Subject: Re:

From: 王宏涛 <[email-masked]>
Date: Tue, 29 Oct 2002 15:53:50 +0800

hello all!

I have a confusion on the section 3.6 of prsctp draft. as following....

   "during processing of a FORWARD TSN, the receiver MUST
   use the stream sequence information to examine all of the listed
   stream reordering queues, and immediately make available for delivery
   stream sequence numbers earlier than or equal to the stream sequence
   number listed inside the FORWARD TSN.

   After receiving and processing a FORWARD TSN, ... The receiver MUST
   remove any partially reassembled message which is still missing one
   or more TSNs earlier than or equal to the new cumulative TSN point."

	Should the receiver delivery the full reliable messages which are not expired and t their SSN are earlier than or equal to the stream sequence number listed inside the FORWARD TSN, but they are still missing some chunks (their TSN is earlier than or equal to the new cumulative TSN point).
    If the receiver do so, the lifetime of full reliable messages are not usful.in fact the reliable messages are not reliable because they are delivered partially before the their lifetime expire.

--------------------------------------------------
Hongtao WANG
National Switching Technology and Communication Network Lab.
Beijing University of Posts and Telecommunications
Beijing ,100876,P.R.China
Tel:(+8610)-62283757
Email:[email-masked]
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From: "Randall Stewart (cisco)" <[email-masked]>
Date: Wed, 30 Oct 2002 07:38:04 -0600

Wang:

I will attempt to answer your question.

>   number listed inside the FORWARD TSN.

The above tells you that you are to deliver anything held in stream
reordering queues... so
if you get

SSN2, SSN3 ... and then get a FWD-TSN that tells you you can deliver up
to SSN3 (skipping
the TSN of SSN1) then you can deliver SSN2 and SSN3...

>	Should the receiver delivery the full reliable messages which are not expired and t their SSN are earlier than or equal to the stream sequence number listed inside the FORWARD TSN, but they are sti…

You would never get this situation...

Consider

SSN5 in TSN1, 2, 3, 4.

sent reliable

SSN6 in TSN5

sent unreliabile

SSN7 in TSN6

sent reliable.

Now lets say TSN5 is lost and dropped.. TSN3 is also missing. In this
case a fwd-tsn would
NOT be issued until the receiver sent a SACK that reported 1-4 present..

Anytime there are reliable un-ack'ed chunks outstanding the sender can
NOT send the FWD-TSN.
Once TSN4 is sacked .. then the sender would send a FWD-TSN (TSN5)---->
to the peer

Hope that helps..

R

-- 
Randall R. Stewart
ITD
Cisco Systems Inc.
[email-masked] 815-342-5222(cell) or 815-477-2127(office)