Transmission of IPv6 Packets over FDDI Networks (RFC2467)
Original Publication Date: 1998-Dec-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
This document specifies the frame format for transmission of IPv6 packets and the method of forming IPv6 link-local addresses and statelessly autoconfigured addresses on FDDI networks. [STANDARDS-TRACK]
Network Working Group M. Crawford Request for Comments: 2467 Fermilab Obsoletes: 2019 December 1998 Category: Standards Track
Transmission of IPv6 Packets over FDDI 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 (C) The Internet Society (1998). All Rights Reserved.
This document specifies the frame format for transmission of IPv6 packets and the method of forming IPv6 link-local addresses and statelessly autoconfigured addresses on FDDI networks. It also specifies the content of the Source/Target Link-layer Address option used in Router Solicitation, Router Advertisement, Neighbor Solicitation, Neighbor Advertisement and Redirect messages when those messages are transmitted on an FDDI network.
This document replaces RFC 2019, "Transmission of IPv6 Packets Over FDDI", which will become historic.
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].
2. Maximum Transmission Unit
FDDI permits a frame length of 4500 octets (9000 symbols), including at least 22 octets (44 symbols) of Data Link encapsulation when long-format addresses are used. Subtracting 8 octets of LLC/SNAP header, this would, in principle, allow the IPv6 [IPV6] packet in the Information field to be up to 4470 octets. However, it is desirable to allow for the variable sizes and possible future extensions of the MAC header and frame status fields. The default MTU size for IPv6 packets on an FDDI network is therefore 4352 octets. This size may be reduced by a Router Advertisement [DISC] containing an MTU option
Crawford Standards Track [Page 1]
RFC 2467 IPv6 over FDDI December 1998
which specifies a smaller MTU, or by manual configuration of each node. If a Router Advertisement received on an FDDI interface has an MTU option specifying an MTU larger than 4352, or larger than a manually configured value, that MTU option may be logged to system management but must be otherwise ignored.
For purposes of this document, information received from DHCP is considered "manually configured" and the term FDDI includes CDDI.
3. Frame Format
FDDI provides both synchronous and asynchronous transmission, with the latter class further subdivided by the use of restricted and unrestricted tokens. Only asynchronous transmission with unrestricted tokens is required for FDDI interoperability. Accordingly, IPv6 packets shall be sent in asynchronous frames using unrestricted tokens. The robustness principle dictates that nodes should be able to receive synchronous frames and asynchronous frames sent using restri...