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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group X. Xu 2 Internet Draft Huawei 3 Category: Standard Track 4 C Pignataro 5 M. Towsley 6 Cisco 8 L. Yong 9 Huawei 11 Y. Lee 12 Comcast 14 Y. Fan 15 China Telecom 17 Expires: May 2013 December 24, 2012 19 Encapsulating IP in UDP 21 draft-xu-softwire-ip-in-udp-00 23 Abstract 25 Existing Softwire encapsulation technologies are not adequate for 26 efficient load balancing of Softwire service traffic across IP 27 networks. This document specifies additional Softwire encapsulation 28 technology, referred to as IP-in-User Datagram Protocol (UDP), which 29 can facilitate the load balancing of Softwire service traffic across 30 IP networks. 32 Status of this Memo 34 This Internet-Draft is submitted to IETF in full conformance with 35 the provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF), its areas, and its working groups. Note that 39 other groups may also distribute working documents as Internet- 40 Drafts. 42 Internet-Drafts are draft documents valid for a maximum of six 43 months and may be updated, replaced, or obsoleted by other documents 44 at any time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 46 The list of current Internet-Drafts can be accessed at 47 http://www.ietf.org/ietf/1id-abstracts.txt. 49 The list of Internet-Draft Shadow Directories can be accessed at 50 http://www.ietf.org/shadow.html. 52 This Internet-Draft will expire on May 24, 2013. 54 Copyright Notice 56 Copyright (c) 2009 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (http://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with 64 respect to this document. 66 Conventions used in this document 68 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 69 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 70 document are to be interpreted as described in RFC-2119 [RFC2119]. 72 Table of Contents 74 1. Introduction ................................................ 3 75 2. Terminology ................................................. 3 76 3. Encapsulation in UDP......................................... 3 77 4. Processing Procedures ....................................... 4 78 5. Security Considerations ..................................... 5 79 6. IANA Considerations ......................................... 5 80 7. Acknowledgements ............................................ 5 81 8. References .................................................. 5 82 8.1. Normative References ................................... 5 83 8.2. Informative References ................................. 6 84 Authors' Addresses ............................................. 6 86 1. Introduction 88 To fully utilize the bandwidth available in IP networks and/or 89 facilitate recovery from a link or node failure, load balancing of 90 traffic over Equal Cost Multi-Path (ECMP) and/or Link Aggregation 91 Group (LAG) across IP networks is widely used. In practice, most 92 existing core routers in IP networks support distributing IP traffic 93 flows over ECMP paths and/or LAG based on the hash of the five-tuple 94 of User Datagram Protocol (UDP)[RFC768] and Transmission Control 95 Protocol (TCP) packets (i.e., source IP address, destination IP 96 address, source port, destination port, and protocol). 98 [RFC5640] describes a method for improving the load balancing 99 efficiency in a network carrying Softwire Mesh service [RFC5565] 100 over Layer Two Tunneling Protocol - Version 3 (L2TPv3) [RFC3931] and 101 Generic Routing Encapsulation (GRE)[RFC2784] encapsulations. However, 102 this method requires core routers to perform hash calculation on the 103 "load-balancing" field contained in tunnel encapsulation headers 104 (i.e., the Session ID field in L2TPv3 headers or the Key field in 105 GRE headers), which is not widely supported by existing core routers. 107 Since most existing core routers support balancing IP traffic flows 108 based on the hash of the five-tuple of UDP packets, encapsulating 109 Softwire service traffic into UDP will immediately enable existing 110 core routers to perform efficient load-balancing without any change 111 to them. 113 Due to above reasons, this specification defines an IP-in-UDP 114 encapsulation method for Software service accordingly. 116 2. Terminology 118 This memo makes use of the terms defined in [RFC5565]. 120 3. Encapsulation in UDP 122 IP-in-UDP encapsulation format is shown as follows: 124 0 1 2 3 125 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 1 126 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 | Source Port = entropy | Dest Port = IP | 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | UDP Length | UDP Checksum | 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 | | 132 ~ IP Packet ~ 133 | | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 Source Port of UDP 138 This field contains an entropy value that is generated 139 by the ingress PE router. For example, the entropy value 140 can be generated by performing hash calculation on 141 certain fields in the customer packets (e.g., the five 142 tuple of UDP/TCP packets). 144 Destination Port of UDP 146 This field is set to a value (TBD) indicating the 147 encapsulated payload in the UDP header is an IP packet. 148 As for whether the encapsulated IP packet is IPv4 or 149 IPv6, it would be determined according to the Version 150 field in the IP header of the encapsulated IP packet. 152 UDP Length 154 The usage of this field is in accordance with the 155 current UDP specification [RFC768]. 157 UDP Checksum 159 The usage of this field is in accordance with the 160 current UDP specification. To simplify the operation on 161 egress PE routers, this field is recommended to be set 162 to zero. 164 4. Processing Procedures 166 When an ingress AFBR receives an E-IP [RFC5565] packet from a 167 client-facing interface and the next-hop is the I-IP [RFC5565] 168 address of an engress AFBR, the ingress must encapsulate the packet 169 into UDP packet and forward the packet over the tunnel. The ingress 170 AFBR SHOULD generate the entropy value and put it in the Source Port 171 field of the UDP header. 173 Transit routers, upon receiving these UDP encapsulated packets, may 174 load-balance these packets based on the hash of the five-tuple of 175 UDP packets. 177 When the egress AFBR receives an E-IP packet from the ingress AFBR 178 over the Softwire interface, the egress AFBR MUST decapsulate the 179 UDP header and forward the packet accordingly. 181 5. Encapsulation Considerations 183 Similar to all other Softwire tunneling technologies, IP-in-UDP 184 encapsualtion introduces overhead and reduces the effective Maximum 185 Transmision Unit (MTU) size. IP-in-UDP encapsulation may also impact 186 Time-to-Live (TTL) and Differentiated Services (DSCP). Hence, IP-in- 187 UDP MUST follow the procedures defined in [RFC2003]. 189 If an ingress AFBR performs fragmentation on an E-IP packet before 190 encapsulating, it MUST use the same source UDP port for all 191 fragmented packets. This ensures the transit routers will forward 192 the fragmented packets on the same data path. 194 5. Security Considerations 196 The security consideration for IP-in-UDP encapsulation format is the 197 same as that for the existing Softwire encapsulation methods for 198 Softwire service such as IP-in-IP. 200 6. IANA Considerations 202 A new UDP destination port number which indicates the encapsulated 203 payload following the UDP header is an IP packet needs to be 204 assigned by IANA. 206 7. Acknowledgements 208 Thanks to Vivek Kumar (Broadcom Corporation) for his valuable 209 comments on the initial idea of this draft. 211 8. References 213 8.1. Normative References 215 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 216 Requirement Levels", BCP 14, RFC 2119, March 1997. 218 8.2. Informative References 220 [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, 221 October 1996. 223 [RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms 224 for IPv6 Hosts and Routers", RFC 4213, October 2005. 226 [RFC5565] Wu, J., Cui, Y., Metz, C. and E. Rosen, "Softwire Mesh 227 Framework", RFC 5565, June 2009. 229 [RFC5640] Filsfils, C., Mohapatra, P., and C. Pignataro, "Load- 230 Balancing for Mesh Softwires", RFC 5640, August 2009. 232 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 233 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 234 March 2000. 236 [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling 237 Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. 239 [RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 240 August 1980. 242 [I-D.ietf-6man-udpchecksums] Eubanks, M., Chimento, P., and M. 243 Westerlund, "UDP Checksums for Tunneled Packets", 244 draft-ietf-6man-udpchecksums-04 (work in progress), 245 September 2012. 247 [I-D.ietf-6man-udpzero] Fairhurst, G. and M. Westerlund, 248 "Applicability Statement for the use of IPv6 UDP Datagrams 249 with Zero Checksums", draft-ietf-6man-udpzero-07 (work in 250 progress), October 2012. 252 Authors' Addresses 254 Xiaohu Xu 255 Huawei Technologies, 256 Beijing, China 257 Phone: +86-10-60610041 258 Email: xuxiaohu@huawei.com 260 Carlos Pignataro 261 Cisco Systems 262 7200-12 Kit Creek Road 263 Research Triangle Park, NC 27709 264 USA 265 EMail: cpignata@cisco.com 267 Mark Townsley 268 Cisco 269 Paris, 270 France 271 Email: mark@townsley.net 273 Lucy Yong 274 Huawei USA 275 5340 Legacy Dr. 276 Plano TX75025 277 Phone: 469-277-5837 278 Email: Lucy.yong@huawei.com 280 Yiu Lee 281 Comcast 282 One Comcast Center 283 Philadelphia, PA 1903 284 USA 285 Email: Yiu_Lee@Cable.Comcast.com 287 Yongbing Fan 288 China Telecom 289 Guangzhou, China. 290 Phone: +86 20 38639121 291 Email: fanyb@gsta.com