Subject: reminder: things todo in august and shortly thereafter

From: Jim Boyle <[email-masked]>
Date: Thu, 23 Aug 2001 11:34:30 -0400 (EDT)

From the minutes:

o) End of August: Operators actually interested in Diffserv TE, read
   the requirements draft draft-ietf-tewg-diff-te-reqts-01.txt and
   provide feedback to list.  Would like to wrapup the requirements
   draft by end of August!

o) First week of September:  After this time, please don't raise new
   issues with draft-team-restore-hierarchy-00.txt. The goal is to
   have the team revise and republish so as to be able to "hand off"
   to ccamp for consideration by last day of September.

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From: "Ash, Gerald R (Jerry), ALCTA" <[email-masked]>
Date: Wed, 29 Aug 2001 13:09:01 -0400

Tricci,

See comments below.

Thanks,
Jerry Ash

> draft-ash-mpls-diffserv-te-alternative-02.txt

> In section 3.2, although there are some brief descriptions on the intents
of the
> "admission-control priority classes" and "restoration priority classes".
To me, it > is still unclear about why these two classes are needed in order
to allow higher
> priority LSP to be set up first and be protected first.  More explanation
on 
> the motivation on these types of priority classes would be very useful.
More 
> importantly, how exactly they are being coordinated with each other when
performing
> the TE function?

See the attached PDF document for further explanation of our thoughts on
class types and the role of admission control priority and restoration
priority.  We plan to issue an I-D on this in the next few weeks.

> I have a lot of trouble of trying to understand how to handle the
crankback 
> situation for the example which is described in section 3.2 for the LSP
setup at 
> the ingress and transit LSRs.  Since there is no mention on how each node 
> recognizes the protected-CT-bandwidth level across the selected hops, when

> performing crankback, how the crankback node recognizes which new hop to
> select to set up the LSP.  More details on this aspect for the example
would 
> be extremely useful.

As specified in the I-D on crankback
http://search.ietf.org/internet-drafts/draft-iwata-mpls-crankback-01.txt,
the transit LSR can either crankback to the ingress LSR or a border LSR.  In
the example, after a transit LSR recognizes that requirements are not met on
the next hop (e.g., lack of sufficient available bandwidth), the transit LSR
sends crankback to the ingress LSR.  The ingress LSR then selects another
LSP choice, based on several possible algorithms.  The attached figure gives
some further details of an example, see also
http://www.ietf.org/internet-drafts/draft-ietf-tewg-qos-routing-01.txt
(e.g., Section 3.4).

---

From: "Naidu, Venkata" <[email-masked]>
Date: Thu, 30 Aug 2001 19:44:26 -0400

Ash,

   Correct me if I am wrong...

-> the example, after a transit LSR recognizes that requirements are not met
on
-> the next hop (e.g., lack of sufficient available bandwidth), the transit
LSR
-> sends crankback to the ingress LSR.  The ingress LSR then selects another

   Why should the crankback reaches till ingress LSR. Any intermediate
   LSR which has sufficient information to route the call/setup 
   can handle crankback well enough (if the ero is not strict but
   aggregated and handled by ABRs for example in MPLS hierarchical TE)

--Venkata Naidu

---

From: "Ash, Gerald R (Jerry), ALCTA" <[email-masked]>
Date: Thu, 30 Aug 2001 19:53:27 -0400

Venkata,

As specified in the I-D on crankback
http://search.ietf.org/internet-drafts/draft-iwata-mpls-crankback-01.txt,
the transit LSR can either crankback to the ingress LSR or a border LSR.  We
gave a simple example where it sends crankback to the ingress LSR; there are
other cases.

Jerry Ash

---

From: [email-masked]
Date: Fri, 31 Aug 2001 07:23:33 +0100

> Venkata,
> 
> >> the example, after a transit LSR recognizes that 
> requirements are not met
> on
> >> the next hop (e.g., lack of sufficient available 
> bandwidth), the transit
> LSR

Jerry Ash
NH=> One (good) reason to crankback to the source is to spread the
restoration load away from (instead on concentrating it near) the point of
failure.
Neil