Network Working Group P. Johansson
Internet-Draft Congruent Software, Inc.
<draft-ietf-ip1394-ipv4-07.txt>
Expires: August, 1998
IPv4 over IEEE 1394
STATUS OF THIS DOCUMENT
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, and
its working groups. Note that other groups may also distribute working
documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."
To view the entire list of current Internet-Drafts, please check the
"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), ftp.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
ftp.isi.edu (US West Coast).
ABSTRACT
This document specifies how to use IEEE Std 1394-1995, Standard for a
High Performance Serial Bus (and its supplements), for the transport of
Internet Protocol Version 4 (IPv4) datagrams. It defines the necessary
methods, data structures and codes for that purpose and additionally
defines a standard method for Address Resolution Protocol (ARP).
Expires: August, 1998 [Page 1]
Internet-Draft 07 IPv4 over 1394 February 1998
TABLE OF CONTENTS
1. INTRODUCTION.......................................................3
2. DEFINITIONS AND NOTATION...........................................4
2.1 Conformance....................................................4
2.2 Glossary.......................................................4
2.3 Abbreviations..................................................5
3. IP-CAPABLE NODES...................................................5
4. NETWORK_CHANNELS REGISTER..........................................6
5. NETWORK PROTOCOL MANAGER (NPM).....................................7
6. LINK ENCAPSULATION AND FRAGMENTATION...............................8
6.1 Link encapsulation header......................................9
6.2 Fragment reassembly...........................................11
7. ADDRESS RESOLUTION PROTOCOL (ARP).................................11
8. IP UNICAST........................................................14
8.1 Asynchronous IP unicast.......................................15
8.2 Isochronous IP unicast........................................15
9. IP BROADCAST......................................................15
10. IP MULTICAST.....................................................16
11. SECURITY CONSIDERATIONS..........................................16
12. ACKNOWLEDGEMENTS.................................................16
13. REFERENCES.......................................................16
14. EDITORS ADDRESS.................................................16
Expires: August, 1998 [Page 2]
Internet-Draft 07 IPv4 over 1394 February 1998
1. INTRODUCTION
This document specifies how to use IEEE Std 1394-1995, Standard for a
High Performance Serial Bus (and its supplements), for the transport of
Internet Protocol Version 4 (IPv4) datagrams. It defines the necessary
methods, data structures and codes for that purpose and additionally
defines a standard method for Address Resolution Protocol (ARP).
The group of IEEE standards and supplements, draft or approved, related
to IEEE Std 1394-1995 is hereafter referred to either as 1394 or as
Serial Bus.
1394 is an interconnect (bus) that conforms to the CSR architecture,
ISO/IEC 13213:1994. Serial Bus implements communications between nodes
over shared physical media at speeds that range from 100 to 400 Mbps.
Both consumer electronic applications (such as digital VCRs, stereo
systems, televisions and camcorders) and traditional desktop computer
applications (e.g., mass storage, printers and tapes), have adopted
1394. Serial Bus is unique in its relevance to both consumer electronic
and computer domains and is expected to form the basis of a home or
small office network that combines both types of devices.
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 nodes 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
to the control and status registers (CSRs) in this area usually have
side effects. Registers 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 ID's are
variable and subject to reassignment each time one or more nodes are
added to or removed from the bus.
The 1394 link layer provides a datagram service with both confirmed
(acknowledged) and unconfirmed datagrams. The confirmed datagram service
is called "asynchronous" while the unconfirmed service is known as
"isochronous." Other than the presence or absence of confirmation, the
principal distinction between the two is quality of service: isochronous
datagrams are guaranteed to be delivered with bounded latency. Datagram
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).
Expires: August, 1998 [Page 3]
Internet-Draft 07 IPv4 over 1394 February 1998
NOTE: Extensions underway in IEEE P1394b contemplate additional speeds
of 800, 1600 and 3200 Mbps; engineering prototypes are planned for early
1998.
2. DEFINITIONS AND NOTATION
2.1 Conformance
When used in this document, the keywords "may", "optional",
"recommended", "required", "shall" and "should" differentiate levels of
requirements and optionality and are to be interpreted as described in
RFC 2119.
Several additional keywords are employed, as follows:
expected: A keyword used to describe the behavior of the hardware or
software in the design models assumed by this standard. Other hardware
and software design models may also be implemented.
ignored: A keyword that describes bits, octets, quadlets, octlets or
fields whose values are not checked by the recipient.
reserved: A keyword used to describe objects-bits, octets, quadlets,
octlets and fields-or the code values assigned to these objects in cases
where either the object or the code value is set aside for future
standardization. Usage and interpretation may be specified by future
extensions to this or other standards. A reserved object shall be zeroed
or, upon development of a future standard, set to a value specified by
such a standard. The recipient of a reserved object shall not check its
value. The recipient of a defined object shall check its value and
reject reserved code values.
2.2 Glossary
The following terms are used in this standard:
address resolution protocol: A method for a requester to determine the
hardware (1394) address of an IP node from the IP address of the node.
bus ID: A 10-bit number that uniquely identifies a particular bus within
a group of bridged buses. The bus ID is the most significant portion of
a node's 16-bit node ID.
IP datagram: An Internet message that conforms to the format specified
by RFC 791.
link fragment: A portion of an IP datagram transmitted within a single
1394 packet. The data payload of the 1394 packet contains both a link
fragment header and its associated link fragment. It is possible to
transmit datagrams without fragmentation.
link fragment header: A structure that precedes all IP datagrams (or
each fragment thereof) when they are transmitted over 1394. See also
link fragment.
Expires: August, 1998 [Page 4]
Internet-Draft 07 IPv4 over 1394 February 1998
local bus ID: A bus ID with the value 0x3FF. A node shall respond to
transaction requests addressed to its 6-bit physical ID if the bus ID in
the request is either 0x3FF or a bus ID explicitly assigned to the node.
node ID: A 16-bit number that uniquely identifies a Serial Bus node .
The most significant 10 bits are the bus ID and the least significant 6
bits are the physical ID.
node unique ID: A 64-bit number that uniquely identifies a node among
all the Serial Bus nodes manufactured worldwide; also known as the
EUI-64 (Extended Unique Identifier, 64-bits).
octet: Eight bits of data.
packet: Any of the 1394 primary packets; these may be read, write or
lock requests (and their responses) or stream data. The term "packet" is
used consistently to differentiate 1394 packets from ARP or IP
datagrams, which are also (generically) packets.
physical ID: On a particular bus, this 6-bit number is dynamically
assigned during the self-identification process and uniquely identifies
a node on that bus.
quadlet: Four octets, or 32 bits, of data.
stream packet: A 1394 primary packet with a transaction code of 0x0A
that contains a block data payload. Stream packets may be either
asynchronous or isochronous according to the type of 1394 arbitration
employed.
2.3 Abbreviations
The following are abbreviations that are used in this standard:
ARP Address resolution protocol
CSR Control and status register
CRC Cyclical redundancy checksum
EUI-64 Extended Unique Identifier, 64-bits (essentially equivalent to
names used elsewhere, such as global unique ID or world-wide
unique ID)
IP Internet protocol (within the context of this document, IPv4)
3. IP-CAPABLE NODES
Not all 1394 devices are capable of the reception and transmission of
ARP or IP datagrams. An IP-capable node shall fulfill the following
minimum requirements:
- the max_rec field in its bus information block shall be at least 8;
this indicates an ability to accept write requests with data
payload of 512 octets. The same ability shall also apply to read
requests; that is, the node shall be able to transmit a response
packet with a data payload of 512 octets;
Expires: August, 1998 [Page 5]
Internet-Draft 07 IPv4 over 1394 February 1998
- it shall be isochronous resource manager capable, as specified by
1394;
- it shall support both reception and transmission of asynchronous
streams as specified by P1394a;
- it shall implement the NETWORK_CHANNELS register; and
- it shall be network protocol manager (NPM) capable.
4. NETWORK_CHANNELS REGISTER
This register is required for IP-capable nodes. It shall be located at
offset 0xFFFF F000 0218 within the node's address space and shall
support quadlet read and write requests, only. The format of the
register is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|v| npm_ID | reserved | channel |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 - NETWORK_CHANNELS format
Upon a node power reset or a bus reset, the entire register (with the
exception of the most significant bit and the npm_ID field) shall be
cleared to zero; the npm_ID field shall be set to ones.
The most significant bit (a constant one) differentiates the presence of
the NETWORK_CHANNELS register in an IP-capable node from the value (all
zeros) returned when offset 0xFFFF Fxxx xxxx is read at node(s) that do
not implement this register.
The valid bit (abbreviated as v above), when set to one, indicates that
the channel field contains meaningful information.
NOTE: IP-capable nodes shall transmit neither ARP nor broadcast IP
datagrams while the valid bit is zero.
The npm_ID field identifies the physical ID of the network protocol
manager (NPM). When npm_ID is equal to 0x3F the physical ID of the NPM
is not specified; otherwise it shall be initialized (by the NPM) to the
6-bit physical ID assigned during the self-identification process.
NOTE: Consensus does not yet exist with respect to the necessity for nor
the usage of the npm_ID field.
The channel field shall be initialized by the NPM (see below) to
identify the channel number shared by IP-capable nodes for ARP and IP
broadcast.
Expires: August, 1998 [Page 6]
Internet-Draft 07 IPv4 over 1394 February 1998
Only the valid bit and the npm_ID and channel fields may be changed by
quadlet write requests; the data value in the write request shall be
ignored for all other bit positions.
5. NETWORK PROTOCOL MANAGER (NPM)
In order for ARP or broadcast IP to function on 1394, a prerequisite is
the presence of a network protocol manager (NPM). The domain of the NPM
is limited to the local Serial Bus; the functions of the NPM are as
follows:
- the allocation of a channel number for ARP and broadcast IP; and
- the communication of that channel number to all IP-capable nodes on
the same bus.
All IP-capable nodes shall be capable of functioning as the NPM.
Since more than one NPM-capable node may be present, it is necessary to
select one node from the candidates. Subsequent to any Serial Bus reset
the new NPM shall be determined by a distributed algorithm executed by
all the NPM-capable nodes. The algorithm is straightforward: the
NPM-capable node with the largest 6-bit physical ID shall be the NPM.
This use of physical ID is arbitrary and was selected to simplify the
election process. The steps in the algorithm are as follows:
a) An NPM-capable node shall also a contender for the role of
isochronous resource manager. The C (contender) bit in its self-ID
packet shall be set to one;
b) Subsequent to a bus reset, isochronous resource manager contention
takes place during the self-identification process specified by
1394;
c) An NPM-capable node that wins the contention process referenced in
b) is the NPM and shall proceed with g). Other NPM-capable node(s)
not selected as the isochronous resource manager (hereafter
referred to as candidates) shall continue with d);
d) A candidate NPM that loses contention for the role of isochronous
resource manager shall delay before it attempts to become the NPM.
The delay time is determined by the physical ID of the candidate
NPM and shall be equal to 15 ms * (irm_ID candidate_ID), where
irm_ID and candidate_ID are the physical IDs of the isochronous
resource manager and the candidate NPM, respectively. After the
delay time has elapsed, the candidate NPM shall examine the npm_ID
field in its own NETWORK_CHANNELS register; if it is not equal to
0x3F, another node is the NPM. The losing candidate shall wait for
the valid bit of its own register to be set before transmitting any
ARP or IP datagrams;
e) Otherwise, the candidate NPM shall attempt to read the
NETWORK_CHANNELS register of any contenders with a larger physical
ID (these nodes were identified by the C bit in their self-ID
packets). The candidate NPM shall read the NETWORK_CHANNELS
register in the contender with the largest physical ID and progress
downward. If the register is implemented, the NPM is determined to
be a different node. The losing candidate shall ignore the contents
Expires: August, 1998 [Page 7]
Internet-Draft 07 IPv4 over 1394 February 1998
of NETWORK_CHANNELS returned in the read response and shall wait
for the valid bit of its own register to be set before transmitting
any ARP or IP datagrams;
f) If no contender with a physical ID larger than the candidate NPM's
physical ID implements the NETWORK_CHANNELS register, the search is
complete and the candidate becomes the new NPM;
g) Once elected, the NPM shall update the npm_ID field in the
NETWORK_CHANNELS register of all the IP-capable nodes on the bus
with its own physical ID. This signals to other candidates that the
NPM election process is complete. Either a broadcast write request
or a series of write requests addressed to individual nodes may be
used;
h) The NPM shall attempt to allocate a channel number from the
CHANNELS_AVAILABLE register (note that the NPM may also be the
isochronous resource manager). If no channel number is available,
the NPM shall take no additional action (all valid bit(s) were
cleared by the bus reset);
i) Otherwise, the NPM shall update its own NETWORK_CHANNELS register
with its own physical ID, the allocated channel number and set the
valid bit to one. The NPM shall then write this value to the
NETWORK_CHANNELS register of all the IP-capable nodes on the bus.
Either a broadcast write request or a series of write requests
addressed to individual nodes may be used to propagate the
information.
In the case that the NPM is unable to allocate a channel for ARP and
broadcast IP, a warning should be communicated to a user that IP
initialization could not complete because of a lack of Serial Bus
resources. The user should be advised to reconfigure or remove other
devices if she wishes to make use of IP.
NOTE: If the NPM is unable to allocate a channel, IP-capable nodes are
unable to use the ARP and broadcast IP methods specified by this
document. If other methods (e.g., a search of configuration ROM) permit
IP-capable nodes to discover each other, they may be able to send and
receive IP datagrams.
An IP-capable node that is not the NPM typically awaits a write to its
NETWORK_CHANNELS to set the valid bit to one; this indicates that the
channel field is valid for ARP and IP broadcast. If some time-out
elapses without this occurrence, an IP-capable node may attempt to
locate the NPM and retrieve valid information from the NETWORK_CHANNELS
register. If the npm_ID field in its own NETWORK_CHANNELS register is
not equal to 0x3F, the address of the NPM is known; otherwise the node
may search for the NPM as described in e) above. In either case, it is
recommended that reads of the NPMs NETWORK_CHANNELS register not be
performed within a tight loop, as this could adversely affect both IP
and overall 1394 performance on the local bus.
6. LINK ENCAPSULATION AND FRAGMENTATION
All IP datagrams (broadcast, unicast or multicast), as well as ARP
requests and responses, that are transferred via 1394 block write
requests or stream packets shall be encapsulated within the packet's
Expires: August, 1998 [Page 8]
Internet-Draft 07 IPv4 over 1394 February 1998
data payload. The maximum size of data payload, in octets, is
constrained by the speed at which the packet is transmitted.
Table 1 - Maximum data payloads
Speed Asynchronous Isochronous
+------------------------------------+
| S100 | 512 | 1024 |
| S200 | 1024 | 2048 |
| S400 | 2048 | 4096 |
| S800 | 4096 | 8192 |
| S1600 | 8192 | 16384 |
| S3200 | 16384 | 32768 |
+------------------------------------+
The maximum data payload may also be restricted by the capabilities of
the sending or receiving node(s); this is specified by max_rec in either
the bus information block or ARP response.
For either of these reasons, the minimum capabilities between
IP-capable nodes may be less than the 1500 octet maximum transmission
unit (MTU) specified by this document. This necessitates 1394 link level
encapsulation of IP datagrams, which provides for the ordering and
reassembly of link fragments as necessary.
6.1 Link encapsulation header
All datagrams transported over 1394 are prefixed by a link encapsulation
header with one of the formats illustrated below.
If an entire IP datagram may be transmitted within a single 1394 packet,
it is unfragmented and the first quadlet of the data payload shall
conform to the format illustrated below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lf| reserved | ether_type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 - Unfragmented datagram header format
The lf field shall be zero to indicate an unfragmented datagram.
The ether_type field shall indicate the nature of the datagram that
follows, as specified by the following table.
ether_type Datagram
+-----------------------+
| 0x800 | IPv4 |
| 0x806 | ARP |
+-----------------------+
Expires: August, 1998 [Page 9]
Internet-Draft 07 IPv4 over 1394 February 1998
In cases where the length of the datagram exceeds the maximum data
payload supported by the sender and all recipients, the datagram shall
be broken into link fragments; the first two quadlets of the data
payload for the first link fragment shall conform to the format shown
below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lf|rsv| buffer_size | ether_type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| dgl | signature |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3 - First fragment datagram header format
The second and subsequent link fragments (up to and including the last)
shall conform to the format shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lf|rsv| buffer_size | rsv | fragment_offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| dgl | signature |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4 - Subsequent fragment(s) datagram header format
The definition and usage of the fields is as follows:
The lf field shall specify the relative position of the link fragment
within the IP datagram, as encoded by the following table.
lf Position
+------------------------+
| 0 | Unfragmented |
| 1 | First |
| 2 | Last |
| 3 | Interior |
+------------------------+
buffer_size: The size of the buffer, expressed as buffer_size + 1)
octets, necessary for the recipient to reassemble the datagram
fragments.
ether_type: This field is present only in the first link fragment and
shall have a value of 0x800, which indicates an IPv4 datagram.
fragment_offset: This field is present only in the second and
subsequent link fragments and shall specify the offset, in octets, of
the fragment from the beginning of the IP datagram. The first octet
of the datagram (the start of the IP header) has an offset of zero;
Expires: August, 1998 [Page 10]
Internet-Draft 07 IPv4 over 1394 February 1998
the implicit value of fragment_offset in the first link fragment is
zero.
NOTE- Other network protocols, identified by different values of
ether_type, may use the encapsulation format defined above but such use
is outside of the scope of this document.
dgl: The value of dgl shall be the same for all fragments of an IP
datagram. The sender shall increment the value of dgl for successive,
fragmented datagrams; the incremented value of dgl shall wrap from
65,535 back to zero.
signature: The sender shall set this field to the most significant
16-bits of its own NODE_IDS register.
All datagrams, regardless of the mode of transmission (block write
requests or stream packets) shall be preceded by one of the above
described link encapsulation headers. This permits uniform software
treatment of datagrams without regard to the mode of their transmission.
6.2 Fragment reassembly
The recipient of a fragmented datagram shall use both signature and dgl
to identify all the fragments from a single datagram. Subsequent to
reassembly, the recipient shall verify the IP header checksum of the
datagram.
NOTE: The use of signature for any purpose other than datagram
reassembly is fraught with error and is strongly discouraged.
Upon receipt of a datagram fragment, the recipient may place the data
payload (absent the link fragment header) within an IP datagram
reassembly buffer at the quadlet offset specified by fragment_offset.
The size of the reassembly buffer may be determined from buffer_size.
If a datagram fragment is received that overlaps another fragment for
the same signature and dgl, the fragment(s) already accumulated in the
reassembly buffer shall be discarded. A fresh reassembly may be
commenced with the most recently received fragment. Fragment overlap is
determined by the combination of fragment_offset from the link fragment
header and data_length from the 1394 packet header.
Upon detection of a Serial Bus reset, recipient(s) shall discard all
fragments of all partially reassembled datagrams and sender(s) shall
discard all not yet transmitted fragments of all partially transmitted
datagrams.
7. ADDRESS RESOLUTION PROTOCOL (ARP)
ARP requests and responses shall be transmitted by the same means as
broadcast IP datagrams. The data payload of an ARP request/response is
56 octets and shall conform to the format illustrated below.
Expires: August, 1998 [Page 11]
Internet-Draft 07 IPv4 over 1394 February 1998
NOTE- The first quadlet of the ARP request/response is the link
encapsulation header for an unfragmented datagram describe in section 6.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | reserved | ether_type (0x0806) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| hardware_type (0x0018) | protocol_type (0x0800) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| hw_addr_len | IP_addr_len | opcode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+--- sender_unique_ID ---+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sender_node_ID | sender_unicast_FIFO_hi |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sender_unicast_FIFO_lo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sender_max_rec| sspd | reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sender_IP_address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+--- target_unique_ID ---+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| target_node_ID | target_unicast_FIFO_hi |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| target_unicast_FIFO_lo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| target_max_rec| tspd | reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| target_IP_address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5 - ARP request/response format
Field usage in an ARP request/response is as follows:
hardware_type: This field indicates 1394 and shall have a value of
0x0018.
protocol_type: This field shall have a value of 0x0800; this
indicates that the protocol addresses in the ARP request or response
conform to the format for IP addresses.
hw_addr_len: This field indicates the size, in octets, of the 1394-
dependent hardware address associated with an IP address and shall
have a value of 20.
IP_addr_len: This field indicates the size, in octets, of an IP
version 4 (IPv4) address and shall have a value of 4.
Expires: August, 1998 [Page 12]
Internet-Draft 07 IPv4 over 1394 February 1998
opcode: This field shall be one to indicate an ARP request and two to
indicate an ARP response.
sender_unique_ID: This field shall contain the node_unique_ID of the
sender and shall be equal to that specified in the sender's bus
information block.
sender_node_ID: This field shall contain the most significant 16 bits
of the sender's NODE_IDS register.
sender_unicast_FIFO_hi and sender_unicast_FIFO_lo: These fields
together shall specify the 48-bit offset of the sender's FIFO
available for the receipt of IP datagrams in the format specified by
section 8. The offset of a sender's unicast FIFO shall not change,
either as a result of a bus reset, power reset or other circumstance,
unless the new FIFO offset is advertised by an unsolicited ARP
response datagram.
sender_max_rec: This field shall be equal to the value of max_rec in
the senders configuration ROM bus information block.
sspd: This field shall be set to the lesser of the senders 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 sspd is specified by the table below; all values not
specified are reserved.
Value Speed
+---------------+
| 0 | S100 |
| 1 | S200 |
| 2 | S400 |
| 3 | S800 |
| 4 | S1600 |
| 5 | S3200 |
+---------------+
sender_IP_address: This field shall specify the IP address of the
sender.
target_unique_ID: In an ARP request, the value of this field is not
specified; it shall be ignored by the recipient. In an ARP response,
it shall be set to the value of sender_unique_ID from the
corresponding ARP request.
target_node_ID: In an ARP request, the value of this field is not
specified; it shall be ignored by the recipient. In an ARP response,
it shall be set to the value of sender_node_ID from the corresponding
ARP request.
target_unicast_FIFO_hi and target_unicast_FIFO_lo: In an ARP request,
the value of these fields is not specified; they shall be ignored by
Expires: August, 1998 [Page 13]
Internet-Draft 07 IPv4 over 1394 February 1998
the recipient. In an ARP response, they shall be set to the value of
sender_unicast_FIFO_hi and sender_unicast_FIFO_lo from the
corresponding ARP request.
target_max_rec: In an ARP request, the value of this field is not
specified; it shall be ignored by the recipient. In an ARP response,
it shall be equal to the value of max_rec from the corresponding ARP
request.
tspd: In an ARP request, the value of this field is not specified; it
shall be ignored by the recipient. In an ARP response, it shall be
equal to the value of sspd from the corresponding ARP request.
target_IP_address: In an ARP request, this field shall specify the IP
address from which the responder desires a response. In an ARP
response, it shall be set to the value of sender_IP_address from the
corresponding ARP request.
8. IP UNICAST
IP unicast may be transmitted to a recipient within a 1394 primary
packet that has one of the following transaction codes:
tcode Description Arbitration
+--------------------------------------+
| 0x01 | Block write | Asynchronous |
| 0x0A | Stream packet | Isochronous |
| 0x0A | Stream packet | Asynchronous |
+--------------------------------------+
Block write requests are suitable when 1394 link-level acknowledgement
of the datagram is desired but there is no need for bounded latency in
the delivery of the packet (quality of service).
Isochronous stream packets provide quality of service guarantees but no
1394 link-level acknowledgement.
The last method, asynchronous stream packets, is mentioned only for the
sake of completeness. This method should not be used, since it provides
for neither 1394 link-level acknowledgment nor quality of service---and
consumes a valuable resource, a channel number.
NOTE: Regardless of the IP unicast method employed, asynchronous or
isochronous, it is the responsibility of the sender of a unicast IP
datagram to determine the maximum data payload that may be used in each
packet. The necessary information may be obtained from:
- the SPEED_MAP maintained by the 1394 bus manager and provides a
maximum transmission speed between any two nodes on the local
Serial Bus. The speed in turn implies a maximum data payload (see
Table 1).
Expires: August, 1998 [Page 14]
Internet-Draft 07 IPv4 over 1394 February 1998
NOTE: The SPEED_MAP is derived from the self-ID packets transmitted by
all 1394 nodes subsequent to a bus reset. An IP-capable node may observe
the self-ID packets directly;
- the target_max_rec field in an ARP response. This document requires
a minimum value of 8 (equivalent to a data payload of 512 octets).
Nodes that operate at S200 and faster are encouraged but not
required to implement correspondingly larger values for
target_max_rec; or
- other methods beyond the scope of this standard.
The maximum data payload shall be the minimum of the largest data
payload implemented by the sender, the recipient and the PHYs of all
intervening nodes.
8.1 Asynchronous IP unicast
Unicast IP datagrams that do not require any quality of service shall be
contained within the data payload of 1394 block write transactions
addressed to the target_node_ID and target_unicast_FIFO obtained from an
ARP response packet.
If no acknowledgement is received in response to a unicast block write
request, the state of the target is ambiguous.
NOTE: An acknowledgment may be absent because the target is no longer
functional, may not have received the packet because of a header CRC
error or may have received the packet successfully but the acknowledge
sent in response was corrupted.
8.2 Isochronous IP unicast
Unicast IP datagrams that require quality of service shall be contained
within the data payload of 1394 isochronous stream packets.
The details of coordination between nodes with respect to allocation of
channel number(s) and bandwidth is beyond the scope of this standard.
9. IP BROADCAST
Broadcast IP datagrams are encapsulated and fragmented according to the
specifications of section 6 and are transported by asynchronous stream
packets. There is no quality of service provision for IP broadcast over
1394. The channel number used for IP broadcast is specified by the
NETWORK_CHANNELS register.
The channel number specified by NETWORK_CHANNELS is intended for
datagrams that the sender wishes to transmit to all IP-capable nodes on
the local bus or subnet. Broadcast addresses include all of the
following:
- TBD: Add list of IP addresses valid for broadcast
Expires: August, 1998 [Page 15]
Internet-Draft 07 IPv4 over 1394 February 1998
All IP datagrams addressed to one of the preceding addresses shall use
asynchronous stream packets whose channel number is equal to the channel
field from the NETWORK_CHANNELS register.
Although 1394 permits the use of previously allocated channel number(s)
for up to one second subsequent to a bus reset, IP-capable nodes shall
not transmit asynchronous stream packets at any time the valid bit in
their NETWORK_CHANNELS register is zero. Since the valid bit is
automatically cleared to zero by a bus reset, this prohibits the use of
ARP or broadcast IP until the NPM allocates a channel number.
10. IP MULTICAST
Many of the details of multicast remain outside the scope of this draft
in its present form (but are expected to be added by the working group
as the draft is advanced).
IP multicast shall use stream packets, either asynchronous or
isochronous, according to the quality of service required.
11. SECURITY CONSIDERATIONS
This document raises no security issues.
12. ACKNOWLEDGEMENTS
This document represents work in progress by the IP / 1394 Working
Group. The editor wishes to acknowledge the contributions made by all
the active participants, either on the reflector or at face-to-face
meetings, which have advanced the technical content.
13. REFERENCES
[1] IEEE Std 1394-1995, Standard for a High Performance Serial Bus
[2] ISO/IEC 13213:1994, Control and Status Register (CSR) Architecture
for Microcomputer Buses
[3] IEEE Project P1394a, Draft Standard for a High Performance Serial
Bus (Supplement)
[4] IEEE Project P1394b, Draft Standard for a High Performance Serial
Bus (Supplement)
14. EDITORS ADDRESS
Peter Johansson
Congruent Software, Inc.
3998 Whittle Avenue
Oakland, CA 94602
(510) 531-5472
(510) 531-2942 FAX
pjohansson@aol.com
Expires: August, 1998 [Page 16]
