you've got the perfect application to encourage UDP lite adoption and
deployment here.
Lloyd Wood
http://about.me/lloydwood
From: Stewart Bryant [stbry...@cisco.com]
Sent: 15 January 2014 11:31
To: Randy Bush
Cc: Wood L Dr (Electronic Eng);
I don't think sayng 'oh, that error source is no longer a problem' disproves
Stone's overall point about undetected errors, though the
examples he uses from the technology of the day are necessarily
dated. Dismissing the overall point because the examples use obsolete
technology is throwing the
Stewart,
your 'I'm not in tunnel applications' suggests you've misunderstood
the argument here. The point is not to protect the tunnel traffic
(which can quite happily checksum itself), it is to protect everything
else on the network from misdelivery. It's not the tunnel application,
it's every
That's robustness _for the tunnelled traffic_.
Not for anything else sharing the network - that hasn't been instrumented and
measured.
Lloyd Wood
http://about.me/lloydwood
From: Curtis Villamizar [cur...@ipv6.occnc.com]
Sent: 15 January 2014 03:43
To:
Curtis
I suggest reading Stone's work, particularly
''When The CRC and TCP Checksum Disagree'
for discussion of corruption.
Particularly its conclusions: 'In the internet, that means
we are sending large volumes of incorrect data without
anyone noticing'.
The Layer-2 check is per link, not
Right, which is probably why routers today can count badly
checksum'ed Ethernet frames, but don't have the equivalent
for MPLS.
If Ethernet frames keep failing the check, you know you
have a local problem that needs fixing. That's why it's
instrumented.
Do any routers count TCP/UDP checksum
The origin of this discussion is zero UDP checksums and
http://www.ietf.org/mail-archive/web/ietf/current/msg85354.html
I suggest reading Jonathan Stone's papers and PhD thesis for a good
understanding of where errors can come from.
Lloyd Wood
http://about.me/lloydwood
Zero UDP checksums are being selected for convenience, without an appreciation
of the overall effects and costs on other traffic. I see this is occurring in
both tsvwg
and lisp, and it's probably happening elsewhere:
From the recently adopted by tsvwg draft:
Noel,
I'm claiming that IPv6 has only the pseudoheader checksum to prevent
misdelivery,
as the header checksum was removed from v6 (rather than simply covering
non-mutable fields,
and leaving out TTL).
When a UDP checksum is set to zero, there is a risk to the payload traffic
carried - which,
Joel,
I'd already read them, I explicitly referenced them in my mail that prompted
Noel's reply
(text not included below, I see - copy
at http://www.ietf.org/mail-archive/web/ietf/current/msg85351.html )
and I have explained where those RFCs have gone wrong.
Those proposed standards are written
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