Cell Relay Archive

[lmercili@cisco.com (Leena Merciline)]

In article <fmo.84.001344BB@info.fundp.ac.be> fmo@info.fundp.ac.be (Frederic Mottiat) writes:
>Could somebody help me with that : I'm looking for specifications of
>LEC, LES, LECS, BUS and LANES in LAN emulation.
>What is their exact function ? how do they achieve it ? How do they
>work together ?
>I have only a few information about these, so I would be really
>gratefull if you could help me with that.

Let me try and simplify it, you can get all the gory details from 
the spec. Say two computers (A & B) on a network want to communicate
with each other via IP over ethernet. A & B would find each other's
MAC address by ARPing, which is a broadcast protocol. In the ATM
world, this is not possible because ATM is connection oriented.

The ATM Forum's LE spec addresses this situation. Now say both A & B
are moving IP traffic over ATM. Both A & B would have device driver
software containing a lan emulation client (LEC) which takes all
broadcasts (arp requests) and directs them to the lan emulation
server (LES). The LES maintains a table of IP address to ATM address
mappings of all hosts in the LE domain. The LES basically replies
to the ATM-ARP request if it can find a match in its table. If not,
the LES consults the broadcast unknown server (BUS). Now how do
A & B determine the addresses of LES and BUS to communicate with 
them? This is done by querying the configuration server (CS). The
CS is probably statically defined at the time of device driver
installation. LAN Emulation Services (LANES) is a trademark. It
comprises of LES, BUS, and CS (also called LECS).

>
>BTW, if somebody has the reference of the LAN Emulation specifications
>from the ATM Forum, I would be very gratefull too, has I managed to find
>it on ATM Forum's Web site, but couldn't get my hands on it.

You can find the LE spec on the forum's server but it is protected.
You need an account on the forum server with userid and password.
To get an account, you (or your organization) must be a member
of the ATM Forum (pay those yearly dues :-))

Hope this helps.

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Leena Merciline                            Cisco Systems Inc.
lmercili@cisco.com                         San Jose, CA
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