Subject: [SIP] Contiguos CSeq number

From: Christer Holmberg <[email-masked]>
Date: Tue, 17 Oct 2000 08:56:13 +0300

Hi,

I have a question about the CSeq number value.

Consider the following case:

A UAC sends a request to a UAS using CSeq=1.

The UAC then sends another request to the same UAS using CSeq=2.
However, for some reason the UAS never gets the request. It may, for
example, be terminated by an intermediate proxy, sending a response to
it, or it may be cancelled before it reaches the UAS.

After that, the UAC sends a third request, using CSeq=3, to the UAS.

So, the UAS will receive two requests, the first and the third, but not
the second.

Chapter 6.20 in the RFCbis says that the CSeq number must be contiguous.
However, in this case the UAS will never receive the second request.
Should it "wait" for it (it will never arrive...) or what is the purpose
of the line in the RFCbis?

Regards,

Christer Holmberg
Ericsson Finland

---

From: "Robert Sparks" <[email-masked]>
Date: Wed, 18 Oct 2000 17:26:50 -0500

All a receiving UA can count on is strictly increasing CSeqs. It must not
care
about gaps. Consider UA A trying to send requests to UA B through a Proxy
that
challenges every request. UA B will only see every other CSeq value.

Emitting contiguous numbers helps ensure there is a large CSeq space (since
they cannot wrap) and helps with debugging :).

RjS

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of Christer Holmberg
> Sent: Tuesday, October 17, 2000 12:56 AM
> To: [email-masked]
> Subject: [SIP] Contiguos CSeq number
>
>
>
> Hi,
>

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