draft-ietf-ipngwg-trans-fddi-net-03.txt   rfc2467.txt 
IPng Working Group Matt Crawford Network Working Group M. Crawford
Internet Draft Fermilab Request for Comments: 2467 Fermilab
September 26, 1997 Obsoletes: 2019 December 1998
Category: Standards Track
Transmission of IPv6 Packets over FDDI Networks Transmission of IPv6 Packets over FDDI Networks
<draft-ietf-ipngwg-trans-fddi-net-03.txt>
Status of this Memo Status of this Memo
This document is an Internet Draft. Internet Drafts are working This document specifies an Internet standards track protocol for the
documents of the Internet Engineering Task Force (IETF), its Areas, Internet community, and requests discussion and suggestions for
and its Working Groups. Note that other groups may also distribute improvements. Please refer to the current edition of the "Internet
working documents as Internet Drafts. Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Internet Drafts are draft documents valid for a maximum of six
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Distribution of this memo is unlimited. Copyright (C) The Internet Society (1998). All Rights Reserved.
1. Introduction 1. Introduction
This document specifies the frame format for transmission of IPv6 This document specifies the frame format for transmission of IPv6
packets and the method of forming IPv6 link-local addresses and packets and the method of forming IPv6 link-local addresses and
statelessly autoconfigured addresses on FDDI networks. It also statelessly autoconfigured addresses on FDDI networks. It also
specifies the content of the Source/Target Link-layer Address option specifies the content of the Source/Target Link-layer Address option
used in Router Solicitation, Router Advertisement, Neighbor used in Router Solicitation, Router Advertisement, Neighbor
Solicitation, Neighbor Advertisement and Redirect messages when Solicitation, Neighbor Advertisement and Redirect messages when those
those messages are transmitted on an FDDI network. messages are transmitted on an FDDI network.
This document replaces RFC 2019, 'Transmission of IPv6 Packets Over This document replaces RFC 2019, "Transmission of IPv6 Packets Over
FDDI', which will become historic. FDDI", which will become historic.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [KWORD]. document are to be interpreted as described in [RFC 2119].
2. Maximum Transmission Unit 2. Maximum Transmission Unit
FDDI permits a frame length of 4500 octets (9000 symbols), including FDDI permits a frame length of 4500 octets (9000 symbols), including
at least 22 octets (44 symbols) of Data Link encapsulation when at least 22 octets (44 symbols) of Data Link encapsulation when
long-format addresses are used. Subtracting 8 octets of LLC/SNAP long-format addresses are used. Subtracting 8 octets of LLC/SNAP
header, this would, in principle, allow the IPv6 [IPV6] packet in header, this would, in principle, allow the IPv6 [IPV6] packet in the
the Information field to be up to 4470 octets. However, it is Information field to be up to 4470 octets. However, it is desirable
desirable to allow for the variable sizes and possible future to allow for the variable sizes and possible future extensions of the
extensions of the MAC header and frame status fields. The default MAC header and frame status fields. The default MTU size for IPv6
MTU size for IPv6 packets on an FDDI network is therefore 4352 packets on an FDDI network is therefore 4352 octets. This size may
octets. This size may be reduced by a Router Advertisement [DISC] be reduced by a Router Advertisement [DISC] containing an MTU option
containing an MTU option which specifies a smaller MTU, or by manual which specifies a smaller MTU, or by manual configuration of each
configuration of each node. If a Router Advertisement received on node. If a Router Advertisement received on an FDDI interface has an
an FDDI interface has an MTU option specifying an MTU larger than MTU option specifying an MTU larger than 4352, or larger than a
4352, or larger than a manually configured value, that MTU option manually configured value, that MTU option may be logged to system
may be logged to system management but must be otherwise ignored. management but must be otherwise ignored.
For purposes of this document, information received from DHCP is For purposes of this document, information received from DHCP is
considered "manually configured" and the term FDDI includes CDDI. considered "manually configured" and the term FDDI includes CDDI.
3. Frame Format 3. Frame Format
FDDI provides both synchronous and asynchronous transmission, with FDDI provides both synchronous and asynchronous transmission, with
the latter class further subdivided by the use of restricted and the latter class further subdivided by the use of restricted and
unrestricted tokens. Only asynchronous transmission with unrestricted tokens. Only asynchronous transmission with
unrestricted tokens is required for FDDI interoperability. unrestricted tokens is required for FDDI interoperability.
Accordingly, IPv6 packets shall be sent in asynchronous frames using Accordingly, IPv6 packets shall be sent in asynchronous frames using
unrestricted tokens. The robustness principle dictates that nodes unrestricted tokens. The robustness principle dictates that nodes
should be able to receive synchronous frames and asynchronous frames should be able to receive synchronous frames and asynchronous frames
sent using restricted tokens. sent using restricted tokens.
IPv6 packets are transmitted in LLC/SNAP frames, using long-format IPv6 packets are transmitted in LLC/SNAP frames, using long-format
(48 bit) addresses. The data field contains the IPv6 header and (48 bit) addresses. The data field contains the IPv6 header and
payload and is followed by the FDDI Frame Check Sequence, Ending payload and is followed by the FDDI Frame Check Sequence, Ending
Delimiter, and Frame Status symbols. Delimiter, and Frame Status symbols.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| FC | | FC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination | | Destination |
+- -+ +- -+
| FDDI | | FDDI |
+- -+ +- -+
skipping to change at page 3, line 39 skipping to change at page 3, line 39
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 | | IPv6 |
+- -+ +- -+
| header | | header |
+- -+ +- -+
| and | | and |
+- -+ +- -+
/ payload ... / / payload ... /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(Each tic mark represents one bit.) (Each tic mark represents one bit.)
FDDI Header Fields: FDDI Header Fields:
FC The Frame Code must be in the range 50 to 57 FC The Frame Code must be in the range 50 to 57
hexadecimal, inclusive, with the three low order bits hexadecimal, inclusive, with the three low order bits
indicating the frame priority. The Frame Code should be indicating the frame priority.
in the range 51 to 57 hexadecimal, inclusive, for
reasons given in the next section.
DSAP, SSAP Both the DSAP and SSAP fields shall contain the value AA DSAP, SSAP Both the DSAP and SSAP fields shall contain the value AA
hexadecimal, indicating SNAP encapsulation. hexadecimal, indicating SNAP encapsulation.
CTL The Control field shall be set to 03 hexadecimal, CTL The Control field shall be set to 03 hexadecimal,
indicating Unnumbered Information. indicating Unnumbered Information.
OUI The Organizationally Unique Identifier shall be set to OUI The Organizationally Unique Identifier shall be set to
000000 hexadecimal. 000000 hexadecimal.
Ethertype The Ethernet protocol type ("ethertype") shall be set to Ethertype The Ethernet protocol type ("ethertype") shall be set to
the value 86DD hexadecimal. the value 86DD hexadecimal.
4. Interaction with Bridges 4. Interaction with Bridges
802.1d MAC bridges which connect different media, for example 802.1d MAC bridges which connect different media, for example
Ethernet and FDDI, have become very widespread. Some of them do Ethernet and FDDI, have become very widespread. Some of them do IPv4
IPv4 packet fragmentation and/or support IPv4 Path MTU discovery packet fragmentation and/or support IPv4 Path MTU discovery [RFC
[PMTU], many others do not, or do so incorrectly. Use of IPv6 in a 1981], many others do not, or do so incorrectly. Use of IPv6 in a
bridged mixed-media environment must not depend on support from MAC bridged mixed-media environment must not depend on support from MAC
bridges, unless those bridges are known to correctly implement IPv6 bridges, unless those bridges are known to correctly implement IPv6
Path MTU Discovery [PMTU, ICMPV6]. Path MTU Discovery [RFC 1981, ICMPV6].
For correct operation when mixed media are bridged together by For correct operation when mixed media are bridged together by
bridges which do not support IPv6 Path MTU Discovery, the smallest bridges which do not support IPv6 Path MTU Discovery, the smallest
MTU of all the media must be advertised by routers in an MTU option. MTU of all the media must be advertised by routers in an MTU option.
If there are no routers present, this MTU must be manually If there are no routers present, this MTU must be manually configured
configured in each node which is connected to a medium with a in each node which is connected to a medium with a default MTU larger
default MTU larger than the smallest MTU. than the smallest MTU.
5. Stateless Autoconfiguration 5. Stateless Autoconfiguration
The Interface Identifier [AARCH] for an FDDI interface is based on The Interface Identifier [AARCH] for an FDDI interface is based on
the EUI-64 identifier [EUI64] derived from the interface's built-in the EUI-64 identifier [EUI64] derived from the interface's built-in
48-bit IEEE 802 address. The EUI-64 is formed as follows. 48-bit IEEE 802 address. The EUI-64 is formed as follows.
(Canonical bit order is assumed throughout.) (Canonical bit order is assumed throughout. See [CANON] for a
caution on bit-order effects in LAN interfaces.)
The OUI of the FDDI MAC address (the first three octets) becomes the The OUI of the FDDI MAC address (the first three octets) becomes the
company_id of the EUI-64 (the first three octets). The fourth and company_id of the EUI-64 (the first three octets). The fourth and
fifth octets of the EUI are set to the fixed value FFFE hexadecimal. fifth octets of the EUI are set to the fixed value FFFE hexadecimal.
The last three octets of the FDDI MAC address become the last three The last three octets of the FDDI MAC address become the last three
octets of the EUI-64. octets of the EUI-64.
The Interface Identifier is then formed from the EUI-64 by The Interface Identifier is then formed from the EUI-64 by
complementing the "Universal/Local" (U/L) bit, which is the next- complementing the "Universal/Local" (U/L) bit, which is the next-to-
to-lowest order bit of the first octet of the EUI-64. For further lowest order bit of the first octet of the EUI-64. For further
discussion on this point, see [ETHER] and [AARCH]. discussion on this point, see [ETHER] and [AARCH].
For example, the Interface Identifier for an FDDI interface whose
built-in address is, in hexadecimal,
For example, the Interface Identifier for an FDDI interface whose
built-in address is, in hexadecimal,
34-56-78-9A-BC-DE 34-56-78-9A-BC-DE
would be would be
36-56-78-FF-FE-9A-BC-DE. 36-56-78-FF-FE-9A-BC-DE.
A different MAC address set manually or by software should not be A different MAC address set manually or by software should not be
used to derive the Interface Identifier. If such a MAC address must used to derive the Interface Identifier. If such a MAC address must
be used, its global uniqueness property should be reflected in the be used, its global uniqueness property should be reflected in the
value of the U/L bit. value of the U/L bit.
An IPv6 address prefix used for stateless autoconfiguration [ACONF] An IPv6 address prefix used for stateless autoconfiguration [ACONF]
of an FDDI interface must have a length of 64 bits. of an FDDI interface must have a length of 64 bits.
6. Link-Local Addresses 6. Link-Local Addresses
The IPv6 link-local address [AARCH] for an FDDI interface is formed The IPv6 link-local address [AARCH] for an FDDI interface is formed
by appending the Interface Identifier, as defined above, to the by appending the Interface Identifier, as defined above, to the
prefix FE80::/64. prefix FE80::/64.
10 bits 54 bits 64 bits 10 bits 54 bits 64 bits
+----------+-----------------------+----------------------------+ +----------+-----------------------+----------------------------+
|1111111010| (zeros) | Interface Identifier | |1111111010| (zeros) | Interface Identifier |
+----------+-----------------------+----------------------------+ +----------+-----------------------+----------------------------+
7. Address Mapping -- Unicast 7. Address Mapping -- Unicast
The procedure for mapping IPv6 unicast addresses into FDDI link- The procedure for mapping IPv6 unicast addresses into FDDI link-layer
layer addresses is described in [DISC]. The Source/Target Link- addresses is described in [DISC]. The Source/Target Link-layer
layer Address option has the following form when the link layer is Address option has the following form when the link layer is FDDI.
FDDI.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+- FDDI -+ +- FDDI -+
| | | |
+- Address -+ +- Address -+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option fields: Option fields:
Type 1 for Source Link-layer address. Type 1 for Source Link-layer address.
2 for Target Link-layer address. 2 for Target Link-layer address.
Length 1 (in units of 8 octets). Length 1 (in units of 8 octets).
FDDI Address FDDI Address
The 48 bit FDDI IEEE 802 address, in canonical bit The 48 bit FDDI IEEE 802 address, in canonical bit order.
order. This is the address the interface currently This is the address the interface currently responds to,
responds to, and may be different from the built-in and may be different from the built-in address used to
address used to derive the Interface Identifier. derive the Interface Identifier.
8. Address Mapping -- Multicast 8. Address Mapping -- Multicast
An IPv6 packet with a multicast destination address DST, consisting An IPv6 packet with a multicast destination address DST, consisting
of the sixteen octets DST[1] through DST[16], is transmitted to the of the sixteen octets DST[1] through DST[16], is transmitted to the
FDDI multicast address whose first two octets are the value 3333 FDDI multicast address whose first two octets are the value 3333
hexadecimal and whose last four octets are the last four octets of hexadecimal and whose last four octets are the last four octets of
DST. DST.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1| |0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[13] | DST[14] | | DST[13] | DST[14] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[15] | DST[16] | | DST[15] | DST[16] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
9. Security Considerations 9. Differences From RFC 2019
The method of derivation of Interface Identifiers from MAC addresses The following are the functional differences between this
is intended to preserve global uniqueness when possible. However, specification and RFC 2019.
there is no protection from duplication through accident or forgery.
10. References "FDDI adjacency detection" has been removed, due to recent work
in IEEE 802.1p.
[AARCH] R. Hinden, S. Deering "IP Version 6 Addressing The Address Token, which was a node's 48-bit MAC address, is
Architecture", Currently draft-ietf-ipngwg-addr-arch-v2- replaced with the Interface Identifier, which is 64 bits in
02.txt. length and based on the EUI-64 format [EUI64]. An IEEE-defined
mapping exists from 48-bit MAC addresses to EUI-64 form.
[ACONF] S. Thomson, T. Narten, "IPv6 Stateless Address A prefix used for stateless autoconfiguration must now be 64 bits
Autoconfiguration", currently draft-ietf-ipngwg-addrconf- long rather than 80. The link-local prefix is also shortened to
v2-00.txt. 64 bits.
[DISC] T. Narten, E. Nordmark, W. A. Simpson, "Neighbor Discovery 10. Security Considerations
for IP Version 6 (IPv6)", currently draft-ietf-ipngwg-
discovery-v2-00.txt.
[ETHER] M. Crawford, "Transmission of IPv6 Packets over Ethernet The method of derivation of Interface Identifiers from MAC addresses
Networks", currently draft-ietf-ipngwg-trans-ethernet- is intended to preserve global uniqueness when possible. However,
02.txt. there is no protection from duplication through accident or forgery.
[EUI64] "64-Bit Global Identifier Format Tutorial", 11. References
http://standards.ieee.org/db/oui/tutorials/EUI64.html.
[ICMPV6]A. Conta, S. Deering, "Internet Control Message Protocol [AARCH] Hinden, R. and S. Deering "IP Version 6 Addressing
(ICMPv6) for the Internet Protocol Version 6 (IPv6)", RFC Architecture", RFC 2373, July 1998.
1885
[IPV6] S. Deering, R. Hinden, "Internet Protocol, Version 6 (IPv6) [ACONF] Thomson, S. and T. Narten, "IPv6 Stateless Address
Specification", currently draft-ietf-ipngwg-ipv6-spec-v2- Autoconfiguration", RFC 2462, December 1998.
00.txt.
[KWORD] S. Bradner, "Key words for use in RFCs to Indicate [CANON] Narten, T. and C. Burton, "A Caution On The Canonical
Requirement Levels," RFC 2119. Ordering Of Link-Layer Addresses", RFC 2469, December 1998.
[PMTU] J. Mogul, S. Deering "Path MTU Discovery", RFC 1191. [DISC] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998.
11. Author's Address [ETHER] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, December 1998.
Matt Crawford [EUI64] "Guidelines For 64-bit Global Identifier (EUI-64)",
Fermilab MS 368 http://standards.ieee.org/db/oui/tutorials/EUI64.html.
PO Box 500
Batavia, IL 60510
USA
Phone: +1 630 840-3461 [ICMPV6] Conta, A. and S. Deering, "Internet Control Message
Protocol (ICMPv6) for the Internet Protocol Version 6
(IPv6) Specification", RFC 2463, December 1998.
EMail: crawdad@fnal.gov [IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC 1981] McCann, J., Deering, S. and J. Mogul, "Path MTU Discovery
for IP version 6", RFC 1981, August 1996.
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
12. Author's Address
Matt Crawford
Fermilab MS 368
PO Box 500
Batavia, IL 60510
USA
Phone: +1 630 840-3461
EMail: crawdad@fnal.gov
13. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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