Transmission of IPv6 Packets over ARCnet Networks
RFC 2497

Document Type RFC - Proposed Standard (January 1999; No errata)
Last updated 2013-03-02
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Network Working Group                                       I. Souvatzis
Request for Comments: 2497                            The NetBSD Project
See Also: 1201                                              January 1999
Category: Standards Track

           Transmission of IPv6 Packets over ARCnet Networks

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

1. Introduction

   This memo specifies a frame format for transmission of IPv6 [IPV6]
   packets and the method of forming IPv6 link-local and statelessly
   autoconfigured addresses on ARCnet networks. It also specifies the
   content of the Source/Target Link-layer Address option used by the
   Router Solicitation, Router Advertisement, Neighbor Solicitation,
   Neighbor Advertisement and Redirect messages described in [DISC],
   when those messages are transmitted on an ARCnet.

      The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
      in this document are to be interpreted as described in RFC 2119

2. Frame Format

   IPv6 packets are link layer fragmented and reassembled according to
   [PHDS]. A brief but sufficient discussion of this fragmentation
   method can be found in [ARCIPV4].

   The protocol ID (System Code in ARCnet terminology) assigned to IPv6
   is C4 hexadecimal.

Souvatzis                   Standards Track                     [Page 1]
RFC 2497                IPv6 Datagrams on ARCnet            January 1999

3. Maximum Transmission Unit

   The maximum IPv6 packet length possible using this encapsulation
   method is 60480 octets. Since this length is impractical because of
   its worst case transmission time of several seconds, all ARCnet
   implementations on a given ARCnet network should agree on a smaller

   The default MTU for IPv6 [IPV6] packets on an ARCnet is 9072 octets.

   In the presence of a router, this size MAY be changed by a Router
   Advertisement [DISC] containing an MTU option. If a Router
   Advertisement is received with an MTU option specifying an MTU larger
   than 60480, or larger than a manually configured value less than
   60480, that MTU option may be logged to system management but MUST be
   otherwise ignored.

   If no router is available, the local MTU MUST be left at 9072 or MUST
   be manually configured to the same different value on all connected

   Implementations MAY accept arriving IPv6 datagrams which are larger
   than their configured maximum transmission unit.  They are not
   required to discard such datagrams. If they can not handle larger
   datagrams, they MAY log the event to the system administration, but
   MUST otherwise silently discard them.

4. Stateless Auto-configuration

   If a node has an EUI-64 which is not used to form the Interface
   Identifier for any other interface, it SHOULD use that EUI-64 to form
   the Interface Identifier for its ARCnet interface.  If that EUI-64 is
   in use for another interface attached to a different link, it MAY be
   used for the ARCnet interface as well.

   The Interface Identifier is then formed from the EUI-64 by
   complementing the "Universal/Local" (U/L) bit, which is the next-
   to-lowest order bit of the first octet of the EUI-64.

   When a node has no EUI-64 available for forming its ARCnet Interface
   Identifer, it MUST form that identifier as specified in [AARCH],
   Appendix A, section "Links with Non-Global Identifier".  That is, the
   8 bit manually configured ARCnet address is appended to the 56 zero

   For example, for an ARCnet interface with the configured address of
   49 hexadecimal this results in the following identifier:

Souvatzis                   Standards Track                     [Page 2]
RFC 2497                IPv6 Datagrams on ARCnet            January 1999

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