Subject: Query - TCP Window Advertisement.

From: "Srinivas" <[email-masked]>
Date: Fri, 7 Dec 2001 14:48:39 +0530

Hi all,

        I have a question regarding window zero advertisement during connection establishment process.

When a TCP at the receiver side receives a SYN packet when it has not got any resource( memory buffer) to support additional connections, how should it respond to the incoming SYN packet.
1) should it send a reset to the other end.
2) or should it send a SYN,ACK in response with a window advertisement of zero.

expecting ur reply.

Regards
srinivas

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From: Alan Cox <[email-masked]>
Date: Fri, 7 Dec 2001 09:40:58 +0000 (GMT)

> When a TCP at the receiver side receives a SYN packet when it has not =
> got any resource( memory buffer) to support additional connections, how =
> should it respond to the incoming SYN packet.
> 2) or should it send a SYN,ACK in response with a window advertisement =
> of zero.

3) drop it

Seriously - if you have a reasonable expectation you might be able to handle
it next time around, throw the frame away. The client will politely retry
and do back off until resource exists or the user gets bored.

If you want to implement some kind of queueing then syn|ack with window zero
is also perfectly reasonable, and will let you hold the connection and then
process it in order.

Sending a reset seems to be wrong in just about all cases. Its not that
nobody is listening on the port (which RST would be saying) its "give me a
minute I'll get around to you"

Alan

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From: Alan Cox <[email-masked]>
Date: Fri, 7 Dec 2001 09:40:58 +0000 (GMT)

3) drop it

Alan