Subject: [Sipping] Comments on draft-ietf-sipping-session-policy-req-00

From: "Miguel A. Garcia" <[email-masked]>
Date: Mon, 30 Jun 2003 12:44:50 +0300

Jonathan:

Here are some thoughts about the Session Policy requirements draft.

First, I am missing a general requirement that describes the general 
mechanism that we want. If you consider the General Requirements, there are 
  many of them explaining different aspects of the solution, but none that 
describes generally what is needed. I would expect something on these lines:

"A mechanism that provides SIP proxies with the ability to convey session 
related policies to SIP User Agents".

You have an open issue in REQ-SEC-4, questioning the validity of the 
requirement:
       The mechanism should allow proxies to ensure the
       confidentiality of the session policies, so that no one but the
       UAC or UAS can observe them.

I think it is a valid requirement. I foresee that the administrators would 
not like to disclose their policies to administrators of other domains. 
Although I suspect this information could be acquired by some other means.

The las issue I want to raise is related to the wireless scenario that you 
describe in the introduction:

    "In another application, SIP is used in a wireless network. The
    network provider has limited resources for media traffic. During
    periods of high activity, the provider would like to restrict codec
    usage on the network to lower rate codecs."

The thing is that I don't foresee dynamic changes in policies, depending on 
the traffic in the network. One could do it, of course, but requires some 
extra administration or having some sort of monitor that acts upon 
thresholds. Instead I foresee another scenario where the administrator has 
certain fixed policies that do not change often. For instance, an 
administrator could permanently disallow the G.711 codec because of the 
high bandwidth. I think this is an important issue to discuss, because the 
solution may go in one or another direction depending on the rate of the 
changes in policy. I would suggest to add a requirement regarding the 
expected changes in the policies.

Regards,

           Miguel

-- 
Miguel-Angel Garcia                     Oy LM Ericsson AB
                                         Jorvas, Finland
mailto:[email-masked]     Phone:  +358 9 299 3553
mailto:[email-masked]        Mobile: +358 40 5140002

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