IPv6 UDP Checksum Considerations
draft-ietf-6man-udpzero-05

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Last updated 2011-12-23 (latest revision 2011-10-25)
Replaces draft-6man-udpzero, draft-fairhurst-tsvwg-6man-udpzero
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Internet Engineering Task Force                             G. Fairhurst
Internet-Draft                                    University of Aberdeen
Intended status: Informational                             M. Westerlund
Expires: June 25, 2012                                          Ericsson
                                                       December 23, 2011

                    IPv6 UDP Checksum Considerations
                       draft-ietf-6man-udpzero-05

Abstract

   This document examines the role of the UDP transport checksum when
   used with IPv6, as defined in RFC2460.  It presents a summary of the
   trade-offs for evaluating the safety of updating RFC 2460 to permit
   an IPv6 UDP endpoint to use a zero value in the checksum field as an
   indication that no checksum is present.  This method is compared with
   some other possibilities.  The document also describes the issues and
   design principles that need to be considered when UDP is used with
   IPv6 to support tunnel encapsulations.  It concludes that UDP with a
   zero checksum in IPv6 can safely be used for this purpose, provided
   that this usage is governed by a set of constraints.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on June 25, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

Fairhurst & Westerlund    Expires June 25, 2012                 [Page 1]
Internet-Draft      IPv6 UDP Checksum Considerations       December 2011

   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Document Structure . . . . . . . . . . . . . . . . . . . .  4
     1.2.  Background . . . . . . . . . . . . . . . . . . . . . . . .  5
       1.2.1.  The Role of a Transport Endpoint . . . . . . . . . . .  5
       1.2.2.  The UDP Checksum . . . . . . . . . . . . . . . . . . .  5
       1.2.3.  Differences between IPv6 and IPv4  . . . . . . . . . .  7
     1.3.  Use of UDP Tunnels . . . . . . . . . . . . . . . . . . . .  7
       1.3.1.  Motivation for new approaches  . . . . . . . . . . . .  8
       1.3.2.  Reducing forwarding cost . . . . . . . . . . . . . . .  8
       1.3.3.  Need to inspect the entire packet  . . . . . . . . . .  9
       1.3.4.  Interactions with middleboxes  . . . . . . . . . . . .  9
       1.3.5.  Support for load balancing . . . . . . . . . . . . . . 10
   2.  Standards-Track Transports . . . . . . . . . . . . . . . . . . 10
     2.1.  UDP with Standard Checksum . . . . . . . . . . . . . . . . 10
     2.2.  UDP-Lite . . . . . . . . . . . . . . . . . . . . . . . . . 11
       2.2.1.  Using UDP-Lite as a Tunnel Encapsulation . . . . . . . 11
     2.3.  General Tunnel Encapsulations  . . . . . . . . . . . . . . 11
   3.  Issues Requiring Consideration . . . . . . . . . . . . . . . . 12
     3.1.  Effect of packet modification in the network . . . . . . . 13
       3.1.1.  Corruption of the destination IP address . . . . . . . 14
       3.1.2.  Corruption of the source IP address  . . . . . . . . . 14
       3.1.3.  Corruption of Port Information . . . . . . . . . . . . 15
       3.1.4.  Delivery to an unexpected port . . . . . . . . . . . . 15
       3.1.5.  Corruption of Fragmentation Information  . . . . . . . 16
     3.2.  Validating the network path  . . . . . . . . . . . . . . . 18
     3.3.  Applicability of method  . . . . . . . . . . . . . . . . . 19
     3.4.  Impact on non-supporting devices or applications . . . . . 20
   4.  Evaluation of proposal to update RFC 2460 to support zero
       checksum . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
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