Transmission of IPv6 Packets over IEEE 1394 Networks
updated by
- rfc-8064 — Recommendation on Stable IPv6 Interface Identifiers
Extracted elements (27)
The 1394 link address (node_ID) is intentionally excluded from the Link-layer Address option in Neighbor Discovery because node_ID is not constant across a 1394 bridge and would therefore be unreliable for address mapping.
The GASP header version field for IPv6 datagrams uses the same value (one) as IPv4 because MCAP is used for both IPv4 and IPv6 multicast channel allocation, and there is an ether_type field to discriminate protocols.
A dual-stack (IPv4 and IPv6) node will have two unit directories, one for IPv4 and one for IPv6 respectively, each with its own Unit_SW_Version.
An IPv6-capable node MUST be isochronous resource manager capable (per IEEE Std 1394a-2000) and MUST support both reception and transmission of asynchronous streams.
An IPv6-capable node MUST implement configuration ROM in the general format of ISO/IEC 13213:1994 and MUST implement the bus information block per IEEE Std 1394a-2000 and a unit directory specified by this document.
By default, all best-effort IPv6 multicast MUST use asynchronous stream packets whose channel number equals the BROADCAST_CHANNEL register channel field. This includes all-nodes, all-routers, and solicited-node multicast addresses.
Configuration ROM for IPv6-capable nodes MUST contain a unit directory as specified by [IP1394] with Unit_SW_Version set to 0x000002 and the textual descriptor for Unit_SW_Version MUST be "IPv6".
If a node wishes to transmit multicast data on other than the default broadcast channel, it MUST first confirm via MCAP whether a channel number for the group address has been already allocated. MCAP implementation is optional for send-only nodes.
In the Link-layer Address option, node_unique_ID MUST equal the node's configuration ROM value; max_rec MUST equal the configuration ROM value; spd MUST be set to the lesser of the node's link speed and PHY speed.
The default MTU for IPv6 on IEEE1394 is 1500 octets. If a Router Advertisement MTU option specifies a value larger than 1500 (or larger than a manually configured value), it MAY be logged but MUST otherwise be ignored.
The encapsulation and fragmentation mechanism MUST be the same as section 4 of [IP1394] (RFC 2734). The ether_type value for IPv6 is 0x86dd.
The Interface Identifier for an IEEE1394 interface is formed from the EUI-64 identifier by complementing the U/L bit (next-to-lowest order bit of the first octet). An IPv6 address prefix for stateless autoconfiguration MUST have a length of 64 bits.
The mapping cache held in a node SHOULD be cleared on 1394 bus-reset, because node_ID may change when a 1394 bus-reset occurs.
The max_rec field in an IPv6-capable node's bus information block MUST be at least 8, indicating the ability to accept block write requests and asynchronous stream packets with data payload of 512 octets; the same ability MUST apply to read requests.
The maximum data payload and transmission speed SHOULD be determined based on the sender's capability, the recipient's capability, and the PHYs of all intervening nodes.
The recipient of a 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 recipient of a Neighbor Discovery packet SHOULD use the source_ID (from the asynchronous packet header or GASP header) in conjunction with the Source link-layer address content to obtain the sender's node_ID.
The reserved fields in the Link-layer Address option MUST be set to all zeros by the sender and ignored by the receiver.
The unicast_FIFO field in the Link-layer Address option MUST specify the 48-bit offset of the node's FIFO for IPv6 datagrams, and this offset MUST NOT change except as the result of a power reset.
When a node wishes to receive multicast data addressed to groups other than all-nodes, all-routers, and solicited-node addresses, it MUST confirm that a channel mapping exists via MCAP as described in [IP1394] section 9.3.
The ether_type field discriminates protocols; the value for IPv6 is 0x86dd. The GASP header version field for IPv6 datagrams is the same value (one) as for IPv4 because MCAP is shared between IPv4 and IPv6.
The MCAP 'type' value for IPv6 group address descriptor is 2. A node MAY transmit multicast data to any multicast address into the default broadcast channel regardless of existing channel allocation.
IANA assigned value 0x000002 for 'Unit_SW_Version for IPv6 over IEEE1394' in the CSR Protocol Identifiers namespace. Additional values are managed as described in [IP1394] section 10.
IANA maintains the MCAP group address descriptor type namespace (8-bit): 0=reserved, 1=IPv4 Multicast Address, 2=IPv6 Multicast Address, 255=reserved; values 3-254 assigned through Standards Action per RFC 2434.
IPv6 over IEEE1394 does not introduce any additional security considerations beyond those of [IP1394] (RFC 2734); the security concerns described in that document's section 11 apply here as well.
The IPv6 link-local address is formed by appending the 64-bit Interface Identifier (EUI-64 with complemented U/L bit) to the FE80::/64 prefix: 10 bits (1111111010) + 54 bits (zeros) + 64-bit Interface Identifier.
The Source/Target Link-layer Address option for IEEE1394 has Length=3 (24 octets) and contains: node_unique_ID (EUI-64, 8 bytes), max_rec (1 byte), spd (1 byte), unicast_FIFO (48-bit offset, 6 bytes), and reserved fields.