Patent ID: 6671281
Filing Date: 2003-12-30
Classification: H04L

Abstract:
An ATM LAN emulation network comprising emulated LANs (ELANs) in which a plurality of terminals are connected to each other via ATM switches and communication between the terminals is managed by a LAN emulation server (LES) mounted at least one ATM switch per ELAN, where the ELANs are interconnected by interconnecting the ATM switches via LAN emulation clients (LECs) mounted at routers, the ATM LAN emulation network comprising:a LAN emulation configuration server (LECS), mounted at each router, for managing communication with the LES, where the ATM address of the LECS is stored in advance in the LES mounted in the ATM switch to which said each router is connected; and a broadcast unknown server (BUS) mounted at the ATM switch which is connected to said each router, and wherein when a specified terminal accesses a first ELAN from the ELANs and communicates with a first LECS mounted on a first router connected to the first ELAN by using a Well-known address, and sends a first request, including its own IP address, for obtaining the ATM address of a second LES which manages a second ELAN from the ELANs to which the specified terminal was previously connected, the first LECS which receives the request then determines whether the specified terminal is registered in the first ELAN, based on the IP address of the specified terminal and IP routing information of the first router, if the specified terminal is not registered in the first ELAN, the first LECS obtains the MAC address of an LEC mounted at a second router as the next hop indicated by the IP routing information, via a candidate BUS mounted at a candidate ATM switch of a candidate ELAN other than the first ELAN, and the first LECS sends a candidate LES which manages the candidate ELAN a second request for obtaining the ATM address of the LEC mounted at the second router, based on the obtained MAC address, the candidate LES which receives the second request then sends its own ATM address together with the ATM address of a second LECS of the second router, which is stored in advance, the first LECS communicating with the specified terminal receives the ATM address of the second LECS of the second router, and transfers the first request received from the specified terminal to the second LECS according to the obtained ATM address, if the second LECS is connected to the second ELAN, the second LECS which receives the transferred request then returns the ATM address of the second LES which manages the second ELAN, and the specified terminal obtains this returned ATM address of the second LES via the first LECS communicating with the specified terminal, and accesses the second ELAN according to the obtained ATM address of the second LES so as to operate on the second ELAN.