From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rick Jones <rick.jones2@hp.com>
Subject: Re: TCP delayed ACK heuristic
Date: Wed, 19 Dec 2012 10:39:37 -0800
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Cc: David Laight <David.Laight@ACULAB.COM>, netdev@vger.kernel.org,
	Ben Greear <greearb@candelatech.com>,
	David Miller <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Stephen Hemminger <shemminger@vyatta.com>,
	Thomas Graf <tgraf@redhat.com>
To: Cong Wang <amwang@redhat.com>
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On 12/18/2012 11:00 PM, Cong Wang wrote:
> On Tue, 2012-12-18 at 16:39 +0000, David Laight wrote:
>> There are problems with only implementing the acks
>> specified by RFC1122.
>
> Yeah, the problem is if we can violate this RFC for getting better
> performance. Or it is just a no-no?
>
> Although RFC 2525 mentions this as "Stretch ACK Violation", I am still
> not sure if that means we can violate RFC1122 legally.

The term used in RFC1122 is "SHOULD" not "MUST."  Same for RFC2525 when 
it talks about "Stretch ACK Violation."   A TCP stack may have behaviour 
which differs from a SHOULD so long as there is a reasonable reason for it.

rick jones