Network Working Group T. Dreibholz Internet-Draft J. Pulinthanath Intended status: Informational University of Duisburg-Essen Expires: December 7, 2007 June 5, 2007 Applicability of Reliable Server Pooling for SCTP-Based Endpoint Mobility draft-dreibholz-rserpool-applic-mobility-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 December 7, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Dreibholz & Pulinthanath Expires December 7, 2007 [Page 1] Internet-Draft SCTP Mobility with RSerPool June 2007 Abstract This document describes a novel mobility concept based on a combination of SCTP with Dynamic Address Reconfiguration extension and Reliable Server Pooling (RSerPool). Dreibholz & Pulinthanath Expires December 7, 2007 [Page 2] Internet-Draft SCTP Mobility with RSerPool June 2007 1. Introduction An increasing amount of Internet devices is getting mobile. Therefore, there is a growing demand for software solutions allowing for a seamless handover of communication sessions between multiple networks, e.g. to allow for a laptop or PDA to use a fast Ethernet connection when available, hand over to a WLAN when moving and hand over again to UMTS when the WLAN becomes unreachable - without interrupting the running communication sessions. Mobility handling is a deficiency of the common IP-based networks. Most of the available solutions are based on the network layer. The disadvantage of such solutions is that fundamental changes in the network infrastructure are needed. Therefore, we propose a new solution based on the upper layers to overcome these disadvantages. In this document, we present our mobility solution based on the SCTP protocol with Dynamic Address Reconfiguration extension and Reliable Server Pooling (RSerPool). Dreibholz & Pulinthanath Expires December 7, 2007 [Page 3] Internet-Draft SCTP Mobility with RSerPool June 2007 2. Existing Mobility Solutions 2.1. Mobile IP and Mobile IPv6 In the concept of Mobile IP [6] every node must register to a Home- Agent (HA) in its own home network. Then, the nodes are reachable under their home addresses managed by the HA. When a node leaves its home network, it must also register at a Foreign Agent (FA) in the new network. After that, a tunnel is established between the HA and the FA. Any traffic to the mobile node is then tunnelled by its HA to the FA and forwarded by the FA to the node itself. Clearly, the detour of all traffic via HA and FA is inefficient and results in an increased transmission delay. Mobile IPv6 [7] is an extension of Mobile IP. In Mobile IPv6, the FA is not needed. The packets will be tunnelled from the HA to the Gateway Router in the foreign network, which forwards the packets to the endpoint. The inefficiency due to the detour of traffic as described for Mobile IP remains. 2.2. SCTP with Dynamic Address Reconfiguration Using the SCTP protocol (see [2], [5]) together with its Dynamic Address Reconfiguration extension (Add-IP, see [8]), it is possible for a mobile endpoint to inform its peer on address changes. That is, when a moving mobile client gets in the vicinity of an additional radio station, it sends an "ASCONF Add Address Request" to tell its peer that it is now reachable under an additional network-layer address. After that, the peer endpoint can use this additional address for a new SCTP path. When the first radio station becomes unreachable, the node can send an "ASCONF Delete Address Request" to the peer endpoint. After that, the peer removes the corresponding SCTP path to the unusable network-layer address. The following two cases for handovers are possible: o Make-before-Break: An additional SCTP path can be used before the original path becomes unusable. This case is trivial, since there is a continuous connectivity. o Break-before-Make: The original SCTP path becomes unusable before a new SCTP path can be used. For the case that only one endpoint performs a handover procedure at the same time, the mobile endpoint can always use Add-IP to communicate its new address to its peer endpoint. However, when both endpoints perform a handover simultaneously, no endpoint is able to tell its corresponding peer the new address. Dreibholz & Pulinthanath Expires December 7, 2007 [Page 4] Internet-Draft SCTP Mobility with RSerPool June 2007 3. Solutions for Simultaneous Handovers 3.1. SCTP with Add-IP and Mobile-IP Using SCTP with Add-IP and Mobile IP/Mobile IPv6, the ASCONF messages will be sent to the home address of the peer node. That is, even when both nodes are mobile, each endpoint is able to reach its peer endpoint using the corresponding home address. However, this solution still requires the full Mobile IP/Mobile IPv6 infrastructure. 3.2. SCTP with Add-IP and RSerPool Using RSerPool (see [3], [9], [10], [11], [13], [12]), at least one node registers as a Pool Element (PE) at an ENRP server under a Pool Handle (PH) known to both endpoints. Upon handover, it is simply necessary for the PE endpoint to re-register, i.e. to update its registration with its new address. The other endpoint can - in the role of a Pool User (PU) - ask an ENRP server for its peer node's new addresses. After the new address is known, it is able to create a new SCTP path and continue the communication. The usage of RSerPool to provide support for mobile endpoints provides the following advantages: o Simplicity: No Mobile IP/Mobile IPv6 infrastructure is needed. In particular, it is not necessary that the providers of used networks (e.g. public WLAN access points, UMTS providers, etc.) provide any support for the mobility solution. o Efficiency: No tunnelling of traffic is necessary. o Applicability: All major SCTP implementations already support the Dynamic Address Reconfiguration extension. It is only necessary to provide support for RSerPool, e.g. in the form of a userspace library, which is much easier to deploy than kernel extensions. o Flexibility: RSerPool provides a complete session layer. That is, providing applications on top of RSerPool makes the support for high availability simple. A more detailed description of our approach for endpoint mobility, as well as a performance analysis using a prototype implementation, can be found in our paper [16]. Dreibholz & Pulinthanath Expires December 7, 2007 [Page 5] Internet-Draft SCTP Mobility with RSerPool June 2007 4. References 4.1. Normative References [1] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene, L., Lin, H., Juhasz, I., Holdrege, M., and C. Sharp, "Framework Architecture for Signaling Transport", RFC 2719, October 1999. [2] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M., Zhang, L., and V. Paxson, "Stream Control Transmission Protocol", RFC 2960, October 2000. [3] Tuexen, M., Xie, Q., Stewart, R., Shore, M., Ong, L., Loughney, J., and M. Stillman, "Requirements for Reliable Server Pooling", RFC 3237, January 2002. [4] Coene, L., "Stream Control Transmission Protocol Applicability Statement", RFC 3257, April 2002. [5] Stone, J., Stewart, R., and D. Otis, "Stream Control Transmission Protocol (SCTP) Checksum Change", RFC 3309, September 2002. [6] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August 2002. [7] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [8] Stewart, R., "Stream Control Transmission Protocol (SCTP) Dynamic Address Reconfiguration", draft-ietf-tsvwg-addip-sctp-14 (work in progress), March 2006. [9] Tuexen, M., "Architecture for Reliable Server Pooling", draft-ietf-rserpool-arch-12 (work in progress), November 2006. [10] Stewart, R., "Aggregate Server Access Protocol (ASAP)", draft-ietf-rserpool-asap-15 (work in progress), January 2007. [11] Stewart, R., "Endpoint Handlespace Redundancy Protocol (ENRP)", draft-ietf-rserpool-enrp-15 (work in progress), January 2007. [12] Stewart, R., "Aggregate Server Access Protocol (ASAP) and Endpoint Handlespace Redundancy Protocol (ENRP) Parameters", draft-ietf-rserpool-common-param-11 (work in progress), October 2006. Dreibholz & Pulinthanath Expires December 7, 2007 [Page 6] Internet-Draft SCTP Mobility with RSerPool June 2007 [13] Tuexen, M. and T. Dreibholz, "Reliable Server Pooling Policies", draft-ietf-rserpool-policies-04 (work in progress), March 2007. 4.2. Informative References [14] Dreibholz, T., "Thomas Dreibholz's RSerPool Page", URL: http://tdrwww.exp-math.uni-essen.de/dreibholz/rserpool/. [15] Dreibholz, T., "Reliable Server Pooling -- Evaluation, Optimization and Extension of a Novel IETF Architecture", Ph.D. Thesis University of Duisburg-Essen, Faculty of Economics, Institute for Computer Science and Business Information Systems, URL: http://duepublico.uni-duisburg-essen.de/servlets/ DerivateServlet/Derivate-16326/Dre2006-final.pdf, March 2007. [16] Dreibholz, T., Jungmaier, A., and M. Tuexen, "A new Scheme for IP-based Internet Mobility", Proceedings of the 28th IEEE Local Computer Networks Conference, November 2003. [17] Dreibholz, T., "An efficient approach for state sharing in server pools", Proceedings of the 27th IEEE Local Computer Networks Conference, October 2002. [18] Dreibholz, T. and E. Rathgeb, "An Application Demonstration of the Reliable Server Pooling Framework", Proceedings of the 24th IEEE Infocom, March 2005. [19] Dreibholz, T. and E. Rathgeb, "Implementing the Reliable Server Pooling Framework", Proceedings of the 8th IEEE International Conference on Telecommunications, June 2005. [20] Dreibholz, T. and E. Rathgeb, "On the Performance of Reliable Server Pooling Systems", Proceedings of the 30th IEEE Local Computer Networks Conference, November 2005. [21] Dreibholz, T. and E. Rathgeb, "The Performance of Reliable Server Pooling Systems in Different Server Capacity Scenarios", Proceedings of the IEEE TENCON, November 2005. Dreibholz & Pulinthanath Expires December 7, 2007 [Page 7] Internet-Draft SCTP Mobility with RSerPool June 2007 Authors' Addresses Thomas Dreibholz University of Duisburg-Essen, Institute for Experimental Mathematics Ellernstrasse 29 45326 Essen, Nordrhein-Westfalen Germany Phone: +49-201-1837637 Fax: +49-201-1837673 Email: dreibh@exp-math.uni-essen.de URI: http://www.exp-math.uni-essen.de/~dreibh/ Jobin Pulinthanath University of Duisburg-Essen, Institute for Experimental Mathematics Ellernstrasse 29 45326 Essen, Nordrhein-Westfalen Germany Phone: +49-201-1837637 Fax: +49-201-1837673 Email: jp@exp-math.uni-essen.de Dreibholz & Pulinthanath Expires December 7, 2007 [Page 8] Internet-Draft SCTP Mobility with RSerPool June 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Dreibholz & Pulinthanath Expires December 7, 2007 [Page 9]