Subject: How to Handle Tear messages in COPS usage for RSVP

From: "N.V.Subbarao" <[email-masked]>
Date: Mon, 04 Oct 1999 17:21:05 +0530

Hi All,

I have two queries in "COPS usage for RSVP" document

1. How to handle PathTear, ResvTear and ResvConfirm messages, since
"COPS usage for RSVP" document does not support these objects.

2. In section 3.5 , it was mentioned, in case PDP is not available, then
decision should be taken at LDP level. But, how LDP knows the current
state of PDP and resources availability (unless resource information is
replicated at PEP). On what basis LDP acept/reject requests.

thanks
N.V.Subbarao

---

From: Shai Herzog <[email-masked]>
Date: Tue, 12 Oct 1999 14:35:33 -0400

>"COPS usage for RSVP" document does not support these objects.

It has been decided not to support these messages because it
is non useful. Tear messages don't need to be checked since
they are semantically equivalent to not refreshing. If the
previous/next hop node wants to kill it can always not refresh
it, and there is nothing policy can do about it anyway.
NOTE: RSVP integrity guarantees that indeed the Tear came
from the right previous hop. If it didn't, it would be ignored
anyway.

As for the CONF message, given that it doesn't impact the actual
reservation, and is more for informational purposes we decided
it doesn't need to be checked.

>replicated at PEP). On what basis LDP acept/reject requests.

The LDP isn't standardized in this framework. Since it is
within a vendor's box, a vendor can make it very smart (almost
full PDP) or non existent. The framework merely mentioned
the function of the LDP, but doesn't care about implementation.
It is not an IETF issue.

However, to answer you question on the merit, the LDP may employ
partial policy capabilities (localized policies). The LDP decisions
probably won't be equivalent to the PDP ones, but it may be good
enough for a short period, until an alternative PDP is found.

Shai

>N.V.Subbarao

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