HIP Working Group G. Camarillo Internet-Draft A. Keranen Intended status: Experimental Ericsson Expires: April 29, 2010 October 26, 2009 Host Identity Protocol (HIP) Multi-hop Routing Extension draft-ietf-hip-via-00.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." 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 April 29, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document specifies two extensions to HIP to implement multi-hop routing. The first extension allows implementing source routing in HIP. That is, a host sending a HIP packet can define a set of hosts Camarillo & Keranen Expires April 29, 2010 [Page 1] Internet-Draft HIP Multi-hop Routing Extension October 2009 that the HIP packet should traverse. The second extension allows a HIP packet to carry and record the list of hosts that forwarded it. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Protocol Definitions . . . . . . . . . . . . . . . . . . . . . 3 3.1. Creating and Processing Via Lists . . . . . . . . . . . . . 3 3.2. Creating Destination Lists . . . . . . . . . . . . . . . . 4 3.3. Processing Destination Lists . . . . . . . . . . . . . . . 4 4. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. Source and Destination Route List Parameters . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6.1. Forwarding Loops . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Camarillo & Keranen Expires April 29, 2010 [Page 2] Internet-Draft HIP Multi-hop Routing Extension October 2009 1. Introduction When HIP [RFC5201] is used in certain contexts (e.g., in a HIP BONE [I-D.ietf-hip-bone] overlay), hosts need the ability to perform source routing. That is, a host needs the ability to send a HIP packet that will traverse a set of hosts before reaching its destination. This document defines an extension that provides HIP with this functionality. Additionally, when HIP packets are routed through multiple hosts, some of these hosts (e.g., the destination host) need the ability to know the hosts a particular packet traversed. This document defines another extension that provides HIP with this functionality. These two extensions enable multi-hop routing in HIP. Before these extensions were specified, HIP only supported a single intermediate host (i.e., a rendezvous server [RFC5204]) between the source of a HIP packet and its destination. 2. Terminology 2.1. Requirements Language 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 [RFC2119]. 2.2. Definitions Destination list: A list of HITs of the hosts that a HIP packet should traverse. Via list: A list of HITs of the hosts that a HIP packet has traversed. Symmetric routing: A response to a message is routed back using the same set of intermediary nodes as the original message used, except in reversed order. 3. Protocol Definitions 3.1. Creating and Processing Via Lists When a host sending a HIP packet needs to record the hosts that are on the path that the HIP packet traverses, it includes an empty ROUTE_VIA parameter to the packet. Camarillo & Keranen Expires April 29, 2010 [Page 3] Internet-Draft HIP Multi-hop Routing Extension October 2009 A host that receives a packet with a ROUTE_VIA parameter SHOULD add its own HIT to the end of the ROUTE_VIA parameter, unless it is the receiver of the packet. If the host uses a different HIT on the HIP association it used for receiving the packet than for sending it forward, it SHOULD also add the receiving HIT to the route list before the sending HIT. If the host is the receiver of the packet, and the received packet generates a response HIP packet, the host checks the SYMMETRIC flag from the ROUTE_VIA parameter. If the SYMMETRIC flag is set, the host SHOULD create a ROUTE_DST parameter from the ROUTE_VIA parameter, as described in Section 3.2, and include it in the response packet. Also, if an intermediary host generates a new HIP packet (e.g., an error NOTIFY packet) due to a HIP packet that had a ROUTE_VIA parameter with SYMMETRIC flag set, and the new packet is intended for the sender of the original HIP packet, the host SHOULD construct and add a ROUTE_DST parameter into the new packet as in the previous case. 3.2. Creating Destination Lists A host that needs to define the other hosts that should be on the path a HIP packet traverses adds a ROUTE_DST parameter to the HIP packet. The host may either decide the path independently, or it may create the path based on a ROUTE_VIA parameter. Only the originator of a signed HIP packet can add a ROUTE_DST parameter to the HIP packet since the parameter is covered by the signature. When a host creates a ROUTE_DST parameter due to receiving a packet with a ROUTE_VIA parameter, it copies all the HITs in the ROUTE_VIA parameter to the ROUTE_DST parameter, but in reversed order. This results in HIP response packet being forwarded using the same set of hosts as the packet for which the response was generated for. 3.3. Processing Destination Lists When a host receives a HIP packet that contains a ROUTE_DST parameter, it first looks up its own HIT from the route list. If host's own HIT is not in the list and the host is not the receiver of the packet, the packet was incorrectly forwarded and MUST be dropped. Next hop for the packet is the HIT after host's own HIT in the list. If the host's HIT was the last HIT in the list, the next hop is the receiver's HIT in the HIP header. 4. Packet Formats This memo defines two new HIP parameters that are used for recording Camarillo & Keranen Expires April 29, 2010 [Page 4] Internet-Draft HIP Multi-hop Routing Extension October 2009 a route via multiple hosts (ROUTE_VIA) and to define a route a packet should traverse by the sender of the packet (ROUTE_DST). The ROUTE_DST parameter is integrity protected with the signature (where present) but ROUTE_VIA is not so that intermediary hosts can add their own HITs to the list. Both parameters have critical type (as defined in Section 5.2.1 of [RFC5201]) since the packet will not be properly routed unless all hosts on path recognize the parameters. 4.1. Source and Destination Route List Parameters 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | HIT #1 | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | HIT #n | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type [ TBD by IANA ROUTE_DST: 971 ROUTE_VIA: 65525 ] Length length in octets, excluding Type and Length (i.e., number-of-HITs * 16 + 4) Flags bit flags that can be used for requesting special handling of the parameter Reserved reserved for future use HIT Host Identity Tag of one of the hosts on the path Figure 1: Format of the ROUTE_VIA and ROUTE_DST parameters Figure 1 shows the format of both ROUTE_VIA and ROUTE_DST parameters. The ROUTE_DST parameter, if present, MUST have at least one HIT, but the ROUTE_VIA parameter can also have zero HITs. Both can contain at Camarillo & Keranen Expires April 29, 2010 [Page 5] Internet-Draft HIP Multi-hop Routing Extension October 2009 most 32 HITs. The Flags field is used for requesting special handling for certain Route lists. The flags defined in this document are shown in Table 1. The Reserved field can be used by future extensions; it MUST be zero when sending and ignored when receiving this parameter. +-----+-----------+-------------------------------------------------+ | Pos | Name | Purpose | +-----+-----------+-------------------------------------------------+ | 0 | SYMMETRIC | The response packet MUST be sent using | | | | ROUTE_DST list made from this ROUTE_VIA list, | | | | i.e., using symmetric routing. | +-----+-----------+-------------------------------------------------+ Table 1: Bit flags in ROUTE_VIA parameter The "Pos" column in Table 1 shows the bit position of the flag (as in Figure 1) in the Flags field, "Name" gives the name of the flag used in this document, and "Purpose" gives brief description of the meaning of that flag. 5. IANA Considerations This section is to be interpreted according to [RFC5226]. This document updates the IANA Registry for HIP Parameter Types [RFC5201] by assigning new HIP Parameter Type values for the new HIP Parameters: ROUTE_VIA and ROUTE_DST (defined in Section 4). 6. Security Considerations 6.1. Forwarding Loops A malicious host could craft a destination route list that contains the same HIT more than once and thus create a forwarding loop. Since the IP layer TTL is decremented on each hop, the loop will be eventually broken, but hosts may additionally protect themselves against this attack by checking that their own HIT is in the destination list only once and drop invalid packets. 7. References Camarillo & Keranen Expires April 29, 2010 [Page 6] Internet-Draft HIP Multi-hop Routing Extension October 2009 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, "Host Identity Protocol", RFC 5201, April 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. 7.2. Informative References [RFC5204] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Rendezvous Extension", RFC 5204, April 2008. [I-D.ietf-hip-bone] Camarillo, G., Nikander, P., Hautakorpi, J., and A. Johnston, "HIP BONE: Host Identity Protocol (HIP) Based Overlay Networking Environment", draft-ietf-hip-bone-02 (work in progress), July 2009. Authors' Addresses Gonzalo Camarillo Ericsson Hirsalantie 11 02420 Jorvas Finland Email: Gonzalo.Camarillo@ericsson.com Ari Keranen Ericsson Hirsalantie 11 02420 Jorvas Finland Email: ari.keranen@ericsson.com Camarillo & Keranen Expires April 29, 2010 [Page 7]