[SIPForum-discussion] About Resource Priority header in SIP

[Deepanshu]

Hi All,

I'm a new subscriber to this mailing list. I need some suggestion and clarification regarding RFC4412 and 4412 (SIP extension for Resource priority). 

 

I studied both the documents and understood the main idea behind these specifications. RFC4412 is about utilizing the resources at SIP entities (Proxies, UA etc) to entertain the high priority session request by preempting (reason for preemption is specified using 'Reason' header in the SIP BYE) the lower priority session request. The specification defines five unique namespace DSN, DRSN, Q735, ETS and WPS. All these namespace have the list of relative priority values.

 

The UAC can generate the 'Resource-Priority' header filed for request that require elevated resource access priority. For example UAC can include the Resource-Priority: dsn.flash (the priority level in dsn namespace are dsn.routine, dsn.priority, dsn.immediate, dsn.flash, dsn.flash-override in the increasing order of their priority) in the SIP INVITE. On receiving the SIP INVITE request UAS MUST terminate a session established with a lower-priority value in favor of a new session setup with a higher relative priority value.

 

Now the question is, who decide the priority of a particular session request? Is it UAC? If it is UAC, then I wonder what will happen in the situation where every UAC is sending session request intentionally with the highest priority to let its session accepted by the UAS. Will one of the UAC get the monopoly over the UAS? Will every request result in the termination of the current session? Both of these results are not at all feasible. 

 

Does the current specification deals with this kind of situation?

 

I request you all to please help and give some comments asap.

 

Thank you all in advance for you help

 

Best Regards

 

Deepanshu Gautam

R&D Engineer

Huawei Technologies Co.,Ltd.

 

 

 
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