Path: utzoo!mnetor!uunet!rlgvax!dennis
From: dennis@rlgvax.UUCP (Dennis.Bednar)
Newsgroups: comp.protocols.tcp-ip
Subject: TCP Keep-alives, also push bit
Message-ID: <900@rlgvax.UUCP>
Date: 14 Mar 88 22:20:55 GMT
Organization: Computer Consoles Inc, Reston VA
Lines: 24

How are TCP keep-alive request packets formatted?  Is this a
data-less TCP packet that doesn't advance the sender's
sequence number field?  What is the proper response; is it a
data-less packet (TCP hdr only) containing the same
acknowledgement number equal to the most recently transmitted copy
(ie a duplicate acknowledgement)?

As for the problem of some TCP implementations not responding
to "keep-alives", is this because the implementers decided
that it is unreasonable for the receiving TCP to respond to
a 0-length TCP data packet (ie a packet containing only the
TCP header)?

By the way, is the TCP "push" bit used for keep-alives?

And what exactly is the push bit used for?  Last time I
read the TCP spec, I saw the mention of the bit, but no
practical description of what to use it for.

-- 
FullName:	Dennis Bednar
UUCP:		{uunet|sundc}!rlgvax!dennis
USMail:		CCI; 11490 Commerce Park Dr.; Reston VA 22091
Telephone:	+1 703 648 3300