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

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 5 Dec 2001 21:50:30 -0500

Issue:

The spec says that if you try to contact a server, and get a 503, you are
supposed to try an alternate server. The question is, does alternate server
mean going back to the SRV record and trying the next one?

Discussion points:

I believe this makes total sense, but it just needs to get floated to see if
there is any kind of problem with it.

Proposal:

503 causes client to try next SRV entry

-Jonathan R.

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 05 Dec 2001 23:16:38 -0500

Agreed. RFC 2782 spells out the process: basically, try among the 
highest priority first and then go down the priority list.

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From: "Dean Willis" <[email-masked]>
Date: Wed, 5 Dec 2001 23:54:19 -0600

There are cases where trying the next SRV record would not apply.

1) No more SRV records

2) Local routing policy which does something besides use SRV, for example,
multiple matching routes

--
Dean

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From: "Brett Tate" <[email-masked]>
Date: Thu, 6 Dec 2001 16:28:40 -0500

> 503 causes client to try next SRV entry

The proposal is fine.  The worst case is 
that the multiple entries for the SRV 
record represent the same device or share 
a device that is causing the 503 to occur.  
Thus it would lead to multiple 503's.  If 
the 503 was because of overload, sending 
a 503 might escalate the problem.

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From: Gonzalo Camarillo <[email-masked]>
Date: Fri, 07 Dec 2001 01:23:19 +0200

Hi,

Agreed. The fact that one of the servers returned by SRV is overloaded
does not mean that the rest are. They should be tried as well.

Regards,

Gonzalo

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