Subject: Re: [Sip] Open Issue #128: 503 and SRV

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 18 Dec 2001 15:08:03 -0500

Fairlie-Cuninghame, Robert wrote:

> This does raise an interesting question though.
> 
> 503 Service Unavailable will be either misleading or meaningless to the
> normal end user. Normally the response should really only be returned to the
> user if this is the _real_ response reason (e.g. down for maintenance). If
> on the other hand, the UAS is just returning this response for some other
> reason (e.g. all lines are busy in a call pool and the UAS is trying to
> trigger an SRV-based load-balancing mechanism), then the UAS needs to know
> that SRV-based load-levelling is being used.

Proxies need to be cautious about propagating 503 upstream, thats in the 
spec already. However, I don't think its the appropriate for the usage 
you have in mind; 503 is really for the case where a set of homogeneous 
servers all provide the same service as a cluster rather than a single 
machine. More intelligent, application layer logic would dictate the 
usage of other response codes.

I will note that there was consensus to have 503 trigger the next SRV 
look up at the IETF meeting.

-Jonathan R.
-- 
Jonathan Rosenberg, PhD                 72 Eagle Rock Avenue
Chief Scientist                         First Floor
dynamicsoft                             East Hanover, NJ 07936
[email-masked]                 FAX: (973) 952-5050
http://www.jdrosen.net                  PH: (973) 952-5000
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---

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 27 Dec 2001 11:26:55 -0500

Since I do not believe the point Robert raised is really an issue here, 
I am going to declare this issue closed. Note that it has already been 
reflected in draft-ietf-sip-srv-03.

Thanks,
Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue