JPH11308236A - Emulated lan system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an emulated LAN system that emulates the same functions as those of an existing LAN on an ATM network to cope with faults without revision of an existing protocol even when a redundant device is provided in preparation for the fault of an LES/BUS server. SOLUTION: Each of LEC clients 301-303 detects a fault of an active LES server 401 and selects autonomously a standby LES server 402 based on an ATM address table. Preferably, when a network monitor detects a fault of the current LES server 401, the monitor informs each of the LEC clients 301-303 of a standby LES server 402 or revises an ATM address of a LES server registered in an LECS server into an ATM address of the standby LES server 402.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an emulated L
AN (Emulated Local Area Network)
In particular, the present invention relates to an emulated LAN device for emulating the same function as an existing LAN on an ATM network.

In recent years, attention has been paid to a technique for applying an ATM (Asynchronous Transfer Mode) having features such as high speed and variability of bandwidth capacity to an existing LAN. When an existing LAN is constructed on an ATM network, the server realizes the function of the existing LAN, and the reliability of the server is important for improving the reliability of the entire system.

[0003]

2. Description of the Related Art LAN emulation
tion: hereinafter referred to as LANE) is a typical LAN in the past, for example, Ethernet and Token Ring standardized by the IEEE 802 committee.
g) is a technology that realizes the same function on an ATM network.
Standard specifications are defined by the TM Forum.

[0004] The function of LANE is as follows.
A LAN emulation server (hereinafter abbreviated as LES or LES server, and referred to as LES in the attached drawings) which provides an ARP function for resolving TM addresses, and a LAN emulation / broadcast / unknown server which provides functions such as broadcast / multicast
LAN Emulation Broadcast and Unknown Server: Hereinafter, abbreviated as BUS server, and described as BUS in the attached drawings), and LANE configuration management and LES server A
LANE Configuration Server that provides TM addresses
This is realized by a server such as an ECS server, which is abbreviated as LECS in the attached drawings).

[0005] That is, the emulated LAN device includes a LES server, a BUS server, a LECS server, and a LAN emulation client (hereinafter referred to as LEC server).
This is abbreviated as client, and is referred to as LEC in the attached drawings). Here, the LEC client is an existing LA
N, a bridge, a router, an ATM directly connected terminal (PC / WS), and the like. LES server, BUS
The server and the LECS server may be physically implemented on the same server, or may be implemented separately on different servers. The LECS server is an optional function and need not be implemented.

The operation of a conventional emulated LAN device will be described below with reference to FIG. 5 in the case where Ethernet is emulated. FIG. 5 shows an embodiment (3) of an emulated LAN device (ELAN) according to the present invention, which will be described later.
1 has the same configuration as the conventional emulated LAN device, and will be described with reference to FIG.

[0007] The LEC client 301 is a LECS client.
It accesses the server 43 and acquires the ATM address of the LES server 411 constituting the LES / BUS server 401 together with the BUS server 421. The LEC client 301 uses the acquired ATM address to establish a control virtual channel connection (Virtual Channel Connectio) with the LES server 411.
n: hereinafter abbreviated as VCC) 721 is set. The LEC client 301 recognizes whether the LAN is an Ethernet type or a token ring type.

[0008] The LEC client 301 has its own M
The AC address and the ATM address are registered in the LES server 411. Similarly, the other LEC clients 302 and 303 execute the initialization operation (1) to register their own addresses. Further, the LEC client 301 and the BUS server 4
21 makes it possible to mutually set a multicast send VCC 73 and a multicast forward VCC 74 to perform broadcasting.

[0009] In order to know the ATM address of the LEC client 302, the LEC client 301
LE_A containing the MAC address of client 302
An RP request is sent to the LES server 411. LES server 4
11 is the A of the registered LEC client 302
The TM address is returned by the LE_ARP response. L
If the ATM address of the EC client 302 is not registered, the LES server 411 broadcasts the LE_ARP request of the LEC client 302 to all the LEC clients 301 to 303 by a point-to-point or multipoint connection. In response, the LEC client 302 sends its ATM address to the LES server 411, and
The LES server 411 returns the TM address to the LEC client 301 by including the TM address in the LE_ARP response.

The LEC client 301 uses the ATM address of the acquired LEC client 302 to
Data Direct VC with EC client 302
C751 is set and this data direct VCC751
Send data via. Further, the LEC client 301 transfers all frames arriving while the data VCC is not set to the BUS server 421, and
Server 421 points to all LEC clients
Broadcast with a two-multipoint connection. LEC
The client 302 recognizes and receives the data addressed to itself.

Incidentally, in an emulated LAN device in which the LECS server 43 is not mounted, all the L
The EC client holds the ATM address of the LES server 411 in advance, and no operation is performed.

[0012]

In such a conventional emulated LAN device, when a failure occurs in the LES server or the BUS server, it becomes impossible to resolve the ATM address and the data communication between the LEC clients becomes impossible. Becomes As a solution to such a problem, a LES server and a BU are required to improve system reliability.
It is sufficient to provide a redundant device for the S server and change the protocol according to the LANE specification.

[0013] However, since the standard specifications of the ATM Forum do not include a rule regarding the redundant configuration of the LES server, the protocol cannot be changed, and the above-mentioned problem cannot be solved at present.

[0014] Accordingly, the present invention provides an existing LA on an ATM network.
It is an object of the present invention to cope with a failure without changing a predetermined protocol even in a case where a redundant device is provided when a LES / BUS server fails in an emulated LAN device emulating the same function as N.

[0015]

In order to solve the above-mentioned problems, an emulated LAN device according to the present invention comprises an active LES / BUS server, a backup LES / BUS server, and an LEC client. The client holds an ATM address table corresponding to the working and backup LES / BUS servers. When the LEC client detects a failure in the active LES / BUS server, the LEC client refers to the table to switch to the backup LES / BUS server, set a control VCC, and register an ATM address.

As a result, the LEC client sets the backup L
The address can be resolved by the ES / BUS server, and the ELAN is reconstructed by the backup LES / BUS server, so that the reliability of the entire apparatus is improved.

The emulated LA according to the present invention
The N device includes an active LES / BUS server and a spare LES /
It is composed of a BUS server, a LEC client, and a network monitoring device, and is also applicable when the storage unit of the LEC client stores the ATM address of the active LES / BUS server.

[0018] The network monitoring device is configured to use the active LES.
When the failure of the / LES server is detected, the ATM addresses of the working LES / BUS server are stored in the storage units of all the LEC clients in the A of the spare LES / BUS server.
Instruct to change to TM address. Each LEC client refers to the changed storage unit and
/ Control server VCC is set and the backup L
Register the ATM address in the ES / BUS server.

As a result, even if the active LES / BUS server fails, the ELAN using the backup LES / BUS server is reconstructed, and all the LEC clients can resolve the addresses using the backup LES / BUS server. Overall reliability is improved.

The emulated LA according to the present invention
The N device is an active LES / BUS server and a spare LES
/ BUS server, ATM of the current LES / BUS server
The present invention can also be applied to a case where the configuration includes a LECS server, an LEC client, and a network monitoring device whose addresses are registered.

[0021] The network monitoring device is configured to use the active LES.
When detecting that the / BUS server has failed, the LE
The ATM address of the working LES / BUS server registered in the CS server is changed to the ATM address of the backup LES / BUS server.
Instruct to change and register to the address.

Each LEC client communicates with the current LES /
The failure of the BUS server is known by notification from the network monitoring device or detection by the own station. Then, each LEC client communicates with the spare LE registered in the LECS server.
The ATM address of the S / BUS server is obtained, and the ATM address is registered in the spare LES / BUS server.

As a result, the ELAN by the spare LES / BUS server is reconstructed, and all the LEC clients can resolve the addresses by the spare LES / BUS server, thereby improving the reliability of the entire LAN device. The above-mentioned spare LES / BUS server is composed of a plurality of LES servers, and when a failure occurs in the first spare LES / BUS server, the next spare LES / BUS server is replaced with the current LES / BUS server.
An ES / BUS server can also be used.

In the present invention, the above-described LE
The S / BUS server can be composed of a LES server that resolves an ATM address from a MAC address, and a BUS server that provides a broadcast / multicast function and an unknown frame processing function.

That is, it is possible to configure the LES / BUS server with an active LES server and a backup BUS server that are physically or logically different from each other, and provide the respective active server and backup server. Then, based on the table or the storage unit described above, the LEC client
Switching from the ES server to the backup LEC server or switching from the active BUS server to the backup BUS server can be performed individually.

Also, in the present invention, the above-mentioned network monitoring device is an SNMP (Simple Network Manag
ement protocol).

That is, the network monitoring device uses the standard network management tool SNMP,
It becomes possible to grasp the state of the interface and to specify the occurrence of a failure and the location that causes the failure. Therefore, LES
/ BUS server failure can be easily detected.

In the present invention, the above-mentioned LE
The C client comprises at least a workstation directly connected to an ATM, a bridge connected to an existing LAN, a router connected to another emulated LAN device, and L
Any of AN-SW may be used. As a result, the emulated LAN device can be connected to an existing LAN, another virtual ELAN device, or the like.

Further, in the present invention, the LEC client recognizes the failure of the active server when detecting that the VCC set between the local station and the active LES / BUS server is disconnected. Can be. Further, the L
The EC client has a timer, and the timer is an ATM client.
The time from when the LE-ARP request, which is an address request, is transmitted until when the LE-ARP response, which is an ATM address response, is received, is measured. When this happens, the LEC client can recognize that the working LES / BUS server has failed.

[0030]

FIG. 1 shows an embodiment (1) of an emulated LAN device according to the present invention. In this embodiment, an emulated LAN device (ELAN) 201 (indicated by a solid line) is placed on an ATM network 10. (Enclosed area) has been constructed. The ELAN 201 is composed of an active LES including an address resolution LES server 411 and a BUS server 421.
/ BUS server 401 and LEC clients 301-
303. In this example, the LEC clients 301 and 302 are workstations, and
The EC client 303 is a bridge or a router.

The address resolution LES server 412
And the LES / BUS server 402 including the BUS server 422 assuming that the active LES / BUS server 401 has failed, so as to configure the spare LES with the LEC clients 301 to 303 so as to configure the ELAN 202 (range enclosed by a broken line). / BUS server.

A of each of the LEC clients 301 to 303
The current LES is stored in the TM address table (not shown).
The ATM addresses of the server 411 and the spare LES server 412 are written.

FIG. 2 shows an operation example of the embodiment (1). Hereinafter, the LES / BUS server 40 will be described with reference to FIG.
The switching operation from 1 to the LES / BUS server 402 will be described. In the join phase (P10), the LEC client 301 knows the ATM address of the active LES server 411 by referring to the ATM address table,
Control direct VCC_ to the LES server 411
A SETUP signal is transmitted to establish a control direct VCC 721 with the LES server 411.

The LEC client 301 transmits an LE_JOIN_REQUEST frame to the LES server 411 via the VCC 721,
The LE_CONFIGURATION_RESPONSE frame is received from the client and the parameters required for operation are exchanged between the LEC client 301 and the LES server 411.

In the registration phase (P11), the LEC
The client 301 uses the LE_REGISTER_RE
QUEST frame is transmitted to the LES server 411,
LE_REGISTER_RES from ES server 411
Upon receiving the PONSE frame, the LEC client 30
1 is registered in the LES server 411.

In the BUS connection phase (P12),
The LEC client 301 transmits an LE_ARP_REQUEST frame including the MAC address of all “1” to the LES server 411, and the LE_ARP_RESP
AT of BUS server 421 after receiving ONSE frame
Know the M address. Then, the LEC client 301
Sends a multicast send VCC to the BUS server 421
_SETUP signal is sent to establish a multicast send VCC 73 with the BUS server 421.

On the other hand, the BUS server 421 transmits a multicast forward VCC_SETUP signal to the LEC client 301, and establishes a multicast forward VCC 74 with the LEC client 301.

In the address resolution phase (P13), the LEC client 301 obtains the ATM address of the LEC 302 with which data communication is to be performed.
LE_ARP_REQU containing the MAC address of 302
The EST frame is transmitted to the LES server 411, and the LE_
ARP_RESPONSE frame received and LEC3
02 ATM address is obtained.

In the data transfer phase (P14),
LEC client 301 uses Data Direct VCC
A _SETUP signal is transmitted to the LEC client 302, a data direct VCC 751 is established with the LEC client 302, and data transfer is performed.

The LEC client 301 always connects at least the control direct VCC to the LES server 411 during operation, and connects the multicast send VCC 73 and the multicast forward VCC 74 to the BUS 421.

Here, when the LES server 411 or the BUS server 421 fails (P15), the LEC client 301 transmits an LE_ARP_REQUESTUT frame to the LES server 411 to resolve the address of the LEC client 302 (phase P16).
At the same time, the timer T1 (not shown) is started (P1
7).

However, since the LES server 411 has failed, there is no response of LE_ARP_RESPONSE. At this time, the LEC client 301 sends a LES message when a timer (not shown) exceeds a predetermined time.
The server 411 is recognized as having failed. The LEC client 301 can also recognize the failure of the LES 411 by disconnecting the control direct VCC 721 set with the LES server 411. Similarly, the LEC client 301 can know the failure of the BUS server when the multicast send VCC 73 and the multicast forward VCC 74 are disconnected.

The LEC client 301 acquires the spare LES server 412 from the ATM address table and
For the ES server 411 and the BUS server 422, an initialization phase (P18) similar to the initialization phase performed in the phases P10 to P12 is executed, and
Direct VCC722 and Multicast Send V
Establish a CC as well as a multicast forward VCC (not shown).

Then, the LEC client 301
The address of the LEC client 302 is resolved to the ES server 412 (phase P19), a data direct VCC 752 is established with the LEC client 302 (P20), and data communication with the LEC client 302 is executed.

As described above, when the active LES server 411 or the BUS server 421 fails without changing the predetermined protocol, the LEC client 301 autonomously operates the backup LES server 412 and the BUS server 42.
By switching to 2, EL by the LES server 411
ELA by LES server 412 instead of AN201
Emulated LA by rebuilding N202
The reliability of the N device can be improved.

FIG. 3 shows an emulated L according to the present invention.
An embodiment (2) of an AN device is shown. This embodiment is different from the embodiment (1) shown in FIG.
The network monitoring device 50 for monitoring the AN device is added, and each of the LEC clients 301 to 303
Is the current LES server instead of the ATM address tables of the current and backup LES server and the current and backup BUS server.
A storage unit for storing ATM addresses of the server and the active BUS server.

FIG. 4 shows an operation example of the embodiment (2). LES / BU in embodiment (1) with reference to FIG.
The switching operation of the S server will be described below. In the initialization phase (P30), the LEC client 301 executes initialization between the LES server 411 and the BUS server 421, as in the phases P10 to P30 of the embodiment (1).

In the device management phase (P31), the network monitoring device 50 performs the GE via the network monitoring VCCs 761 and 762 according to the SNMP protocol.
LES server 411, BUS with T_REQUEST signal
The management information of the server 421 or the like is inquired, and GET_RE is
It is known from the SPONSE signal that the LES server 411 and the BUS server 421 are normal.

When the LEC client 301 communicates with the LEC client 302, the PEC
3, P14, based on the ATM address of the active LES server 411 held in the storage unit, performs address resolution of the LEC client 302 to the LES server 411, and then establishes data direct VCC to establish communication. Do.

Here, the LES server 411 or BUS4
If a failure occurs in the server 21 (P32), the LES server 4
11 or the BUS 421 notifies the GET_REQUEST signal from the network monitoring device 50 that the local station is abnormal with the GET_RESPONSE signal (phase P33). The LES server 411 may report no response or autonomous notification of an abnormality in its own station.

The network monitoring device 50 instructs the GET_REQUEST signal to change the ATM address of the LEC client held in the storage unit of each LEC client to the ATM address of the backup LES server 412 (P34).

In the initialization phase (P35), each L
The EC client performs phases P10 to P shown in FIG.
LES server 412 and BUS
Execute for server 422.

When the LEC client 301 communicates with the LEC client 302, after performing the address resolution of the LEC client 302 to the LES server 412 based on the ATM address held in the storage unit (P36), the data The direct VCC 752 is established (P37), and communication is performed.

That is, the network monitoring device 50 detects an abnormality in the active LES server and instructs all LEC clients to switch to the backup LES server.
In the embodiment (1), each LEC client independently detects an abnormality of the active LES server at a different time, and
Although the server is switched to the ES server, in the embodiment (2), each LEC client knows the abnormality of the LES server, and at the same time, performs the switching operation to the spare LES server. As a result, the reliability of the emulated LAN device is improved without changing the default protocol.

FIG. 5 shows an emulated L according to the present invention.
15 shows an embodiment (3) of an AN device. This example is different from the embodiment (2) in that the LECS server 43 is added, and that each LEC client has no function of holding the ATM address of the active LES server / BUS server as an initial value. . Also, the LECS server 43
Stores the ATM address of the active LES server 411.

FIG. 6 shows an operation example of the embodiment (3). Referring to FIG. 5, active LES server 411 and active B
Replace the US server 421 with the spare LES server 412 and the BUS
The operation of switching to the server 422 will be described below. LE
In the CS connection phase (P40), the LEC client 301 sends a configuration direct VCC_SETUP signal to the LECS server 43, and establishes a configuration direct VCC 71 with the LECS server 43.

The configuration phase (P4
In 1), the LEC client 301
Server 43 and LE_CONFIGURE_REQUESTS
T and the LE_CONFIGURATION_RESPONSE frame are transmitted and received to obtain the ATM address of the LES server 411 and the parameters of the own station.

LEC based on the obtained ATM address
The client 301 uses the LES server 411 and the BUS
The server executes the initialization phase (P42) with the server 421.
The network monitoring device 50 obtains management information from the LES server 411 via the network monitoring VCC 761 according to the SNMP protocol, and knows that the LES server 411 is normal (P43). The LEC client 301 includes the LES server 411 and the LEC client 3
02 address resolution, then LEC client 3
02 and perform data communication.

Here, in the device management phase (P44), when a failure occurs in the LES server 411, the network monitoring device 50 detects the failure of the LES server 411 via the network monitoring VCC 761 according to the SNMP protocol. Then, the network monitoring device 50 sends the L through the network monitoring VCC 763.
Active LES server 411 stored in ECS server 43
Is changed to the ATM address of the backup LES server 412 (P45).

Each LEC in the emulated LAN device
The client, for example, the LEC client 301, communicates with the LES server 41 via the network monitoring VCC 762.
After the failure of No. 1 is known and the configuration phase (P46) is executed again on the LECS server 43, the LES
The initialization phase (P47) is executed for the server 412 and the BUS server 422.

The LEC client 301 resolves the address of the LEC client 302 with respect to the LES server 412 (P48), and establishes the data direct VCC 752 with the LEC client 302 (P4).
9) Start data communication.

As described above, when a failure occurs in the LES server 411 without changing the predetermined protocol, each LEC client immediately switches to the spare LES server 412 and the BUS server 422 to perform data communication. And the reliability of the emulated LAN device is improved.

In the above-described embodiments (1) to (3), the LES server 411 and the BUS server 421 are used as the LES / BUS server 401, and the LES server 412 and the BUS server 422 are used as shown in FIGS. LE
The S / BUS server 402 may be treated as one server with each of the S / BUS servers 402 to perform switching at the time of failure.

[0064]

As described above, according to the emulated LAN device of the present invention, each LEC client detects a failure of the active LES / BUS server,
Backup LES / BUS autonomously based on address table
Because it was configured to switch to the server, the standard LANE
The reliability of the system specified by the standard LANE specification is improved without defining a special protocol different from the specification.

Further, the network monitoring device determines that the current LE
When a failure of the S / BUS server is detected, the spare LES /
Even when the BUS server is configured to notify each LEC client, the reliability of the system can be improved. Then, unlike the case where the LEC client holds the table, only the specific LEC is
LEC for line failure between own station and LEC / BUS server
It does not mistakenly recognize that the / BUS server is stopped, and does not switch to the backup LEC / BUS.

Further, when the network monitoring device determines that the current L
When a failure of the ES / BUS server is detected, the AT of the working LES / BUS server registered in the LECS server is used.
Even if the M address is changed to the ATM address of the spare LES / BUS server, the reliability of the system can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment (1) of an emulated LAN device according to the present invention.

FIG. 2 is a sequence diagram showing an operation procedure of an embodiment (1) of the emulated LAN device according to the present invention.

FIG. 3 is a block diagram showing an embodiment (2) of an emulated LAN device according to the present invention.

FIG. 4 is a sequence diagram showing an operation procedure of the emulated LAN device according to the embodiment (2) of the present invention.

FIG. 5 is a block diagram showing an embodiment (3) of an emulated LAN device according to the present invention.

FIG. 6 is a sequence diagram illustrating an operation procedure of the emulated LAN device according to the embodiment (3) of the present invention.

[Explanation of symbols]

10 ATM network 201, 202 Emulated LAN (ELAN) 301, 302, 303 LEC client (LE
C) 401, 402 LES / BUS server 411, 412 LES server (LES) 421, 422 BUS server (BUS) 43 LECS server (LECS) 50 Network monitoring device (SNMP manager) 71 Configuration direct VCC 721, 722 Control Direct VCC 73 Multicast send VCC 74 Multicast forward VCC 751, 752 Data direct VCC 761, 762, 763 Network monitoring VCC In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (8)

[Claims] 1. An emulated L including a LES / BUS server and a LAN emulation client.
In the AN device, the server is composed of a working server and a spare server, and the client holds an ATM address table corresponding to each server, and based on the table when the failure of the working server is detected. An emulated LAN device characterized by switching connection to the spare server. 2. An emulated LAN device comprising a LES / BUS server, a LAN emulation client, and a network monitoring device, wherein the server comprises an active server and a spare server, and wherein the client is a client of the active server. A storage unit for storing an ATM address; when the network monitoring device detects that the active server has failed, instructs the storage unit to change the ATM address to the ATM address of the spare server; Emulated LAN device characterized by performing. 3. A LAN emulation / configuration server, a LAN emulation client, and a network monitoring device, wherein the client is a LAN emulation / configuration server in which the ATM address of the working LES / BUS server is registered. In an emulated LAN device for acquiring the ATM address from a configuration server, the LES / BUS server is composed of an active server and a spare server, and the network monitoring device detects that the active server has failed. An emulated LAN device for instructing the LAN emulation configuration server to change the ATM address to the ATM address of the spare server. 4. The LES / BUS server according to claim 1, wherein the LES / BUS server uses an ATM from a MAC address.
An LES server for resolving an address, and a BUS server for providing a broadcast / multicast function and an unknown frame processing function, wherein the LES server and the BUS server comprise an active server and a spare server, respectively. Emulated LAN device. 5. The emulated LAN device according to claim 2, wherein said network monitoring device monitors a network based on SNMP. 6. The client according to claim 1, wherein the client is an ATM end device, and at least a workstation, a bridge, a router, and a LAN.
An emulated LAN device, which is any one of -SW. 7. The method according to claim 1, wherein the client recognizes a failure of the active server when the client detects that a VC connection set between the local station and the active server is disconnected. An emulated LAN device characterized by the following. 8. The client according to claim 1, further comprising a timer for measuring a time from when the client transmits the address request to the active server to when the client receives the address response, wherein the timer is equal to or more than a predetermined value. An emulated LAN device for recognizing a failure of the active server when a failure occurs.