rfc1221.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

   will reply with a Create Stream Reply message (Figure 9).  If the
   reply code in the Create Stream Reply indicates that the stream has
   been created successfully, the host may proceed to transmit stream
   data messages after sending a Reply Acknowledgment.

   During the lifetime of a stream, the host which created it may decide
   that some of its characteristic properties should be modified.  All
   but one of the properties can be modified using the Change Stream
   Request message (Figure 10).  The one property that cannot be changed
   is whether or not the stream is willing to share its resources with
   other streams.  After the network has processed the Change Stream
   Request, the Service Agent will respond by sending a Change Stream
   Reply (Figure 11) to the host.  A host requesting a reduced channel
   allocation should decrease its sending rate immediately without
   waiting for receipt of the Change Stream Reply.  A host requesting an
   increased allocation should not proceed to transmit according to the
   new set of parameters without first having received a Reply Code
   indicating that the requested change has taken effect.

   When the host no longer needs the stream it created, it should first
   stop sending traffic via the stream and then send the Service Agent a
   Delete Stream Request message (Figure 12).  After the network has
   processed the Delete Stream Request, the Service Agent will respond
   by sending a Delete Stream Reply (Figure 13) to the host.

   If the host has crashed or restarted, it may no longer know what
   streams it owns.  The host may use an Information Request (see
   Section 6.5) to determine what streams it owns, or the host may use a
   Delete All Streams Request (Figure 14) to discard whatever stream
   resources it may own.  The format for the Delete All Streams Reply is
   shown in Figure 15.

   Note that streams, like all other resources allocated by the Service
   Agent, may be reclaimed by the network if unused.  Currently, if no
   traffic is sent to a stream in a 6 minute interval, and if the owner
   of the steam is down or unreachable, the stream may be deleted.













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RFC 1221                          HAP2                        April 1991


                 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S0        |           1           |           5           |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S1        |                 SETUP CHECKSUM                |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S2        |                  REQUEST ID                   |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S3        |  MAX MES  | PRE | INT | RLY |      RLEN       |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S4        |            DATA WORDS PER INTERVAL            |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S5        |                 INTERVAL                      |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S6        |           0           |  ADDRESS LIST LENGTH  |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
               |                                               |
     S7-SN     :            DESTINATION ADDRESS LIST           :
               |                                               |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+


                           CREATE STREAM REQUEST
                                 Figure 8



     S0[0-7]   Setup Type = 1 (Request).

     S0[8-15]  Request Type = 5 (Create Stream).

     S1[0-15]  Setup Checksum.  (See setup header description.)

     S2[0-15]  Request ID.

     S3[0-3]   Maximum Messages Per Interval (1-15).  This field
               specifies the maximum number of stream messages the
               host will deliver to the WPS in any single stream
               interval.

     S3[4-5]   Precedence.  This field specifies the precedence of the
               stream.  When there are insufficient network resources
               to support all the requested streams, requests for
               higher precedence streams will preempt existing lower
               precedence streams, and requests for streams with
               insufficient precedence will be rejected.  Medium
               precedence is recommended as the default choice.




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RFC 1221                          HAP2                        April 1991


                    0 = Low Precedence
                    1 = Medium Precedence
                    2 = High Precedence

     S3[6-7]   Interval.  This field specifies the interval, in
               multiples of 21.22 milliseconds.  (For backward
               compatibility only.  New applications should use 3.
               Use of this field to specify an interval is being
               phased out.)

                    0 =  21.22 milliseconds
                    1 =  42.44 milliseconds
                    2 =  84.88 milliseconds
                    3 =  use interval in word S5

     S3[8-9]   Reliability.  This field specifies the basic bit-error
               rate requirement for the data portion of all messages
               in the stream.  The exact error rate obtained by each
               choice is not specified.

                    0 = Low Reliability
                    1 = Medium-Low Reliability
                    2 = Medium-High Reliability
                    3 = High Reliability

     S3[10-15] Reliability Length.  This field specifies how many
               words beyond the stream message header should be
               transmitted at maximum reliability for all messages in
               the host stream.

     S4[0-15]  Data words per interval.  This field specifies the
               maximum number of 16-bit words of this stream's data
               the network will need to carry during each interval,
               not counting HAP stream message header words.  The
               stream data may be carried in however many messages (up
               to MAX MES) in each interval the host chooses.

     S5[0-15]  Interval (125 microsecond units).  This field specifies
               the time interval over which the <data words per
               interval> data in <max mes> messages will be sent.  For
               backward compatibility, an interval of 0 selects an
               interval of 169.76 milliseconds.  This field is ignored
               unless the INT field is 3.

     S6[0-7]   Reserved.  Must be zero.

     S6[8-15]  Destination address list length.  This field specifies
               the number of entries in the Destination Address List



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RFC 1221                          HAP2                        April 1991


               field.  Allowed values are 1-8.

     S7-SN     Destination address list.  This list must specify, at
               least indirectly, all the intended recipients of this
               stream's traffic.  At least one destination address
               must be supplied.  Any valid network address,
               specifically including group addresses, may be used
               (except the Service Agent's address, 0).  Messages sent
               in the stream are not limited to using the HAP
               addresses listed.  E.g., if the list consists of only
               group address G, and host A is a member of G, a stream
               message may be sent to A, which was not in the list.

   Caution: Group membership is only evaluated at setup time.  Changes
   in group membership do not cause the stream to be modified.

   Caution: Stream creation involves allocation of specific network
   resources along specific routes for delivery of that traffic.  A
   stream message sent to hosts other than those specified via Setup
   will probably be undeliverable.  A stream message to a group address
   that has gained new members since the stream's last Setup may be
   undeliverable to the new members.


                 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S0        |           2           |      REPLY CODE       |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S1        |                 SETUP CHECKSUM                |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S2        |                  REQUEST ID                   |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S3        |        0        |         STREAM ID           |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S4        |        0        |     ADDRESS LIST LENGTH     |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
               |                                               |
     S5-SN     :                 ADDRESS LIST                  :
               |                                               |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+


                            CREATE STREAM REPLY
                                 Figure 9



     S0[0-7]   Setup Type = 2 (Reply).



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RFC 1221                          HAP2                        April 1991


     S0[8-15]  Reply Code.  Any reply other than "Stream created"
               means the stream was not created.

                    0 = Stream created
                    8 = Network trouble
                   12 = Stream precedence not being accepted
                   17 = Insufficient network resources
                   18 = Requested bandwidth too large
                   21 = Max. messages per interval too small
                   22 = Reply lost in network
                   23 = Illegal precedence value
                   24 = Invalid destination address in list

     S1[0-15]  Setup Checksum.  (See setup header description.)

     S2[0-15]  Request ID.

     S3[0-5]   Reserved.  Must be zero.

     S3[6-15]  Stream ID.  This field contains a stream ID assigned by
               the network.  It must be included in all stream data
               messages sent by the host to allow the WPS to associate
               the message with stored stream characteristics and the
               resources reserved for that stream's traffic.

     S4[0-5]   Reserved.  Must be zero.

     S4[6-15]  Address list length.  The number of entries in the
               Address List field.

     S5-SN     Address list.  This contains the destination addresses
               from the Create Stream Request that were invalid or
               unreachable.  Unreachable destinations are listed as a
               group if every member of the group was unreachable, or
               individually otherwise; i.e., group addresses are
               expanded and the unreachable members are included in
               the list.  The list of unreachable destinations will be
               truncated, if needed, to limit this Reply to a single,
               maximum length HAP message.












Edmond                                                         [Page 26]

RFC 1221                          HAP2                        April 1991


                 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S0        |           1           |           7           |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S1        |                 SETUP CHECKSUM                |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S2        |                  REQUEST ID                   |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S3        |        0        |         STREAM ID           |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S4        |  MAX MES  | PRE | INT | RLY |      RLEN       |
               +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
     S5        |            DATA WORDS PER INTERVAL            |
               +--+--+--+--+--+--