JP3189755B2 - LAN emulation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a LAN emulation system, and more particularly, to a LAN emulation system that enables data transmission between terminals having different communication speeds.

[0002]

2. Description of the Related Art A LAN emulation system emulates a terminal on a LAN connected by Ethernet or <IEEE802.5> and a terminal connected by an ATM network as if the whole were a LAN (emulation).
This is the technology to connect.

[0003] For the specifications of the conventional LAN emulation, refer to the document "LAN Emulation Over A".
TM Version 1.0 (af-lane-00
21) issued in January 1995 ATM Forum.

[0004] The LAN emulation described in this document is a system for transmitting data transmitted from an existing network to an ATM network at a MAC layer level.

[0005] The LAN emulation system uses the AT
A LAN emulation server (hereinafter, referred to as LES) for managing terminals connected to the M network, a broadcast / unknown server (hereinafter, referred to as BUS) for transmitting broadcast packets, and these two servers. LAN emulation configuration (Configuration) server (hereinafter referred to as L
ECS) and a LAN emulation client (LEC) which is a terminal terminal of the ATM network.

[0006] The LES contains the MAC address of the LEC and the AT.
Although the correspondence of the M address is registered, the correspondence between the MAC address of the terminal (client) on the existing LAN and the ATM address is not registered. When the LEC receives a data transmission request from the existing LAN or the LEC itself, the LEC makes an inquiry to the LES as to which LEC the communication partner is in. If the information of the communication partner is not in LES, LE
S sends a "query" to the LEC. When the transmission destination is determined, the LEC establishes a data transfer path (hereinafter, referred to as a connection) with the LEC, and transmits data via this connection.

[0007] Further, the technology of the band setting system related to the conventional LAN emulation is disclosed in Japanese Patent Laid-Open No. 9-9326.
No. 6 ". The bandwidth setting system described in this publication is a system for securing a transfer bandwidth for each protocol above the third layer in OSI, and is configured by an extended LAN emulation client and a protocol table having bandwidth information for each protocol. ing. In the protocol table, band information for each protocol and whether or not it can be used in combination with other protocols are set.

In this system, a transfer band is determined by a method of establishing a data transfer path based on information set by referring to a protocol table when a data transfer request is received from a higher-level protocol of a LAN emulation client. I am taking.

[0009]

A first problem of the above-mentioned prior art is that LANs having different physical maximum transfer bands are different.
Alternatively, transmission data may be lost to a terminal (client) on the LAN. The reason is that, in the above-described conventional technology, the maximum transfer band is set in accordance with the protocol, so that the LAN or LA connected with the protocol and having a lower maximum transfer band is used.
This is because transmission is performed to the terminal (client) on N in the maximum transfer band of the protocol.

A second problem is that the operability is poor. The reason is that it is necessary to add information to the protocol table every time a new protocol is added on the connected network.

[0011]

A first LAN emulation system according to the present invention is an LA emulation system having different LAs having different maximum transfer bands.
A LAN emulation system in which a plurality of N emulation clients and terminals under the LAN emulation client are connected via an ATM network, wherein the LAN emulation client indicates a transfer band that can be processed in consideration of the maximum transfer band of itself and the terminals under the LAN emulation client. Built- in available bandwidth information , said LAN emulation
LAN emulation, a server that manages
Send broadcast packets to the
Broadcast / unknown server
And information on the LAN emulation server.
Retain LAN emulation configuration
Server is connected to the ATM network, and each of the LA
N emulation server is an address in the ATM network.
A of the LAN emulation client
TM address and the LAN emulation client
Address of the terminal under the client and the available bandwidth
An address correspondence table including information and
From the terminal under its own
Transfer to the LAN emulation client
If data is received, the LAN emulation
The client acquires the transfer destination ATM address by itself
Check if it is possible, and if you cannot
The transfer destination ATM address from the
get.

[0012] A second LAN emulation system according to the present invention is the first LAN emulation system, wherein the LAN emulation server comprises
ATM address acquisition request from LAN emulation
By referring to the address correspondence table owned by itself,
The transfer destination ATM address and the available bandwidth information
The LAN emulation client
To the LAN emulation client
Is the available bandwidth information of the resolution response and its own available
The transfer band used for the data transfer path based on the band
decide.

[0013]

[0014]

[0015]

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a block diagram showing an embodiment of the present invention. Figure 2 shows the LE
5 is an address correspondence table held by S. Referring to FIG. 1, an embodiment of the present invention employs LES1 (LEC10-1).
2), BUS2 (server for transmitting broadcast packets), and LECS3 (LES1).
) And LECs 10 to 12 (clients for transmitting data).

Next, the operation of the embodiment of the present invention will be described.

LES1 is composed of LECs 10 to 10 as shown in FIG.
It has an address correspondence table of 12 MAC addresses and ATM addresses, and has LECs having MAC addresses as data transmission destinations for LECs 10 to 12 of each transmission source.
The ATM addresses of 10 to 12 are notified. Hereafter, MAC
Detecting the ATM address corresponding to the address;
It states that the address resolution request is resolved.

The address correspondence table of FIG.
12 participates in the LAN emulation environment when LES1 has its own MAC address and AT
The M address and the available bandwidth are registered.

Each of the LECs 10 to 12 has a built-in available band that can be serviced to itself and its subordinate terminals by a physical configuration, and this available band can be read. The available bandwidth that the LECs 10 to 20 can service is not limited to the maximum transfer bandwidth of the terminal under its control.
Is provided with a physical buffer, so that the band can be transmitted on the ATM network.

When the address resolution request from the LECs 10 to 12 cannot be resolved, the LES 1 transmits a packet for address resolution to each of the LECs 10 to 12. LEC10
LEC 12 returns a response to LES 1 only when the transmitted address resolution request can be resolved.

In BUS2, the broadcast packets transmitted by the LECs 10 to 12 and the destination of transmission are unknown (Un
know) packet is transmitted to all LECs 10-12. LECS3 manages information about LES1, and LES1 manages information about BUS2.

The LECs 10 to 12 know the possible bands that can be transmitted and received on the ATM network, and also know the MAC address of the terminal under the control if there is an existing LAN under their control. LECs 10-12 are the existing LAs
When there is a data transmission request from N or another LEC 10-20, LES1 resolves the address of the destination, establishes a connection 21 with the LEC, and transmits the data.

Next, an embodiment of the present invention will be described in detail with reference to FIGS. 3, 4, 5 and 6. FIG. FIG.
FIG. 1 is a block diagram showing an embodiment of the present invention. FIG.
It is a block diagram which shows the possible band of a connection. FIG.
FIG. 4 is an explanatory diagram showing the contents of address resolution. FIG.
6 is a flowchart illustrating the operation of the embodiment.

Referring to FIG. 3, an embodiment of the present invention provides an A
LES1, BUS2, LEC via TM switch 20
S3, LECs 10 to 12 are connected via an ATM network,
Under the LEC 10, a terminal 101 as a client
To 103 are connected by an Ethernet LAN.

Referring to FIG. 4, each LEC 10, LEC
11 and LEC 12 are the addresses in the address correspondence table of FIG.
Has a MAC address, an ATM address, and a possible band. Therefore, the possible bandwidth of the connection between LEC10 and LEC11 is LEC10 and LEC1.
The minimum value of 1 possible band is 25 [Mbps]. Similarly, the possible bandwidth of the connection between the LEC 10 and the LEC 12 is 40 [Mbps], and the LEC 11 and the LEC 12
The possible bandwidth of the connection between them is 25 [Mbps].

Terminal 1 of existing LAN under LEC 10
When the LEC 10 receives the data from 01 to the LEC 11 (procedure 30 in FIG. 6), the LEC 10 first checks whether the ATM address of the LEC 11 can be resolved in its own information (procedure 31 in FIG. 6).

If the LEC 10 cannot resolve the ATM address of the LEC 11, the LEC 10 obtains the ATM address of the LEC 11 from the LES 1 in order to know the ATM address of the LEC 11. That is, the LEC 10 sends the address resolution request shown in FIG. 5 to the LES 1 (procedure 32 in FIG. 6). Upon receiving the address resolution request from the LEC 10 (procedure 40 in FIG. 6), the LES 1 refers to its own address correspondence table (FIG. 2) (procedure 41 in FIG. 6), and if the ATM address of the requested LEC 11 can be resolved. The address resolution response shown in FIG. 5 is returned to the LEC 10 (procedure 42 in FIG. 6). At this time, the LES 1 adds information on the optimal data transfer band of the LEC 11 as option information.
The LEC 10 analyzes the option information from the returned information and compares the band of the other party with its own band (procedure 33 in FIG. 6).

After the comparison, the band to be used is determined (procedures 34-1 and 34-2 in FIG. 6). L not corresponding to the present invention
The EC cannot analyze the option information, but there is no problem in the protocol. When there is no connection with the partner, the LEC 10 establishes a connection using the determined bandwidth (procedures 35 and 36 in FIG. 6).

Finally, a connection having a possible bandwidth as shown in FIG. 4 is established for each of the LECs 10 to 12.

[0031]

A first effect of the present invention is that LECs can set mutually effective transfer bands. The reason is,
This is because knowing each other's effective data transfer band allows only the effective data transfer area to be used.

The second effect is that the load on the ATM switch can be reduced. The reason is that when data is transmitted from a terminal with a large band to a terminal with a small band, it is not necessary to absorb the difference in the switch, so that the cell disappears in the switch and the memory for storing the cell This is because the reduction of the amount can be achieved.

A third effect is that transmission data is not lost to LANs having different physical maximum transfer bands or terminals (clients) on the LANs. The reason is that the data transmission available band is set regardless of the protocol.

A fourth effect is that operability is improved. The reason is that even if a new protocol is added on the connected network, it is not necessary to add information to the protocol table.

[Brief description of the drawings]

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

FIG. 2 is an address correspondence table held by LES.

FIG. 3 is a block diagram showing an embodiment of the present invention.

FIG. 4 is a block diagram showing the connection of FIG. 3;

FIG. 5 is an explanatory diagram of information when performing address resolution.

FIG. 6 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

 1 LES 2 BUS 3 LECS 10-12 LEC 20 ATM switch 21 Connection 101-103 Terminal

Claims (2)

(57) [Claims] 1. A LAN to which a plurality of LAN emulation clients having different maximum transfer bandwidths and a plurality of terminals under the LAN emulation clients are connected via an ATM network.
An emulation system, wherein the LAN emulation client incorporates available band information indicating a transfer band that can be processed in consideration of the maximum transfer band of the LAN emulation client and the terminal under the LAN emulation client.
LAN emulation server, a server that manages
Server that sends broadcast packets.
Broadcast / unknown server and the LAN
LAN holding information about emulation server
Emulation configuration server
Each of the LAN emulations connected to the ATM network
The location server is an address in the ATM network.
ATM address of AN emulation client
And an end under the LAN emulation client
MAC address and the available bandwidth information
Holds the address correspondence table, and executes the LAN emulation
The client sends a message from another terminal to the LAN
Receives transfer data for the simulation client
If taken, the LAN emulation client
Checks whether the ATM address of the transfer destination can be obtained by itself.
If the LAN emulation cannot be obtained,
LAN emulation system, wherein the this <br/> to obtain the ATM address of the transfer destination from Nsaba. 2. The LAN emulation server according to claim 1 ,
Obtaining an ATM address from the LAN emulation
Upon request, refer to the address correspondence table owned by itself,
The requested transfer destination ATM address and the available bandwidth information
Information and a resolution response containing the
Return to the Ant and the LAN emulation client
The client sends the available bandwidth information of the resolution response and its own
Transfer band used for data transfer path based on available band
The LAN emulation system according to claim 1, wherein the area is determined .