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Versions: 00
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
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Please send comments on this draft to the Nimrod Working Group,
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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.
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