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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 HIP Working Group T. Sun 3 Internet-Draft H. Deng 4 Intended status: Informational D. Liu 5 Expires: January 11, 2011 China Mobile 6 July 10, 2010 8 Route Configuration by DHCPv6 Option for Hosts with Multiple Interfaces 9 draft-sun-mif-route-config-dhcp6-02 11 Abstract 13 Currently, more and more hosts have multiple interfaces such as GPRS, 14 WiFi etc. One key issue is how to make the applications on the host 15 access the network accordingly through the proper interfaces. The 16 approach presented in this document is to extend DHCPv6 option to 17 configure route tables of the hosts. In this way, the hosts can 18 select a appropriate route. 20 Status of this Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on January 11, 2011. 37 Copyright Notice 39 Copyright (c) 2010 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 2. Solution of Multiple Interface Usage . . . . . . . . . . . . . 4 56 3. DHCPv6 Option Extensions . . . . . . . . . . . . . . . . . . . 6 57 3.1. Host and Server Behavior . . . . . . . . . . . . . . . . . 6 58 3.2. Route Information Option . . . . . . . . . . . . . . . . . 6 59 3.3. Some Considerations of the DHCPv6 Option . . . . . . . . . 7 60 3.3.1. Conflict of Route Rules . . . . . . . . . . . . . . . 7 61 3.3.2. Application Situations . . . . . . . . . . . . . . . . 7 62 3.3.3. Not Limited to DHCP Servers . . . . . . . . . . . . . 7 63 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 64 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 65 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 66 6.1. Normative References . . . . . . . . . . . . . . . . . . . 11 67 6.2. Informative References . . . . . . . . . . . . . . . . . . 11 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 70 1. Introduction 72 A host such as a laptop or a smart-phone may have multiple interfaces 73 for connections, e.g., a wired Ethernet LAN, a 802.11 LAN, a 3G 74 cellular network, one or multiple VPNs or tunnels. In view of more 75 and more versatile applications, users may expect a host to utilize 76 several interfaces simultaneously. 78 An application uses certain interface through select the 79 corresponding source IP address. if the applicaiton does not specifiy 80 it, the transport layer must ask the IP layer. According to 81 [RFC1122] all the packets whose destination IP addresses are not 82 specified in the route table will be sent to the default gateway for 83 forwarding. Accordingly, the IP address corresponding to the default 84 gateway will be chosen as the source IP address. 86 To avoid all packets passing through the same interface corresponding 87 to the default gateway, the approach proposed in this document 88 configures certain routes in route tables of the host. The 89 configuration information is obtained through DHCP messages which 90 extend the DHCPv6 option. 92 An optional extension to Router Advertisement messages is described 93 in [RFC4191] for communicating default router preferences and more- 94 specific routes from routers to hosts. To address multi-homed 95 problems in a flexible way, [I-D.hui-mif-dhcpv4-routing-02] extends 96 DHCPv4 through introducing TOS and specific routes into DHCP options. 97 This document considers the situations for IPv6 cases. Similar 98 approach was presented in [I-D.dec-dhcpv6-route-option-03] , however, 99 TOS and metrics information have not been involved. 101 2. Solution of Multiple Interface Usage 103 The procedures for a host to configure the routing information and 104 select the interface are depicted in Figure 1. The routing 105 configuration procedures are shown as steps a1) to a3). 107 a1) An interface sends Information-requirement when the connection 108 is established or when an existing connection receives 109 reconfiguration message from the server. 111 a2) The server sends routing information through DHCPv6 option as to 112 be defined in Section 3.2. 114 a3) The routing information received from the interface is used to 115 update the routing table of the host. 117 The procedures that an application employs an interface for network 118 access are depicted in Figure 1 as steps b1) to b4). 120 b1) An application calls sockets to build IP packets. 122 b2) The socket selects source address based on the routing table. 124 b3) The socket sends packets to the corresponding interface. 126 b4) The interface will forward the packets to the next hop (the 127 corresponding gateway). 129 +----+ a1 +---------+ b4 +-------+ 130 |DHCP|<--------- |Interface|--------->|Network| 131 +----+ --------> +---------+ +-------+ 132 a2 | | 133 | | 134 b3 | | 135 ^ | a3 136 | ----->----+ 137 | | 138 +-----------+ b1 +------+ +-----------+ 139 |Application|---->|Socket|<------|Route Table| 140 +-----------+ +------+ b2 +-----------+ 142 Figure 1: The procedures of updating a routing table and select an 143 interface for an application 145 Notice that the approach proposed in this document is feasible under 146 the strong ES model as defined in [RFC1122]. 148 3. DHCPv6 Option Extensions 150 3.1. Host and Server Behavior 152 The host must include "Option Request" option to let the server know 153 the option the host interested. The request option code is set as 154 the "Route Information" defined in Section 3.2. 156 The server constructs a Reply message to provide route information to 157 the host. Also, a server may send a Reconfigure Message to a host. 158 The host may initiate a request when receiving the Reconfigure 159 message for the host. 161 3.2. Route Information Option 163 The DHCPv6 option is extended to contain multiple pieces of route 164 information. Each piece of route information contains TOS, metric, 165 destination IP address and the next hop IP address. The ROUTE_INFO 166 option is depicted in Figure 2. 168 0 1 2 3 169 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 170 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 171 | OPTION_ROUTE_INFO | option-len | Preference 1 | 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 + TOS 1 | Metric 1 | Dest. Add. Pref. Len| Dest. Add. Pref. | 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . 175 . . 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 + Next Hop IPv6 Address . 178 . . 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 . . 181 . . 182 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 183 + Preference N | TOS N | Metric N | Dest. Add. Pref. Len | 184 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 + Dest. Add. Pref. . 186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 187 + Next Hop IPv6 Address . 188 . . 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 Figure 2: The Route Information Option 193 option-code:OPTION_ROUTE_INFO (should be defined by IANA). 195 option-len: length of the route rule field in octets. 197 Preference N: An integer to indicate the priority of applying the Nth 198 route rule. The Preference identified the priority of a rule. if 199 there are conflications, e.g., two rules have the same "Dest. Add. 200 Pref." but different "Next Hop IPv6 Address", the rule with high 201 preference SHOULD be applied by the host. 203 TOS N: The Nth TOS (Type-of-Service, 8 bits). 205 Metric N:The Nth route metric ranging from 1 to 9999. 207 Dest. Add. Prefix Len: Length of the IPv6 destination address 208 prefix, an 8-bit unsigned integer ranging from 0 to 128. 210 Dest. Add. Prefix: The IPv6 destination address prefix 212 Next Hop IPv6 Address: A 128-bit IPv6 address that will be used as 213 the next hop when forwarding packets. 215 In the above, the "Preference" of one route rule comes before the 216 "metric." Namely, if there are conflict routes for one destination, 217 the one with highest preference value should be used. For example, 218 the network administrator may prefer one route in a connection for 219 security or reliability considerations, even though the metric of the 220 route is large. 222 3.3. Some Considerations of the DHCPv6 Option 224 3.3.1. Conflict of Route Rules 226 The host can use such information obatined from the DHCP message to 227 build a "connection manager" on the host or to update the "Policy 228 Table" defined in [RFC3484]. For the situations where a route option 229 conflicts with one previous route rules, the latter one will override 230 the previous rule. 232 3.3.2. Application Situations 234 There are two situations when DHCPv6 is applied, i.e., with or 235 without stateless autoconfiguration. For the stateless case, since 236 the address has been configured based on the link-local/site-local 237 address, the DHCPv6 is used to obtain options. 239 3.3.3. Not Limited to DHCP Servers 241 The solution presented in this document is with the context of DHCP 242 message. It should be pointed out that similar message may not be 243 conveyed by certain node in the network instead of a DHCP server. 244 Such a node, for example in mobile network, may be the "ANDSF (Access 245 Network Discovery and Selection function)" defined in TS 23.402. 247 4. IANA Considerations 249 The option code of OPTION_ROUTE_INFO will be defined by IANA. 251 5. Security Considerations 253 The security issues in this document are similar with those that have 254 been met when using DHCPv6 options. 256 The interface selection is affected by the routing and address 257 selection rules sent from servers. Therefore, incorrect information 258 received by hosts will cause improper interface selection leading to 259 bad user experiences. Attacks such as deny of services (DoS) or man- 260 in-the-middle may redirect host's solicitation, change the 261 information or flood the host with invalidate messages. Approaches 262 to guarantee the communication securities between hosts and servers 263 should be applied based on the network access types of the 264 interfaces. 266 6. References 268 6.1. Normative References 270 [RFC1122] Braden, R., "Requirements for Internet Hosts - 271 Communication Layers", STD 3, RFC 1122, October 1989. 273 [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor 274 Discovery for IP Version 6 (IPv6)", RFC 2461, 275 December 1998. 277 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 278 and M. Carney, "Dynamic Host Configuration Protocol for 279 IPv6 (DHCPv6)", RFC 3315, July 2003. 281 [RFC3484] Draves, R., "Default Address Selection for Internet 282 Protocol version 6 (IPv6)", RFC 3484, February 2003. 284 [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and 285 More-Specific Routes", RFC 4191, November 2005. 287 6.2. Informative References 289 [I-D.blanchet-mif-problem-statement] 290 Blanchet, M. and P. Seite, "Multiple Interfaces Problem 291 Statement", May 2010, . 294 [I-D.dec-dhcpv6-route-option-03] 295 Dec, W. and R. Johnson, "DHCPv6 Route Option", March 2010, 296 . 298 [I-D.hui-mif-dhcpv4-routing-02] 299 Hui, M. and H. Deng, "Extension of DHCPv4 for policy 300 routing of multiple interfaces terminal", March 2010, 301 . 303 Authors' Addresses 305 Tao Sun 306 China Mobile 307 Unit2, 28 Xuanwumenxi Ave,Xuanwu District 308 Beijing 100053 309 China 311 Email: suntao@chinamobile.com 313 Hui Deng 314 China Mobile 315 Unit2, 28 Xuanwumenxi Ave,Xuanwu District 316 Beijing 100053 317 China 319 Email: denghui@chinamobile.com 321 Dapeng Liu 322 China Mobile 323 Unit2, 28 Xuanwumenxi Ave,Xuanwu District 324 Beijing 100053 325 China 327 Email: liudapeng@chinamobile.com