The MPLS WG Archive

[<neil.2.harrison@bt.com>]

Title: Message

An observation.  There is no such construct as a mp2mp *connection*.....one can have any-any in a cl-ps mode network (precisely because there are no connections) but it is NOT possible to have mp2mp connections in either a co-ps or co-cs mode network.  This can be proved by an appeal to (Shannon) information theory.....but it would require a very lengthy explanation, especially wrt how labelling works (its not as simple as some folks might assume).

 

However, let me simply state here what the bottom-line conclusions/rules are:

A connection must:
- only have a single source
- only have connectivity of 1

....so only p2p and p2mp connection constructions are allowed.

Further, and consequential from the above:
- ordering of traffic units is preserved in a connection
- once created there is no routing choice available in a connection

A trail is 'the source to a specific-sink' relationship in these connection constructs.

regards, Neil

-----Original Message-----
From: HeinerHummel@aol.com [mailto:HeinerHummel@aol.com]
Sent: 02 March 2006 10:59
To: mpls@lists.ietf.org
Subject: Re: [mpls] I-D ACTION:draft-ietf-mpls-ldp-p2mp-00.txt

Some critical notes wrt mp2mp LSP:

 

The terms upstream and downstream relate to the terms ingress and egress, but not to root (and three times not to root while keeping open whether the root is an ingress(+egress) at all).

 

The mp2mp LSP is supposed to be a mesh-less delivery channel which interconnects a specific set of leaf nodes such that at any junction traffic is forwarded to all other directions except the one from where it is received. This is my understanding about the mp2mp stream direction. The presented design with its upstreams and downstreams all over the place is fairly a sign of ossification, isn’t it ?

 

Heiner Hummel

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