Re: [sip-overload] draft-shen-soc-avalanche-restart-overload

Charles Shen <> Mon, 06 June 2011 03:25 UTC

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From: Charles Shen <>
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Cc: Volker Hilt <>, Arata Koike <>, Henning Schulzrinne <>
Subject: Re: [sip-overload] draft-shen-soc-avalanche-restart-overload
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Hi all,

The IETF80 minutes below show mixed feedbacks about the avalanche
restart draft. I would therefore like to follow up discussing about
the comments raised.

1. There is an explicite mention of the "Outbound proxy RFC" which
"has timer to solve the issue". I assumed that means RFC5626 and took
a second look at it. One section I found could be most relevant is
Section 4.5 Flow Recovery, where it says each new registration "is
done in much the same way as forming a brand new flow as described in
Section 4.2; however, if there is a failure in forming this flow, the
UA needs to wait a certain amount of time before retrying to form a
flow to this particular next hop". The subsequent paragraphs in that
section define a way to compute the backoff time.

Back to Section 4.2, I did not find discussion about whether and how
the *initial registation* should be randomized. If that is the case,
the solution is different from what is presented in this avalanche
restart draft. The mechanism in this draft seeks to avoid the initial
storm of registration or similar message causing avalanche restart.
And if this effort is successful, subsequent backoff might not be
necessary, although I think inclusion of RFC5626 backoff timers would
certainly increase robustness.

2. There is also a suggestion to discuss this in dispatch. Since
"avalanche restart" is a problem described in the overload requirement
RFC 5390, maybe AD and/or chairs can advice whether we should cross
post this discussion or keep it in either one list for now.



On Thu, Apr 28, 2011 at 1:54 PM, Salvatore Loreto
<> wrote:
> Hi there,
> below the notes from the SoC session during the IETF80 meeting in Prague.
> (I have already uploaded this initial version to ietf proceeding site)
> Please review them and submit any correction to the chairs by May 11.
> The chairs have to send the notes  by May18th.
> (many thanks to Partha for taking notes during the meeting)
> cheers
> /Sal
> --
> Salvatore Loreto

snipped ...

> Avalanche restart overload  (Presenter: Arate Koike)
> ------------------------
> Hadriel: Let register has restart-timer instead of subscribe as it is
> register avalanche. SUBSCRIBE may not go to Registrar.
> Partha: SUBSCRIBE message itself may overload
> Open discussion:
> Hadriel: Mention this problem may not be solved by the proposed mechanism.
> Partha: The problem solved by Avalanche is in the boot up time only.
> Hadriel, Robert: Outbound proxy RFC has timer to solve the issue and it is
> not generic
> Partha: Agreed, It will not solve all the problem
> Robert: Discuss in dispatch
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