Subject: Clarifiaction on processing of ERO object in RSVP-TE

From: [email-masked]
Date: Thu, 23 Nov 2000 22:31:34 +0900

Hi,

	This is regarding processing of ERO object. This is in page no.31 of 
draft-ietf-mpls-rsvp-lsp-tunnel-07.txt and section 4.3.4.1
In this section, point 5b is not clear.

   5b) Otherwise, if the second subobject is a loose subobject, the node
   selects any next hop that is along the path to the next abstract
   node.  If no path exists, there is an error, and the node SHOULD
   return a "Bad loose node" error.

	This is what is there in draft. 5a is about strict ERO. It's fine.
But 5b is about loose ERO. I think, it's not completely supporting 
loose ERO concept.

	What i'm thinking is, if there is no path exists to second subobject's
abstract node and if it is a loose subobject, we node selects next hop
that is along the path to the next abstract node. If no path exists,
It should try to find out next hop to next abstract node. Like that 
it has to do for all subobjects in the list. If it is find a next
hop to any abstract node, it can stop. If it is not found, then only
it can give a error with "Bad loose node". But draft is telling, only
after checking with next abstract node, it can give the error. It's not
fully supporting loose ERO concept. Isn't it?

Here i'm giving an example, which will give u clear idea:

	|A|-------|B|-------|C|-------|D|------|E|

	Let us take one LSP like this. Here A,B,C,D,E are abstract nodes.
Ans let us assume now processing is going on at B and by that time,
ERO is like this |B|C|D|E|. 

	If it is strict, B has to try to find out next hop, which is on the 
path to C. If it is not there, it has to send "Bad strict node" error.
It's fine.

	But if it is loose, if there is no path to C, it has to try to find 
out a next hop, on path to D. If it is there, it's fine. If it is
not there, it has to try for E. If this one also not there, then only
it can give a error like "Bad loose node" b'coz that is the last 
object. The concept of loose itself is that only. 

	But according to draft, after trying for D, itself it's giving "Bad
loose node". In my view, it's not correct.

	Here, i'm giving my opinion. If i'm not correct, please forgive me 
and correct me. Suggestions and clarifications on this one, would be
greatly appreciated.

Thanks in advance

Regards,
Reddy.