Subject: [mpls] draft-boutros-mpls-lsp-ping-ttl-tlv

From: Vishwas Manral <[email-masked]>
Date: Sun, 28 Mar 2010 21:12:27 -0700

Hi,

I find the draft useful and concise. I read the draft and found a
basic issue - it cannot be used the way it is defined. I had a few
suggestions and an issue with the draft(point 3):

1. I think the draft can be made more generic as it can be used to
test hops in heirarchical bidirectional LSP's or even just plain
bidirectional LSP from an LSR to another LSR.
2. Though the TLV we talk about is an LSP Ping TLV, I at first thought
it is probably a TLV in the ACH header. May be that should be made
clear.
3. I am not sure how you can assume that a node that does not
understand the TLV will just ignore the TLV (Type value 11). RFC 4379
which mentions that

   Types greater than or equal to 32768 (i.e., with the high-order bit
   equal to 1) are optional TLVs that SHOULD be ignored if the
   implementation does not understand or support them.

In that context the statement is very interesting:

If a receiver does not understand the TTL TLV, it can simply ignore the TLV.

I am not sure but it may be nice to remove the statement above instead
of making an exception. We cannot make reccomedations of what to do
with a TLV if someone does not understand the TLV as the equipment
that does not understand it is already deployed.

Thanks,
Vishwas