rfc998.txt

RFC 相关的技术文档

   Connection UID: the 32 bit connection UID specified in the
   section "Connection Setup".

   Buffer size: the size in bytes of each NETBLT buffer (save the
   last)




Clark, Lambert, & Zhang                                        [Page 16]

RFC 998                                                       March 1987


   Transfer size: (optional) the size in bytes of the transfer.

   This is for client information only; the receiving NETBLT should
   NOT make use of it.

   Data packet size: length of each DATA packet in bytes

   Burst Size: Number of DATA packets in a burst

   Burst Rate: Transmit time in milliseconds of a single burst

   Death timer: Packet sender's death timer value in seconds

   "M": the transfer mode (0 = READ, 1 = WRITE)

   "C": the DATA packet data checksum flag (0 = do not checksum
   DATA packet data, 1 = do)

   Maximum Outstanding Buffers: maximum number of buffers that can
   be transferred before waiting for an OK message from the
   receiving NETBLT.

   Client string: an arbitrary, null-terminated, longword-aligned
   string for use by NETBLT clients.

   KEEPALIVE (type 2), QUITACK (type 4), and DONE (type 11)

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |           Checksum            |    Version    |     Type      |
   +---------------+---------------+---------------+---------------+
   |           Length              |           Local Port          |
   +---------------+---------------+---------------+---------------+
   |        Foreign Port           | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+


















Clark, Lambert, & Zhang                                        [Page 17]

RFC 998                                                       March 1987


   QUIT (type 3), ABORT (type 5), and REFUSED (type 10)

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |           Checksum            |    Version    |     Type      |
   +---------------+---------------+---------------+---------------+
   |           Length              |           Local Port          |
   +---------------+---------------+---------------+---------------+
   |        Foreign Port           | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+
   | Reason for QUIT/ABORT/REFUSE...
   +---------------+---------------+---------------
                                     Longword Alignment Padding    |
                    ---------------+-------------------------------+

   DATA (type 6) and LDATA (type 7):

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |           Checksum            |    Version    |     Type      |
   +---------------+---------------+---------------+---------------+
   |           Length              |           Local Port          |
   +---------------+---------------+---------------+---------------+
   |        Foreign Port           | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+
   |                       Buffer Number                           |
   +---------------+---------------+---------------+---------------+
   | High Consecutive Seq Num Rcvd |         Packet Number         |
   +---------------+---------------+---------------+---------------+
   |    Data Area Checksum Value   |      Reserved (MBZ)         |L|
   +---------------+---------------+---------------+---------------+

   Buffer number: a 32 bit unique number assigned to every buffer.
   Numbers are monotonically increasing.

   High Consecutive Sequence Number Received: Highest control
   message sequence number below which all sequence numbers received
   are consecutive.

   Packet number: monotonically increasing DATA packet identifier

   Data Area Checksum Value: Checksum of the DATA packet's data.
   Algorithm used is the same as that used to compute checksums of
   other NETBLT packets.

   "L" is a flag set when the buffer that this DATA packet belongs
   to is the last buffer in the transfer.





Clark, Lambert, & Zhang                                        [Page 18]

RFC 998                                                       March 1987


   NULL-ACK (type 8)

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |           Checksum            |    Version    |     Type      |
   +---------------+---------------+---------------+---------------+
   |           Length              |           Local Port          |
   +---------------+---------------+---------------+---------------+
   |        Foreign Port           | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+
   | High Consecutive Seq Num Rcvd |        New Burst Size         |
   +---------------+---------------+---------------+---------------+
   |       New Burst Rate          |  Longword Alignment Padding   |
   +---------------+---------------+---------------+---------------+

   High Consecutive Sequence Number Received: same as in DATA/LDATA
   packet

   New Burst Size:  Burst size as negotiated from value given by
   receiving NETBLT in OK message

   New burst rate: Burst rate as negotiated from value given
   by receiving NETBLT in OK message.  Value is in milliseconds.

   CONTROL (type 9):

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |           Checksum            |    Version    |     Type      |
   +---------------+---------------+---------------+---------------+
   |           Length              |           Local Port          |
   +---------------+---------------+---------------+---------------+
   |        Foreign Port           | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+

   Followed by any number of messages, each of which is longword
   aligned, with the following formats:

   GO message (type 0):

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |    Type       | Word Padding  |       Sequence Number         |
   +---------------+---------------+---------------+---------------+
   |                        Buffer Number                          |
   +---------------+---------------+---------------+---------------+

   Type: message type (GO = 0, OK = 1, RESEND = 2)



Clark, Lambert, & Zhang                                        [Page 19]

RFC 998                                                       March 1987


   Sequence number: A 16 bit unique message number.  Sequence
   numbers must be monotonically increasing, starting from 1.

   Buffer number: as in DATA/LDATA packet

   OK message (type 1):

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |    Type       | Word Padding  |       Sequence Number         |
   +---------------+---------------+---------------+---------------+
   |                        Buffer Number                          |
   +---------------+---------------+---------------+---------------+
   |    New Offered Burst Size     |   New Offered Burst Rate      |
   +---------------+---------------+---------------+---------------+
   | Current control timer value   | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+

   New offered burst size: burst size for subsequent buffer
   transfers, possibly based on performance information for previous
   buffer transfers.

   New offered burst rate: burst rate for subsequent buffer
   transfers, possibly based on performance information for previous
   buffer transfers.  Rate is in milliseconds.

   Current control timer value: Receiving NETBLT's control timer
   value in milliseconds.

   RESEND Message (type 2):

                      1                   2                   3
    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 2
   +---------------+---------------+---------------+---------------+
   |    Type       | Word Padding  |       Sequence Number         |
   +---------------+---------------+---------------+---------------+
   |                        Buffer Number                          |
   +---------------+---------------+---------------+---------------+
   |  Number of Missing Packets    | Longword Alignment Padding    |
   +---------------+---------------+---------------+---------------+
   |       Packet Number (2 bytes) ...
   +---------------+---------------+----------
                                   |    Padding (if necessary)     |
                        -----------+---------------+---------------+

   Packet number:  the 16 bit data packet identifier found in each
   DATA packet.






Clark, Lambert, & Zhang                                        [Page 20]

RFC 998                                                       March 1987


NOTES:

   <1>  When the buffer size is large, the variances in the round trip
   delays of many packets may cancel each other out; this means the
   variance value need not be very big.  This expectation will be
   explored in further testing.
















































Clark, Lambert, & Zhang                                        [Page 21]