Flem, thanks for the confirmation.
Chuck, given the age of the RFC, I seriously doubt that Nagle intended the
router to do anything too complicated. My reading of RFC 896 implied that
the algorithm would be implemented in the end station - "Implementation
typically requires one or two lines inside a TCP program". However, "The
past is a different country" (probably misquoted) and for some of these
older RFCs I think I could use an interpreter :-)
RFC 2001 (and 2581, which obseletes it) doesn't mention Nagle - it's
talking about different algorithms.
The Cisco command reference I suspect was written by somebody who didn't
delve too deeply into what the command does. I guess I would have expected
some note pointing out that it only applies to sessions terminating at the
router, if that is the case, as most IOS commands affect through traffic
(OK, most commands don't deal with the transport layer...)
And how many people use XWindows to connect to a router?
JMcL
"Chuck Larrieu" <[EMAIL PROTECTED]>@groupstudy.com on 15/12/2000 05:29:54
pm
Please respond to "Chuck Larrieu" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
To: <[EMAIL PROTECTED]>
<[EMAIL PROTECTED]>
cc:
Subject: RE: Nagle's algorithm
Jen, I see your point. I just finished a quick read of RFC 896 (Congestion
Control in IP/TCP Internetworks)
Recognizing that TCP is responsible for end to end reliable data
communications, it would seem reasonable to think that the Nagle service
should not effect transit traffic.
On the other hand, the RFC does mention issues on slow links, and does
mention gateways ( routers ) in a couple of places in a way that imply that
the edge router is the place where the mechanism is best put to use. The
Cisco references I browsed appear to quote verbatim from the RFC, talking
about the single character of data in a TCP packet, and the overhead
involved. The further description of the service Nagle implies ( but does
not state - in my reading, anyway ) that a router running service Nagle
acts
as a host proxy, almost in a stateful manner, examining the behaviour of
the
traffic, and acting accordingly.
I'm too sleepy to attempt to get through RFC 2001 this evening. The intro
to
that one talks about modern TCP implementations, saying to me, anyway, that
maybe congestion control mechanisms such as Nagle are now built into end
station stacks.
What were your thoughts from your reading?
Chuck
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
[EMAIL PROTECTED]
Sent: Thursday, December 14, 2000 6:34 PM
To: [EMAIL PROTECTED]
Subject: Nagle's algorithm
Does setting 'service nagle' on a router have any effect on TCP sessions
transitting the router, or does it only have an effect on sessions that
terminate at the router?
Various bits on CCO vaguely imply that it affects through traffic, but
having read up on how Nagle's algorithm works, I can't see how it could -
as it works at the TCP layer, I think it should only affect sessions where
the router is a session endpoint.
Can anyone confirm this, or am I missing something?
Ta,
JMcL
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