Subject: RE: [Sipping] 100 and retransmissions

From: [email-masked]
Date: Tue, 11 Sep 2001 13:54:53 -0600

Stateless proxies will not generate a 100.  They will proxy it if received.
The 100 could be generated by a UAC or stateful proxy.  If the latter, it
then becomes responsponsible for handling any retransmits, so a single lost
request will not cause the transaction to fail.

-----Original Message-----
From: Terry L Anderson [mailto:[email-masked]]
Sent: Tuesday, September 11, 2001 11:01 AM
To: SIPPING Mailing List
Subject: [Sipping] 100 and retransmissions

Should a UAC cease retransmission of INVITE after receiving a 100
response?

bis-04 14.4.1 says:
    "The client ceases retramissions if it receives a provisional..."
and the state diagram in Figure 10 indicates the same.  These do not
appear to make 100 an exception.  However, 100 will often come from a
proxy rather from the far UAS.  I  believe that even a state-less proxy
will may send 100 but does not retransmit, so if the UAC also ceases
retransmissions, a single lost request may fail the transaction.

11.1 also states (with regard to 1xx):
    "...and clients can inquire about the current state of call
processing by re-sending the request."

which sound like UAC are at least allowed to retransmit after any 1xx.

It seems reasonable to cease retransmission after non-100 1xx's, but NOT
after receiving 100.  Am I missing something?

--

------------------------------------------------------------
Terry L Anderson              mailto:[email-masked]
Tel:908.582.7013   Fax:908.582.6729
Lucent Technologies/INS/Voice Over IP Access Networks
Rm 2B-121, 600 Mountain Av, Murray Hill, NJ 07974
http://its.lucent.com/~tla (Lucent internal) http://www.gti.net/tla

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---

From: Terry L Anderson <[email-masked]>
Date: Wed, 12 Sep 2001 10:07:49 -0400

Thanks.  I agree this will work fine if stateless proxies never generate 100.
Where is this restriction stated.  I could find no statement that stateless
proxies MUST NOT generate 100.

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