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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. Dreibholz 3 Internet-Draft SimulaMet 4 Intended status: Informational J. Pulinthanath 5 Expires: March 13, 2020 University of Duisburg-Essen 6 September 10, 2019 8 Applicability of Reliable Server Pooling for SCTP-Based Endpoint 9 Mobility 10 draft-dreibholz-rserpool-applic-mobility-26 12 Abstract 14 This document describes a novel mobility concept based on a 15 combination of SCTP with Dynamic Address Reconfiguration extension 16 and Reliable Server Pooling (RSerPool). 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at https://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on March 13, 2020. 35 Copyright Notice 37 Copyright (c) 2019 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (https://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 2. Existing Mobility Solutions . . . . . . . . . . . . . . . . . 2 54 2.1. Mobile IP and Mobile IPv6 . . . . . . . . . . . . . . . . 2 55 2.2. SCTP with Dynamic Address Reconfiguration . . . . . . . . 3 56 3. Solutions for Simultaneous Handovers . . . . . . . . . . . . 3 57 3.1. SCTP with Add-IP and Mobile-IP . . . . . . . . . . . . . 3 58 3.2. SCTP with Add-IP and RSerPool . . . . . . . . . . . . . . 4 59 4. Reference Implementation . . . . . . . . . . . . . . . . . . 4 60 5. Testbed Platform . . . . . . . . . . . . . . . . . . . . . . 5 61 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 62 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 63 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 8.1. Normative References . . . . . . . . . . . . . . . . . . 5 65 8.2. Informative References . . . . . . . . . . . . . . . . . 7 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 68 1. Introduction 70 An increasing amount of Internet devices is getting mobile. 71 Therefore, there is a growing demand for software solutions allowing 72 for a seamless handover of communication sessions between multiple 73 networks, e.g. to allow for a laptop or PDA to use a fast Ethernet 74 connection when available, hand over to a WLAN when moving and hand 75 over again to UMTS when the WLAN becomes unreachable - without 76 interrupting the running communication sessions. 78 Mobility handling is a deficiency of the common IP-based networks. 79 Most of the available solutions are based on the network layer. The 80 disadvantage of such solutions is that fundamental changes in the 81 network infrastructure are needed. Therefore, we propose a new 82 solution based on the upper layers to overcome these disadvantages. 83 In this document, we present our mobility solution based on the SCTP 84 protocol with Dynamic Address Reconfiguration extension and Reliable 85 Server Pooling (RSerPool). 87 2. Existing Mobility Solutions 89 2.1. Mobile IP and Mobile IPv6 91 In the concept of Mobile IP [RFC5944] every node must register to a 92 Home-Agent (HA) in its own home network. Then, the nodes are 93 reachable under their home addresses managed by the HA. When a node 94 leaves its home network, it must also register at a Foreign Agent 95 (FA) in the new network. After that, a tunnel is established between 96 the HA and the FA. Any traffic to the mobile node is then tunnelled 97 by its HA to the FA and forwarded by the FA to the node itself. 99 Clearly, the detour of all traffic via HA and FA is inefficient and 100 results in an increased transmission delay. 102 Mobile IPv6 [RFC6275] is an extension of Mobile IP. In Mobile IPv6, 103 the FA is not needed. The packets will be tunnelled from the HA to 104 the Gateway Router in the foreign network, which forwards the packets 105 to the endpoint. The inefficiency due to the detour of traffic as 106 described for Mobile IP remains. 108 2.2. SCTP with Dynamic Address Reconfiguration 110 Using the SCTP protocol (see [RFC4960] together with its Dynamic 111 Address Reconfiguration extension (Add-IP, see [RFC5061]), it is 112 possible for a mobile endpoint to inform its peer on address changes. 113 That is, when a moving mobile client gets in the vicinity of an 114 additional radio station, it sends an "ASCONF Add Address Request" to 115 tell its peer that it is now reachable under an additional network- 116 layer address. After that, the peer endpoint can use this additional 117 address for a new SCTP path. When the first radio station becomes 118 unreachable, the node can send an "ASCONF Delete Address Request" to 119 the peer endpoint. After that, the peer removes the corresponding 120 SCTP path to the unusable network-layer address. 122 The following two cases for handovers are possible: 124 o Make-before-Break: An additional SCTP path can be used before the 125 original path becomes unusable. This case is trivial, since there 126 is a continuous connectivity. 128 o Break-before-Make: The original SCTP path becomes unusable before 129 a new SCTP path can be used. For the case that only one endpoint 130 performs a handover procedure at the same time, the mobile 131 endpoint can always use Add-IP to communicate its new address to 132 its peer endpoint. However, when both endpoints perform a 133 handover simultaneously, no endpoint is able to tell its 134 corresponding peer the new address. 136 3. Solutions for Simultaneous Handovers 138 3.1. SCTP with Add-IP and Mobile-IP 140 Using SCTP with Add-IP and Mobile IP/Mobile IPv6, the ASCONF messages 141 will be sent to the home address of the peer node. That is, even 142 when both nodes are mobile, each endpoint is able to reach its peer 143 endpoint using the corresponding home address. However, this 144 solution still requires the full Mobile IP/Mobile IPv6 145 infrastructure. 147 3.2. SCTP with Add-IP and RSerPool 149 Using RSerPool (see [RFC3237], [RFC5351], [RFC5352], [RFC5353], 150 [RFC5354], [RFC5355], [RFC5356], at least one node registers as a 151 Pool Element (PE) at an ENRP server under a Pool Handle (PH) known to 152 both endpoints. Upon handover, it is simply necessary for the PE 153 endpoint to re-register, i.e. to update its registration with its new 154 address. The other endpoint can - in the role of a Pool User (PU) - 155 ask an ENRP server for its peer node's new addresses. After the new 156 address is known, it is able to create a new SCTP path and continue 157 the communication. 159 The usage of RSerPool to provide support for mobile endpoints 160 provides the following advantages: 162 o Simplicity: No Mobile IP/Mobile IPv6 infrastructure is needed. In 163 particular, it is not necessary that the providers of used 164 networks (e.g. public WLAN access points, UMTS providers, etc.) 165 provide any support for the mobility solution. 167 o Efficiency: No tunnelling of traffic is necessary. 169 o Applicability: All major SCTP implementations already support the 170 Dynamic Address Reconfiguration extension. It is only necessary 171 to provide support for RSerPool, e.g. in the form of a userspace 172 library, which is much easier to deploy than kernel extensions. 174 o Flexibility: RSerPool provides a complete session layer. That is, 175 providing applications on top of RSerPool makes the support for 176 high availability simple. 178 A more detailed description of our approach for endpoint mobility, as 179 well as a performance analysis using a prototype implementation, can 180 be found in our paper [LCN2003]. 182 4. Reference Implementation 184 The RSerPool reference implementation RSPLIB can be found at 185 [RSerPool-Website]. It supports the functionalities defined by 186 [RFC5351], [RFC5352], [RFC5353], [RFC5354] and [RFC5356] as well as 187 the options [I-D.dreibholz-rserpool-asap-hropt], 188 [I-D.dreibholz-rserpool-enrp-takeover] and 189 [I-D.dreibholz-rserpool-delay]. An introduction to this 190 implementation is provided in [Dre2006]. 192 5. Testbed Platform 194 A large-scale and realistic Internet testbed platform with support 195 for the multi-homing feature of the underlying SCTP protocol is 196 NorNet. A description of NorNet is provided in [PAMS2013-NorNet], 197 some further information can be found on the project website 198 [NorNet-Website]. 200 6. Security Considerations 202 Security considerations for RSerPool systems are described by 203 [RFC5355]. 205 7. IANA Considerations 207 This document introduces no additional considerations for IANA. 209 8. References 211 8.1. Normative References 213 [I-D.dreibholz-rserpool-asap-hropt] 214 Dreibholz, T., "Handle Resolution Option for ASAP", draft- 215 dreibholz-rserpool-asap-hropt-24 (work in progress), March 216 2019. 218 [I-D.dreibholz-rserpool-delay] 219 Dreibholz, T. and X. Zhou, "Definition of a Delay 220 Measurement Infrastructure and Delay-Sensitive Least-Used 221 Policy for Reliable Server Pooling", draft-dreibholz- 222 rserpool-delay-23 (work in progress), March 2019. 224 [I-D.dreibholz-rserpool-enrp-takeover] 225 Dreibholz, T. and X. Zhou, "Takeover Suggestion Flag for 226 the ENRP Handle Update Message", draft-dreibholz-rserpool- 227 enrp-takeover-21 (work in progress), March 2019. 229 [RFC3237] Tuexen, M., Xie, Q., Stewart, R., Shore, M., Ong, L., 230 Loughney, J., and M. Stillman, "Requirements for Reliable 231 Server Pooling", RFC 3237, DOI 10.17487/RFC3237, January 232 2002, . 234 [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", 235 RFC 4960, DOI 10.17487/RFC4960, September 2007, 236 . 238 [RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M. 239 Kozuka, "Stream Control Transmission Protocol (SCTP) 240 Dynamic Address Reconfiguration", RFC 5061, 241 DOI 10.17487/RFC5061, September 2007, 242 . 244 [RFC5351] Lei, P., Ong, L., Tuexen, M., and T. Dreibholz, "An 245 Overview of Reliable Server Pooling Protocols", RFC 5351, 246 DOI 10.17487/RFC5351, September 2008, 247 . 249 [RFC5352] Stewart, R., Xie, Q., Stillman, M., and M. Tuexen, 250 "Aggregate Server Access Protocol (ASAP)", RFC 5352, 251 DOI 10.17487/RFC5352, September 2008, 252 . 254 [RFC5353] Xie, Q., Stewart, R., Stillman, M., Tuexen, M., and A. 255 Silverton, "Endpoint Handlespace Redundancy Protocol 256 (ENRP)", RFC 5353, DOI 10.17487/RFC5353, September 2008, 257 . 259 [RFC5354] Stewart, R., Xie, Q., Stillman, M., and M. Tuexen, 260 "Aggregate Server Access Protocol (ASAP) and Endpoint 261 Handlespace Redundancy Protocol (ENRP) Parameters", 262 RFC 5354, DOI 10.17487/RFC5354, September 2008, 263 . 265 [RFC5355] Stillman, M., Ed., Gopal, R., Guttman, E., Sengodan, S., 266 and M. Holdrege, "Threats Introduced by Reliable Server 267 Pooling (RSerPool) and Requirements for Security in 268 Response to Threats", RFC 5355, DOI 10.17487/RFC5355, 269 September 2008, . 271 [RFC5356] Dreibholz, T. and M. Tuexen, "Reliable Server Pooling 272 Policies", RFC 5356, DOI 10.17487/RFC5356, September 2008, 273 . 275 [RFC5944] Perkins, C., Ed., "IP Mobility Support for IPv4, Revised", 276 RFC 5944, DOI 10.17487/RFC5944, November 2010, 277 . 279 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 280 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 281 2011, . 283 8.2. Informative References 285 [Dre2006] Dreibholz, T., "Reliable Server Pooling - Evaluation, 286 Optimization and Extension of a Novel IETF Architecture", 287 March 2007, . 291 [LCN2003] Dreibholz, T., Jungmaier, A., and M. Tuexen, "A New Scheme 292 for IP-based Internet Mobility", Proceedings of the 28th 293 IEEE Local Computer Networks Conference (LCN) Pages 294 99-108, ISBN 0-7695-2037-5, DOI 10.1109/LCN.2003.1243117, 295 October 2003, . 299 [NorNet-Website] 300 Dreibholz, T., "NorNet - A Real-World, Large-Scale Multi- 301 Homing Testbed", Online: https://www.nntb.no/, 2019, 302 . 304 [PAMS2013-NorNet] 305 Dreibholz, T. and E. Gran, "Design and Implementation of 306 the NorNet Core Research Testbed for Multi-Homed Systems", 307 Proceedings of the 3nd International Workshop on Protocols 308 and Applications with Multi-Homing Support (PAMS) Pages 309 1094-1100, ISBN 978-0-7695-4952-1, 310 DOI 10.1109/WAINA.2013.71, March 2013, 311 . 315 [RSerPool-Website] 316 Dreibholz, T., "Thomas Dreibholz's RSerPool Page", 317 Online: https://www.uni-due.de/~be0001/rserpool/, 2019, 318 . 320 Authors' Addresses 321 Thomas Dreibholz 322 Simula Metropolitan Centre for Digital Engineering 323 Pilestredet 52 324 0167 Oslo, Oslo 325 Norway 327 Phone: +47-6782-8200 328 Fax: +47-6782-8201 329 Email: dreibh@simula.no 330 URI: https://www.simula.no/people/dreibh 332 Jobin Pulinthanath 333 University of Duisburg-Essen, Institute for Experimental Mathematics 334 Ellernstrasse 29 335 45326 Essen, Nordrhein-Westfalen 336 Germany 338 Phone: +49-201-1837637 339 Fax: +49-201-1837673 340 Email: jp@iem.uni-due.de.de