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Internet Engineering Task Force (IETF)                S. Gundavelli, Ed.Request for Comments: 6909                                         CiscoCategory: Standards Track                                        X. ZhouISSN: 2070-1721                                          ZTE Corporation                                                             J. Korhonen                                                          Renesas Mobile                                                                G. Feige                                                               R. Koodli                                                                   Cisco                                                              April 2013IPv4 Traffic Offload Selector Option for Proxy Mobile IPv6Abstract   This specification defines a new mobility option, the IPv4 Traffic   Offload Selector option, for Proxy Mobile IPv6.  This option can be   used by the local mobility anchor and the mobile access gateway for   negotiating IPv4 traffic offload policy for a mobility session.   Based on the negotiated IPv4 traffic offload policy, a mobile access   gateway can selectively offload some of the IPv4 traffic flows in the   access network instead of tunneling back to the local mobility anchor   in the home network.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 inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6909.Gundavelli, et al.           Standards Track                    [Page 1]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013Copyright Notice   Copyright (c) 2013 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.  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.Table of Contents1. Introduction ....................................................22. Conventions and Terminology .....................................42.1. Conventions ................................................42.2. Terminology ................................................43. Solution Overview ...............................................43.1. IPv4 Traffic Offload Selector Option .......................63.2. MAG Considerations .........................................83.3. LMA Considerations .........................................94. Protocol Configuration Variables ...............................115. IANA Considerations ............................................116. Security Considerations ........................................127. Acknowledgements ...............................................128. References .....................................................138.1. Normative References ......................................138.2. Informative References ....................................131.  Introduction   Mobile operators are expanding their network coverage by integrating   various access technology domains (e.g., Wireless LAN, CDMA, and   Long-Term Evolution (LTE)) into a common IP mobility core.  The Third   Generation Partnership Project (3GPP) S2a Proxy Mobile IPv6 [TS23402]   reference point, specified by the 3GPP system architecture, defines   the protocol interworking for building such integrated multi-access   networks.  In this scenario, the mobile node's IP traffic is always   tunneled back from the mobile access gateway [RFC5213] in the access   network to the local mobility anchor in the home network.  Currently,   there is no mechanism for allowing some of the subscriber's IP flows   to be offloaded in the access network.Gundavelli, et al.           Standards Track                    [Page 2]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013   With the exponential growth in mobile data traffic, mobile operators   are exploring new ways to offload some of the IP traffic flows at the   nearest access edge.  The offload is intended either for local   service access in the access network or for Internet offload through   the access network when there is an Internet peering point.  Not all   IP traffic flows need to be routed back to the home network; the   traffic that does not require IP mobility support can be offloaded at   the mobile access gateway in the access network.  This approach   allows efficient usage of the mobile packet core, which helps in   lowering transport costs.  To identify the IP flows that need to be   offloaded, the local mobility anchor in the home network can deliver   the IP flow policy to the mobile access gateway in the access   network.  It is up to an operator's discretion to classify the   traffic for offload.  One operator might choose to offload everything   except traffic (such as Voice over IP) that requires QoS services.   Another might choose to offload only HTTP traffic.  This   specification is only concerned with matching IP traffic against a   given flow selector and classification of IP traffic for offloading   purposes.  This approach has one limitation with respect to   identifying encrypted traffic: IPsec-encrypted traffic with no   visibility into the application payload cannot be selected for   offload.   This document defines a new mobility option, the IPv4 Traffic Offload   Selector option (seeSection 3.1), for Proxy Mobile IPv6 (PMIPv6).   This option can be used by the local mobility anchor and the mobile   access gateway for negotiating IPv4 traffic offload policy for a   mobility session.  This IPv4 traffic offload policy identifies the   flow selectors that can be used for selecting the flows that can be   offloaded at the access edge.  Since the mobile node's IP address   topologically belongs to the home network, the offloaded IPv4 traffic   flows may need to be NAT [RFC2663] translated.  These offloaded flows   will not have mobility support as the NAT becomes the anchor point   for those flows.  However, when the traffic is offloaded for local   service access as opposed to Internet offload, NAT translation may   not be needed if the mobile access gateway is in the path for the   return traffic.  The decision on when to apply NAT translation can be   based on local configuration on the mobile access gateway.  There are   better ways to address the offload problem for IPv6, and with the   goal not to create a NAT66 requirement, this specification therefore   does not address traffic offload support for IPv6 flows.Gundavelli, et al.           Standards Track                    [Page 3]

RFC 6909          IPv4 Traffic Offload Selector Option        April 20132.  Conventions and Terminology2.1.  Conventions   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 inRFC 2119 [RFC2119].2.2.  Terminology   All the mobility-related terms used in this document are to be   interpreted as defined in the base Proxy Mobile IPv6 specifications   [RFC5213] [RFC5844].  Additionally, this document uses the following   terms:   IP Flow      IP flow [RFC5101] represents a set of IP packets that match a      traffic selector (TS).  The selector is typically based on the      source IP address, destination IP address, source port,      destination port, and other fields in upper-layer headers.   IP Traffic Offload      IP traffic offload is the approach of selecting specific IP flows      and routing them through the access network instead of tunneling      them to the home network.  Offload can also be between two access      networks (e.g., moving some of the traffic from LTE access to WLAN      access).3.  Solution Overview   Figure 1 illustrates the scenario where the mobile access gateway in   an access network has enabled IPv4 traffic offload support for a   mobility session.  The offload decision is based on the IPv4 traffic   offload policy that it negotiated with the local mobility anchor in   the home network.  For example, all the HTTP flows may be offloaded   at the mobile access gateway, and all the other flows for that   mobility session are tunneled back to the local mobility anchor.  The   offloaded flows typically have to be NAT translated, and this   specification does not impose any restrictions on the location of the   NAT function.  It is possible for the NAT function to be co-located   with the mobile access gateway or located somewhere at the edge of   the access network.  When the NAT function is not co-located with the   mobile access gateway, offloaded traffic flows must be delivered   through the local access network between the mobile access gateway   and the NAT function, for example, through a VLAN or a point-to-point   link.  The exact means for this delivery are outside the scope ofGundavelli, et al.           Standards Track                    [Page 4]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013   this document.  If the offloaded IPv4 flows are for local service   access and reverse traffic from the local service device can be   routed to the mobile node through the mobile access gateway, the   offloaded flows may be delivered directly to a local service device.   The traffic selectors in the IPv4 traffic offload policy are used to   classify the traffic, so it can be offloaded at the access network.   These parameters include source IP address, destination IP address,   TCP/UDP port numbers, and other fields.  The format of the IPv4   binary traffic selector is specified inSection 3.1 of [RFC6088].                                      _----_                                    _(      )_                 :-----------------( Internet )---------------:                 |                  (_      _)                |                 |                    '----'                  |                 |                                            |                 :                                            |      (IPv4 Traffic Offload Point)                            |                 :                                            |                 |                                            |      ........................................................|....                 |                              |             |      +--------+ |                   +---------------------+  |      |  Local | |                   | Services requiring  |  |      |Services| |                   | mobility, or service|  |      +--------+ |                   | treatment           |  |           |     |                   +---------------------+  |           |   +---+                            |             |           |   |NAT|                            |             |           |   +---+                            |             |           +-----|            _----_            |             |              +-----+       _(      )_       +-----+          |      [MN]----| MAG |======(    IP    )======| LMA |----------              +-----+       (_      _)       +-----+  Internet                              '----'                                 .                                 .          [Access Network]       .        [Home Network]      ..........................................................             Figure 1: IPv4 Traffic Offload Support at the MAG   Figure 2 explains the operational sequence of the Proxy Mobile IPv6   protocol signaling message exchange between the mobile access gateway   (MAG) and the local mobility anchor (LMA) for negotiating the IPv4   traffic offload selectors.  The details related to DHCP transactions   or Router Advertisements on the access link are not shown here asGundavelli, et al.           Standards Track                    [Page 5]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013   that is not the key focus of this specification.  The use of IPv4   Traffic Selector option in the Proxy Binding Update is for allowing   the MAG to request the LMA for the IPv4 traffic offload policy.      MN    MAG(NAT)   LMA      |------>|        |    1.  Mobile Node Attach      |       |------->|    2.  Proxy Binding Update (IPv4TS)      |       |<-------|    3.  Proxy Binding Acknowledgement (IPv4TS)      |       |========|    4.  Tunnel/Route Setup      |       +        |    5.  Installing the traffic offload rules      |------>|        |    6.  IPv4 packet from mobile node      |       +        |    7.  Offload rule applied (Tunnel/offload)      |       |        |           Figure 2: Exchange of IPv4 Traffic Offload Selectors3.1.  IPv4 Traffic Offload Selector Option   A new mobility option, the IPv4 Traffic Offload Selector option (53),   is defined for use in Proxy Binding Update (PBU) and Proxy Binding   Acknowledgement (PBA) messages exchanged between a mobile access   gateway and a local mobility anchor.  This option is used for   carrying the IPv4 traffic offload policy.  This policy identifies the   IPv4 traffic flow selectors that can be used by the mobile access   gateway for enforcing the offload policy.   The alignment requirement for this option is 4n.   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                                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                                   |      Type     |   Length      |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |M|                         Reserved                            |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |                  Traffic Selector Sub-option   ...   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+              Figure 3: IPv4 Traffic Offload Selector Option   Type      53   Length      8-bit unsigned integer indicating the length in octets of the      option, excluding the type and length fields.Gundavelli, et al.           Standards Track                    [Page 6]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013   Offload Mode (M) Flag      This field indicates the offload mode.         If the (M) flag value is set to a value of (0), it is an         indication that the IPv4 flow(s) that match the traffic         selectors in the Traffic Selector sub-option [RFC6089] and that         are associated to that mobility session have to be offloaded at         the mobile access gateway.  All the other IPv4 flows associated         with that mobility session and not matching the traffic         selectors have to be tunneled to the local mobility anchor.         If the (M) flag value is set to a value of (1), it is an         indication that all the IPv4 flows associated to that mobility         session except the IPv4 flow(s) matching the traffic selectors         in the Traffic Selector sub-option have to be offloaded at the         mobile access gateway.  All the IPv4 flows associated with that         mobility session and matching the traffic selectors have to be         tunneled back to the local mobility anchor.   Reserved      This field is unused for now.  The value MUST be initialized to 0      by the sender and MUST be ignored by the receiver.   Traffic Selector Sub-option      The Traffic Selector sub-option includes the parameters used to      match packets for a specific flow binding.  This is an optional      sub-option when the IPv4 Traffic Selector option is carried in a      Proxy Binding Update message but is a mandatory sub-option when      the IPv4 Traffic Selector option is carried in a Proxy Binding      Acknowledgement message.  The format of the Traffic Selector sub-      option is defined inSection 4.2.1.4 of [RFC6089].  This sub-      option includes a TS Format field, which identifies the format of      the flow specification included in that sub-option.  The values      for that field are defined inSection 3 of [RFC6088] and are      repeated here for completeness.  When the value of the TS Format      field is set to (1), the format that follows is the IPv4 binary      traffic selector specified inSection 3.1 of [RFC6088], and that      support is mandatory for this specification.  The text specified      in this section takes precedence over what is specified in      [RFC6088] and [RFC6089].         1: IPv4 binary traffic selector         2: IPv6 binary traffic selector (not used by this         specification)Gundavelli, et al.           Standards Track                    [Page 7]

RFC 6909          IPv4 Traffic Offload Selector Option        April 20133.2.  MAG Considerations   o  If the mobile access gateway is configured to enable IPv4 traffic      offload support, then it includes the IPv4 Traffic Offload      Selector option (Section 3.1) in the Proxy Binding Update message      that it sends to the local mobility anchor.  Optionally, the      mobile access gateway can also propose a specific offload policy.      *  The mobile access gateway MAY choose not to propose any         specific IPv4 traffic offload policy but request the local         mobility anchor for the offload policy.  In this scenario, the         IPv4 Traffic Offload Selector option that is carried in the         Proxy Binding Update message does not include the Traffic         Selector sub-option (seeSection 3.1), and the (M) flag (seeSection 3.1) in the option MUST be set to a value of (0).         Including the IPv4 Traffic Offload Selector option in the Proxy         Binding Update without the Traffic Selector sub-option serves         as an indication that the mobile access gateway is not         proposing any specific offload policy for that mobility         session, but rather it makes a request to the local mobility         anchor to provide the offload policy.      *  The mobile access gateway MAY choose to propose a specific IPv4         traffic offload policy by including the Traffic Selector sub-         option in the IPv4 Traffic Offload Selector option (seeSection 3.1).  The specific details on how the mobile access         gateway obtains the mobile node's IPv4 traffic offload policy         are outside the scope of this document.  When this offload         policy is included in the Proxy Binding Update message, it         serves as a proposal to the local mobility anchor.  The local         mobility anchor can override with its own offload policy, or it         can agree to the proposed policy.  The offload policy has to be         translated to a set of selectors that can be used to match the         mobile node's IP flows, and these selectors have to be carried         in the Traffic Selector sub-option.  The Traffic Selector sub-         option MUST be constructed as specified inSection 4.2.1.4 of         [RFC6089].  This sub-option includes a TS Format field, which         identifies the format of the flow specification included in the         sub-option.  The values for that field and the corresponding         message format are defined inSection 3.1 of [RFC6088].         Considerations fromSection 3.1 apply with respect to setting         the Offload Mode (M) flag.   o  When sending a Proxy Binding Update either for Binding Lifetime      Extension or for Binding De-Registration, the mobile access      gateway SHOULD copy the IPv4 Traffic Offload Selector option from      the initial Proxy Binding Update message.  Considerations from      Sections6.9.1.3 and6.9.1.4 of [RFC5213] MUST be applied.Gundavelli, et al.           Standards Track                    [Page 8]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013   o  If the mobile access gateway is not configured to support IPv4      traffic offload support as specified in this specification, but if      the received Proxy Binding Acknowledgement message has the IPv4      Traffic Offload Selector option, then the mobile access gateway      MUST ignore the option and process the rest of the message as per      [RFC5213].   o  If there is no IPv4 Traffic Offload Selector option in the Proxy      Binding Acknowledgement message received from the local mobility      anchor, it is an indication that the local mobility anchor did not      enable IPv4 traffic offload support for that mobility session.      Upon accepting the Proxy Binding Acknowledgement message, the      mobile access gateway SHOULD NOT enable IPv4 traffic offload      support for that mobility session.   o  If there is an IPv4 Traffic Offload Selector option in the Proxy      Binding Acknowledgement message, then the mobile access gateway      SHOULD enable IPv4 traffic offload support for that mobility      session.  The mobility access gateway has to provision the data      plane using the flow selectors present in the Traffic Selector      sub-option.  The IPv4 flows matching the flow selectors have to be      offloaded or tunneled back based to the local mobility anchor      based on the value of the Offload Mode (M) flag (seeSection 3.1).3.3.  LMA Considerations   o  If the received Proxy Binding Update message does not include the      IPv4 Traffic Offload Selector option (Section 3.1), then the local      mobility anchor MUST NOT enable IPv4 traffic offload support for      that mobility session, and the Proxy Binding Acknowledgement      message that will be sent in response MUST NOT contain the IPv4      Traffic Offload Selector option.   o  If the Proxy Binding Update message includes the IPv4 Traffic      Offload Selector option, but the local mobility anchor is not      configured to support IPv4 traffic offload support, then the local      mobility anchor will ignore the option and process the rest of the      message as per [RFC5213].  This would have no effect on the      operation of the rest of the protocol.   o  If the Proxy Binding Update message has the IPv4 Traffic Offload      Selector option and if the local mobility anchor is configured to      support IPv4 traffic offload support, then the local mobility      anchor MUST enable IPv4 traffic offload support for that mobility      session.  The Proxy Binding Acknowledgement message that will be      sent in response MUST include the IPv4 Traffic Offload Selector      option.  The following considerations apply with respect to      constructing the IPv4 Traffic Offload Selector option.Gundavelli, et al.           Standards Track                    [Page 9]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013      *  The local mobility anchor can obtain the offload policy from         the local configuration store or from a network function such         as AAA (Authentication, Authorization, and Accounting) or PCRF         (Policy and Charging Rule Function).  The offload policy has to         be translated to a set of selectors that can be used to match         the mobile node's IP flows, and these selectors have to be         carried in the Traffic Selector sub-option.  The Traffic         Selector sub-option MUST be constructed as specified inSection4.2.1.4 of [RFC6089].  Considerations fromSection 3.1 apply         with respect to the Offload Mode (M) flag setting.      *  If the Proxy Binding Update message includes a specific IPv4         traffic offload policy proposal in the form of the Traffic         Selector sub-option [RFC6089], then the local mobility anchor         MAY choose to agree to that request by including the same IPv4         traffic offload policy in the Proxy Binding Acknowledgement         message.  This implies the local mobility anchor has agreed to         the IPv4 traffic offload policy provided by the mobile access         gateway.  The local mobility anchor MAY also choose to override         the request by including a different IPv4 traffic offload         policy that it wants the mobile access gateway to enforce for         that mobility session.  This is entirely based on the policy         configuration on the local mobility anchor.      *  The IPv4 traffic offload policy that is sent to the mobile         access gateway has to be specific to the mobility session         identified using the Mobile Node Identifier option [RFC5213].         The offload policy MUST be specific to a mobile node's         application traffic.  The traffic selectors have to match only         the mobile node's application traffic and MUST NOT match any         other mobile node's IP traffic.  Furthermore, control-plane         traffic such as DHCP, Neighbor Discovery (ND), or any other IP         traffic that is used for IP address configuration, mobility         management, or other control-plane functions MUST NOT be         subject to offload.      *  The local mobility anchor MUST NOT make any changes to the         mobile node's offload policy during the middle of a mobility         session, as long as the mobile node continues to attach to the         mobile access gateway that negotiated the offload policy.         However, when the mobile node performs an inter-MAG handover,         the new mobile access gateway may not be capable of supporting         IP Traffic offload and in this scenario, the offload policy may         change.  Therefore, the IPv4 Traffic Selector option with the         Traffic Selector sub-option that is delivered during the         initial mobility signaling MUST be the same as the one that is         delivered as part of the mobility signaling related to lifetime         extension from the same mobile access gateway.Gundavelli, et al.           Standards Track                   [Page 10]

RFC 6909          IPv4 Traffic Offload Selector Option        April 20134.  Protocol Configuration Variables   This specification defines the following configuration variable that   controls the IPv4 traffic offload support feature.  This   configuration variable is internal to the system and has no bearing   on interoperability across different implementations.   The mobility entities, local mobility anchor, and the mobile access   gateway have to allow these variables to be configured by the system   management.  The configured values for these protocol variables have   to survive server reboots and service restarts.   EnableIPv4TrafficOffloadSupport         This flag indicates whether or not IPv4 traffic offload support         needs to be enabled.  This configuration variable is available         at both the mobile access gateway and the local mobility         anchor.  The default value for this flag is set to (0),         indicating that IPv4 traffic offload support is disabled.         When this flag on the mobile access gateway is set to a value         of (1), the mobile access gateway has to enable IPv4 traffic         offload support for all mobility sessions, by specifically         requesting the IPv4 traffic offload policy from the local         mobility anchor by including the IPv4 Traffic Offload Selector         option in the Proxy Binding Update message.  If the flag is set         to a value of (0), the mobile access gateway has to disable         IPv4 traffic offload support for all mobility sessions.         Similarly, when this flag on the local mobility anchor is set         to a value of (1), the local mobility anchor has to enable IPv4         traffic offload support.  If the local mobility anchor chooses         to enable IPv4 traffic offload support when there is an offload         policy specified for a mobile node, it has to deliver the IPv4         traffic offload policy to the mobile access gateway by         including the IPv4 Traffic Offload Selector option in the Proxy         Binding Acknowledgement message.5.  IANA Considerations   Per this specification, IANA has assigned a new mobility option: the   IPv4 Traffic Offload Selector option (53).  This option is described   inSection 3.1.  The Type value for this option has been assigned   from the same numbering space as allocated for the other mobility   options [RFC6275].Gundavelli, et al.           Standards Track                   [Page 11]

RFC 6909          IPv4 Traffic Offload Selector Option        April 20136.  Security Considerations   The IPv4 Traffic Offload Selector option defined in this   specification is for use in Proxy Binding Update and Proxy Binding   Acknowledgement messages.  This option is carried like any other   mobility header option as specified in [RFC5213].  Therefore, it   inherits from [RFC5213] its security guidelines and does not require   any additional security considerations.  Carrying IPv4 traffic   offload selectors does not introduce any new security   vulnerabilities.   When IPv4 traffic offload support is enabled for a mobile node, the   mobile access gateway selectively offloads some of the mobile node's   IPv4 traffic flows to the access network.  Typically, these offloaded   flows get NAT translated, which essentially introduces certain   vulnerabilities that are common to any NAT deployment.  These   vulnerabilities and the related considerations have been well   documented in the NAT specification [RFC2663].  There are no   additional considerations above and beyond what has already been   documented by the NAT specifications and that are unique to the   approach specified in this document.   The mobile node's home network may be equipped with firewall and   other security devices to guard against any security threats.  When   IPv4 traffic offload support is enabled, it potentially exposes the   mobile node to some security risks in the access network.  This   threat can be mitigated by deploying the security features both in   the access network and in the home network.   When IPv4 traffic offload support is enabled for a mobile node, some   of the IP flows are sent through the home network, and some other IP   flows are routed through the access network.  This potentially   introduces some complexity with respect to enabling diagnostics or   monitoring on the user traffic.  The tools that are used for such   diagnostics have to be aware of the offload policy that in enabled in   the network.7.  Acknowledgements   The authors would like to thank Ahmad Muhanna, Basavaraj Patil,   Carlos Bernardos, Eric Voit, Frank Brockners, Hidetoshi Yokota, Marco   Liebsch, Mark Grayson, Pierrick Seite, Ryuji Wakikawa, Steve Wood,   Barry Leiba, Sean Turner, Pete Resnick, Wesley Eddy, Mary Barnes,   Vincent Roca, Ralph Droms, Scott Bradner, Stephen Farrell, Adrian   Farrel, Benoit Claise, and Brian Haberman for all the reviews and   discussions related to the topic of IPv4 traffic offload.Gundavelli, et al.           Standards Track                   [Page 12]

RFC 6909          IPv4 Traffic Offload Selector Option        April 20138.  References8.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,              and B. Patil, "Proxy Mobile IPv6",RFC 5213, August 2008.   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy              Mobile IPv6",RFC 5844, May 2010.   [RFC6088]  Tsirtsis, G., Giarreta, G., Soliman, H., and N. Montavont,              "Traffic Selectors for Flow Bindings",RFC 6088,              January 2011.   [RFC6089]  Tsirtsis, G., Soliman, H., Montavont, N., Giaretta, G.,              and K. Kuladinithi, "Flow Bindings in Mobile IPv6 and              Network Mobility (NEMO) Basic Support",RFC 6089,              January 2011.   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support              in IPv6",RFC 6275, July 2011.8.2.  Informative References   [RFC2663]  Srisuresh, P. and M. Holdrege, "IP Network Address              Translator (NAT) Terminology and Considerations",RFC 2663, August 1999.   [RFC5101]  Claise, B., "Specification of the IP Flow Information              Export (IPFIX) Protocol for the Exchange of IP Traffic              Flow Information",RFC 5101, January 2008.   [TS23402]  3GPP, "Architecture enhancements for non-3GPP accesses",              2010.Gundavelli, et al.           Standards Track                   [Page 13]

RFC 6909          IPv4 Traffic Offload Selector Option        April 2013Authors' Addresses   Sri Gundavelli (editor)   Cisco   170 West Tasman Drive   San Jose, CA  95134   USA   EMail: sgundave@cisco.com   Xingyue Zhou   ZTE Corporation   No.68 Zijinghua Rd   Nanjing   China   EMail: zhou.xingyue@zte.com.cn   Jouni Korhonen   Renesas Mobile   Porkkalankatu 24   Helsinki  FIN-00180   Finland   EMail: jouni.nospam@gmail.com   Gaetan Feige   Cisco   France   EMail: gfeige@cisco.com   Rajeev Koodli   Cisco   3650 Cisco Way   San Jose, CA  95134   USA   EMail: rkoodli@cisco.comGundavelli, et al.           Standards Track                   [Page 14]