Re: [sipcore] Session-timer: Result below an acceptable value

[OKUMURA Shinji <[e-mail]>]

Hi,

If a proxy decreases the S-E, the next proxy is more likely to reject
the request by 422.
So I think that a proxy should adjust the Min-SE rather than decrease
the S-E.
And ultimately, a UAS should decrease the S-E as low as possible after
considering it's own wishes.

Regards,
Shinji

On 2018/10/04 22:33, Christer Holmberg wrote:
> Hi,
>
>
> The UAS is not allowed to include Min-SE to begin with (unless it sends a 422 response).
>
>
> The UAS is currently allowed to reduce the S-E value in the response, as long as it it's larger than the Min-SE value in the corresponding request. My suggestion would be to say that a UAS SHOULD NOT reduce the S-E. Again, assuming the proxies know better how often they want session refreshes, there is no need for the UAS to reduce the value.
>
>
> Regards,
>
>
> Christer
>
>
>
> ________________________________
> From: [e-mail] <[e-mail]>
> Sent: Thursday, October 4, 2018 4:21 PM
> To: Christer Holmberg
> Cc: Roman Shpount; OKUMURA Shinji; SIPCORE
> Subject: Re: [sipcore] Session-timer: Result below an acceptable value
>
> Hi
> Reading this. I understand that the proxy should be allowed to increase the Min SE.
> For my understanding.
> Following that the UAS cannot lower it again. Correct?
> That would be my understanding.
>
> Best Regards
> Roland
>
> Am 04.10.2018 20:05 schrieb Christer Holmberg <[e-mail]>:
>
> Hi,
>
>
> In order to keep track of the suggested RFC modifications, I suggest that we create GitHub issues.
>
>
> As an example, I created one for Shinji's suggestion to allow a proxy to increase the Min-SE header field value.
>
>
> https://github.com/cdh4u/draft-sessiontimer-race/issues/1
>
> [https://avatars0.githubusercontent.com/u/9333380?s=400&v=4]<https://github.com/cdh4u/draft-sessiontimer-race/issues/1>
>
> Proxy allowed to increase Min-SE header field value · Issue #1 · cdh4u/draft-sessiontimer-race<https://github.com/cdh4u/draft-sessiontimer-race/issues/1>
> github.com
> BACKGROUND: Section 8.1 of RFC 4028 says: "A proxy MUST NOT insert a Min-SE header field or modify the value of an existing header field in a proxied request if that request contains a Support...
>
>
>
>
>
> (As always, any formal decision whether to modify something will be made on the list)
>
>
> Regards,
>
>
> Christer
>
>
>
>
> ________________________________
> From: sipcore <[e-mail]> on behalf of Christer Holmberg <[e-mail]>
> Sent: Thursday, October 4, 2018 2:43 PM
> To: Roman Shpount
> Cc: OKUMURA Shinji; SIPCORE
> Subject: Re: [sipcore] Session-timer: Result below an acceptable value
>
>
> Hi,
>
>
> Sorry, I read your first e-mail wrong: I thought you said that the proxy would DECREASE Min-SE. But, now I see that you talk about INCREASE 😊
>
>
> I see no reason why a proxy couldn't increase Min-SE.
>
>
> As we have learned, the main users of session timer are proxies, not UAs, so a UA should not care if the minimum value is increased.
>
>> Technically speaking UA still care about how often they need to generate refresh since this can result in extra load on the UA.
> Sure, but increasing the Min-SE value will not result in extra load - on the contrary it may reduce load :)
>
>> When session timer is negotiated, S-E specifies the max acceptable value and Min-SE specifies min acceptable value, so proxy should be able to increase Min-SE and decrease SE.
> Correct.
>
> Regards,
>
> Christer
>
>
>