Network Working Group D.Liu Internet Draft China Mobile Intended status: Standards Track J.SONG Expires: May 31, 2012 W.LUO ZTE December 1, 2011 PMIP Based Distributed Mobility Management Approach draft-liu-dmm-pmip-based-approach-01.txt 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), 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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Abstract Distributed mobility management (DMM) approach is needed, because the mobile networks are moving towards flat architectures. This document defines a PMIPv6 based distributed mobility management protocol. Liu, et. al Expires May 31, 2012 [Page 1] Internet-Draft Requirements of DMM December 2011 Table of Contents 1. Introduction ................................................... 2 2. Conventions used in this document .............................. 3 3. Overview of PMIP Based Distributed Mobility Management Approach .3 3.1. Basic Data Deliver Approaches ............................. 3 3.2. Handoff Approaches ........................................ 5 3.3. Locate Mobility Anchor Locating Considerations ............ 6 3.3.1. Depend on Configuration .............................. 7 4. Mobile Access Gateway Operation ................................ 7 4.1. Extensions to Binding Update List Entry Data Structure .... 7 4.2. Extended Operations for Mobile Access Gateway ............. 8 4.2.1. Receiving traffic generated by attached mobile node .. 8 4.2.2. Receiving traffic designated to attached mobile node . 8 5. Local Mobility Anchor Operation ................................ 9 5.1. Extensions to Binding Cache Entry Data Structure ........ 9 5.2. Extended Operations of Local Mobility Anchor ............ 9 6. Security Considerations ....................................... 10 7. IANA Considerations ........................................... 10 8. References .................................................... 10 8.1. Normative References ..................................... 10 8.2. Informative References ................................... 10 1. Introduction As the mobile networks are moving towards flat architectures, the distributed mobility management (DMM) approaches are needed to relieve many disadvantages of using centralized mobility management in a flatten network described in [DMM-PS]. Both mobile access gateway and local mobility anchor specified in this draft are fully compatible with [RFC5213] only with limited extensions to enable PMIP based distributed mobility management approaches. The enhanced mobile access gateway specified in this draft is extended to support determining of IP address of correspondent node's mobile access gateway when receiving traffic from its attached mobile node to enable a optimized routing between two communicating parties. Meanwhile, the local mobility anchor specified in this draft is extended to support the query of IP address of mobile node's mobile access gateway according to mobile node's HoA. Furthermore, this draft also considers the approaches in handoff scenario to guarantee the session continuity. Liu, et. al Expires May 31, 2012 [Page 2] Internet-Draft Requirements of DMM December 2011 2. 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]. 3. Overview of PMIP Based Distributed Mobility Management Approach PMIP based Distributed Mobility Management approach does not change basic PMIP architecture defined in [RFC5213], only with limited extension to both mobile access gateway and local mobility anchor to support distributed approaches. 3.1. Basic Data Deliver Approaches +-----+ +------+ +-----+ +------+ +-----+ | MN1 | | MAG1 | | LMA | | MAG2 | | MN2 | +-----+ +------+ +-----+ +------+ +-----+ | | | | | | 1.attach and PMIP Reg. | 1.attach and PMIP Reg. | |<------------|----------->|<------------|------------>| | | | | | |2.uplink Data| | | | |============>| 3. PBQR | | | | |----------->| | | | | 4. PBQA | | | | |<-----------| | | | +----------------+ | | | | | 5.Recording PB | | | | | | of the MN2 | | | | | +----------------+ | | | | | 6.uplink data | | | |=========================>| | | | | +---------------+ | | | | | 7.Recording PB| | | | | | of MN1 | | | | | +---------------+ | | | | |8.uplink data| | | | |============>| | | 9. Ongoing traffic | | |<===========>|<========================>|<===========>| | | | | | Figure1. Basic Data Delivery Approaches Liu, et. al Expires May 31, 2012 [Page 3] Internet-Draft Requirements of DMM December 2011 Figure1 shows basic data delivery approaches of PMIP based Distributed Mobility Management approaches specified in this draft. In the beginning, when mobile nodes enter Proxy Mobile IPv6 domain and attach to the access link, and if determines that the mobile nodes are authorized for network-based mobility service, the network performs standard PMIP approaches according to [RFC5213], i.e. PBU and PBA transaction, for mobile nodes to provide home prefixes for them. Some assumptions list as following: - Both communicating peers are mobile nodes, denoted as MN1 and MN2 respectively. - Both communicating peers have already attached to their mobile access gateways denoted as MAG1 and MAG2 respectively. When MN1 tries to establish a session with MN2, it sends IP packets denoted as uplink traffic to MN2. The uplink traffic will first arrive at MN1's MAG1. According to PMIP protocol [RFC5213], MAG1 will forward the uplink traffic to MN1's local mobility anchor (LMA) via a bi-directional tunnel between the two. In additional, as specified in this draft, MAG1 needs to determine how to forward the uplink traffic in a optimized way to enable distributed approaches by querying LMA the IP address of the mobile access gateway to which the MN2 attaches currently (i.e. MAG2) according to the MN2's HoA which is the destination IP address of the uplink traffic. For achieving this, MAG1 sends a PMIP Binding Query Request (PBQR) message which is a new message specified in this draft to related LMA who holds the Binding Cache Entry (BCE) for MN2. Based on the HoA of MN2, the LMA could derive the IP address of MAG2 in corresponding BCE. Then the LMA sends a PMIP Binding Query Answer (PBQA) message with the IP address as a response to MAG1. Upon receiving the PBQA, MAG1 records PMIP Binding information of MN2 including MN2's HoA and MAG2's IP address (CoA) locally and sets up its endpoint of a tunnel (e.g. IP in IP tunnel) to MAG2 and forward all follow-up uplink traffic to MAG2 via the tunnel directly to bypass the LMA. When receiving encapsulated packet contains the uplink traffic from MN1 in the tunnel, MAG2 parses the packet and records PMIP Binding information of MN1 including MN1's HoA and MAG1's IP address (CoA) Liu, et. al Expires May 31, 2012 [Page 4] Internet-Draft Requirements of DMM December 2011 which can be derived from the inner IP header and outer IP header of the encapsulated packet respectively. Then MAG2 decapsulates the packet and forwards the uplink traffic to MN2 in access link and sets up its endpoint of a tunnel to MAG1 for any follow-up IP packet form MN2 to MN1 denoted as downlink traffic. At this moment, a bi-directional tunnel between MAG1 and MAG2 has been established for all uplink and downlink traffic between the two mobile nodes. 3.2. Handoff Approaches +---+ +----+ +----+ +---+ +----+ +---+ |MN1| |MAG1| |MAG3| |LMA| |MAG2| |MN2| +---+ +----+ +----+ +---+ +----+ +---+ | | | | | | | | 1. Ongoing traffic | | |<==========>|<==================================>|<==========>| | | | | | | | | 2.attach and PMIP Reg. | | | |<----------------------->|<--------->| | | | | 3.PBCI | | | | | |<-----------| | | | | | 4.PBCA | | | | | |----------->| | | | | 5. Uplink traffic | | | | |========================>| | | | | | +--------------------------------------------+ | | | 6. Process of uplink traffic is similar | | | | with the approaches in figure 1 | | | +--------------------------------------------+ | | | 7. Downlink Traffic | | | |<===================================|<===========| | |===========>| | | | |<========================| | | | | | | 8. PBCI | | | | |----------------------------------->| | | | | | +--------------+ | | | | | | 9. Update PB | | | | | | | of MN1 | | | | | | +--------------+ | | | | 10. PBCA | | | Liu, et. al Expires May 31, 2012 [Page 5] Internet-Draft Requirements of DMM December 2011 | |<-----------------------------------| | | | 11. Ongoing Downlink Traffic | | |<========================|<======================|<===========| | | | | | Figure 2. Handoff Approaches Figure 2 shows approaches for the MN1's handoff from the previously attached mobile access gateway (MAG1) to the newly attached mobile access gateway (MAG3). During the handoff, the network performs PMIP [RFC5213] specified procedures for MN1 to maintain its HoA unchanged. The MAG3 on the new access link, upon detecting the MN1 on its access link, assigns a new CoA for MN1 and send PBU message to LMA for updating binding state. The LMA responses MAG3 with a PBA message in sequence according to [RFC5213]. In additional, as specified in this draft, the PBA message from LMA to MAG3 (n-MAG) should carry IP address of MAG1 which plays the role of p-MAG. Upon receiving the PBA, MAG3 sends a PMIP Binding Change Inform (PBCI) message with its IP address to MAG1. MAG1 records the information provided in PBCI and may response MAG3 with a PMIP Binding Change Ack (PBCA) message. At this moment, the uplink traffic from MN1 to MN2 will first arrival at MAG3 instead of MAG1. And the process of the uplink traffic is quite similar with the approaches described in section 3.1. The route of the uplink traffic becomes: MN1->MAG3->MAG2->MN2. In case MN1 has active session with MN2 before the handoff, then after the handoff, the downlink traffic from MN2 to MN1 may still be forwarded to MAG1 by MAG2 in the tunnel between the two. To ensure the session continuity, when receiving the downlink traffic, MAG1 can forward the received traffic to MAG3 and send back a PBCI message to MAG2 with IP address of MAG3 to update the PMIP Binding information of MN1 stored in MAG2 locally in order to prevent MAG2 from forwarding upcoming downlink traffic to MAG1 but to MAG3 directly. 3.3. Locate Mobility Anchor Locating Considerations According to [RFC5213], only the local mobility anchor which is involved in PMIP registration for a mobile node holds this mobile node's Binding Cache Entry. Liu, et. al Expires May 31, 2012 [Page 6] Internet-Draft Requirements of DMM December 2011 If the MN1 and MN2 have different LMA, then in section 3.1, the MAG1 should determine to which local mobility anchor it should send a PBQR message. 3.3.1. Depend on Configuration Every local mobility anchor is configured to hold one or more IPv6 prefix pools. In case MAG is aware of the configuration, e.g. via management plane, it could determine the corresponding local mobility anchor to which it should send the PBRQ message, according to the mobile node's HoA. 4. Mobile Access Gateway Operation The enhanced mobile access gateway specified in this draft is fully compatible with the mobile access gateway defined in [RFC5213] only with limited additional functions. To support these additional functions, four new messages named PMIP Binding Query Request (PBQR), PMIP Binding Query Answer (PBQA), PMIP Binding Change Inform (PBCI) and PIMP Binding Change Acknowledgement(PBCA) for mobile access gateway are defined in this draft as extensions to [RFC5213]. 4.1. Extensions to Binding Update List Entry Data Structure As specified in section 6.1 of [RFC5213], every mobile access gateway MUST maintain a Binding Update List, and each entry in the Binding Update List represents a mobile node's mobility binding with its local mobility anchor. In this draft, the concept Binding Update List entry data structure needs to be extends with one additional field as following: * CN-Location, the IP address of a mobile access gateway to which the correspondent node attaches currently together with HoA of this correspondent node. This field enables the enhanced mobile access gateway to determine the location of correspondent node locally according to its HoA. Generally, one Binding Update List entry may have multiple CN- location fields depends on how many correspondent nodes the mobile node has. Liu, et. al Expires May 31, 2012 [Page 7] Internet-Draft Requirements of DMM December 2011 4.2. Extended Operations for Mobile Access Gateway 4.2.1. Receiving traffic generated by attached mobile node According to [RFC5213], whenever a mobile access gateway intercepts traffic generated by its attached mobile node which is a traffic sender, it shall check the corresponding Binding Update List entry to determine the local mobility anchor to which it should forward the traffic for that mobile node. As extensions in this draft, the enhanced mobile access gateway should also check CN-Location field in the corresponding Binding Update List entry locally to determine the IP address of correspondent node's mobile access gateway by using destination IP address of the traffic as input parameter. In case the IP address cannot be determined locally, the enhanced mobile access gateway should query a corresponding LMA by sending a PBQR message with IP address of the correspondent node to request the information. If the enhanced MAG acquires the IP address in a PBQA message, it shall record the information locally. In case the IP address can be determined either locally or from the LMA, the enhance mobile access gateway should set up a tunnel by using the IP address of correspondent node's MAG as endpoint and forward any follow-up traffic generated by the mobile node via the tunnel to the correspondent node's mobile access gateway directly. In case the IP address cannot be determined anyway, the enhanced MAG will forward all follow-up traffic to mobile node's LMA according to [RFC5213]. In case when the enhanced mobile access gateway receives a PBCI message with IP address of correspondent node's mobile access gateway, it should update the CN-Location filed of corresponding Binding Update List entry. 4.2.2. Receiving traffic designated to attached mobile node Whenever a enhanced mobile access gateway receives traffic designated to its attached mobile node which is the traffic receiver in a tunnel, it should determine the tunnel is originated by a LMA or another MAG to which the correspondent node which is traffic sender attached. Liu, et. al Expires May 31, 2012 [Page 8] Internet-Draft Requirements of DMM December 2011 The mobile access gateway should decapsulate the tunneled packet and send the traffic to the designated mobile node. In case the traffic is from the correspondent node's MAG, the enhanced MAG who receives the traffic should: * If it is a handoff scenario, the enhanced mobile access gateway who plays the role of p-MAG should forward any received traffic towards to the mobile node to the n-MAG and inform IP address of the n-MAG to the correspond mobile node's mobile access gateway by sending a PBCI message. * Otherwise, the enhanced MAG should update the CN-Location field in corresponding Binding Update List entry for the mobile node who is the traffic receiver with new IP address of the correspondent node's MAG if changes. 5. Local Mobility Anchor Operation The enhanced local mobility anchor specified in this draft is fully compatible with the local mobility anchor defined in [RFC5213] only with limited additional functions. The only extension is the enhanced local mobility anchor specified in this draft supports the query for IP address of a mobile node's mobile access gateway based on this mobile node's HoA. To support the additional function, two new messages named PMIP Binding Query Request (PBQR) and PMIP Binding Query Answer (PBQA) for the local mobility anchor are defined in this draft as extensions to [RFC5213]. 5.1. Extensions to Binding Cache Entry Data Structure No extension to binding cache entry data structure for the local mobility anchor is needed in this draft. 5.2. Extended Operations of Local Mobility Anchor Extended operations of enhanced local mobility anchor are defined in this section as extensions to [RFC5213]. In case the enhanced local mobility anchor accepts a PBQR message from a enhanced mobile access gateway, it should locate the binding cache entry of mobile node which is identified by the IP address carried in the PBQR message to acquire the IP address of this mobile node's mobile access gateway. Liu, et. al Expires May 31, 2012 [Page 9] Internet-Draft Requirements of DMM December 2011 In case when getting the IP address of the mobile node's MAG, the enhanced LMA should response a PBQA message with the IP address acquired. 6. Security Considerations None. 7. IANA Considerations TBD 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. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 8.2. Informative References [I-D. DMM-PS] D. Liu, " Distributed mobility management", draft-liu- distributed-mobility-02 (work in progress), July 10, 2010. Authors' Addresses Dapeng Liu China Mobile Unit2, 28 Xuanwumenxi Ave,Xuanwu District Beijing 100053 China Email: liudapeng@chinamobile.com Jun Song ZTE No.68,Zijinghua Road, Yuhuatai District Nanjing 210012 China Email: song.jun@zte.com.cn Wen Luo ZTE Liu, et. al Expires May 31, 2012 [Page 10] Internet-Draft Requirements of DMM December 2011 No.68,Zijinghua Road, Yuhuatai District Nanjing 210012 China Email: luo.wen@zte.com.cn Liu, et. al Expires May 31, 2012 [Page 11]