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Versions: 00 01 02 03                                                   
Network Working Group                                             X. Xu
Internet Draft                                                   Huawei
Category: Standard Track
                                                            C Pignataro
                                                             M. Towsley
                                                                  Cisco

                                                                L. Yong
                                                                 Huawei

                                                                 Y. Lee
                                                                Comcast

                                                                 Y. Fan
                                                          China Telecom


Expires: May 2013                                     December 24, 2012


                          Encapsulating IP in UDP

                      draft-xu-softwire-ip-in-udp-00

Abstract

   Existing Softwire encapsulation technologies are not adequate for
   efficient load balancing of Softwire service traffic across IP
   networks. This document specifies additional Softwire encapsulation
   technology, referred to as IP-in-User Datagram Protocol (UDP), which
   can facilitate the load balancing of Softwire service traffic across
   IP networks.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."




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Internet-Draft          Encapsulating IP in UDP           December 2012

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on May 24, 2013.

Copyright Notice

   Copyright (c) 2009 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
   carefully, as they describe your rights and restrictions with
   respect to this document.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [RFC2119].

Table of Contents


   1. Introduction ................................................ 3
   2. Terminology ................................................. 3
   3. Encapsulation in UDP......................................... 3
   4. Processing Procedures ....................................... 4
   5. Security Considerations ..................................... 5
   6. IANA Considerations ......................................... 5
   7. Acknowledgements ............................................ 5
   8. References .................................................. 5
      8.1. Normative References ................................... 5
      8.2. Informative References ................................. 6
   Authors' Addresses ............................................. 6









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1. Introduction

   To fully utilize the bandwidth available in IP networks and/or
   facilitate recovery from a link or node failure, load balancing of
   traffic over Equal Cost Multi-Path (ECMP) and/or Link Aggregation
   Group (LAG) across IP networks is widely used. In practice, most
   existing core routers in IP networks support distributing IP traffic
   flows over ECMP paths and/or LAG based on the hash of the five-tuple
   of User Datagram Protocol (UDP)[RFC768] and Transmission Control
   Protocol (TCP) packets (i.e., source IP address, destination IP
   address, source port, destination port, and protocol).

   [RFC5640] describes a method for improving the load balancing
   efficiency in a network carrying Softwire Mesh service [RFC5565]
   over Layer Two Tunneling Protocol - Version 3 (L2TPv3) [RFC3931] and
   Generic Routing Encapsulation (GRE)[RFC2784] encapsulations. However,
   this method requires core routers to perform hash calculation on the
   "load-balancing" field contained in tunnel encapsulation headers
   (i.e., the Session ID field in L2TPv3 headers or the Key field in
   GRE headers), which is not widely supported by existing core routers.

   Since most existing core routers support balancing IP traffic flows
   based on the hash of the five-tuple of UDP packets, encapsulating
   Softwire service traffic into UDP will immediately enable existing
   core routers to perform efficient load-balancing without any change
   to them.

   Due to above reasons, this specification defines an IP-in-UDP
   encapsulation method for Software service accordingly.

2. Terminology

   This memo makes use of the terms defined in [RFC5565].

3. Encapsulation in UDP

   IP-in-UDP encapsulation format is shown as follows:












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   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Source Port = entropy      |       Dest Port = IP          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           UDP Length          |        UDP Checksum           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         IP Packet                             ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Source Port of UDP

                This field contains an entropy value that is generated
                by the ingress PE router. For example, the entropy value
                can be generated by performing hash calculation on
                certain fields in the customer packets (e.g., the five
                tuple of UDP/TCP packets).

            Destination Port of UDP

                This field is set to a value (TBD) indicating the
                encapsulated payload in the UDP header is an IP packet.
                As for whether the encapsulated IP packet is IPv4 or
                IPv6, it would be determined according to the Version
                field in the IP header of the encapsulated IP packet.

            UDP Length

                The usage of this field is in accordance with the
                current UDP specification [RFC768].

            UDP Checksum

                The usage of this field is in accordance with the
                current UDP specification. To simplify the operation on
                egress PE routers, this field is recommended to be set
                to zero.

4. Processing Procedures

   When an ingress AFBR receives an E-IP [RFC5565] packet from a
   client-facing interface and the next-hop is the I-IP [RFC5565]
   address of an engress AFBR, the ingress must encapsulate the packet
   into UDP packet and forward the packet over the tunnel. The ingress




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   AFBR SHOULD generate the entropy value and put it in the Source Port
   field of the UDP header.

   Transit routers, upon receiving these UDP encapsulated packets, may
   load-balance these packets based on the hash of the five-tuple of
   UDP packets.

   When the egress AFBR receives an E-IP packet from the ingress AFBR
   over the Softwire interface, the egress AFBR MUST decapsulate the
   UDP header and forward the packet accordingly.

   5. Encapsulation Considerations

   Similar to all other Softwire tunneling technologies, IP-in-UDP
   encapsualtion introduces overhead and reduces the effective Maximum
   Transmision Unit (MTU) size. IP-in-UDP encapsulation may also impact
   Time-to-Live (TTL) and Differentiated Services (DSCP). Hence, IP-in-
   UDP MUST follow the procedures defined in [RFC2003].

   If an ingress AFBR performs fragmentation on an E-IP packet before
   encapsulating, it MUST use the same source UDP port for all
   fragmented packets. This ensures the transit routers will forward
   the fragmented packets on the same data path.

5. Security Considerations

   The security consideration for IP-in-UDP encapsulation format is the
   same as that for the existing Softwire encapsulation methods for
   Softwire service such as IP-in-IP.

6. IANA Considerations

   A new UDP destination port number which indicates the encapsulated
   payload following the UDP header is an IP packet needs to be
   assigned by IANA.

7. Acknowledgements

   Thanks to Vivek Kumar (Broadcom Corporation) for his valuable
   comments on the initial idea of this draft.

8. References

   8.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.



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   8.2. Informative References

   [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
             October 1996.

   [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
             for IPv6 Hosts and Routers", RFC 4213, October 2005.

   [RFC5565] Wu, J., Cui, Y., Metz, C. and E. Rosen, "Softwire Mesh
             Framework", RFC 5565, June 2009.

   [RFC5640] Filsfils, C., Mohapatra, P., and C. Pignataro, "Load-
             Balancing for Mesh Softwires", RFC 5640, August 2009.

   [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
             Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
             March 2000.

   [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
             Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.

   [RFC768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
             August 1980.

   [I-D.ietf-6man-udpchecksums] Eubanks, M., Chimento, P., and M.
             Westerlund, "UDP Checksums for Tunneled Packets",
             draft-ietf-6man-udpchecksums-04 (work in progress),
             September 2012.

   [I-D.ietf-6man-udpzero] Fairhurst, G. and M. Westerlund,
             "Applicability Statement for the use of IPv6 UDP Datagrams
             with Zero Checksums", draft-ietf-6man-udpzero-07 (work in
             progress), October 2012.

Authors' Addresses

   Xiaohu Xu
   Huawei Technologies,
   Beijing, China
   Phone: +86-10-60610041
   Email: xuxiaohu@huawei.com


   Carlos Pignataro
   Cisco Systems
   7200-12 Kit Creek Road
   Research Triangle Park, NC  27709



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Internet-Draft          Encapsulating IP in UDP           December 2012

   USA
   EMail: cpignata@cisco.com


   Mark Townsley
   Cisco
   Paris,
   France
   Email: mark@townsley.net


   Lucy Yong
   Huawei USA
   5340 Legacy Dr.
   Plano TX75025
   Phone: 469-277-5837
   Email: Lucy.yong@huawei.com


   Yiu Lee
   Comcast
   One Comcast Center
   Philadelphia, PA 1903
   USA
   Email: Yiu_Lee@Cable.Comcast.com


   Yongbing Fan
   China Telecom
   Guangzhou, China.
   Phone: +86 20 38639121
   Email: fanyb@gsta.com