rfc2383.txt

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   o setup.ind
     This primitive indicates a SETUP message delivery from the UNI 3.1
     signaling layer entity to the ST2+ SCMP layer entity.  The ST2+
     SCMP layer entity that received this primitive sends an
     acknowledgment.  If the setup is accepted the acknowledgment is a
     setup.resp primitive and if the setup is rejected it is a
     release.resp primitive if the state of the UNI 3.1 signaling layer
     entity is U6; otherwise it is a release.req primitive.

   o setup.resp
     This primitive sends a request for a CONNECT message transfer from
     the ST2+ SCMP layer entity to the UNI 3.1 signaling layer entity.
     The ST2+ SCMP layer entity that sent this primitive receives an
     acknowledgment.  If the setup is completed the acknowledgment is a
     setup-complete.ind primitive and if the setup fails it is a
     release.ind or release.conf primitive.

   o setup-complete.ind
     This primitive indicates a CONNECT ACKNOWLEDGE message delivery
     from the UNI 3.1 signaling layer entity to the ST2+ SCMP layer
     entity.

   o release.req
     This primitive sends a request for a RELEASE message transfer from
     the ST2+ SCMP layer entity to the UNI 3.1 signaling layer entity.
     The ST2+ SCMP layer entity that sent this primitive receives an
     acknowledgment that is a release.conf primitive.

   o release.conf
     This primitive indicates a RELEASE COMPLETE message delivery, or
     indicates a RELEASE message delivery when the status of the UNI 3.1
     signaling layer entity is U11, or indicates detection of an
     abnormal status such as an illegal message or timeout in the UNI
     3.1 signaling layer entity, from the UNI 3.1 signaling layer entity



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     to the ST2+ SCMP layer entity.

   o release.ind
     This primitive indicates a RELEASE message delivery from the UNI
     3.1 signaling layer entity to the ST2+ SCMP layer entity when the
     status of the UNI 3.1 signaling layer entity is other than U11.
     The ST2+ SCMP layer entity that received this primitive sends an
     acknowledgment that is a release.resp primitive.  And this
     primitive also indicates detection of an abnormal status such as an
     illegal message or timeout in the UNI 3.1 signaling layer entity
     and then a REFUSE message is transferred.  In this case, the ST2+
     SCMP layer entity that received this primitive receives a
     release.conf primitive in succession.

   o release.resp
     This primitive sends a request for a RELEASE COMPLETE message
     transfer from the ST2+ SCMP layer entity to the UNI 3.1 signaling
     layer entity.

   o add-party.req
     This primitive sends a request for an ADD PARTY message transfer
     from the ST2+ SCMP layer entity to the UNI 3.1 signaling layer
     entity.  The ST2+ SCMP layer entity that sent this primitive
     receives an acknowledgment.  If the setup is succeeds the
     acknowledgment is an add-party.conf primitive and if the setup
     fails it is a drop-party.conf primitive.

   o add-party.conf
     This primitive indicates an ADD PARTY ACKNOWLEDGE message delivery
     from the UNI 3.1 signaling layer entity to the ST2+ SCMP layer
     entity.

   o drop-party.req
     This primitive sends a request for a DROP PARTY message transfer
     from the ST2+ SCMP layer entity to the UNI 3.1 signaling layer
     entity.  The ST2+ SCMP layer entity that sent this primitive
     receives an acknowledgment that is a drop-party.conf primitive.

   o drop-party.conf
     This primitive indicates an ADD PARTY REJECT message delivery, or
     indicates a DROP PARTY ACKNOWLEDGE message delivery, or indicates
     detection of an abnormal status such as an illegal message or
     timeout in the UNI 3.1 signaling layer entity, from the UNI 3.1
     signaling layer entity to the ST2+ SCMP layer entity.

   o drop-party.ind
     This primitive indicates a DROP PARTY message delivery from the UNI
     3.1 signaling layer entity to the ST2+ SCMP layer entity.  The ST2+



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     SCMP layer entity that sent this primitive receives an
     acknowledgment that is a drop-party.resp primitive.

   o drop-party.resp
     This primitive sends a request for a DROP PARTY ACKNOWLEDGE message
     transfer from the ST2+ SCMP layer entity to the UNI 3.1 signaling
     layer entity.

6.4 VC Style Selection Criteria

   The ST2+ over ATM protocol supports PVC, the reverse channel of bi-
   directional SVC, point-to-point SVC, and point-to-multipoint SVC for
   ST2+ Data PDU transfer.  And SVC supports both upstream and
   downstream call initiation styles.

   A 32-bit PVC identifier that is unique between neighboring ST2+
   agents is assigned to each PVC.  And the reverse channel of the bi-
   directional point-to-point SVC used by the existing stream is
   identified by the SID of the stream that occupies the forward
   channel.

   When the ST2+ agent sets up a stream or changes QoS, the ST2+ agent
   must select one VC style from these SVC and PVC styles as a hop that
   is part of the stream.  In the ST2+ over ATM protocol, VC style
   selection criteria depend on the implementation.

   This subsection describes examples of VC style selection criteria for
   the ST2+ over ATM protocol as a reference for implementors.  Note
   that the following descriptions in this subsection are not part of
   the ST2+ over ATM protocol specification.

6.4.1 Examples of PVC selection criteria

   At least, the ST2+ agent may have to manage the following information
   for each PVC that can be used by ST2+ Data PDU transfer.

   o PVC identifier

   o ATM interface identifier in the ST2+ agent

   o VPI/VCI

   o State of VC: e.g. enabled or disabled, occupied or vacant

   o QoS of VC

   o Nexthop IP address




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   When a PVC is selected for a hop of a stream, at least confirmations,
   that is the state of the PVC is vacant and the next hop IP address
   and QoS are consistent with the requirements from the stream, may be
   needed.

   It is also feasible to introduce access lists to each PVC and to
   consider the access lists in the selection process.  Examples of an
   access list are shown in the following.

   o Permit or deny use by a stream whose the previous hop is specified.

   o Permit or deny use by a stream whose the origin is specified.

   o Permit or deny use by a stream whose the SID is specified.

   o Permit or deny use by a stream whose the target is specified.

   o Permit or deny use by a stream whose the target and SAP are
     specified.

   o Any combination of the above.

6.4.2 Examples of reverse channel of bi-directional SVC selection
      criteria

   At least, the ST2+ agent may have to manage the following information
   for each reverse channel of bi-directional SVCs.

   o SID of the stream that occupies the forward channel

   o ATM interface identifier in the ST2+ agent

   o VPI/VCI

   o State of the reverse channel in the VC: e.g. enabled or disabled,
     occupied or vacant

   o QoS of VC

   o Nexthop IP address

   When a reverse channel of the bi-directional point-to-point SVC used
   by the existing stream is selected for a hop of a stream, at least
   confirmations, that is the state of the channel is vacant and the
   next hop IP address and QoS are consistent with the requirements from
   the stream, may be needed.





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   It is also feasible to introduce selection rules to the ST2+ agent.
   Examples of selection rule are shown in the following.

   o Permit reuse of the reverse channel by a stream whose the origin is
     one of targets in the stream that occupies the forward channel.

   o Permit reuse of the reverse channel by a stream whose one of
     targets is the origin in the stream that occupies the forward
     channel.

   o Permit reuse of the reverse channel by a stream whose the previous
     hop is one of the next hops in the stream that occupies the forward
     channel.

   o Any combination of the avobe.

6.4.3 Examples of SVC selection criteria

   When an SVC is used for a hop of a stream, at first, the ST2+ agent
   must select point-to-point or point-to-multipoint SVC.  Examples of
   this selection rule are shown in the following.

   o If the network supports only point-to-point SVC, select it.

   o If the network supports point-to-multipoint SVC, select it.

   If point-to-point SVC is selected, the ST2+ agent must select
   upstream or downstream call initiation style.  Examples of this
   selection rule are shown in the following.

   o A VC for a stream whose previous hop is specified is initiated from
     upstream or downstream.

   o A VC for a stream whose next hop is specified is initiated from
     upstream or downstream.

   o A VC for a stream whose origin is specified is initiated from
     upstream or downstream.

   o A VC for a stream whose SID is specified is initiated from upstream
     or downstream.

   o A VC for a stream whose target is specified is initiated from
     upstream or downstream.

   o A VC for a stream whose target and SAP are specified is initiated
     from upstream or downstream.




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   o Any combination of the above.

6.5 VC Management

   This subsection specifies VC management in the ST2+ over ATM
   protocol.

6.5.1 Outgoing call processing of SVC

   When outgoing call processing of the first leaf of a point-to-
   multipoint SVC or a point-to-point SVC is required inside the ST2+
   SCMP layer entity, a setup.req primitive is sent to the UNI 3.1
   signaling layer entity.  If the UNI 3.1 signaling layer entity
   responds with a setup.conf primitive, the call processing is assumed
   to have succeeded.  If the UNI 3.1 signaling layer entity responds
   with anything other than this primitive, the processing rule is the
   same as the SVC disconnect processing that is shown in section 6.5.4
   and the outgoing call processing is assumed to have failed.

   When outgoing call processing of a later leaf of a point-to-
   multipoint SVC is required, an add-party.req primitive is sent to the
   UNI 3.1 signaling layer entity.  If the UNI 3.1 signaling layer
   entity responds with an add-party.conf primitive, the call processing
   is assumed to have succeeded.  If the UNI 3.1 signaling layer entity
   responds with anything other than this primitive, the processing rule
   is the same as the SVC disconnect processing that is shown in section
   6.5.4 and the outgoing call processing is assumed to have failed.

6.5.2 Incoming call processing of SVC

   When an incoming call processing of SVC is required inside the ST2+
   SCMP layer entity, it sets a watchdog timer.  The time interval of
   the timer depends on the implementation.

   The ST2+ SCMP layer entity waits for a setup.ind primitive indication
   from the UNI 3.1 signaling layer entity.  When this primitive is
   indicated and the parameters in it are acceptable, the ST2+ SCMP
   layer entity responds with a setup.resp primitive.  If the parameters
   are not acceptable, the ST2+ SCMP layer entity stops the timer, and
   if the state of the UNI 3.1 signaling layer entity is U6, the entity
   responds with a release.resp primitive, and if the state is other
   than this, the entity responds with a release.req primitive, and then
   waits for a release.conf primitive response and the incoming call
   processing is assumed to have failed.

   If the ST2+ SCMP layer entity responds with a setup.resp primitive,
   then the entity waits for the next primitive indication, and when the
   next primitive is indicated, the ST2+ SCMP layer entity stops the



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   timer.  If a setup-complete.ind primitive is indicated, the incoming
   call processing is assumed to have succeeded.  If the UNI 3.1
   signaling layer entity responds with anything other than this
   primitive or if the timer expires, the processing rule is the same as
   the SVC disconnect processing that is shown in section 6.5.4 and the
   incoming call processing is assumed to have failed.

6.5.3 VC release processing inside ST2+ SCMP layer

   When a VC release is required inside an ST2+ SCMP layer entity, if
   the previous hop or next hop is connected with a PVC, the PVC state
   is set to vacant and the VC release processing is assumed to be
   completed.

   If the previous hop or next hop is connected with a point-to-point
   SVC whose reverse channel is occupied, the state of the channel in
   the VC is set to vacant, the SID information of the VC is updated,
   and the VC release processing is assumed to be completed.

   If the previous hop or next hop is connected with a point-to-point
   SVC whose reverse channel is vacant, if the previous hop is connected
   with a point-to-multipoint SVC, or if the next hop is connected with
   a point-to-multipoint SVC and the number of leaves is 1, then the
   ST2+ SCMP layer entity sends a release.req primitive to the UNI 3.1
   signaling layer entity, then waits for a release.conf primitive
   indication; when one is indicated, the VC release processing is
   assumed to be completed.

   If the next hop is connected with a point-to-multipoint SVC and the
   number of leaves is other than 1, the ST2+ SCMP layer entity sends a
   drop-party.req primitive to the UNI 3.1 signaling layer entity, then
   waits for a drop-party.conf primitive indication; when one is
   indicated, the VC re