TCP receiver and Duplicate packets

Ronny Tittoto <barret@dei.unipd.it> Thu, 28 February 2002 14:27 UTC

Date: Thu, 28 Feb 2002 15:27:08 +0100 (MET)
From: Ronny Tittoto <barret@dei.unipd.it>
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To: tcp-impl@grc.nasa.gov
Subject: TCP receiver and Duplicate packets
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Dear all,
I'm working on TCP performances over GPRS and UMTS networks.
I've observed a singular behaviour of TCP receiver in presence of
duplicate packets.
When a receiver receives a packet with sequence number equal to a packet
received before it reply with a duplicate ack.
For example:
- suppose the reciever has already received packets 1 to 40
- a packet with sequence number 35 arrives
- the receiver doesn't need this packet, it has already received it!
- the receiver reply with a multiple ack requesting packet 41.

My question is:
Why does the receiver replay when it receives an old packet already
received?
Is it an implementation need or a simplification?

Thanks a lot!
Best regards

Ronny   

._____________________________________________________________________. 
|Ronny Tittoto 380560/IL  barret@dei.unipd.it                         |
|                         ronny@chiara.dei.unipd.it                   |
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|                                                                     |
|_____________________________________________________________________|

TCP receiver and Duplicate packets Ronny Tittoto
Re: TCP receiver and Duplicate packets Philippe Ragon