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Transmission of IPv6 Packets Over FDDI (RFC2019)

IP.com Disclosure Number: IPCOM000002572D
Original Publication Date: 1996-Oct-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 5 page(s) / 11K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Crawford: AUTHOR

Abstract

This memo specifies the MTU and frame format for transmission of IPv6 [IPV6] packets on FDDI networks, including a method for MTU determination in the presence of 802.1d bridges to other media. It also specifies the method of forming IPv6 link-local addresses on FDDI networks and the content of the Source/Target Link-layer Address option used the the Router Solicitation, Router Advertisement, Neighbor Solicitation, and Neighbor Advertisement messages described in [DISC], when those messages are transmitted on an FDDI network.

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Network Working Group M. Crawford

Request for Comments: 2019 Fermilab

Category: Standards Track October 1996

A Method for the 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.

Introduction

This memo specifies the MTU and frame format for transmission of IPv6

[IPV6] packets on FDDI networks, including a method for MTU

determination in the presence of 802.1d bridges to other media. It

also specifies the method of forming IPv6 link-local addresses on

FDDI networks and the content of the Source/Target Link-layer Address

option used the the Router Solicitation, Router Advertisement,

Neighbor Solicitation, and Neighbor Advertisement messages described

in [DISC], when those messages are transmitted on an FDDI network.

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 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 to 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

which specifies a smaller MTU, or by manual configuration of a

smaller value on each node. If a Router Advertisement is received

with an MTU option specifying an MTU larger than the default or the

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".

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 princi...