Hi,
As per RFC#3261, Section 16.6 SubSection 8 ( Add a Via header field
value ), proxy must include top most via header field.
The excerpt from RFC is as follows:
" Loop detection is performed by verifying that, when a request
returns to a proxy, those fields having an impact on the
processing of the request have not changed. The value placed
in this part of the branch parameter SHOULD reflect all of
those fields (including any Route, Proxy-Require and Proxy-
Authorization header fields). This is to ensure that if the
request is routed back to the proxy and one of those fields
changes, it is treated as a spiral and not a loop (see Section
16.3). A common way to create this value is to compute a
cryptographic hash of the To tag, From tag, Call-ID header
field, the Request-URI of the request received (before
translation), *the topmost Via header*, and the sequence number
from the CSeq header field, in addition to any Proxy-Require
and Proxy-Authorization header fields that may be present."
Thanks,
Poojan.
Atul kumar Jha wrote:
>Hi,
>
>
>
>I have some doubts regarding the Loop detection in case of Stateful
>Proxy.
>
>
>
>Q1. Should we include the top via branch ID in the branch ID calculation
>for Loop detection?
>
>
>
>Q2. And in the case of spiral should we suppress the Record Route or not
>as it might lead to extra processing load for the Proxy?
>
>
>
>Thanking you in advance.
>
>Regards,
>
>Atul
>
>
>
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