Re: [sipcore] draft-ietf-sipcore-keep - Peter's comments

[Paul Kyzivat <[e-mail]>]

at end...

Christer Holmberg wrote:
> Hi Peter, 
> 
> Some proposed new/modified text based on your comments.
> 
>>> I have read draft-ietf-sipcore-keep in detail for the first time.
>>>
>>> I have one questions and some Nits.
>>>
>>> Question: 7.3 Should the TRYING (not shown) from P1 to Alice have 
>>> keep=30 in it? What if the 200 OK takes e.g. longer than 30sec and the 
>>> NAT pinhole closes?
>> It is true that the flow only shows the 200 OK, but the text 
>> in section 4.4 responses in general.
>>
>> I guess we could add some text that points out that the keep 
>> value should be sent as soon as possible, as it may take a 
>> while before the final response is sent.
> 
> What about the following new text in section 4.4.
> 
> 	"In the case of an INVITE request, if a SIP entity sends or forwards multiple responses (provisional and final) associated with the 
> 	request, and it indicates willingness to receive keep-alives, it only needs to insert a "keep" parameter value in one of the responses. The
> 	SIP entity SHOULD indicate the willingess to receive keep-alives as soon as possible."

You really need to consider reliable and unreliable provisionals separately.

Either restrict to reliable responses (provisional or final), or else 
allow in unreliable provisionals preceding a reliable response. (Which 
might get it going sooner.)

As we have seen with o/a, allowing in unreliable provisionals introduces 
complications, especially when changing values are used.

	Thanks,
	Paul