Internet Engineering Task Force Matt Crawford INTERNET-DRAFT Fermilab <draft-ietf-ipngwg-ethernet-ntwrks-01.txt> October 9, 1995 A Method for the Transmission of IPv6 Packets over Ethernet Networks 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." To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Distribution of this memo is unlimited. Introduction This memo specifies the frame format for transmission of IPv6 [IPV6] packets and the method of forming IPv6 link-local addresses on Ethernet networks. It also specifies 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 Ethernet. Maximum Transmission Unit The default MTU size for IPv6 packets on an Ethernet is 1500 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 each node. If a Router Advertisement is received with an MTU option specifying an MTU larger than 1500, or larger than a manually configured value less than 1500, that MTU option must be ignored. Crawford Expires April 1996 [Page 1]
=0C INTERNET-DRAFT Transmission of IPv6 Packets Over Ethernet 9 October 1995 Frame Format IPv6 packets are transmitted in standard Ethernet frames. The ethernet header contains the Destination and Source ethernet addresses and the ethernet type code, which must contain the value 86DD hexadecimal. The data field contains the IPv6 header followed immediately by the payload, and possibly padding octets to meet the minimum frame size for Ethernet. +-------+-------+-------+-------+-------+-------+ ^ | Destination Ethernet address | | +-------+-------+-------+-------+-------+-------+ ethernet | Source Ethernet address | header +-------+-------+-------+-------+-------+-------+ | | 86 DD | v +-------+-------+-------+-------+-------+------+------+ | IPv6 header and payload ... / +-------+-------+-------+-------+-------+------+------+ Stateless Autoconfiguration and Link-Local Addresses The address token [CONF] for an Ethernet interface is the interface's built-in 48-bit IEEE 802 address, in canonical bit order and with the octets in the same order in which they would appear in the header of an ethernet frame. (The individual/group bit is in the first octet and the OUI is in the first three octets.) A different MAC address set manually or by software should not be used as the address token. An IPv6 address prefix used for stateless autoconfiguration of an ethernet interface must be 80 bits in length. The IPv6 Link-local address [AARCH] for an Ethernet interface is formed by appending the interface's IEEE 802 address to the 80-bit prefix FE80::. +-------+-------+-------+-------+-------+-------+------+------+ | FE 80 00 00 00 00 00 00 | +-------+-------+-------+-------+-------+-------+------+------+ | 00 00 | Ethernet Address | +-------+-------+-------+-------+-------+-------+------+------+ Address Mapping -- Unicast The procedure for mapping IPv6 addresses into Ethernet link-layer addresses is described in [DISC]. The Source/Target Link-layer Address option has the following form when the link layer is Ethernet. Crawford Expires April 1996 [Page 2]
=0C INTERNET-DRAFT Transmission of IPv6 Packets Over Ethernet 9 October 1995 +-------+-------+-------+-------+-------+-------+-------+-------+ | Type |Length | Ethernet Address | +-------+-------+-------+-------+-------+-------+-------+-------+ Option fields: Type 1 for Source Link-layer address. 2 for Target Link-layer address. Length 1 (in units of 8 octets). Ethernet Address The 48 bit Ethernet IEEE 802 address, in canonical bit order. Address Mapping -- Multicast An IPv6 packet with a multicast destination address DST is transmit- ted to the Ethernet multicast address whose first two octets are the value 3333 hexadecimal and whose last four octets are the last four octets of DST, ordered from more to least significant. +-------+-------+-------+-------+-------+-------+ | 33 | 33 | DST13 | DST14 | DST15 | DST16 | +-------+-------+-------+-------+-------+-------+ Security Considerations Security considerations are not addressed in this memo. References [AARCH] R. Hinden, S. Deering, IP Version 6 Addressing Architecture. Currently draft-ietf-ipngwg-addr-arch-03.txt. [CONF] S. Thomson, IPv6 Stateless Address Autoconfiguration. Currently draft-ietf-addrconf-ipv6-03.txt. [DISC] T. Narten, E. Nordmark, W. A. Simpson, Neighbor Discovery for IP Version 6 (IPv6). Currently draft-ietf-ipngwg-discovery-01.txt. Crawford Expires April 1996 [Page 3]
=0C INTERNET-DRAFT Transmission of IPv6 Packets Over Ethernet 9 October 1995 [IPV6] S. Deering, R. Hinden, Internet Protocol, Version 6 (IPv6) Specification. Currently draft-ietf-ipngwg-ipv6-spec-02.txt. Author's Address Matt Crawford Fermilab MS 368 PO Box 500 Batavia, IL 60510 USA Phone: +1 708 840-3461 EMail: crawdad@fnal.gov Crawford Expires April 1996 [Page 4]
