< draft-ietf-ipngwg-fddi-ntwrks-02.txt   draft-ietf-ipngwg-fddi-ntwrks-03.txt >
Internet Engineering Task Force Matt Crawford Internet Engineering Task Force Matt Crawford
INTERNET-DRAFT Fermilab INTERNET-DRAFT Fermilab
<draft-ietf-ipngwg-fddi-ntwrks-02.txt> December 11, 1995 <draft-ietf-ipngwg-fddi-ntwrks-03.txt> February 26, 1996
A Method for the Transmission of IPv6 Packets over FDDI Networks A Method for the Transmission of IPv6 Packets over FDDI Networks
Status of this Memo Status of this Memo
This document is an Internet Draft. Internet Drafts are working This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas, documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts. working documents as Internet Drafts.
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option used the the Router Solicitation, Router Advertisement, option used the the Router Solicitation, Router Advertisement,
Neighbor Solicitation, and Neighbor Advertisement messages described Neighbor Solicitation, and Neighbor Advertisement messages described
in [DISC], when those messages are transmitted on an FDDI network. in [DISC], when those messages are transmitted on an FDDI network.
Maximum Transmission Unit 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
=0C INTERNET-DRAFT Transmission of IPv6 Packets Over FDDI 1996-02-26
header, this would, in principle, allow the IPv6 packet in the header, this would, in principle, allow the IPv6 packet in the
Information field to be up to 4470 octets. However, it is desirable Information field to be up to 4470 octets. However, it is desirable
to allow for the variable sizes and possible future extensions to the to allow for the variable sizes and possible future extensions to the
MAC header and frame status fields. The default MTU size for IPv6 MAC header and frame status fields. The default MTU size for IPv6
packets on an FDDI network is therefore 4352 octets. This size may packets on an FDDI network is therefore 4352 octets. This size may
be reduced by a Router Advertisement [DISC] containing an MTU option be reduced by a Router Advertisement [DISC] containing an MTU option
which specifies a smaller MTU, or by manual configuration of a which specifies a smaller MTU, or by manual configuration of a
smaller value on each node. If a Router Advertisement is received smaller value on each node. If a Router Advertisement is received
with an MTU option specifying an MTU larger than the default or the with an MTU option specifying an MTU larger than the default or the
manually configured value, that MTU option may be logged to system manually configured value, that MTU option may be logged to system
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+-------+-------+-------+-------+-------+-------+ FDDI +-------+-------+-------+-------+-------+-------+ FDDI
| Source FDDI address | header | Source FDDI address | header
+-------+-------+-------+-------+-------+-------+ | +-------+-------+-------+-------+-------+-------+ |
| DSAP | SSAP | CTL | OUI | | | DSAP | SSAP | CTL | OUI | |
+-------+-------+-------+-------+-------+-------+ | +-------+-------+-------+-------+-------+-------+ |
| Ethertype | v | Ethertype | v
+-------+-------+-------+-------+-------+------+------+ +-------+-------+-------+-------+-------+------+------+
| IPv6 header and payload ... / | IPv6 header and payload ... /
+-------+-------+-------+-------+-------+------+------+ +-------+-------+-------+-------+-------+------+------+
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FDDI Header Fields: FDDI Header Fields:
FC The Frame Code must be in the range 50 to 57 hexadecimal, FC The Frame Code must be in the range 50 to 57 hexadecimal,
inclusive, with the three low order bits indicating the inclusive, with the three low order bits indicating the
frame priority. The Frame Code should be in the range 51 to frame priority. The Frame Code should be in the range 51 to
57 hexadecimal, inclusive, for reasons given in the next 57 hexadecimal, inclusive, for reasons given in the next
section. 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
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Interaction with Bridges Interaction with Bridges
For correct operation when mixed media are bridged together, the For correct operation when mixed media are bridged together, the
smallest MTU of all the media must be manually configured in each smallest MTU of all the media must be manually configured in each
node or advertised by routers in an MTU option. Nodes transmitting node or advertised by routers in an MTU option. Nodes transmitting
IPv6 on FDDI should implement the following simple mechanism for IPv6 on FDDI should implement the following simple mechanism for
``FDDI adjacency detection''. ``FDDI adjacency detection''.
If a node N1 receives, in an FDDI frame with a non-zero LLC priority, If a node N1 receives, in an FDDI frame with a non-zero LLC priority,
a valid Router Advertisement or Neighbor Advertisement from a node a valid Router Advertisement, Neighbor Advertisement, or Neighbor
N2, then N1 may send unicast IPv6 packets to N2 with sizes up to the Solicitation from a node N2, then N1 may send unicast IPv6 packets to
default IPv6 FDDI MTU (4352 octets), regardless of any smaller MTU N2 with sizes up to the default IPv6 FDDI MTU (4352 octets),
configured manually or received in a Router Advertisement MTU option. regardless of any smaller MTU configured manually or received in a
N2 may be the IPv6 destination or the next hop router to the Router Advertisement MTU option. N2 may be the IPv6 destination or
destination. the next hop router to the destination.
Nodes implementing FDDI adjacency detection must provide a Nodes implementing FDDI adjacency detection must provide a
configuration option to disable the mechanism. This option may be configuration option to disable the mechanism. This option may be
used when a smaller MTU is desired for reasons other than mixed-media used when a smaller MTU is desired for reasons other than mixed-media
bridging. By default, FDDI adjacency detection should be enabled. bridging. By default, FDDI adjacency detection should be enabled.
The only contemplated use of the LLC priority field of the FC octet The only contemplated use of the LLC priority field of the FC octet
is to aid in per-destination MTU determination. It would be is to aid in per-destination MTU determination. It would be
sufficient for that purpose to require only that Router sufficient for that purpose to require only that Router
Advertisements and Neighbor Advertisements sent on FDDI always have Advertisements, Neighbor Advertisements, and Neighbor Solicitations
non-zero priority. However, it may be simpler or more useful to sent on FDDI always have non-zero priority. However, it may be
transmit all IPv6 packets on FDDI with non-zero priority. simpler or more useful to transmit all IPv6 packets on FDDI with
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non-zero priority.
Stateless Autoconfiguration and Link-Local Addresses Stateless Autoconfiguration and Link-Local Addresses
The address token [CONF] for an FDDI interface is the interface's The address token [CONF] for an FDDI interface is the interface's
built-in 48-bit IEEE 802 address, in canonical bit order and with the built-in 48-bit IEEE 802 address, in canonical bit order and with the
octet in the same order in which they would appear in the header of octet 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 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 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. set manually or by software should not be used as the address token.
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| Type |Length | FDDI Address | | Type |Length | FDDI 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).
=0C
FDDI Address FDDI Address
The 48 bit FDDI IEEE 802 address, in canonical bit order. The 48 bit FDDI IEEE 802 address, in canonical bit order.
This is the address the interface currently responds to, and
may be different from the built-in address used as the
INTERNET-DRAFT Transmission of IPv6 Packets Over FDDI 1996-02-26
address token.
Address Mapping -- Multicast Address Mapping -- Multicast
An IPv6 packet with a multicast destination address DST is An IPv6 packet with a multicast destination address DST is
transmitted to the FDDI multicast address whose first two octets are transmitted to the FDDI multicast address whose first two octets are
the value 3333 hexadecimal and whose last four octets are the last the value 3333 hexadecimal and whose last four octets are the last
four octets of DST, ordered from more to least significant. four octets of DST, ordered from more to least significant.
+-------+-------+-------+-------+-------+-------+ +-------+-------+-------+-------+-------+-------+
| 33 | 33 | DST13 | DST14 | DST15 | DST16 | | 33 | 33 | DST13 | DST14 | DST15 | DST16 |
+-------+-------+-------+-------+-------+-------+ +-------+-------+-------+-------+-------+-------+
Security Considerations Security Considerations
Security considerations are not addressed in this memo. Security considerations are not addressed in this memo.
Acknowledgments
Erik Nordmark contributed to the method for interaction with bridges.
References References
[AARCH] R. Hinden, S. Deering, IP Version 6 Addressing Architecture. [AARCH] R. Hinden, S. Deering, IP Version 6 Addressing Architecture.
Currently draft-ietf-ipngwg-addr-arch-03.txt. RFC1884.
[CONF] S. Thomson, IPv6 Stateless Address Autoconfiguration. Currently [CONF] S. Thomson, IPv6 Stateless Address Autoconfiguration. Currently
draft-ietf-addrconf-ipv6-auto-06.txt. draft-ietf-addrconf-ipv6-auto-07.txt.
[DISC] T. Narten, E. Nordmark, W. A. Simpson, Neighbor Discovery for IP [DISC] T. Narten, E. Nordmark, W. A. Simpson, Neighbor Discovery for IP
Version 6 (IPv6). Currently draft-ietf-ipngwg-discovery-03.txt. Version 6 (IPv6). Currently draft-ietf-ipngwg-discovery-05.txt.
[IPV6] S. Deering, R. Hinden, Internet Protocol, Version 6 (IPv6) [IPV6] S. Deering, R. Hinden, Internet Protocol, Version 6 (IPv6)
Specification. Currently draft-ietf-ipngwg-ipv6-spec-02.txt. Specification. RFC1883.
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Author's Address Author's Address
Matt Crawford Matt Crawford
Fermilab MS 368 Fermilab MS 368
PO Box 500 PO Box 500
Batavia, IL 60510 Batavia, IL 60510
USA USA
Phone: +1 708 840-3461 Phone: +1 708 840-3461
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