T. Sun Internet Draft H. Deng Intended status: Informational China Mobile Expires: September 2009 March 10, 2009 Route Configuration by DHCPv6 Option for Hosts with Multiple Interfaces draft-sun-mif-route-config-dhcp6-01.txt 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." 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Abstract Sun & Deng Expires September 10, 2009 [Page 1] Internet-Draft Route Configuration by DHCPv6 March 2009 For hosts with multiple interfaces, the problem is how to make it run several applications simultaneously on variant interfaces such as GPRS, Wifi etc. To achieve this, one key issue here is to select appropriate route according to RFC 1122. The approach presented in this document is extending DHCPv6 option to configure route tables of the hosts. Table of Contents 1. Introduction................................................2 2. Solution of Multiple Interface Usage.........................3 3. DHCPv6 Option Extensions.....................................4 3.1. Host and Server Behavior................................4 3.2. Route Information Option................................4 3.3. Some Considerations of the DHCPv6 Option................6 3.3.1. Conflict of Route Rules............................6 3.3.2. Application Situations.............................6 3.3.3. Not Limited to DHCP Servers........................6 4. IANA Considerations.........................................6 5. Security Considerations......................................6 6. References..................................................7 6.1. Normative References....................................7 6.2. Informative References..................................7 1. Introduction A host such as a laptop or a smart-phone may have multiple interfaces for connections, e.g., a wired Ethernet LAN, a 802.11 LAN, a 3G cell network, one or multiple VPNs or tunnels. In view of more and more versatile applications, users may expect a host to utilize several interfaces at the same time. If the source IP address is selected and bind by an application, then the application can use certain interface in this way. However, source IP addresses are generally added by sockets in IP layer. According to [RFC 1122], all the packets whose destination IP addresses is not specified in the route table will be send to a default gateway for forwarding. Accordingly, the IP address corresponding to the default gateway is chosen as the source IP address. To avoid all packets passing through the same interface corresponding to the default gateway, the approach in this document configures certain routes in route tables of hosts. The configuration information is sent through extending DHCPv6 option. Sun & Deng Expires September 10, 2009 [Page 2] Internet-Draft Route Configuration by DHCPv6 March 2009 In [RFC 4191], multiple default routers and specific routes are used to handle multi-homed scenarios. To address multi-homed problems in a flexible way, [I-D-hui-mif-dhcpv4-routing-00] extends DHCPv4 through introducing TOS and specific routes into DHCP options. This document considers IPv6 situations. Similar approach was presented in [I-D- dec-dhcpv6-route-option-00] where TOS and metrics information have not been involved. 2. Solution of Multiple Interface Usage The procedures of configuring routing information and selecting interface are depicted in Figure 1. The routing configure procedures are shown as steps a1 to a3. o a1) An interface sends Information-requirement when the connection is established or when an existing connection receives reconfiguration message from the server. o a2) The server sends routing information through DHCPv6 option as to be defined in Section 3.2. o a3) The routing information received from the interface is used to configure the routing table of the host. The procedures that an application employs an interface for network access are depicted in Figure 1 as steps b1 to b4. o b1) An application calls sockets to build IP packets. o b2) The socket selects source address based on the routing table. o b3) The socket sends packets to the corresponding interface. o b4) The interface will forward the packets to the next hop (the corresponding gateway). Sun & Deng Expires September 10, 2009 [Page 3] Internet-Draft Route Configuration by DHCPv6 March 2009 +----+ a1 +---------+ b4 +-------+ |DHCP|<--------- |Interface|--------->|Network| +----+ --------> +---------+ +-------+ a2 | | | | b3 | | ^ | a3 | ----->----+ | | +-----------+ b1 +------+ +-----------+ |Application|---->|Socket|<------|Route Table| +-----------+ +------+ b2 +-----------+ Figure 1 The procedures of updating a routing table and select an interface for an application. Notice that the approach proposed in this document is feasible under the strong ES model as defined in RFC1122. 3. DHCPv6 Option Extensions 3.1. Host and Server Behavior The host must include "Option Request" option to let the server know the option the host interested. The request option code is set as the "Route Information" defined in 3.2. The server constructs a Reply message to provide route information to the host. Also, a server may send a Reconfigure Message to a host. The host may initiate a request when receiving the Reconfigure message for the host. 3.2. Route Information Option The DHCPv6 option is extended to contain multiple pieces of route information. Each piece of route information contains TOS, metric, destination IP address and the next hop IP address. The ROUTE_INFO option is depicted in Figure 2. Sun & Deng Expires September 10, 2009 [Page 4] Internet-Draft Route Configuration by DHCPv6 March 2009 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_ROUTE_INFO | option-len | Preference 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + TOS 1 | Metric 1 | Dest. Add. Pref. Len| Dest. Add. Pref. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Next Hop IPv6 Address . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Preference N | TOS N | Metric N | Dest. Add. Pref. Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Dest. Add. Pref. . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + Next Hop IPv6 Address . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 The Route Information Option. option-code OPTION_ROUTE_INFO (should be defined by IANA). option-len length of the route rule field in octets. Preference N An integer to indicate the priority of applying the Nth route rule. TOS N The Nth TOS (Type-of-Service, 8 bits). Metric N The Nth route metric ranging from 1 to 9999. Dest. Add. Prefix Len Length of the IPv6 destination address prefix, an 8-bit unsigned integer ranging from 0 to 128. Dest. Add. Prefix The IPv6 destination address prefix Next Hop IPv6 Address A 128-bit IPv6 address that will be used as the next hop when forwarding packets. In the above, the "Preference" of one route rule comes before the "metric." Namely, if there are conflict routes for one destination, Sun & Deng Expires September 10, 2009 [Page 5] Internet-Draft Route Configuration by DHCPv6 March 2009 the one with highest preference value should be used. For example, the network administrator uses one route in a connection for security or reliability considerations, even though the metric of the route is large. 3.3. Some Considerations of the DHCPv6 Option 3.3.1. Conflict of Route Rules For the situations where a route option conflicts with one previous route rules, the latter one will override the previous rule. 3.3.2. Application Situations There are two situations when DHCPv6 is applied, i.e., with or without stateless autoconfiguration. For the stateless case, since the address has been configured based on the link-local/site-local address, the DHCPv6 is used to obtain options. 3.3.3. Not Limited to DHCP Servers The solution presented in this document is with the context of DHCP message. It should be pointed out that similar message may not be conveyed by certain node in the network instead of a DHCP server. 4. IANA Considerations The option code of ROUTE RULE will be defined by IANA. 5. Security Considerations The security issues in this document are similar with those that have been met when using DHCPv6 options. The interface selection is affected by the routing and address selection rules sent from servers. Therefore, incorrect information received by hosts will cause improper interface selection leading to bad user experiences. Attacks such as deny of services (DoS) or man- in-the-middle may redirect host's solicitation, change the information or flood the host with invalidate messages. Approaches to guarantee the communication securities between hosts and servers should be applied based on the network access types of the interfaces. Sun & Deng Expires September 10, 2009 [Page 6] Internet-Draft Route Configuration by DHCPv6 March 2009 6. References 6.1. Normative References [RFC1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, October 1989. [RFC3484] R. Draves, "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC3484, February 2003. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and More-Specific Routes", RFC 4191, November 2005. 6.2. Informative References [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [I-D.blanchet-mif-problem-statement] Blanchet, M., "Multiple Interfaces Problem Statement", draft-blanchet-mif-problem- statement-00 (work in progress), December 2008. [I-D.hui-mif-dhcpv4-routing-00] Hui, M., and Deng, H. "Extension of DHCPv4 for policy routing of multiple interfaces terminal," draft-hui-mif-dhcpv4-routing-00(work in progress), February 2009 [I-D.dec-dhcpv6-route-option-00] Dec, W., and Johnson, R, "DHCPv6 Route Option," draft-dec-dhcpv6-route-option-00(work in progress), February 2009 [I-D.yang-mif-req] Yang, P., Seite, P., Williams, C., and J. Qin, "Requirements on multiple Interface (MIF) of simple IP", draft-yang-mif-req-00 (work in progress), March 2009. Sun & Deng Expires September 10, 2009 [Page 7] Internet-Draft Route Configuration by DHCPv6 March 2009 Authors' Addresses Tao Sun China Moible 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: suntao@chinamobile.com Hui Deng China Moible 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: denghui@chinamobile.com Sun & Deng Expires September 10, 2009 [Page 8]