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

From: "Fairlie-Cuninghame, Robert" <[email-masked]>
Date: Mon, 10 Dec 2001 15:34:49 -0800

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.

It seems that some sort of header would be better suited for this. In this
manner the response is always correct to user (e.g. 486 Busy) but the
UAS/proxy also knows that it is okay to try the next SRV entry. 

Robert.

> -----Original Message-----
> From: Gonzalo Camarillo [mailto:[email-masked]]
> Sent: 06 December 2001 23:23
> To: Jonathan Rosenberg
> Cc: [email-masked]'
> Subject: Re: [Sip] Open Issue #128: 503 and SRV
> 
> 
> 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
> 
> Jonathan Rosenberg wrote:
> > 
> > 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.
> > 
> > ---
> > Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
> > Chief Scientist                             First Floor
> > dynamicsoft                                 East Hanover, NJ 07936
> > [email-masked]                     FAX:   (973) 952-5050
> > http://www.jdrosen.net                      PHONE: (973) 952-5000
> > http://www.dynamicsoft.com
> > 
> > 
> > _______________________________________________
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> 
> -- 
> Gonzalo Camarillo                    Phone :   +1 212 939 71 71
> Columbia University                  Mobile:  +358 40 702 35 35
> 472 Computer Science Building        Fax   :  +358  9 299 30 52
> 1214 Amsterdam Ave., Mail Code 0401  http://www.hut.fi/~gonzalo
> New York, NY 10027                   
> USA                              [email-masked]
> 
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