On 5/28/12 1:06 AM, pranab sahoo wrote:
> Hi Paul,
>
> If it will be a call forwarding case of B(going to forward
> the call to c) receiving INVITE with MAX FORWARD=0,then it generate
> any error?
In the situation you show, where the message is sent by A with M-F:0, if
B is a forwarding proxy, then B must fail the message, with 483
response. It isn't permitted to forward in that case.
If the message was sent with M-F:1, then B could forward with M-F:0. In
that case, since C is a UAS, it won't be forwarding, and so the M-F:0 is
not an error.
Thanks,
Paul
> thanks in advance.
>
> pranab
> Brazil
>
> On 5/25/12, Paul Kyzivat<pkyzi...@alum.mit.edu> wrote:
>> On 5/25/12 10:26 AM, pranab sahoo wrote:
>>> Hi all,
>>>
>>> Thanks for providing a forum for healthy disscussion on SIP.
>>> I have an issue regarding MAX FORWARD
>>>
>>>
>>> Invite
>>> Max Forward=0
>>> A--------------------------------->B
>>>
>>> There is another user C.
>>> Actually my scenario is a call forwarding case,in which B going to
>>> forward the call.
>>>
>>> 302
>>> contact:c
>>> server<-------------------------------B
>>>
>>> Is max forward=0 has any role to discard the call and send error
>>> response to A.Or it will be as a normal call.
>>
>> What you show is redirection, not forwarding.
>> Because B is not forwarding the message, the M-F value of zero is not an
>> error, and its ok to return the 302. It then becomes A's responsibility
>> to detect a loop. For instance, if the 302 contained the address of B,
>> its A's responsibility to realize it has already tried B and shouldn't
>> do so again.
>>
>> If B were to act as a proxy and desire to forward the request to C, then
>> it would be obligated to notice that the M-F value is zero and instead
>> return a 483 response.
>>
>> Thanks,
>> Paul
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>
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