , E-support number P or AAI, and age value AGE.

In addition to these, as an interface between modules, an interrupt for notifying a put or full state or an empty state to a queue, starting a process such as dequeuing of a queue from the CPU 17 to the forward controller 16 and setting parameters therefor, It has a register interface for knowing the result of processing. The CAM
If a MAC address is given to, a match flag indicating that there is an entry with the same MAC address, the entry number if there is a match, the entry number that is empty if there is no match, or that all entries are in use Returns the full flag that represents it. Note that the entry number is F
FDB OFS is the product of the DB entry size.

The forward controller 16 uses the Ethernet port number as an index to obtain the BDI.
BDI register file, port map to get the Ethernet port to which it belongs, using BDI as an index, LE
LEC register file to get CID, get VCI to BUS
The MPVCI register file has a control LECID comparator (determines all 1's of the first 8 bits of LECID) for determining a control packet based on the LECID of the packet received from the ELAN.

The start address, end address, read pointer, and write pointer of the queue are those related to the ATM free queue 11b and the ATM receive queue 11a.
a, ATM transmission completion queue 12b related to ATM
The transmission controller 12 uses the Ethernet controller 13 for the items related to the E transmission queue 13a, the E transmission completion queue 13b, the E free queue 13c, and the E reception queue 13d.
However, for the SC queue 17a, the SR queue 17b, the AR queue 17c, the CW queue 17d, the FR queue 17e, and the CR queue 17f, the forward controller 16
And the other module that has an interface to the queue can read and write their values. After writing / reading an entry, the write pointer / read pointer is incremented by the number of entries. If the read / write pointer becomes equal to the end address, it returns to the start address instead of incrementing it. When the read pointer and the write pointer are equal, the queue is empty, and when the write pointer is updated and becomes equal to the read pointer, it can be regarded as full.

The forward controller 16 has a dequeue start address, a dequeue end address, a dequeue pointer, and a dequeue end pointer for copying the values of the start address, end address, read pointer, and write pointer of the AR queue 17c or CW queue 17d, respectively. It has a dequeue end comparator that determines whether the dequeue pointer and the dequeue end pointer match. The dequeue pointer also returns to the dequeue start address when it matches the dequeue end address. In the initial state, the queues other than the free queue are empty, and the free queue stores the identifier of the buffer that stores the packet. When a packet enters the buffer, the buffer identifier also serves as the packet identifier. In the ATM table 17h,
Set the entry corresponding to the VCI from BUS. At this time, V = 1 and T = 1. AAI and RX TIME are meaningless. Also, register V = 1 and T = 0 for VCI from LES and VCI used for connection management. VC
Table 17i invalidates all entries. CA
Only static entries for bridge operation are registered in M and FDB.

Next, packet transmission and reception operations will be described. (ATM reception) The ATM reception controller 11 stores the received packet in the buffer obtained from the ATM free queue 11b (the data body is the data memory 15, the reception VCI,
The packet length and the pointer to the data memory 15 are described in the ATM reception descriptor 11c) and the forward controller 16 is notified through the ATM reception queue 11a. (Ethernet reception) The Ethernet controller 13 stores the received packet in the buffer obtained from the E free queue 13c (the data body is the data memory 15, the reception port number, the packet length, and the pointer to the data memory 15 is stored in the E transmission / reception descriptor 13e). (Described), and notifies the forward controller 16 through the E reception queue 13d. (ATM transmission) The forward controller 16 requests the ATM transmission controller 12 for transmission through the ATM transmission queue 12a. The VCI, packet length, and pointer to the data memory 15 are described in the ATM transmission descriptor 12c. After transmitting the packet, the ATM transmission controller 12 changes the status to the ATM transmission descriptor 12
It is described in c and returned to the forward controller 16 through the ATM transmission completion queue 12b. The returned packet is finally released (described later). (Ethernet transmission) Forward controller 16 is E
Ethernet controller 1 through transmission queue 13a
Send to 3 The port number, packet length, and pointer to the data memory 15 are E transmission / reception descriptor 13e.
It is described in. After transmitting the packet, the Ethernet controller 13 describes the status in the E transmission / reception descriptor 13e and returns it to the forward controller 16 through the E transmission completion queue 13b. The returned packet is finally released. (Release) The origin of the packet is checked, and A is received if ATM is received.
The identifier is returned to the TM free queue 11b, to the E free queue 13c for Ethernet reception, and to the SR queue 17b for transmission request from the CPU 17. SR queue 1
When returning to 7b, the transmission completion is described in the CPU17 communication descriptor.

Next, the relay operation between ELAN and Ethernet will be described. Here, the port state defined by IEEE 802.1d is premised on the forwarding state. (When a unicast packet with an unknown destination is received from Ethernet, or when the destination is on the ELAN side but a direct connection has not been established) The forward controller 16 extracts the PDI from the E reception queue 13d. , E transmit / receive descriptor 13
e to port number, packet length PBC, data memory 15
Get pointer PBUF to. Forward controller 1
6 is the DA from the data memory 15, the source MAC address
Read SA and search whether DA is registered in CAM of BDI (BDI can be found from port number). As a result you get no match. The forward controller 16 gets the Ethernet ports belonging to the BDI from the port map and sends them to all of those ports except the receiving port. After that, set PDI to V = 1, BD
Put it in AR queue 17c with I. Set SA and receiving port number to BDI CAM and FDB (S = 0, E = 0, Q = X,
Register to P = receiving port number, AGE = initial value) (learning function).

The CPU 17 reads an entry from the AR queue 17c (the read pointer is unchanged), constructs a LE-ARP packet, and requests the forward controller 16 to send ATM through the SC queue 17a. At this time, CPU
17 VCI described in the transmission descriptor represents the connection to LES. Forward controller 16 is AT
Request transmission from the M transmission controller 12 and send a completion notification
It returns to the CPU 17 through the R queue 17b. When the forward controller 16 receives the LE-ARP response from the LES from the ATM receiving controller 11, it knows that it is a packet to be delivered from the VC to the CPU (the connection with the LES is T = 0). Cue 17
Notify the CPU 17 through b.

The CPU 17 interprets the LE-ARP response and learns the ATM address of the destination LEC (this index is AAI). The LAN-to-LAN connecting device of this embodiment does not use the direct connection while the traffic is low. The CPU 17 causes the forward controller 16 to register values in BDI, DA, and FDB (S = 0, E = 1, Q =
Specify 0, AAI) to activate the AR queue send command.

The forward controller 16 puts into the AR queue 17c the packet with the unknown destination received from the Ethernet before the processing of the AR queue transmission command. The CPU 17 does nothing for the DA that has already issued the LE-ARP, but otherwise executes the processing after the LE-ARP issuance. The forward controller 16 performs the following AR queue transmission command processing. AR cue 1
The start address, end address, read pointer, and write pointer of 7c are copied to the dequeue start address, dequeue end address, dequeue pointer, and dequeue end pointer, respectively. (a) If the dequeue pointer and the dequeue end pointer match, proceed to (e). (b) The entry of the AR queue 17c designated by the dequeue pointer is read. When V = 0, the dequeue pointer and the AR queue 17c read pointer are incremented, and the process returns to (a). If BDI and DA match with the value of the command parameter when V = 1, the AR queue common processing (described later) is performed on PDI. Dequeue pointer and AR queue 1
7c Increment the read pointer and return to (a).
When V = 1 and BDI or DA does not match the command parameter value, the dequeue pointer is incremented. (c) If the dequeue pointer and the dequeue end pointer match, proceed to (e). (d) The entry of the AR queue 17c designated by the dequeue pointer is read. When V = 0, the dequeue pointer is incremented and the process returns to (c). When V = 1 and BDI and DA match with the command parameter value, AR queue common processing is performed on PDI. The V flag of the AR queue 17c designated by the dequeue pointer is set to 0. Increment the dequeue pointer and return to (c). B with V = 1
If DI or DA does not match the command parameter value, dequeue pointer is incremented and (c)
Return to (e) DA and AAI in BDI CAM and FDB S = 0, E = 1,
Register with Q = 0.

In the AR queue common processing, first, the VC table 17i is searched based on BDI and AAI. If V = 0, MP
Get VCI MPVCI from VCI register file to BUS.
When V = 1, VCI DVC is obtained from the VC table 17i.
Next, LECID is obtained from the LEC register file and added as a LE header to the beginning of the packet data. Finally, the modified PBC and PBUF are described in the ATM transmission descriptor 12c together with the VCI, and the PDI is put in the ATM transmission queue 12a. In parallel with these, BDI, FDB OFS, time TIM
Put E in the CR queue 17f and make a direct connection request.

In the above AR queue transmission command processing, relay processing is exclusively performed in the forward controller 16. (When a unicast packet whose destination is known) is received from the Ethernet, the forward controller 16 takes out PDI from the E reception queue 13d and obtains the port number, packet length PBC, and pointer PBUF to the data memory 15 from the E transmission / reception descriptor 13e. The forward controller 16 reads DA and the source MAC address SA from the data memory 15 and searches whether or not DA is registered in the CAM of BDI (BDI can be identified from the port number). Matches as a result, forward controller 1
6 finds FDB OFS from the matched entries,
Read the entry. If S = 1, PDI is put in the SR queue 17b. If S = 0, E = 0 and P = (receive port number), release PDI (discard). S = 0, E = 0
If P ≠ (reception port number), write P to the transmission port number of the E transmission / reception descriptor 13e and write PDI
Is sent to the E transmission queue 13a (Ethernet transmission). If S = 0 and E = 1, the same processing as the AR queue common processing is performed based on the AAI read from the FDB (ELAN transmission). SA and receiving port number in BDI CAM and FDB
(S = 0, E = 0, Q = X, P = receive port number, AGE = initial value)
Register to (learning function). (When receiving unicast packet from ELAN)
The forward controller 16 is the ATM reception queue 11a
PDI is extracted from ATM receive descriptor 11c and received from VCI RVCI, packet length PBC, data memory 15
Get pointer PBUF to. The ATM table 17h is read based on RVCI to obtain V = 1, T = 1, and BDI (when T = 0, PDI is put in the SR queue 17b). The LE header information is read from the data memory 15 and it is confirmed that it is a data packet from another LEC (PDI is put in the SR queue 17b in the case of a control packet. Release).

PBC and PBUF are modified to remove the LE header. The forward controller 16 is the data memory 1
Read DA and SA from 5 and check whether DA is registered in CAM of BDI. I have to match the CAM
Send to all Ethernet ports belonging to BDI. C
When matching to AM, the forward controller 16 obtains FDB OFS from the matched entry and reads the FDB entry. If S = 1, the PDI is SR queue 17b
Put. If S = 0 and E = 0, write P to the transmission port number of the E transmission / reception descriptor 13e and set PDI to E.
Put in the transmission queue 13a. If S = 0, E = 1, P
Release DI (discard).

An entry enters the AR queue 17c and LE
-If the destination is on the Ethernet side even after issuing the ARP request, the LE-ARP response times out. In this case, since the packet is transferred to the Ethernet side,
It is highly possible that you are learning by the response from the destination. C
PU17 searches the CAM when the LE-ARP response times out, and if the destination is learned, B
By designating DI and DA, an AR queue flush command (described later) is activated to the forward controller 16. If it has not been learned, it will be sent to BUS.
A DA and AR queue BUS transmission command (described later) is activated to the forward controller 16.

The AR queue flush command process is A
This is the same as the AR queue send command processing, except that the PDI release processing is performed instead of the R queue common processing and that it is not registered in the CAM or FDB. AR queue BUS transmission command processing considers that V = 0 is obtained instead of pulling the VC table in the AR queue common processing, and CAM,
This is the same as the AR queue transmission command processing except that it is not registered in the FDB. (Operation when establishing a direct connection) CP
U17 monitors traffic for each BDI and FDB OFS by the CR queue 17f, and decides to switch to the direct connection. ATM of destination LEC from contents of FDB
Know the address and establish a direct connection by signaling protocol. For this, LE-ARP
Similarly, an ATM transmission request via the SC queue 17a and SR
Via queue 17b (reception VCI in ATM table 17h
Is the CPU 17 delivery type). After establishing the direct connection DVC, the CPU 17 sets the Q flag of FDB. And with AAI
The correspondence of DVC is ATM table 17h and VC table 17
i. The MAC address MAC is obtained from the CAM specified by BDI and FDB OFS, and the flash protocol is performed for the connection via BUS. Flush requests and replies go through a queue similar to LE-ARP. Upon receiving the response to the flash protocol, the CPU 17 activates the CW queue transmission command to the forward controller 16 using BDI and FDB OFS as parameters.

The forward controller 16 puts in the CW queue 17d the packet matching the entry of Q = 1 in the FDB received from the Ethernet before the processing of the CW queue 17d transmission command is processed, and learns the SA and the receiving port number. . The forward controller 16 performs the following CW queue transmission command processing. CW queue 1
The 7d start address, end address, read pointer, and write pointer are copied to the dequeue start address, dequeue end address, dequeue pointer, and dequeue end pointer, respectively. (a) If the dequeue pointer and the dequeue end pointer match, proceed to (e). (b) The entry of the CW queue 17d designated by the dequeue pointer is read. When V = 0, the dequeue pointer and the CW queue 17d read pointer are incremented, and the process returns to (a). If VDI and FDB OFS match with the parameter value when V = 1, perform virtual port transmission processing (described later) for PDI. Dequeue pointer and CW queue 17
Increment the d-read pointer and return to (a). V =
If the BDI or FDB OFS does not match the parameter value in 1, the dequeue pointer is incremented. (c) If the dequeue pointer and the dequeue end pointer match, proceed to (e). (d) The entry of the CW queue 17d designated by the dequeue pointer is read, and if V = 0, the dequeue pointer is incremented and the process returns to (c). V = 1, BDI, FDB OF
If S matches with the parameter value, send virtual port to PDI. The V flag of the CW queue 17d designated by the dequeue pointer is set to 0. Increment the dequeue pointer and return to (c). B = 1 at V = 1
Or if FDB OFS does not match the parameter value, increment the dequeue pointer and return to (c). (e) Set the Q flag of FDB designated by BDI and FDB OFS to 0
To

In the virtual port transmission process, first, the VC table 17i is searched based on BDI and AAI to check the connection state (in this case, the direct connection DVC is obtained). If there is a direct connection, write the time to TX TIME. If there is no direct connection
MPVCI Register file to BUS connection MPV
Get CI. Furthermore, LECID is obtained from the LEC register file and added as a LE header to the beginning of the packet data. Finally, describe the modified PBC and PBUF together with DVC or MPVCI in the ATM transmission descriptor 12c, and
Into the ATM transmission queue 12a.

The above CW queue 17d transmission command processing is exclusively executed in the forward controller 16.
After that, when a packet to the same destination is received from the Ethernet, AAI is obtained by searching the FDB and further DVC is obtained from the VC table 17i to relay the packet to the direct connection and also to the VC table 17i.
Write the sending time to and learn the SA and receiving port number. (When a unicast packet is received from the ELAN BUS) The forward controller 16 extracts the PDI from the ATM reception queue 11a, and the ATM reception descriptor 1
From 1c, VCI, packet length PBC, and pointer PBUF to the data memory 15 are obtained. ATM table 1 based on VCI
If 7h is searched, V = 1, T = 1, D = 0, and the bridge identifier BDI is known (when T = 0, PDI is SR queue 17
Put in b). The LE header information is read from the data memory 15 and it is confirmed that it is a data packet from another LEC (PDI is put in the SR queue 17b in the case of a control packet. Release). PBC and PBUF are modified to remove the LE header. Forward controller 16
Reads DA, SA from the data memory 15 and C of BDI
Check if DA is registered in AM. If it does not match the CAM, it sends to all Ethernet ports belonging to BDI. When the CAM is matched, the forward controller 16 obtains the FDB OFS from the matched entry and reads the FDB entry. PDI if S = 1
To the SR queue 17b. If S = 0, E = 0,
P is written in the transmission port number of the E transmission / reception descriptor 13e, and PDI is put in the E transmission queue 13a. S =
If 0, E = 1, release PDI (discard).

Since the LEC of the transmission source cannot be specified (because packets from various LECs are multiplexed from BUS), learning is not performed. Forward controller 16
Reads DA from data memory 15 and BDI CAM
Search whether DA is registered in. As a result you get no match. The forward controller 16 obtains the Ethernet ports belonging to the BDI from the port map, and relays these ports to Ethernet in order.

When the destination terminal is connected to those Ethernets, the reception port RP and the source MAC address MAC are registered in the CAM and the FDB when the returned packet is received. Continue to M from ELAN via BUS
When a packet addressed to AC is received, the CAM and FDB are searched and the e-support number RP is obtained, so the packet is relayed to the RP. (When unicast packet is received from ELAN direct connection) Forward controller 16
Retrieves PDI from the ATM receive queue 11a and obtains VCI, packet length PBC, and pointer PBUF to the data memory 15 from the ATM receive descriptor 11c. When the ATM table 17h is searched based on VCI, V = 1, T =
1, D = 0, bridge identifier BDI, sender LEC ATM
Know the address index AAI. When using a direct connection, write the time to RX TIME of ATM table 17h. Subsequent relay operation is the same as when receiving from BUS. Since the AAI can be specified, there is a difference in learning, and this is explained.

The forward controller 16 is a CA of BDI.
Search whether SA is registered in M and FDB. Q =
If 0 and the matching entry of AAI is registered, AGE
Initialize and exit. If Q = 1 or an entry that does not match AAI is registered, set the FDB entry to S = 0,
Change E = 1, Q = 1, AAI = AAI, AGE = initial value, and if SA is not registered, SA in CAM and S = 0, E = 1, Q = 1 in corresponding FDB entry, AAI = AAI, AGE = initial value
Register In these cases, BD in the FR queue 17e
Insert I and FDB OFS, notify CPU 17 and end.

At the time of relaying, the packet matching the entry of Q = 1 is put in the CW queue 17d. This is because the packet passing through the direct connection after learning is
This is to prevent overtaking packets via the BUS. The CPU 17 obtains the connection to be flushed and the destination MAC address from the FR queue 17e, confirms the flush, and then transmits the suspended packet to the CW queue 17d. These procedures are the same as the flush when the direct connection is established. (When disconnecting the direct connection) The latest time received from the direct connection is recorded in the ATM table 17h, and the latest time transmitted to the direct connection is recorded in the VC table 17i. Check the usage of the connection, and if it is not used recently, switch the direct connection to BUS. The simplest way to do this is to invalidate (V = 0) the corresponding entries in the ATM table 17h and VC table 17i. This is based on the assumption that the direct connection is fast, so that subsequent packets via the BUS will not pass.

In order to surely prevent overtaking, the MAC address under the direct connection is managed (the CPU 17 has an opportunity to know the subordinate MAC address by the AR queue 17c and the FR queue 17e), and the following processing is performed. I do. It sets the Q flag of all entries in the FDB corresponding to the subordinate MAC address.
The entry corresponding to the connection to be disconnected in the ATM table 17h and the VC table 17i is invalidated. The flash protocol is performed for the subordinate MAC address.
If there is a flush response, CW queue transmission processing is performed for the corresponding MAC address.

[0067]

As described above, according to the LAN-to-LAN connecting device of the present invention, it is possible to multiplex and store information corresponding to a plurality of LAN groups and a plurality of MAC addresses in one queue. It can be used effectively.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an inter-LAN connection device of the present invention in which an ELAN and a plurality of conventional LANs are connected.

2A and 2B are structure diagrams of a queue, in which FIG. 2A shows stored contents before dequeue processing for MAC _a , and FIG. 2B shows stored contents after dequeue processing.

FIG. 3 shows a plurality of ELANs and a plurality of conventional LANs,
It is a conceptual diagram which shows the inter-LAN connecting device bridge-connected in the AC layer.

FIG. 4 is a structural diagram of a queue.

FIG. 5 is a conceptual diagram showing an inter-LAN connection device that is functionally divided into LE service means and forwarding means.

FIG. 6 is a diagram showing a hardware configuration of a LAN-to-LAN connecting device of the present invention.

FIG. 7 is a diagram showing a data structure for interfacing between controllers and CPUs.

FIG. 8 is a diagram showing the contents of entries in an AR queue.

FIG. 9 is a diagram showing the contents of entries in a CW queue.

FIG. 10 is a diagram showing the contents of entries in an ATM table.

FIG. 11 is a diagram showing the contents of an entry in a VC table.

FIG. 12 is a diagram showing the contents of an entry in the FDB.

FIG. 13 is a diagram showing contents of entries of an FR queue and a CR queue.

FIG. 14 is a diagram showing each element for executing a LAN emulation service in which an access function of a conventional LAN is connected to another MAC on the ATM network on the ATM network.

[Explanation of symbols]

 1 first-in first-out storage means (queue) 2 comparison means 3 relay means 3a forwarding means 3b LE service means 11 ATM reception controller 12 ATM transmission controller 13 Ethernet controller 14 control memory 15 data memory 16 forward controller 17 CPU 17c AR queue 17d CW queue

Claims (3)

[Claims] 1. A LAN-to-LAN connecting device configured to bridge-connect a LAN simulated on an ATM network and a conventional LAN in a MAC layer, wherein packets to be transmitted through the simulated LAN are transmitted. The first-in first-out storage means for temporarily storing the information indicating and the information indicating the destination MAC address of the packet in common regardless of the difference of the destination MAC address, and the LAN on which the packet related to one destination MAC address is simulated. When transmitting through the established data direct VCC, comparing means for comparing the destination MAC address to be transmitted with the destination MAC address stored in the storage means, and the result of the comparison by the comparing means, matching of the MAC addresses It has a relay means for transmitting the packet when the packet is present. LAN-to-LAN connecting device to be. 2. A plurality of LANs simulated on an ATM network,
An inter-LAN connecting device configured to bridge-connect a plurality of conventional LANs in a MAC layer, wherein the plurality of conventional LANs and the plurality of simulated LANs are vertically grouped, Information indicating a packet to be transmitted through any one of the LANs, the destination MAC address of the packet, and the information indicating the corresponding group identifier,
Through the first-in first-out storage means for temporarily temporarily storing the same regardless of the difference in the address or the group identifier, and the data direct VCC established on the simulated LAN for the packet related to one destination MAC address and the group identifier. When transmitting, the destination MAC address and the group identifier to be transmitted are compared with the destination MAC address and the group identifier stored in the storage means, and the comparison result by the comparison means, the MAC address and the group identifier And a relay means for transmitting the packet when there is a matched packet.
Inter-connection device. 3. A LAN-to-LAN connecting device in which a LAN simulated on an ATM network and a conventional LAN are bridge-connected in a MAC layer, and the LAN-to-LAN connecting device is a connection of an ATM network. The LE service means that manages and interprets the protocol and requests the forwarding means to dequeue the packet stored in the first-in first-out storage means, the packet to be transmitted to the simulated LAN, and the destination MAC address of the packet. First-in first-out storage means commonly stored regardless of different destination MAC addresses, and data direct VC established on a simulated LAN
The destination MAC address to be transmitted through C and the destination MAC address stored in the storage unit are compared with each other, and the forwarding unit is provided, and the forwarding unit is a packet from a simulated LAN or a conventional LAN. When the packet is received, the relay destination is determined from the destination MAC address of the packet, and the packet that should be relayed to the simulated LAN but must be temporarily held is stored in the first-in first-out storage means, and the LE service means is stored. When receiving a request for dequeuing processing from the storage unit, the storage unit is opened, and the destination MAC address to be transmitted and the destination MAC address stored in the storage unit are compared by the comparison unit.
A LAN characterized in that a packet corresponding to the destination MAC address is transmitted to a simulated LAN.
Inter-connection device.