RFC 2734 (rfc2734) - Page 3 of 29
IPv4 over IEEE 1394
Alternative Format: Original Text Document
RFC 2734 IPv4 over IEEE 1394 December 1999
The CSR architecture describes a memory-mapped address space that
Serial Bus implements as a 64-bit fixed addressing scheme. Within the
address space, ten bits are allocated for bus ID (up to a maximum of
1,023 buses), six are allocated for node physical ID (up to 63 per
bus) while the remaining 48 bits (offset) describe a per node address
space of 256 terabytes. The CSR architecture, by convention, splits a
node's address space into two regions with different behavioral
characteristics. The lower portion, up to but not including 0xFFFF
F000 0000, is EXPECTED to behave as memory in response to read and
write transactions. The upper portion is more like a traditional IO
space: read and write transactions in this area usually have side
effects. Control and status registers (CSRs) that have FIFO behavior
customarily are implemented in this region.
Within the 64-bit address, the 16-bit node ID (bus ID and physical
ID) is analogous to a network hardware address---but 1394 node IDs
are variable and subject to reassignment each time one or more nodes
are added to or removed from the bus.
NOTE: Although the 16-bit node ID contains a bus ID, at present there
is no standard method to connect separately enumerated Serial Buses.
Active development of a standard for Serial Bus to Serial Bus bridges
is underway in the IEEE P1394.1 working group. Unless extended by
some future standard, the IPv4 over 1394 protocols specified by this
document may not operate correctly across bridges.
The 1394 link layer provides a packet delivery service with both
confirmed (acknowledged) and unconfirmed packets. Two levels of
service are available: "asynchronous" packets are sent on a best-
effort basis while "isochronous" packets are guaranteed to be
delivered with bounded latency. Confirmed packets are always
asynchronous but unconfirmed packets may be either asynchronous or
isochronous. Data payloads vary with implementations and may range
from one octet up to a maximum determined by the transmission speed
(at 100 Mbps, named S100, the maximum asynchronous data payload is
512 octets while at S400 it is 2048 octets).
NOTE: Extensions underway in IEEE P1394b contemplate additional
speeds of 800, 1600 and 3200 Mbps.
Johansson Standards Track