Network Working Group F. Xia Internet-Draft Huawei Technologies Expires: August 22, 2009 February 18, 2009 Flow Binding in Proxy Mobile IPv6 draft-xia-netext-flow-binding-00 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." 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 August 22, 2009. 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. Xia Expires August 22, 2009 [Page 1] Internet-Draft Flow Binding in PMIPv6 February 2009 Abstract This document introduces extensions to Proxy Mobile IPv6 that allows networks dynamically binding IP flows to different interfaces of a mobile node. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . . 5 5. MAG Operation . . . . . . . . . . . . . . . . . . . . . . . . 7 6. LMA Operation . . . . . . . . . . . . . . . . . . . . . . . . 7 7. MN Operation . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. Message formats . . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Alternative Interface Indicator . . . . . . . . . . . . . 8 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 10. IANA considerations . . . . . . . . . . . . . . . . . . . . . 10 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 12.1. Normative References . . . . . . . . . . . . . . . . . . . 10 12.2. Informative references . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11 Xia Expires August 22, 2009 [Page 2] Internet-Draft Flow Binding in PMIPv6 February 2009 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 binding 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 Expires August 22, 2009 [Page 3] Internet-Draft Flow Binding in PMIPv6 February 2009 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. Xia Expires August 22, 2009 [Page 4] Internet-Draft Flow Binding in PMIPv6 February 2009 4. 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 Notification Exchange | | | |<-------------------------->| | | | 6 PBU(Flow Binding) | | | |--------------------------->| | | | | 7 Request | | | | |<------------| | | | | 8 Ack | | | | |------------>| | | | 9 PBA(Flow Binding) | | | |<---------------------------| | | | | 10 Packets | | | 11 Packets |<============| | |<=========================| | | | | | | 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 signalling from the mobile node, a mobile access gateway, herein acting as SMAG, sends a PBU to a LMA. Access Technology Type Option is carried in PBU. The LMA assigns a unique prefix for the mobile node through PBA message to SMAG. 3. SMAG extracts the prefix, and advertises it to the mobile node through Router Advertisement message. The mobile configure its address, herein acting as a SIP, through stateless address configuration procedure specified in [RFC4862]. Then, MN runs applications using this address, such as, VoIP,IPTV, and p2p Xia Expires August 22, 2009 [Page 5] Internet-Draft Flow Binding in PMIPv6 February 2009 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, herein acting as TIP. According to Proxy Mobile IPv6 specification [RFC5213], the SIP is different from TIP. 5. 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]. Alternative Interface Indicator option defined in Section 8.1 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. 6. Based on the mobile node's profile, or operator's policy, the SMAG decides to offload some traffic flows from IF1 to IF2. SMAG then sends 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. The LMA 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 may also inquire the TMAG through step 7 and 8 the acceptability of the offloading request. Step 7 and 8 are skipped if the LMA makes decision locally. 7. The LMA sends Generic Signaling Request message to the TMAG for inquiring if the offloading is allowed. Flow Identification option is included in the message. 8. The TMAG responses with 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 130 which means insufficient resources. 9. The LMA sends a PBA to indicate the operation result of the flow binding request. 10. All the offloaded packets with SIP as destination address are encapsulated with an additional outer header which destination address is TIP. Then the LMA processes the encapsulated packets as specified in [RFC5213], that is, the LMA forwards the packet through the bi-directional tunnel set up for IF2 of the mobile node. The redirected packets from the LMA to the TMAG have have two layer encapsulations. 11. The TMAG strips the outer layer encapsulation, and forwards the packets to the mobile node's IF2. The mobile node strips remaining encapsulation, and then processes the packets with SIP as the destination address. Xia Expires August 22, 2009 [Page 6] Internet-Draft Flow Binding in PMIPv6 February 2009 5. 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 triggering flow binding. o The SMAG is notified by a LMA the availability of other MAGs which the same mobile node currently attaches to. 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). FID and BID are mainly defined for mutiple-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. The same situation applies to FID. All BID and FID fields in Flow Identification option SHOULD be set to 0. 6. 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 is attaching to. Generic Signalling Request with Access Technology Type Option is used for this notification. 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 if accepting offloading request, the LMA SHOULD inquire other MAGs using Generic Signaling Request message. o Encapsulating downstream packets. Packets destining serving IP address SHOULD be encapsulated with an outer IP header which a target IP address and the LMA are the destination and source address respectively. The LMA then processes these encapsulated packets as specified in [RFC5213]. Xia Expires August 22, 2009 [Page 7] Internet-Draft Flow Binding in PMIPv6 February 2009 o Redirecting upstream packets. When the LMA receives packets belonging to a offloaded flow from a serving MAG, the LMA forwards the packets and the sends ICMP messages which destination address is the target address of the mobile node. The ICMP message serves as a notification so that the mobile node sends upstream packets of the offloaded flow through the target interface. When the target address is IPv4, the Type field of the ICMPv4 [RFC0792] SHOULD be set 3 (Destination Unreachable Message), and Code field SHOULD be set 5 (source route failed); When the target address is IPv6, the Type field of the ICMPv6 [RFC4443] SHOULD be set to 1 (Destination Unreachable Message), and Code field SHOULD be set to 6 (Reject route to destination). 7. 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. However, the mechanism described in this document is also applicable to the cast that different interfaces share an IP address. Thus, only one layer encapsulation is needed when the LMA process packets. When the mobile node receives a ICMP message from a target interface, the mobile node SHOULD use the target interface to send packets belonging to a flow which is described in the ICMP message. 8. Message formats 8.1. Alternative Interface Indicator A new option, Alternative Interface Indicator, is defined for use in Generic Signaling Request and Generic Signaling Acknowledgement messages exchanged between a local mobility anchor and a mobile access gateway. This option is used for advertising the availability of a new interface of a mobile node. Xia Expires August 22, 2009 [Page 8] Internet-Draft Flow Binding in PMIPv6 February 2009 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 | Reserved (R) | ATT | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Proxy CoA | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type TBD Length 8-bit unsigned integer indicating the length of the option in octets, excluding the type and length fields. This field MUST be set to 6 if Proxy CoA is IPv4, or 18 if Proxy CoA is IPv6. Reserved (R) This 8-bit field is unused for now. The value MUST be initialized to 0 by the sender and MUST be ignored by the receiver. Access Technology Type (ATT) An 8-bit field that specifies the access technology through which the mobile node is connected to the access link on the mobile access gateway. This field has the same meaning as the definition in Access Technology Type in RFC5213. Proxy CoA An IP address of a MAG to which a new interface is attaching. 9. 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. Xia Expires August 22, 2009 [Page 9] Internet-Draft Flow Binding in PMIPv6 February 2009 10. IANA considerations A new mobile option, Alternative Interface Indicator, is defined. Option type SHOULD be assigned by IANA. 11. Acknowledgements 12. References 12.1. 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 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. 12.2. Informative references [I-D.ietf-mext-flow-binding] Soliman, H., Montavont, N., Fikouras, N., and K. Kuladinithi, "Flow Bindings in Mobile IPv6 and Nemo Basic Support", draft-ietf-mext-flow-binding-01 (work in progress), February 2009. [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. Xia Expires August 22, 2009 [Page 10] Internet-Draft Flow Binding in PMIPv6 February 2009 Author's Address Frank Xia Huawei Technologies 1700 Alma Dr. Suite 500 Plano, TX 75075 Phone: +1 972-509-5599 Email: xiayangsong@huawei.com Xia Expires August 22, 2009 [Page 11]