Applicability Statement for the Use of IPv6 UDP Datagrams with Zero Checksums
RFC 6936
Internet Engineering Task Force (IETF) G. Fairhurst
Request for Comments: 6936 University of Aberdeen
Category: Standards Track M. Westerlund
ISSN: 2070-1721 Ericsson
April 2013
Applicability Statement for the Use of IPv6 UDP Datagrams
with Zero Checksums
Abstract
This document provides an applicability statement for the use of UDP
transport checksums with IPv6. It defines recommendations and
requirements for the use of IPv6 UDP datagrams with a zero UDP
checksum. It describes the issues and design principles that need to
be considered when UDP is used with IPv6 to support tunnel
encapsulations, and it examines the role of the IPv6 UDP transport
checksum. The document also identifies issues and constraints for
deployment on network paths that include middleboxes. An appendix
presents a summary of the trade-offs that were considered in
evaluating the safety of the update to RFC 2460 that changes the use
of the UDP checksum with IPv6.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6936.
Fairhurst & Westerlund Standards Track [Page 1]
RFC 6936 Applicability of Zero UDP Checksum with IPv6 April 2013
Copyright Notice
Copyright (c) 2013 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
publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Fairhurst & Westerlund Standards Track [Page 2]
RFC 6936 Applicability of Zero UDP Checksum with IPv6 April 2013
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Document Structure . . . . . . . . . . . . . . . . . . . . 5
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Use of UDP Tunnels . . . . . . . . . . . . . . . . . . . . 6
1.3.1. Motivation for New Approaches . . . . . . . . . . . . 6
1.3.2. Reducing Forwarding Costs . . . . . . . . . . . . . . 6
1.3.3. Need to Inspect the Entire Packet . . . . . . . . . . 7
1.3.4. Interactions with Middleboxes . . . . . . . . . . . . 7
1.3.5. Support for Load Balancing . . . . . . . . . . . . . . 8
2. Standards-Track Transports . . . . . . . . . . . . . . . . . . 9
2.1. UDP with Standard Checksum . . . . . . . . . . . . . . . . 9
2.2. UDP-Lite . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.1. Using UDP-Lite as a Tunnel Encapsulation . . . . . . . 10
2.3. General Tunnel Encapsulations . . . . . . . . . . . . . . 10
2.4. Relationship of Zero UDP Checksum to UDP-Lite and UDP
with Checksum . . . . . . . . . . . . . . . . . . . . . . 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 Field . . . . 14
3.1.2. Corruption of the Source IP Address Field . . . . . . 15
3.1.3. Corruption of Port Information . . . . . . . . . . . . 16
3.1.4. Delivery to an Unexpected Port . . . . . . . . . . . . 16
3.1.5. Corruption of Fragmentation Information . . . . . . . 18
3.2. Where Packet Corruption Occurs . . . . . . . . . . . . . . 20
3.3. Validating the Network Path . . . . . . . . . . . . . . . 20
3.4. Applicability of the Zero UDP Checksum Method . . . . . . 21
3.5. Impact on Non-Supporting Devices or Applications . . . . . 22
4. Constraints on Implementation of IPv6 Nodes Supporting
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