Network Working Group F. Xia Internet-Draft B. Sarikaya Expires: December 27, 2010 Huawei USA June 25, 2010 Flow Binding in Proxy Mobile IPv6 draft-xia-netext-flow-binding-02 Abstract This document introduces extensions to Proxy Mobile IPv6 that allows networks dynamically binding IP flows to different interfaces of a mobile node. Mobile Access Gateways can move flows to other mobile access gateways by establishing flow bindings at the local mobility anchor. Local mobility anchor sends packets from the offloaded flow seamlessly to the new mobile access gateway. 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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on December 27, 2010. Copyright Notice Copyright (c) 2010 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. 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 Xia & Sarikaya Expires December 27, 2010 [Page 1] Internet-Draft Flow Binding in PMIPv6 June 2010 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Design Assumptions and Principles . . . . . . . . . . . . . . 4 5. Protocol Operation . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Other Enhancements . . . . . . . . . . . . . . . . . . . . 7 6. MAG Operation . . . . . . . . . . . . . . . . . . . . . . . . 7 7. LMA Operation . . . . . . . . . . . . . . . . . . . . . . . . 8 8. MN Operation . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. Message formats . . . . . . . . . . . . . . . . . . . . . . . 9 9.1. Target Care-of-Address sub-option . . . . . . . . . . . . 9 10. Security Considerations . . . . . . . . . . . . . . . . . . . 10 11. IANA considerations . . . . . . . . . . . . . . . . . . . . . 10 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 13.1. Normative References . . . . . . . . . . . . . . . . . . . 10 13.2. Informative references . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Xia & Sarikaya Expires December 27, 2010 [Page 2] Internet-Draft Flow Binding in PMIPv6 June 2010 1. Introduction Assume a mobile node equipped with two interfaces namely IF1 (e.g. 3GPP) and IF2 (e.g WiFi), and IF1 is active while IF2 is not activated. There are two flows running on IF1, that is, VoIP and file downloading. At some time, e.g., the mobile node moves into a WiFi hotspot, IF2 becomes active, and the file downloading flow is then offloaded to IF2 while VoIP flow remains on IF1. When the mobile node moves out of the hotspot, the file downloading flow is moved back to IF1 again. In this document, a flow is defined as one or more connections that are identified by a flow identifier. A single connection is typically identified by the source and destination IP addresses, transport protocol number and the source and destination port numbers. [I-D.ietf-mext-flow-binding] allows a mobile node to bind a particular flow to a care-of address without affecting other flows using the same home address. Flow Identification option is defined and included in Binding Update (BU) / Binding Acknowledgement(BA) messages. However, the mechanism specified in the document can't be directly applied to Proxy Mobile IPv6 in which the mobile node is not involved in mobility management. A Mobile Access Gateway (MAG) is then introduced to take on mobility management on behalf of the mobile node. This document introduces extensions to Proxy Mobile IPv6 that allows networks dynamically bind IP flows to different interfaces of a mobile node. In the aforementioned scenario, the IF1 attaches to a mobile access gateway forwarding VoIP and file downloading flows at the beginning. When the mobile node moves into a WiFi hotspot, IF2 becomes active and connects to another mobile access gateway which then takes over file downloading flow. Based on operator policy or the mobile node profile, the mobile access gateways may signal a Local Mobility Anchor (LMA) to redirect flows from one to another. 2. Terminology 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 [RFC2119]. The terminology in this document is based on the definitions in [RFC5213], in addition to the ones specified in this section. Xia & Sarikaya Expires December 27, 2010 [Page 3] Internet-Draft Flow Binding in PMIPv6 June 2010 Serving Interface: a mobile node's interface on which some application flows are running. Based on the MN's profile, operator's policy, or other reasons, some of the flows are supposed to be offloaded to the other interfaces of the mobile node when they become available. Target Interface: a mobile node's interface which is taking over some application flows from a serving interface of the mobile node. Serving IP Address (SIP): an IPv4 or IPv6 address configured on a serving interface. Target IP Address (TIP): an IPv4 or IPv6 address configured on a target interface. Serving Mobile Access Gateway(SMAG): A mobile access gateway which a serving interface attaches to. Target Mobile Access Gateway(TMAG): A mobile access gateway which a target interface attaches to. 3. Use Cases Michael is using 3GPP access to different services with different characteristics in terms of QoS requirements and bandwidth: o a VoIP call. o a non-conversational video streaming, e.g.IPTV. o a p2p download. When Michael gets into his home where WiFi access is available, Michael prefers running the p2p download and IPTV through the WiFi network, and leaving the VoIP call still on 3GPP networks. At some time, Michael's device starts ftp file synchronization with a backup server. Due to the synchronization, the WiFi access becomes congested and the IPTV flow is then moved back to 3GPP access. After a while, Michael moves out of his home and loses the WiFi connectivity. Triggered by this event, all the IP flows through the WiFi access need to be moved to the 3GPP access which is the only access available. 4. Design Assumptions and Principles The following are assumptions and principles when this solution is Xia & Sarikaya Expires December 27, 2010 [Page 4] Internet-Draft Flow Binding in PMIPv6 June 2010 proposed. o This document only deals with scenarios that multiple interfaces of a mobile node are registered at the same local mobility anchor. o This document also tries to avoid any new layer 2 or layer 3 protocols introduced between a mobile node and a mobile access gateway. o Mobile access gateways can detect attachments or detachments of mobile nodes through existing layer 2 mechanism (e.g. 3GPP, WiMAX, or WiFi). The attachment or detachment events can serve as triggers for mobile access gateways to initiate flow mobility procedure. o There are no direct communications among mobile access gateways to which multiple interfaces of a mobile node attach. One mobile access gateway may be able to learn the presence of another mobile access gateway through message exchanges with the common local mobility anchor. o When a local mobility anchor receives a flow binding request from a mobile access gateway, it can make a decision by itself or consult a mobile access gateway to which the flow will move. 5. Protocol Operation +--------+ +------+ +------+ +------+ | MN | | SMAG | | TMAG | | LMA | +--------+ +------+ +------+ +------+ IF1 IF2 | | | | | | | | | 1 Attachment | | | |<-------------->| 2 PBU&PBA | | 3 Addr Cfg |<-------------------------->| |<-------------->| | | Running | | | | Applications | | | | | 4 Attachment/PBU&PBA/Addr Cfg | | |<------------------------>|<----------->| | | | | | | | | 5 PBU(Flow Binding) | | | |--------------------------->| | | | | | | | 6 PBA(Flow Binding) | | | |<---------------------------| | | | | 7 Packets | | | 8 Packets |<============| | |<=========================| | | | | | | Xia & Sarikaya Expires December 27, 2010 [Page 5] Internet-Draft Flow Binding in PMIPv6 June 2010 Figure 1: Protocol Operation 1. A mobile node has two interfaces, IF1 and IF2. At the beginning, only IF1 is activated and attachment procedure is triggered. 2. On receiving attachment signaling from the mobile node, a mobile access gateway, acting as a SMAG, sends a PBU to a LMA. Access Technology Type Option defined in [RFC5213] is carried in the PBU. The LMA assigns a unique prefix for the mobile node through a PBA message to the SMAG. 3. The SMAG extracts the prefix, and advertises it to the mobile node through Router Advertisement message. The mobile node then configures its address, acting as a SIP, through stateless address configuration procedure specified in [RFC4862]. Then, the mobile node runs applications using this address, such as, VoIP,IPTV, and p2p downloading. 4. When the mobile node moves into some other places where IF2 is activated, the mobile node follows similar steps to 1,2,3 to configure IP address for IF2, acting as TIP. According to Proxy Mobile IPv6 specification [RFC5213], this is an attachment over a new interface with the Handoff Indicator field set to a value of 1 and the SIP is different from TIP. Here the binding cache entry is modified as described in [I-D.sarikaya-netext-fb-support-extensions]. 5. Based on the mobile node's profile, operator's policy, or network status the SMAG decides to offload some traffic flows from IF1 to IF2. The SMAG then sends a PBU with Flow Identification option defined in [I-D.ietf-mext-flow-binding]. This message indicates the LMA to change the direction of the requested flows from the SMAG to the TMAG. SMAG first assigns a Flow Identifier (FID) value to this flow and then sets Action field to Forward. SMAG adds the flow description using the Traffic Selector sub-option. SMAG indicates TMAG address in Target Care-of-Address Sub-option defined in Section 9.1. 6. It is the LMA that makes a decision if offloading request is granted or not. The LMA may decide based on local information, such as, access technology types, bandwidth, service types, and so on. The LMA inquires the TMAG of acceptability of the offloading request and establishes this new flow at the TMAG. Section 5.1 explains message exchanges between the LMA and the SMAG. TMAG adds a new entry for this flow in its Flow Binding Entries Table. The LMA sends a PBA to indicate the operation result of the flow binding request. 7. All the offloaded packets with SIP as destination address (if it belongs to the home interface as described in [I-D.sarikaya-netext-fb-support-extensions]) received by LMA are encapsulated and sent to the TMAG. Xia & Sarikaya Expires December 27, 2010 [Page 6] Internet-Draft Flow Binding in PMIPv6 June 2010 8. The TMAG strips the encapsulation, and checks that an entry for this flow exists in the flow binding entries table and then forwards the packets to the mobile node's IF2. The mobile node then processes the packets with SIP as the destination address. 5.1. Other Enhancements It is helpful for a SMAG when initiating flow movement if the SMAG is aware of the presence of the potential TMAGs. This awareness can be achieved through notification from a local mobility anchor because all MAGs of mobile node are associated to the same local mobility anchor. The LMA notifies SMAG about IF2's presence through Generic Signaling Request / Generic Signaling Acknowledgement message exchanges specified in [I-D.ietf-mext-generic-signaling-message]. Flow Identification Mobility Option with Target Care-of Address sub-option defined in Section 9.1 is included in the message from the LMA to the SMAG. Through this message exchange, the SMAG has an idea of availability of other interfaces of the mobile node, and the address of the TMAG. To make a better decision, the LMA may send a Generic Signaling Request message to the TMAG for inquiring if the offloading is allowed. Flow Identification option is included in the message. The TMAG responds with a Generic Signaling Acknowledgment message. If the TMAG accepts the flows, the Status field of the message SHOULD be set to 0, otherwise, the field is set to a value of 128 or higher. Flow binding extensions described in [I-D.sarikaya-netext-fb-support-extensions] are assumed. These extensions are needed to avoid LMA sending packets with double encapsulation to MN over LMA-MAG tunnel after a particular flow is moved from one interface to another interface. The extensions require LMA to distinguish the home interface, e.g. 3G interface from the secondary interfaces, e.g. WiFi and the mobile node always uses the home interface address as the source address in the packets it sends over a virtual interface. 6. MAG Operation Flow binding is always initiated by a SMAG, that is, the SMAG wants to offload its traffic flow to other MAGs. There are several reasons for triggering flow binding. o The SMAG is notified by a LMA the availability of other MAGs which the same mobile node currently attaches to. Xia & Sarikaya Expires December 27, 2010 [Page 7] Internet-Draft Flow Binding in PMIPv6 June 2010 o Congestion occurs in the SMAG which knows there are other MAGs connecting to the same mobile node. o The SMAG detects the serving interface of the mobile node is out of service. o ... ... As to Flow Identification option used in this document, there are two fields needing special consideration, that is, Flow ID (FID) and Binding Identification number (BID). BID is mainly defined for multiple-interfaced mobile nodes with Mobile IPv6 functionalities. The BID is an identification number used to distinguish multiple bindings registered by the mobile node. Each BID is generated and managed by a mobile node in Mobile IPv6. In Proxy Mobile IPv6, mobility management of mobile nodes with multiple interfaces is run in different independent MAGs, and BID loses its meaning. All BID fields in Flow Identification option SHOULD be set to 0. In this document flows are identified using FID. FID is set by the initiator, e.g. SMAG. Thereafter it is used by all other entities like LMA and any other MAGs to which this flow is forwarded to. 7. LMA Operation The LMA is the center of the flow binding processing. It has following functionalities: o Advertising the availability of a new interface of a mobile node. When an interface of the mobile node becomes active, a corresponding MAG SHOULD sends a PBU to the LMA. Triggered by the PBU, the LMA then notifies all the other MAGs which the mobile node is attaching to. Generic Signalling Request with Flow Identification Mobility Option is used for this notification. The new MAG's address is sent in Target Care-of Address Sub-option. o Deciding if an offloading request is acceptable. On receiving PBU from a SMAG with a flow binding request, the LMA makes a decision based on operator's local policy, mobile node's preference, bandwidth of the flow, and so on. o Inquiring a TMAG for acceptability of the offloaded flows. If the LMA can't decide on accepting offloading request, the LMA SHOULD inquire other MAGs using Generic Signaling Request message with Flow Identification Mobility Option copying the fields from the PBU sent by the originating SMAG. TMAG sends a Generic Signaling Acknowledgement message and sets Status field to 0 indicating acceptance. TMAG also inserts the new flow in its flow binding entries table. o Redirecting upstream packets. In Mobile IPv6, the home agent tunnels the upstream packets to the Care-of Address indicated in the flow binding entry table for this flow. In Proxy Mobile IPv6, LMA keeps a flow binding entry table as in Xia & Sarikaya Expires December 27, 2010 [Page 8] Internet-Draft Flow Binding in PMIPv6 June 2010 [I-D.ietf-mext-flow-binding] and links binding cache entries for each mobile node to this table. The table contains an entry for each active flow that the mobile node has indicating to which MAG, i.e. Proxy-CoA1 to forward the flow to. LMA first matches the traffic selectors given in the table entry and then tunnels the packet to the corresponding MAG. Together with provisions in [I-D.sarikaya-netext-fb-support-extensions], the destination MAG can simply decapsulate the packet and forward to the mobile node's interface connected to this MAG. 8. MN Operation In this document, it is assumed that different interfaces are assigned different prefixes, and the same interface is configured with the same IP address even after resetting of the interface. Once one interface becomes inactive, the software SHOULD map the address to another interface, or to a virtual interface,so that ongoing sessions with the address can survive. When the interface becomes active again, and receive the same prefix from a LMA, the address SHOULD be moved back to the interface. 9. Message formats 9.1. Target Care-of-Address sub-option This section introduces the Target Care-of-Address, which may be included in the Flow Identification Mobility Option. This sub-option is used by the TMAG to indicate the Local Mobility Anchor to move a flow binding from SMAG to the Target Care-of Address, i.e. TMAG. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-opt Type | Sub-opt Len | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Target Care-of-Address | . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Target Care-of-Address Sub-option Xia & Sarikaya Expires December 27, 2010 [Page 9] Internet-Draft Flow Binding in PMIPv6 June 2010 Sub-opt Type To be assigned by IANA Sub-opt Len Length of the sub-option in 8-octet units Reserved This field is unused. It MUST be initialized to zero by the sender and MUST be ignored by the receiver. Target Care-of-Address An IP address of a MAG to which a new interface is attaching. This address could be IPv4 or IPv6 address. 10. Security Considerations This specification allows a mobile access gateway to offload traffic to other mobile access gateway. This mechanism facilitate a serving mobile access gateway to launch DoS attacks to a target mobile access gateway. However, a local mobility anchor finally decides acceptability of an offloading request, as mitigates DoS attacks threat. 11. IANA considerations A new mobile option, Alternative Interface Indicator, is defined. Option type SHOULD be assigned by IANA. 12. Acknowledgements TBD. 13. References 13.1. 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. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support Xia & Sarikaya Expires December 27, 2010 [Page 10] Internet-Draft Flow Binding in PMIPv6 June 2010 in IPv6", RFC 3775, June 2004. [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007. [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, September 1981. [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 4443, March 2006. 13.2. Informative references [I-D.ietf-mext-flow-binding] Soliman, H., Tsirtsis, G., Montavont, N., Giaretta, G., and K. Kuladinithi, "Flow Bindings in Mobile IPv6 and NEMO Basic Support", draft-ietf-mext-flow-binding-06 (work in progress), March 2010. [I-D.ietf-mext-generic-signaling-message] Haley, B. and S. Gundavelli, "Mobile IPv6 Generic Signaling Message", draft-ietf-mext-generic-signaling-message-00 (work in progress), August 2008. [I-D.sarikaya-netext-fb-support-extensions] Sarikaya, B. and F. Xia, "PMIPv6 Multihoming Support for Flow Mobility", draft-sarikaya-netext-fb-support-extensions-00 (work in progress), February 2010. Xia & Sarikaya Expires December 27, 2010 [Page 11] Internet-Draft Flow Binding in PMIPv6 June 2010 Authors' Addresses Frank Xia Huawei USA 1700 Alma Dr. Suite 500 Plano, TX 75075 Phone: +1 972-509-5599 Email: xiayangsong@huawei.com Behcet Sarikaya Huawei USA 1700 Alma Dr. Suite 500 Plano, TX 75075 Phone: +1 972-509-5599 Email: sarikaya@ieee.org Xia & Sarikaya Expires December 27, 2010 [Page 12]