Subject: User-TLVs in RSVP

From: "Hariom P" <[email-masked]>
Date: Sun, 03 Mar 2002 19:58:51 -0800

I am looking to find more info about how "user tlvs" are transported in RSVP 
/ RSVP-TE ? Any pointers will be really helpful. Is there a seperate 
classNum defined for user(proprietory) TLVs etc? I understand that 
interpretation and/or usage of the TLV contents is totally proprietory and 
implementation specific..Thanks.

with regards,
hmp

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From: David Charlap <[email-masked]>
Date: Mon, 04 Mar 2002 10:20:52 -0500

Hariom P wrote:
> 
> I am looking to find more info about how "user tlvs" are
> transported in RSVP / RSVP-TE ? Any pointers will be really helpful.

RFC 2205.

When an unsupported object is encountered, the following behavior is
used:

	- If the class number is 0-127, the entire message is
	  rejected.  A PathErr or ResvErr for "unknown object
	  class" is generated, if the source message is Path or
	  Resv.

	- If the class number is 128-191, the unknown object is
	  discarded and the message is processed as if it was
	  not present.

	- If the class number is 192-255, the unknown object is
	  forwarded, but not processed.

> Is there a seperate classNum defined for user(proprietory) TLVs
> etc?

No.  If you invent a new class number, there is no mechanism to prevent
it fron conflicting with classes that may be defined in the future, nor
is there any mechanism to prevent it from conflicting with custom
classes that other vendors may define.

IMO, this is a serious problem with RSVP, but I don't think it's
something that can be changed without making a change to the object
header format, which would be incompatible with all existing RSVP
implementations.

-- David