Internet Draft C. Lynn Nimrod Working Group BBN Systems and Technologies Expiration Date: May 1996 November 1995 draft-ietf-nimrod-eid-00.txt Endpoint Identifier Destination Option Status of this Memo This document is an Internet-Draft. 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". To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Please send comments on this draft to the Nimrod Working Group, nimrod-wg@BBN.Com. This Internet Draft expires May 1996. Abstract This document describes a Destination Option that is used to convey topologically independent endpoint identification information between source and destination endpoints in either IPv4 or IPv6 packets. The general format of Destination Options are described in [5]. The Nimrod Routing System [1] will make use of this option to convey Nimrod EIDs. 1 Introduction Nimrod is a scalable internetwork routing architecture [1,2,3]. The Nimrod architecture is designed to accommodate an internetwork of arbitrary size, with heterogeneous service requirements and restrictions, and to admit incremental deployment throughout an internetwork. The key to Nimrod's scalability is its ability to represent and manipulate routing-related information at multiple levels of abstraction. draft-ietf-nimrod-eid-00.txt [Page 1]
Internet Draft Endpoint Identifier Destination Option November 1995 To do this efficiently, Nimrod separates the identification of communicating entities (endpoints, or "hosts") from any topological location information. Endpoint Identifiers (EIDs) are used to specify and uniquely identify endpoints connected to the network. Information about the topological location of an endpoint in an internetwork is given by a locator. An endpoint's locator may change as the network topology changes. Ongoing communication is not disrupted when a locator changes since the communicating endpoints are identified by their EIDs and not their locators. The mapping from an endpoint name to an EID and set of locators will be stored in the existing DNS system as two additional RRs [4] under the Domain Name of the endpoint. This document describes how the Source and Destination EIDs are communicated in IP packets using the Destination Options Extension Header. A Nimrod EID is a short binary identifier for an endpoint of a communication (e.g., a host) and has no structure or significance to the routing system other than global uniqueness. An endpoint can retain the same EID forever, no matter where in the network it is located. 2 Definition of the Endpoint Identifier Option The Endpoint Identifier Option is contained in the Destinations Options Extension Header (type 60) of an IPv4 or IPv6 packet. An endpoint identifier may be of variable length and is not restricted to the format used by Nimrod. This document specifies the encoding for 8-octet Nimrod EIDs, which results in an option containing twenty (20) octets. The alignment requirement for the encoding specified herein is 8n. Subsequent versions of this document may specify encodings for endpoint identifiers of other lengths or formats. Implementations are expected to verify that the Opt Data Len field contains 18 and that the Src and Dst Len fields contain 8 when using the following encoding. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Type | Opt Data Len | Src Len | Dst Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 1 0 0 | +-+- Source EID -+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 1 0 0 | +-+- Destination EID -+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ draft-ietf-nimrod-eid-00.txt [Page 2]
Internet Draft Endpoint Identifier Destination Option November 1995 Option Type 8-bit selector. The value <TBD> is used for the 5 least-significant bits of the Endpoint Identifier Option. The two most significant bits of the Option Type may vary from instance to instance. The value 00 should not be used. An endpoint may use other values as it deems appropriate to indicate whether or not an ICMP error message should be returned. See [5]. Since endpoint identifiers do not change en- route, the third most significant bit should be zero. Opt Data Len 8-bit unsigned integer. The length, in octets, of the endpoint identification data in the Source and Destination EID fields. Src Len 8-bit unsigned integer. The length, in octets, of the endpoint identifier in the Source EID field. Dst Len 8-bit unsigned integer. The length, in octets, of the endpoint identifier in the Destination EID field. Source EID The endpoint identifier of the source. Nimrod EIDs begin with the five bits 00100. Other formats may be defined in subsequent versions of this document. Destination EID The endpoint identifier of the destination. Nimrod EIDs begin with the five bits 00100. Other formats may be defined in subsequent versions of this document. 3 Option Processing The endpoint identifiers specified in the Endpoint Identifier Option are used to perform demultiplexing of IP packets at the transport layer. The Source EID field replaces the Source IP Address, and the Destination EID replaces the Destination IP Address, when identifying transport layer associations. They are also used in any pseudo headers [5,6,7] that are included in transport layer checksums. The Endpoint Identifier Option need not appear in every packet. When the communicating peers retain state information, as is the case for connection oriented transports such as TCP [7], or the draft-ietf-nimrod-eid-00.txt [Page 3]
Internet Draft Endpoint Identifier Destination Option November 1995 packets are part of an IPv6 Flow [5], the endpoint identifiers should be retained as part of the communication state, and thus their presence in subsequent packets is optional. Note that the option should not be omitted until the sending endpoint has received notification from its communication peer(s) indicating that they have received the identification information. For example, the ACK of a TCP SYN is sufficient notification in the case of TCP [7]. The endpoint identifiers are included in any pseudo header even when they are not present in a given packet. 4 Security Considerations In order to detect spoofing, packets that contain the Endpoint Identifier Option should be protected by an authentication and integrity mechanism. 5 Author's Address Charles Lynn Email: CLynn@BBN.Com BBN Systems and Technologies Phone: (617) 873 3367 10 Moulton Street Cambridge, MA, 02138 6 References [1] "The Nimrod Routing Architecture", I. Castineyra, J. N. Chiappa, M. Steenstrup, draft-ietf-nimrod-routing-arch-00.txt, March 1995. [2] "Mobility Support for Nimrod : Requirements and Solution Approaches", Ram Ramanathan, draft-ietf-nimrod-mobility-01.txt, .ps, March 1995. [3] "Multicast Support for Nimrod : Requirements and Solution Approaches", Ram Ramanathan, draft-ietf-nimrod-multicast-01.txt, .ps, March 1995. [4] "DNS Resource Records for Nimrod Routing Architecture", M. A. Patton, draft-ietf-nimrod-dns-01.txt, October 1995. [5] "Internet Protocol, Version 6 (IPv6) Specification", S. Deering, R. Hinden, draft-ietf-ipngwg-ipv6-spec-02.txt, June 19, 1995. [6] "User Datagram Protocol", J. Postel, RFC 768, 28 August 1980. [7] "TRANSMISSION CONTROL PROTOCOL", Information Sciences Institute, RFC 793, September 1981. draft-ietf-nimrod-eid-00.txt [Page 4]
