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List:       sip-implementors
Subject:    Re: [Sip-implementors] Info on Hops in SIP?
From:       "Scott Lawrence" <scott.lawrence () nortel ! com>
Date:       2009-06-17 13:39:00
Message-ID: 1245245940.6527.33.camel () scott
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chandan kumar <chandan_psr@yahoo.co.in>:

> > Could any clarify what does HOP do in SIP?
> >
> > whether HOP is related to a register request or Call request?
> >
> > Issue faced : Phone comes up & tries to regsiter to the server.Lets say the
> > server is not available.So registration fails .Now I will try to make an IP
> > call to other SIP phone.Call is not going .
> > Both the phones are in same Network.
> > When i checked ethereal shows 483 error response too many hops.
> 

Tomasz Zieleniewski wrote:

> The issue You are facing is related to the sip routing loop detection.
> Any SIP request must contain a mandatory Max-Forwards header
> which sets the maximum number of intermediary nodes which can
> be traversed by this particular SIP request.
> Whenever sip node (proxy or gateway) receives SIP request it checks
> Max-Forwards
> value. If it is greater then 0 then SIP element decreases the value and
> forwards request
> further downstream. If the value is equal to zero then such intermediary
> node generates
> 483 Too Many Hops response.

... which probably means that either your request is addressed in an
invalid way, or the proxy you're sending it to is misconfigured.  When
I've encountered this, it's usually a loop somewhere that's the real
culprit.


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