NetExt Working Group M. Jeyatharan Internet-Draft C. Ng Intended status: Informational Panasonic Expires: April 19, 2010 October 16, 2009 Bulk PBU using Bitmaps draft-jeyatharan-netext-pmip-bulkpbu-bitmap-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 April 19, 2010. 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract In Proxy Mobile Internet Protocol version 6 (PMIPv6), each mobile node attached to a mobile access gateway (MAG) requires separate signaling. This might result in excessive network signaling if there Jeyatharan & Ng Expires April 19, 2010 [Page 1] Internet-Draft BulkPBU-Bitmaps October 2009 a large number of mobile nodes attached to a MAG. In this draft we outline a bulk PBU optimization approach based on bitmap, in order to reduce the signaling load tied to numerous PBUs originating at the same time. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Bulk PBU Optimization Approaches . . . . . . . . . . . . . . . 4 2.1. Conventional bulk PBU Approach . . . . . . . . . . . . . . 4 2.2. Bitmap based bulk PBU Approach . . . . . . . . . . . . . . 5 3. Synergy with other Approaches . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Normative Reference . . . . . . . . . . . . . . . . . . . . 8 6.2. Informative Reference . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Jeyatharan & Ng Expires April 19, 2010 [Page 2] Internet-Draft BulkPBU-Bitmaps October 2009 1. Introduction The Proxy Mobile IPv6 protocol (RFC-5213 [1]) allows a mobile access gateway (MAG) to perform a PBU on behalf of a mobile node that is served by the MAG. The PBU originating from the MAG can be of different types such as initial registration PBU, handoff PBU, re- registration PBU and de-registration PBU, all representing the attachment state of a mobile node. If there are numerous mobile nodes being served by the MAG, and each PBU associated with the mobile node has multiple mobility options attached, then multiple such PBUs originating from the MAG increases network signaling load. It is preferable to reduce such signaling load for better network operation and maintenance. Rather than performing a simple concatenation of multiple PBUs tied to multiple mobile nodes, a bulk PBU with only a single instance of a given mobility option type attached and an additional bitmap option used to locate the usage of the attached mobility option type by a mobile node tied to the bulk PBU is described in this draft. Conceptually, the bitmap is a matrix whose fields represent whether a particular mobility option (can be mandatory or optional mobility option) type is used by the mobile node that is tied to the bulk PBU. Since bitmaps collapse multiple instances of a given mobility option type (or value) to a single instance, it is considered as a compressed identifier of multiple mobility options and hence provides better optimization for bulk PBU. The bitmap based optimization approach discussed in this draft is a general approach for bulk PBU optimization, and it can be used at any instance when bulk PBU needs to be sent from the MAG. Although the bitmap based approach described in this draft can be used independently to optimize signaling efficiency, it can also be used with other bulk PBU approaches as well. For instance, [2] illustrates a PBU with MN group ID option attached that is used to perform either bulk re-registration or bulk de-registration of the mobile nodes that are grouped by a group ID. Additionally, [3] also describes a similar approach which uses a bulk set ID option in the PBU to perform bulk re-registration of multiple mobile nodes which are reference by a single bulk set ID. As will be discussed later, the bitmap based bulk PBU optimization approach described in this draft can be used together with these approaches described in [2] and [3]. Section 2 describes the conventional bulk PBU optimization approach and bitmap based bulk PBU optimization approach. Following that in Section 3, we illustrate how this bitmap based bulk PBU optimization approach can be combined or interwork with the MN group ID mechanism that is described in [2] and also briefly highlight the differences Jeyatharan & Ng Expires April 19, 2010 [Page 3] Internet-Draft BulkPBU-Bitmaps October 2009 between the bitmap based optimization approach the MN group ID based optimization approach. 2. Bulk PBU Optimization Approaches In this section, two bulk PBU optimization approaches are described. The first one is the conventional bulk PBU optimization approach or conventional approach and the second one is the bitmap based bulk PBU optimization approach. The conventional bulk PBU optimization approach is mainly described to understand the benefits tied the bitmap approach. 2.1. Conventional bulk PBU Approach The conventional way of combining multiple PBU messages for different mobile nodes is to have a single IPv6 header and a single PBU mobility header, and insert all the mobility options for each mobile node into the bulk PBU message. This takes advantage of sequential processing of the bulk PBU message at the LMA, as if multiple individual PBU messages are being processed. In such an arrangement, the mobility options associated with each mobile node are inserted into the PBU message together sequentially, with the Mobile Node Identifier option inserted first. Hence, it can be treated as if the appearance of a Mobile Node Identifier option signals the start of another individual PBU (which shares the same PBU mobility header). For example, the bulk PBU for mobile nodes MN1 and MN2 will appears as follows: IPv6 Header Mobility Header PBU Header Mobility Options Mobile Node Identifier option for MN1 Other mobility options for MN1 Mobile Node Identifier option for MN2 Other mobility options for MN2 The main disadvantage of this approach is that although there is packet size savings in terms of the number of IPv6 headers and the number PBU mobility headers (only one IPv6 header and one PBU mobility header), the mobility options of the same type (or value) are repeated in the bulk PBU message. For example, one of MN1's mobility option can be Handoff Indicator option of value "2" and the MN2 may also use the same Handoff Indicator option with the same value "2". This may lead to the resulting bulk PBU packet size being too big, and thus the packet may be dropped en-route or will need to be broken into multiple PBU messages to overcome the path MTU. Jeyatharan & Ng Expires April 19, 2010 [Page 4] Internet-Draft BulkPBU-Bitmaps October 2009 2.2. Bitmap based bulk PBU Approach The bitmap approach is such that only one mobility option of a certain type (or value) is attached to the bulk PBU message regardless of the number of mobile nodes that are tied to the message. Similar to the conventional approach, the bulk PBU message will have only one IPv6 header and one PBU mobility header. After the PBU mobility header, the mobility options will be attached. The MAG will attach the union of all the mobility options used by all the mobile nodes tied to the bulk PBU. To indicate the association of the mobility options with each mobile node, a bitmap mobility option will be attached in the bulk PBU. To better illustrate this, we assume that a bulk PBU message will contain registration for mobile nodes MN1, MN2 and MN3. It is assumed that the mobility options for each mobile node are: MN1: Mobile Node Identifier option: MN1-ID Access Technology Type option: ATT1 Home Network Prefix option: HNP=P1 Home Network Prefix option: HNP=P2 mobility option X Handoff Indicator option: HI=1 MN2: Mobile Node Identifier option: MN2-ID Access Technology Type option: ATT2 Home Network Prefix option: HNP=P3 Home Network Prefix option: HNP=P4 mobility option X Handoff Indicator option: HI=1 MN3: Mobile Node Identifier option: MN3-ID Access Technology Type option: ATT2 Home Network Prefix option: HNP=P5 mobility option Y Handoff Indicator option: HI=2 Using the bitmap approach, the resulting PBU will be: Jeyatharan & Ng Expires April 19, 2010 [Page 5] Internet-Draft BulkPBU-Bitmaps October 2009 IPv6 Header Mobility Header PBU Header Mobility Options Mobile Node Identifier option: MN1-ID Mobile Node Identifier option: MN2-ID Mobile Node Identifier option: MN3-ID Home Network Prefix option: HNP=P1 Home Network Prefix option: HNP=P2 Home Network Prefix option: HNP=P3 Home Network Prefix option: HNP=P4 Home Network Prefix option: HNP=P5 Handoff Indicator option: HI=1 Handoff Indicator option: HI=2 Access Technology Type option: ATT1 Access Technology Type option: ATT2 mobility option X mobility option Y Bitmap option = 11000101010 00110100110 00001010101 It can be seen that for certain type and value only single mobility option is attached using the bitmap based approach. For example, if conventional bulk PBU method of combining is used, then for HI and ATT, 6 mobility options will be used. However, using the bitmap approach only 4 mobility options to represent HI and ATT are used in the bulk PBU message. The trick lies in the Bitmap option, which indicates the association of each Mobile Node Identifier option with the other mobility options. Figure 1 provides the illustration on how the association is derived from the Bitmap option. +=======================================================+ | | P1| P2| P3| P4 | P5|HI1 | HI2 | ATT1| ATT2 |X |Y | |----|---|---|---|----|---|----|-----|-----|------|--|--| | MN1| 1 | 1| 0| 0 | 0| 1 | 0 | 1 | 0 |1 |0 | | MN2| 0 | 0| 1| 1 | 0| 1 | 0 | 0 | 1 |1 |0 | | MN3| 0 | 0| 0| 0 | 1| 0 | 1 | 0 | 1 |0 |1 | +=======================================================+ Figure 1: Bitmap Illustration The LMA will use the bitmap shown in Figure 1 to determine the mobility options associated to a particular mobile node. To obtain the bitmap, the LMA will use the number of mobility options that are not Mobile Node Identifier option in the PBU to determine the number of columns in the bitmap and will use the number of Mobile Node Identifier options to determine the number of rows. Each row then contains the association information to form the binding cache entry for each mobile node. Jeyatharan & Ng Expires April 19, 2010 [Page 6] Internet-Draft BulkPBU-Bitmaps October 2009 3. Synergy with other Approaches The bitmap approach described in this draft is a general approach of optimization and can work along with the mobile node group ID approach described in [2] and [3] as well. Three such use cases are outlined below to highlight such combined usage: o Use Case 1: MAG sending a bitmap based bulk PBU to LMA and requesting the LMA to associate the MNs to the attached MN group identifier(s). For example, if there are mobile nodes MN1 and MN2 that are going to be tied to group GID1 and mobile nodes MN3 and MN4 are going to be tied to group GID2, then the bitmap based bulk PBU message will contain a union of all the mobile nodes related mobility options, followed by Group Identifier options for GID1 and GID2. The bitmap option in the message will indicate the association of each mobile node to the group IDs. o Use Case 2: MAG sending mobility options for multiple groups in a single bulk PBU. In this case, the bitmap option can indicate the association of mobility options to each group (i.e. rows in the bitmap matrix will contain the association information for each group). o Use Case 3: MAG sending a bulk PBU containing information pertaining to both groups and un-grouped mobile nodes. Hence the bulk PBU will contain Mobile Node Identifier options, Group Identifier options, and other related mobility options. For example, a bulk PBU may contain indications for newly handed over mobile nodes and re-registration for existing groups of mobile nodes. In such a combination, the bitmap matrix rows are tied to the Mobile Node Identifier and Group Identifier options. To differentiate between the three use cases, the bitmap option can contain a flag to indicate whether (a) only Mobile Node Identifier options, (b) only Group Identifier options, or (c) both Mobile Node Identifier and Group Identifier options are used to as rows in the derived bitmap matrix. 4. IANA Considerations This memo highlights a need for a new mobility option to carry the bitmap matrix and IANA needs to assign an appropriate type for it. 5. Security Considerations The bitmap approach described in this memo highlights a need for a Jeyatharan & Ng Expires April 19, 2010 [Page 7] Internet-Draft BulkPBU-Bitmaps October 2009 new mobility option which will be tied to the PBU message and thus the security considerations tied to PMIPv6 protocol as given in (RFC- 5213 [1]) applies here as well. 6. References 6.1. Normative Reference [1] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 6.2. Informative Reference [2] Gundavelli, S., Leung, K., Patil, B., and D. Premec, "Mobile Node Group Identifier option", draft-gundavelli-netext-mn-groupid-option-01 (work in progress), June 2009. [3] Premec, D., Patil, B., and S. Krishnan, "Bulk Re-registration for Proxy Mobile IPv6", draft-premec-netlmm-bulk-re-registration-02 (work in progress), March 2009. Authors' Addresses Mohana Dahamayanthi Jeyatharan Panasonic Singapore Laboratories Pte Ltd Blk 1022 Tai Seng Ave #06-3530 Tai Seng Industrial Estate Singapore 534415 SG Phone: +65 65505494 Email: mohana.jeyatharan@sg.panasonic.com Chan-Wah Ng Panasonic Singapore Laboratories Pte Ltd Blk 1022 Tai Seng Ave #06-3530 Tai Seng Industrial Estate Singapore 534415 SG Phone: +65 65505420 Email: chanwah.ng@sg.panasonic.com Jeyatharan & Ng Expires April 19, 2010 [Page 8]