Subject: MARS (RFC2022)

From: Sebastien Faure <[email-masked]>
Date: Thu, 18 Dec 1997 17:04:39 +0100 (MET)

Hi all,

	I am currently trying to code a MARS that can support several
layer 3 (Ipv4 and Ipv6) protocol. Something seems to me to be inadequate
in the RFC:
- In section 4.1, it is said that a single instance of a
MARS(corresponding to a full ATM address) may not support more than one
cluster.
- In section 9: it is said that Every MARS must implement entirely
separate logical mapping tables and support.
	That means that there must be a at least one separate cluster for
each layer 3 protocol supported. Thus to support several layer3 we must
use several MARS "logical" instance. Thus a MARS Client that support IPv4
and IPv6 must be configured with two different MARS Server address, one
for each protocol and must establish a point to point VC with each MARS
Server address. And then what is the protocol id carried in each MARS
message for? Indeed the VC used to send the message will correspond to a
protocol id, and if MARS server and MARS Client have the right behaviour,
they will only send message corresponding to the associated protocol id on
a given VC.
	I think that a MARS "logical" instance corresponding to an unique
atm address should be able to manage several cluster (one for each
protocol that it supports). For that it will manage for each supported
protocol:
- a separate cluster member list
- a separate Cluster Control VC
- a separate layer 3 address <-> ATM addresses mapping table
but it will have an unique ATM address.
	Thus a MARS Client that must support IPv4 and IPv6 will establish
only one bidirectional point to point VC with this MARS and on this VC the
protocol id field of MARS message will be used by the MARS Server and the
MARS Client to know which mapping table or Cluster member list or CCVC is
concerned.

What do you think about this? Is it something that I've misunderstood in
the RFC?
Thanks for help

Sebastien FAURE.

---

From: [email-masked]
Date: Fri, 19 Dec 1997 10:59:08 -0500 (EST)

Sebastien,

>
> |I am currently trying to code a MARS that can support several

Section 4.1 is saying that each ATM node or MARS needs to have a unique
ATM address. The unique ATM address can support 1 to N logical MARS
instances (IPV4, IPV6, etc..). The wording is a little trickey but its
saying you can't have 2 MARS with the same ATM address, regardless of what
protocols they're supporting.

So your statement:

> |I think that a MARS "logical" instance corresponding to an unique
 
Is not correct and you can do what you would like by:

> |Thus a MARS Client that must support IPv4 and IPv6 will establish
> only one bidirectional point to point VC with this MARS and on this VC
> the protocol id field of MARS message will be used by the MARS Server
> and the MARS Client to know which mapping table or Cluster member list
> or CCVC is concerned.  

cheers, 

Anthony