Subject: [lisp] (#11) Do we still have a reason to ignore non-zero UDP checksums?

From: Sam Hartman <[email-masked]>
Date: Tue, 25 Aug 2009 11:23:04 -0400

Hi.  So it sounds like from discussions between Darrel, Noel and
Margaret last week, Last week, discussion between Darrel, Noel and
Margaret indicated that Darrel is unaware of NATs that replace 0 UDP
checksums with invalid UDP checksums.

Are their remaining arguments in favor of permitting a receiver to
ignore a non-zero UDP checksum?

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From: Dino Farinacci <[email-masked]>
Date: Tue, 25 Aug 2009 08:46:00 -0700

> ignore a non-zero UDP checksum?

There is still the cost of doing it in router hardware. That, in and  
of itself, is reason to ignore it regardless if the encapsulator is  
setting the UDP checksum to zero or non-zero.

Dino

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From: Marshall Eubanks <[email-masked]>
Date: Tue, 25 Aug 2009 12:36:50 -0400

On Aug 25, 2009, at 11:23 AM, Sam Hartman wrote:

> checksums with invalid UDP checksums

This is clearly not a protocol compliant behavior. Will they do this  
in 10 years ? Should protocols be limited
for all time because of what "widely-deployed, buggy NAT boxes" do now ?

I would be in favor (of Margaret's 3 choices)

(1) Decide that it is not that important for LISP to work across those  
buggy NAT boxes (or that other things are more important), AND  
convince the IETF that is okay to send zero UDP checksums in IPv6.

As for what to do with incorrect buggy NAT checksums, I would say that  
these MAY be ignored by implementations of LISP (i.e., that these be  
left to implementors).

Regards
Marshall

Regards
Marshall

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