Subject: RE: WG last calls

From: "Ash, Gerald R \(Jerry\), ALABS" <[email-masked]>
Date: Fri, 1 Apr 2005 07:02:38 -0600

Zhang,

> From draft-ietf-ccamp-crankback-04.txt ,section 4.5, the
> number of crankback rerouting is limited, so there will
> be a result: there is another LSP,but for the reason of
> limiting, the path may be not found.  I think sometimes
> it is unacceptable.The LSP may be prefered to enhancing
> performance.

This problem can be avoided by the setting the node retry threshold
(configurable per node) very high (~infinity), so retries aren't
limited.

Thanks,
Jerry

---

From: "Adrian Farrel" <[email-masked]>
Date: Sat, 2 Apr 2005 18:05:17 +0100

Hi,

Yes, to clarify what Jerry says, the number of crankback attempts MAY be
limited. At the moment, the only way that we provide to limit the attempts
is implemented per LSR. That is, any LSR MAY decide that it has performed
enough attempts at rerouting and pass the error back to the upstream LSR.

Note that the use of crankback to derive a path through a network is not
recommended. This approach is almost equivalent to random walk routing and
is neither efficient nor effective.

The use of crankback, as described in the draft is intended for use in
specific circumstances, such as inter-domain routing. In these cases only
selective LSRs (such as domain boundaries) perform rerouting attempts.

Adrian

----- Original Message ----- 
From: "Ash, Gerald R (Jerry), ALABS" <[email-masked]>
To: "Zhang Renhai" <[email-masked]>; "Adrian Farrel"
<[email-masked]>; <[email-masked]>; "Kireeti Kompella"
<[email-masked]>
Cc: "Ash, Gerald R (Jerry), ALABS" <[email-masked]>
Sent: Friday, April 01, 2005 2:02 PM
Subject: RE: WG last calls

Zhang,

Thanks,
Jerry

---

From: Zhang Renhai <[email-masked]>
Date: Mon, 04 Apr 2005 16:51:03 +0800

Hi, Adrian 
In RFC 3209,LSP is provided with attribute of  Priority(Setup Priority,Holding Priority),
so it is more reasonable to  process different LSPs according to the Priority, for the LSP
with higher priority, more retry number should be given, lower priority with less number.
Extremely, to the highest LSP, can the interception be concelled by ABR?(although multi LSPs
may be derived simultaneously, sellection can be done by egress on receiving Path massege
.So we can get another LSP with most possibility because of its highest priority)

Just my suggestion.

Regard,
Zhang

---

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 5 Apr 2005 20:11:56 +0100

Hi Zhang,

There is certainly nothing to prevent your suggestion.

This would be an implementation choice, although an operator would
probably want to configure identical behavior on all crankback-capable
LSRs in the network.

Adrian
----- Original Message ----- 
From: "Zhang Renhai" <[email-masked]>
To: "Adrian Farrel" <[email-masked]>
Cc: "Ash, Gerald R (Jerry), ALABS" <[email-masked]>; <[email-masked]>
Sent: Monday, April 04, 2005 9:51 AM
Subject: Re: WG last calls

> To: "Ash, Gerald R (Jerry), ALABS" <[email-masked]>; "Zhang Renhai"
<[email-masked]>; <[email-masked]>; "Kireeti Kompella"
<[email-masked]>