Network Working Group K. Fujisawa
Request for Comments: 3146 A. Onoe
Category: Standards Track Sony Corporation
October 2001

Transmission of IPv6 Packets over IEEE 1394 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 Notice

Copyright (C) The Internet Society (2001). All Rights Reserved.

Abstract

This document describes the frame format for transmission of IPv6
packets and the method of forming IPv6 link-local addresses and
statelessly autoconfigured addresses on IEEE1394 networks.

1. INTRODUCTION

IEEE Std 1394-1995 (and its amendment) is a standard for a High
Performance Serial Bus. IETF IP1394 Working Group has standardized
the method to carry IPv4 datagrams and ARP packets over IEEE1394
subnetwork [IP1394].

This document describes the frame format for transmission of IPv6
[IPV6] packets and the method of forming IPv6 link-local addresses
and statelessly autoconfigured addresses on IEEE1394 networks. It
also describes the content of the Source/Target Link-layer Address
option used in Neighbor Discovery [DISC] when the messages are
transmitted on an IEEE1394 network.

2. SPECIFICATION TERMINOLOGY

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 RFC2119.

3. IPv6-CAPABLE NODES

An IPv6-capable node MUST fulfill the following minimum requirements:

- it MUST implement configuration ROM in the general format
specified by ISO/IEC 13213:1994 and MUST implement the bus
information block specified by IEEE Std 1394a-2000 [1394a] and a
unit Directory specified by this document;

- the max_rec field in its bus information block MUST be at least 8;
this indicates an ability to accept block write requests and
asynchronous stream packets with data payload of 512 octets. The
same ability MUST also apply to read requests; that is, the node
MUST be able to transmit a block response packet with a data
payload of 512 octets;

- it MUST be isochronous resource manager capable, as specified by
IEEE Std 1394a-2000;

- it MUST support both reception and transmission of asynchronous
streams as specified by IEEE Std 1394a-2000.

4. LINK ENCAPSULATION AND FRAGMENTATION

The encapsulation and fragmentation mechanism MUST be the same as "4.
LINK ENCAPSULATION AND FRAGMENTATION" of [IP1394].

Note: Since there is an ether_type field to discriminate protocols
and MCAP (multicast channel allocation protocol) is used for both
IPv4 and IPv6, the version field in GASP (global asynchronous
stream packet) header of IPv6 datagrams is the same value (one) as
[IP1394].

The ether_type value for IPv6 is 0x86dd.

The default MTU size for IPv6 packets on an IEEE1394 network 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 received on an
IEEE1394 interface has an MTU option specifying an MTU larger than
1500, or larger than a manually configured value, that MTU option may
be logged to system management but MUST be otherwise ignored. The
mechanism to extend MTU size between particular two nodes is for
further study.

5. CONFIGURATION ROM

Configuration ROM for IPv6-capable nodes MUST contain a unit
directory in the format specified by [IP1394] except following rules.

- The value for Unit_SW_Version is 0x000002.

- The textual descriptor for the Unit_SW_Version MUST be "IPv6".

Note: A dual-stack (IPv4 and IPv6) node will have two unit
directories for IPv4 and IPv6 respectively.

6. STATELESS AUTOCONFIGURATION

The Interface Identifier [AARCH] for an IEEE1394 interface is formed
from the interface's built-in EUI-64 identifier by complementing the
"Universal/Local" (U/L) bit, which is the next-to-lowest order bit of
the first octet of the EUI-64 identifier. Complementing this bit
will generally change a 0 value to a 1, since an interface's built-in
EUI-64 identifier is eXPected to be from a universally administered
address space and hence have a globally unique value. A universally
administered EUI-64 identifier is signified by a 0 in the U/L bit
position, while a globally unique IPv6 Interface Identifier is
signified by a 1 in the corresponding position. For further
discussion on this point, see [AARCH].

An IPv6 address prefix used for stateless autoconfiguration [ACONF]
of an IEEE1394 interface MUST have a length of 64 bits.

7. LINK-LOCAL ADDRESSES

The IPv6 link-local address [AARCH] for an IEEE1394 interface is
formed by appending the Interface Identifier, as defined above, to
the prefix FE80::/64.

10 bits 54 bits 64 bits
+----------+-----------------------+----------------------------+
1111111010 (zeros) Interface Identifier
+----------+-----------------------+----------------------------+

8. ADDRESS MAPPING FOR UNICAST

The procedure for mapping IPv6 unicast addresses into IEEE1394 link-
layer addresses uses the Neighbor Discovery [DISC]. Since 1394 link
address (node_ID) will not be constant across a 1394 bridge, we have
chosen not to put it in the Link-layer Address option. The recipient
of the Neighbor Discovery SHOULD use the source_ID (oBTained from
either the asynchronous packet header or the GASP header) in

conjunction with the content of the Source link-layer address. An
implementation MAY use some other methods to obtain a node_ID of the
sender utilizing a mapping table between node_unique_ID (EUI-64
identifier) and node_ID. The mechanism to make such mapping table is
out of scope of this document.

The recipient of an Neighbor Discovery packet MUST ignore it unless
the most significant ten bits of the source_ID are equal to either
0x3FF or the most significant ten bits of the recipient's NODE_IDS
register.

The Source/Target Link-layer Address option has the following form
when the link layer is IEEE1394.

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type Length = 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---+
node_unique_ID (EUI-64 identifier)
+--- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
max_rec spd
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
unicast_FIFO
+--- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
reserved
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
reserved
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type 1 for Source Link-layer address.
2 for Target Link-layer address.
Length 3 (in units of 8 octets).

node_unique_ID This field contains the node unique ID of the
node and MUST be equal to that specified in the
node's configuration ROM.

max_rec This field MUST be equal to the value of max_rec
in the node's configuration ROM.

spd This field MUST be set to the lesser of the node's
link speed and PHY speed. The link speed is the
maximum speed at which the link may send or
receive packets; the PHY speed is the maximum
speed at which the PHY may send, receive or repeat
packets. The encoding used for spd is specified in
the Table 2 of [IP1394].

unicast_FIFO This field MUST specify the 48-bit offset of the
node's FIFO available for the receipt of IPv6
datagrams. The offset of a node's unicast FIFO
MUST NOT change, except as the result of a power
reset.

reserved This field MUST be set to all zeros by the sender
and ignored by the receiver.

Note that node_ID may change when 1394 bus-reset occurs. The mapping
cache held in the node SHOULD be cleared on 1394 bus-reset.

According to [1394], the maximum data payload and the transmission
speed SHOULD be determined based on the sender's capability, the
recipient's capability, and the PHYs of all intervening nodes.

9. IPv6 MULTICAST

By default, all best-effort IPv6 multicast MUST use asynchronous
stream packets whose channel number is equal to the channel field
from the BROADCAST_CHANNEL register. In particular, datagrams
addressed to all-nodes multicast addresses, all-routers multicast
addresses, and solicited-node multicast addresses [AARCH] MUST use
the default channel specified by the BROADCAST_CHANNEL register.

Best-effort IPv6 multicast for other multicast group addresses may
utilize a different channel number if such a channel number is
allocated and advertised prior to use, by the multicast channel
allocation protocol (MCAP), as described in [IP1394].

When a node wishes to receive multicast data addressed to other than
all-nodes multicast addresses, all-routers multicast addresses, and
solicited-node multicast addresses, it MUST confirm if the channel
mapping between a multicast group address and a channel number exists
using MCAP, as described in "9.3 Multicast Receive" in [IP1394].

The implementation of MCAP is optional for send-only nodes. A node
MAY transmit multicast data addressed to any multicast addresses into
the default broadcast channel regardless of the existing allocation
of the channel. If a node wishes to transmit multicast data on other
than the default channel, it MUST first confirm by MCAP whether or
not a channel number for the group address has been already
allocated. The implementors are encouraged to use this protocol when
transmitting high-rate multicast streams.

The MCAP 'type' value for IPv6 group address descriptor is 2.

10. IANA CONSIDERATIONS

IANA has assigned a value of 0x000002 for "Unit_SW_Version for IPv6
over IEEE1394" out of the "CSR Protocol Identifiers" name space, as
described in section 5. The details of the "CSR Protocol
Identifiers" namespace is described in "10. IANA CONSIDERATIONS" of
[IP1394].

Section 9.1 of [IP1394] defines MCAP group address descriptors, which
include an 8-bit type name space. This document requests that IANA
maintain a name space to manage MCAP group address descriptors. The
initial assignments for that table are:

Value Usage
0 reserved
1 IPv4 Multicast Address
2 IPv6 Multicast Address
255 reserved

Additional values from the range 3-254 can be assigned through
Standards Action [RFC2434].

11. Security Considerations

IPv6 over IEEE1394 does not introduce any additional security
considerations over [IP1394]. The security concerns described in
"11. SECURITY CONSIDERATIONS" in [IP1394] apply here as well.

12. Acknowledgment

The authors would like to acknowledge the authors of [IP1394] and
[ETHER] since some part of this document has been derived from them.

13. References

[1394] IEEE Std 1394-1995, Standard for a High Performance Serial
Bus

[1394a] IEEE Std 1394a-2000, Standard for a High Performance Serial
Bus - Amendment 1

[IP1394] Johansson, P., "IPv4 over IEEE 1394", RFC2734, December
1999.

[IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC2460, December 1998.

[AARCH] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC2373 December 1998.

[ACONF] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC2462, December 1998.

[DISC] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC2461, December 1998.

[ETHER] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC2464, December 1998.

14. Authors' Addresses

Kenji Fujisawa
Network & Software Technology Center, Sony Corporation
6-7-35 Kitashinagawa,
Shinagawa-ku, Tokyo 141-0001, JAPAN

Phone: +81-3-5795-8507
Fax: +81-3-5795-8977
EMail: fujisawa@sm.sony.co.jp

Atsushi Onoe
Internet Systems Laboratory,
Internet Laboratories, Sony Corporation
6-7-35 Kitashinagawa,
Shinagawa-ku, Tokyo 141-0001, JAPAN

Phone: +81-3-5448-4620
Fax: +81-3-5448-4622
EMail: onoe@sm.sony.co.jp

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