Seamoby Working Group H. Jung Internet Draft S. Koh Document:draft-jung-seamoby-paging-buffload-00.txt ETRI/KOREA Category: Informational December 2001 Reducing the Buffering Load of Paging Agent in IP Paging <draft-jung-seamoby-paging-buffload-00.txt> Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026. 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 Convention used in this draft 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. Abstract This draft defines two procedures to distribute buffering load in IP paging using PA. A couple of documents using the PA, which includes all functions defined RFC 3154 in an entity, have beee submitted for cadidate protocol for IP paging. In this PA paging approach, the centralized buffering in PA can be a bottleneck point if a PA has to manage large paging area and a number of idle mobile hosts. To address the problem, it can be good solution to distribute buffering load among ARs in the paging area. 1. Introduction IP paging has been designed to decrease the signaling load for location registration and to prevent rapid power consumption of mobile nodes. For these purposes, the IETF SeaMoby WG has recently produced substantial documents, including Problem Statement and Requirements for IP paging protocol [1, 2]. Based on the functional H. Jung, et al. draft-jung-seamoby-paging-buffload-00.txt [Page 1]
INTERNET-DRAFT Expires: June 2002 December 2001 requirements, specific proposals for IP paging protocol have been made in the Working Group. In some IP paging schemes currently considered, an agent called Paging Agent(PA), or Paging Function(PF), is employed to perform all the functionalities required for IP paging which are specified in RFC3154 [3, 4]. In this document, we consider the buffering functionality of PA, which is one of the IP paging functionalities. The PA temporarily buffers the data destined to a idle MN, until the location of MN is known to PA. In this approach, a PA must perform the buffering for all of the MNs in the network. Therefore, the PA is likely to be overloaded due to the buffering operations for all the MNs in the network. The buffering load at the PA becomes more severe, as the size of paging area gets larger and the number of idle MNs in the area increases. In this document, we propose an alternate buffering scheme designed to ensure that the buffering load of PA can be reduced significantly, compared to the existing scheme. The main idea of the proposed scheme is that the buffering for a MN is performed by its last-registered AR other than PA. The last- registered AR represents an AR which a MN has registered to, after it entered the current paging area. By this, the buffering load of PA can be distributed into the boundary ARs of the paging area. 2. Buffering Scheme Using the Last-Registered ARs The proposed scheme is designed based on the principle that the processing load of PA can be alleviated by distributing its buffering load over the ARs(or Foreign Agents) in the paging area, which can also be described in the literature [5, 6]. In the proposed scheme, the buffering functionality is performed by ARs other than PA, diffferently from the existing paging schemes. Figure 1 illustrates the distribution of buffering load using the last-registered ARs in the paging area. We assume that MN's idle registration is acomplished by registrating its serving PA address as CoA to HA. Then the location update will be done only if the serving PA is changed. In the figure a MN registered its idle state to PA through AR-A. It means that AR-A is the last-registered AR of the MN. We assume that the MN is now located in the coverage of AR-D by way of AR-B and AR- C. When the PA receives data packets destined to idle MN from HA(1a), it realizes that the MN is in the idle state, and it thus forwards the recevied packets to the last registered AR, AR-A(1b). The AR-A will save these packets in its buffer. The PA now initiates the paging procedure(1c) to locate the MN in the paging area. Each router in the area will receive the L3 paging message and then H. Jung, et al. draft-jung-seamoby-paging-buffload-00.txt [Page 2]
INTERNET-DRAFT Expires: June 2002 December 2001 translate it into the corresponding L2 paging signaling through air interface(2). The MN receives the paging signal and then responds with the registration message to the last-registered AR-A(3b) as well as the PA(3a), through its currently serving AR-D. The last-registered AR-A will then forward the buffered data packets to the MN by way of AR- D(4). Hereafter, the MN comes back to the active state, and thus it will receive the subsequent data packets directly from HA, not via the last-registered AR-A. | | (1a) V +------+ | | | PA |<--------------+ | | | +------+ | | | | (1b)| | | +------------+ | | | |(1c) | | | |(3a) | | | +----|--------------|------------------|--------+ | | +---------+--+------+-----------|-+ | | | | | (3b) | | | | | | | +---------------------------+-+ | | | | | | | | (4)| | | | | V V V V V V | V | | +------+ +------+ +------+ +------+ | | | AR-A | | AR-B | | AR-C | | AR-D | | | +------+ +------+ +------+ +------+ | | |(2) |(2) |(2) ^ |(2) | | | | | | | ^ | | V V V | V | | | +------+ | | | MN | | | +------+ | | | | IP paging area | +-----------------------------------------------+ Figure 1: Buffering Using the Last-Registered AR H. Jung, et al. draft-jung-seamoby-paging-buffload-00.txt [Page 3]
INTERNET-DRAFT Expires: June 2002 December 2001 The only requirement to implement the proposed scheme is that each of ARs in the area needs to have the buffer capacity. On the other hand, it is relatively easy to extend the paging signaling algorithm and messages to support the proposed scheme. 3. Further Enhancement of the Proposed Scheme The proposed scheme is effective in that the buffering load of PA can be alleviated. However, it is noted that the border routers of the paging area are usually the last-registered ARs, and thus the buffering loads for the area may be concentrated on these border ARs. Another concern of the scheme is that a failure of the buffering(last-registered) AR, which may not be on the data path, induces overall failure of data delivery. One possible way to address the problems described above is to select and use the most suitable AR in the paging area as the buffering AR for each MN. The selection of the most suitable AR will be made by PA, based on the state information gathered by interaction between PA and candidate ARs in the area. Such state information may be the simple status of AR(running or failed), or may include more detailed system status such as available buffer memory and current processing loads. In any way, the PA needs to collect the state information from ARs in the area. On the reverse, each AR must report its state information to the PA. For this purpose, a new signaling mechanism may be specified along with signaling messages on the basis of periodic time or a pre-configured rule. Alternatively, an existing IP routing or management protocols such as RIP, OSPF, SNMP may be used or extended for conveying the status information. In the enhanced scheme using the most suitable AR, the buffering procedures are similar to those using the last-registered AR, other than the following differences: When PA receives the packet destined to MN from HA, it first selects the best candidate AR as the buffering AR for the MN, based on the collected state information. After that, the PA begins to locate the idle MN by sending paging signal message. The paging message must contain information(like an identifier) to indicate which AR is serving for the MN as the buffering AR in the area. In resonse to the paging message, the MN sends registration message to PA as well as its buffering AR. The buffering AR will then forwards the buffered packets to MN. H. Jung, et al. draft-jung-seamoby-paging-buffload-00.txt [Page 4]
INTERNET-DRAFT Expires: June 2002 December 2001 4. Implementation Notes TBD 5. Security Considerations TBD 6. References [1] J. Kempf. Dormant mode host alerting(ip paging) problem statement. Request for Comments 3132, Internet Engineering Task Force, June 2001. [2] J. Kempf, C. Castelluccia, et. al., Requirements and Functional Architecture for an IP Host Alerting Protocol, Request for Comments 3154, Internet Engineering Task Force, August 2001 [3] Rajeev Koodli, et. al., Dormant Mode Handover Support in Mobile Networks, Internet draft, draft-koodli-paging-01.txt, Internet Engineering Task Force, May 2002 [4] G. Renker, et. al., Paging Concept for IP based Networks, internet draft, draft-renker-paging-ipv6-00.txt, Internet Engineering Task Force, June 2001 [5] R. Ramjee, et. al., IP Paging Service for Mobile Hosts, ACM MOBICOM, 2001 [6] X. Zhang, et. al., P-MIP: Paging in Mobile IP, The Fourth International Workshop on Wireless Mobile Multimedia, Rome, Italy, July 2001 H. Jung, et al. draft-jung-seamoby-paging-buffload-00.txt [Page 5]
INTERNET-DRAFT Expires: June 2002 December 2001 7. Authors' Addresses HeeYoung Jung Protocol Engineering Center Electronics and Telecommunication Research Institute 161 Kajung-Dong, Yusong-Gu, Taejon, Korea Phone: +82 42 860-4928 EMail: hyjung@etri.re.kr Fax: +82 42 861-5404 Seok Joo Koh Protocol Engineering Center Electronics and Telecommunication Research Institute 161 Kajung-Dong, Yusong-Gu, Taejon, Korea Phone: +82 42 860-6218 EMail: sjkoh@etri.re.kr Fax: +82 42 861-5404 Full Copyright Statement "Copyright(C) The Internet Society(2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." H. Jung, et al. draft-jung-seamoby-paging-buffload-00.txt [Page 6]