Re: [tcpm] draft-eggert-tcpm-historicize-00
Joe Touch <touch@isi.edu> Mon, 28 June 2010 16:40 UTC
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Date: Mon, 28 Jun 2010 09:28:54 -0700
From: Joe Touch <touch@isi.edu>
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To: L.Wood@surrey.ac.uk
References: <20100609151532.8E75E28C0D0@core3.amsl.com><33D3BDE9-7E8D-4DF0-B8D5-BFFC66CF9C99@nokia.com><2262C708-DF9A-4DD9-9378-D84C5AF330AC@nokia.com><C304DB494AC0C04C87C6A6E2FF5603DB48105A5A82@NDJSSCC01.ndc.nasa.gov> <0C53DCFB700D144284A584F54711EC580A0CE306@xmb-sjc-21c.amer.cisco.com> <5FDC413D5FA246468C200652D63E627A0935F804@LDCMVEXC1-PRD.hq.netapp.com> <4C24F73F.9060402@isi.edu> <87877965-FBC4-4A67-917A-EB48BED2CBB1@surrey.ac.uk> <4C26424F.3020005@isi.edu> <9858250F-96F1-427A-A211-004A9FE3FE82@surrey.ac.uk> <4C264F64.4010908@isi.edu> <AE08BDBD-CD39-4BE0-9E93-DA669C67BE0D@surrey.ac.uk> <4C265435.3010601@isi.edu> <A3A73BD7-045B-4C56-ACCF-7D996D110BA5@surrey.ac.uk>
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Cc: tcpm@ietf.org, ananth@cisco.com, Anumita.Biswas@netapp.com
Subject: Re: [tcpm] draft-eggert-tcpm-historicize-00
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L.Wood@surrey.ac.uk wrote: > On 26 Jun 2010, at 20:25, Joe Touch wrote: >> The only way a packet is accepted erroneously at a receiver, but would cause an >> problem, would be: >> link check OK >> TCP (1s compl) checksum OK >> new checksum FAIL >> >> I.e., the only reason a new TCP checksum would be useful is in this case. If >> either of the link or existing TCP checks succeed, there's no new problem. > > An example of that scenario is an echo server: > http://en.wikipedia.org/wiki/Echo_protocol > http://www.faqs.org/rfcs/rfc862.html This RFC defines TCP and UDP echo services. Both loop data back to the source, but at "layer 7" to the transport protocols. Both create new transport packets to send data back - in fact, the TCP variant might have different segment boundaries, e.g., if the return path MTU is different. Both thus compute a new transport checksum, so errors in either would not be detected by a stronger transport checksum per se. > http://www.faqs.org/rfcs/rfc2075.html > > which swaps source and destination addresses. These are covered by the pseudo-header > check; ... > A stronger TCP checksum would detect this modification, and have to be > recomputed. much as payload checksums are recomputed through NAT boxes. The pseudoheader is not covered by the current proposal, specifically to support NAT traversal. Any device that recomputes the checksum on traversal (explicitly, or because that calculation is buried in the NIC and done automatically) will defeat the ability of the checksum to detect errors inside that node. The only L7-L7 protection would be a full transfer checksum, which is not being proposed. Joe
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Hagen Paul Pfeifer
- [tcpm] draft-eggert-tcpm-historicize-00 Lars Eggert
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Ron Bonica
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Hagen Paul Pfeifer
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Anantha Ramaiah (ananth)
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Lars Eggert
- [tcpm] draft-anumita-tcpm-stronger-checksum (was:… Lars Eggert
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Duke, Martin
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Hagen Paul Pfeifer
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Hagen Paul Pfeifer
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Alejandro Acosta
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Anantha Ramaiah (ananth)
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Scheffenegger, Richard
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Joe Touch
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Scheffenegger, Richard
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Scheffenegger, Richard
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Joe Touch
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Biswas, Anumita
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Biswas, Anumita
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Joe Touch
- Re: [tcpm] draft-anumita-tcpm-stronger-checksum Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Lars Eggert
- Re: [tcpm] draft-eggert-tcpm-historicize-00 David Ros
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Lars Eggert
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Alexander Zimmermann
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Yuchung Cheng
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Eddy, Wesley M. (GRC-MS00)[ASRC AEROSPACE CORP]
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Anantha Ramaiah (ananth)
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Scheffenegger, Richard
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Scheffenegger, Richard
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Fernando Gont
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Biswas, Anumita
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Biswas, Anumita
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 L.Wood
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 rick jones
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 rick jones
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Lars Eggert
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Scheffenegger, Richard
- Re: [tcpm] draft-eggert-tcpm-historicize-00 Joe Touch