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Versions: 00                                                            
TUBA Working Group                                             Dave Katz
INTERNET-DRAFT                                             cisco Systems
<draft-ietf-tuba-eon-00.txt>                                  March 1994


             Tunneling the OSI Network Layer over IP (EON)


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.  Internet Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet
   Drafts as reference material or to cite them other than as a "working
   draft" or "work in progress."

   Please check the I-D abstract listing contained in each Internet
   Draft directory to learn the current status of this or any Internet
   Draft.


Abstract

   This memo documents the subset of the Experimental OSI Net (EON) [1]
   that is in active use today.  It serves to document current practice,
   which deviates somewhat from the usage described in the original RFC.

   Potential implementors should note that the protocol described herein
   is archaic and is likely to be replaced in the near future.


1. Introduction

   RFC 1070 [1] describes a scheme for experimenting with OSI Network
   Layer protocols over an IP backbone.  The memo describes methods for
   mapping aspects of subnetwork operation (such as multicast and
   broadcast) and an NSAP address allocation and mapping scheme, as well
   as a packet encapsulation format.

   In the time since the EON RFC was published, three independent
   implementations have been fielded and are currently deployed in
   production use.  These implementations use a small subset of the
   functionality described in the original memo.


2. Functionality

   The EON protocol as implemented and fielded is simply a virtual
   point-to-point encapsulation technology, using statically configured
   tunnel endpoints.  There is no support for simulating a multipoint
   subnetwork, nor for dynamic mapping between NSAP addresses and IP
   addresses.  Instead, IP addresses are simply viewed as Subnetwork
   Point of Attachment (SNPA) addresses that must be statically
   configured to create the tunnel.

   Once a tunnel is established, data is transmitted using CLNP [2].
   The ES-IS [3], IS-IS [4], and IDRP [5] protocols may be used to
   dynamically establish neighbor adjacencies and routing.  Any NSAP
   addresses may be assigned to the systems at either end of the tunnel.
   There is no need to constrain the NSAP address format as documented
   in RFC 1070, since there is no need to perform dynamic address
   mapping.


3. Encapsulation

   Only the direct IP encapsulation described in RFC 1070 is used.
   Within that encapsulation, only the unicast format is used.  This
   results in a constant header value (after calculating the checksum).
   To summarize, the encapsulation is as follows:

      IP header (protocol = 80 decimal)
      EON header (value = hexadecimal 01 00 FC 02)
      OSI Network Layer packet


4. Errors on the IP subnetwork

   No attempt has been made to implement feedback of error indications
   from ICMP in the IP subnetwork into CLNP error PDUs.  The tunnel is
   ignorant of problems in the IP subnetwork, and depends upon
   mechanisms in the OSI routing protocols to detect connectivity
   failures.


References

   [1] Hagens, R., N. Hall, and M. Rose.  "Use of the Internet as a
   Subnetwork for Experimentation with the OSI Network Layer," RFC 1070,
   U of Wisconsin/The Wollongong Group, February 1989.

   [2] ISO, "Protocol for providing the Connectionless-mode Network
   Service," ISO 8473:1988.

   [3] ISO, "End system to Intermediate system routeing exchange
   protocol for use in conjunction with the Protocol for providing the
   connectionless-mode network service (ISO 8473)," ISO 9542:1988.

   [4] ISO, "Intermediate system to Intermediate system routeing
   information exchange protocol for use in conjunction with the
   Protocol for providing the Connectionless-mode Network Service (ISO
   8473)," ISO/IEC 10589:1992.

   [5] ISO, "Intermediate system to Intermediate system interdomain
   routeing information exchange protocol for use in conjunction with
   the Protocol for providing the Connectionless-mode Network Service
   (ISO 8473)," ISO/IEC 10747:1993.


Author's Address

   Dave Katz
   cisco Systems, Inc.
   1525 O'Brien Dr.
   Menlo Park, CA 94025
   +1 (415) 688-8284

   EMail:  dkatz@cisco.com