tech-invite   World Map     

3GPP     Specs     Glossaries     Architecture     IMS     UICC       IETF     RFCs     Groups     SIP     ABNFs       Search

RFC 2297

Informational
Pages: 109
Top     in Index     Prev     Next
in Group Index     Prev in Group     No Next: Highest Number in Group     Group: ~ipsilon

Ipsilon's General Switch Management Protocol Specification Version 2.0

Part 1 of 4, p. 1 to 29
None       Next RFC Part

Updates:    1987


Top       ToC       Page 1 
Network Working Group                                    P. Newman, Nokia
Request for Comments: 2297                             W. Edwards, Sprint
Updates: 1987                                            R. Hinden, Nokia
Category: Informational                                 E. Hoffman, Nokia
                                                            F. Ching Liaw
                                                           T. Lyon, Nokia
                                                   G. Minshall, Fiberlane
                                                               March 1998


       Ipsilon's General Switch Management Protocol Specification
                              Version 2.0

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.


Abstract

   This memo specifies enhancements to the  General Switch Management
   Protocol (GSMP) [RFC1987]. The major enhancement is the addition of
   Quality of Service (QoS) messages. Other improvements have been made
   to the protocol resulting from operational experience. GSMP is a
   general purpose protocol to control an ATM switch. It allows a
   controller to establish and release connections across the switch;
   add and delete leaves on a multicast connection; manage switch ports;
   request configuration information; and request statistics.

Top       Page 2 
Table of Contents

   1. Introduction....................................................3

   2. GSMP Packet Encapsulation.......................................4
      2.1 ATM Encapsulation...........................................4
      2.2 Ethernet Encapsulation......................................6

   3. Common Definitions and Procedures...............................7
      3.1 GSMP Packet Format..........................................8
      3.2 Failure Response Messages..................................11

   4. Connection Management Messages.................................16
      4.1 Add Branch Message.........................................21
      4.2 Delete Tree Message........................................23
      4.3 Verify Tree Message........................................24
      4.4 Delete All Message.........................................24
      4.5 Delete Branches Message....................................25
      4.6 Move Branch Message........................................27

   5. Port Management Messages.......................................29
      5.1 Port Management Message....................................29
      5.2 Label Range Message........................................34

   6. State and Statistics Messages..................................37
      6.1 Connection Activity Message................................38
      6.2 Statistics Messages........................................40
          6.2.1 Port Statistics Message..............................44
          6.2.2 Connection Statistics Message........................44
          6.2.3 QoS Class Statistics Message.........................44
      6.3 Report Connection State Message............................45

   7. Configuration Messages.........................................49
      7.1 Switch Configuration Message...............................50
      7.2 Port Configuration Message.................................51
      7.3 All Ports Configuration Message............................57

   8. Event Messages.................................................59
      8.1 Port Up Message............................................60
      8.2 Port Down Message..........................................60
      8.3 Invalid VPI/VCI Message....................................61
      8.4 New Port Message...........................................61
      8.5 Dead Port Message..........................................61

   9. Quality of Service Messages....................................61
      9.1 Abstract Switch Model......................................62
      9.2 QoS Configuration Message..................................66
      9.3 Scheduler Establishment Message............................74

Top      ToC       Page 3 
      9.4 QoS Class Establishment Message............................78
      9.5 QoS Release Message........................................85
      9.6 QoS Connection Management Message..........................86
      9.7 QoS Failure Response Codes.................................97

   10. Adjacency Protocol............................................97
      10.1 Packet Format.............................................98
      10.2 Procedure.................................................101
      10.3 Loss of Synchronization...................................103

   11. Summary of Failure Response Codes.............................104

   12. Summary of Message Set........................................105

   References........................................................107
   Security Considerations...........................................107
   Authors' Addresses................................................107
   Full Copyright Statement..........................................109



1. Introduction

   The General Switch Management Protocol (GSMP), is a general purpose
   protocol to control an ATM switch. GSMP allows a controller to
   establish and release connections across the switch; add and delete
   leaves on a multicast connection; manage switch ports; request
   configuration information; and request statistics. It also allows the
   switch to inform the controller of asynchronous events such as a link
   going down. GSMP runs across an ATM link connecting the controller to
   the switch, on a control connection (virtual channel) established at
   initialization. GSMP operation across an Ethernet link is also
   specified. The GSMP protocol is asymmetric, the controller being the
   master and the switch being the slave. Multiple switches may be
   controlled by a single controller using multiple instantiations of
   the protocol over separate control connections.

   A switch is assumed to contain multiple "ports". Each port is a
   combination of one "input port" and one "output port". Some GSMP
   requests refer to the port as a whole whereas other requests are
   specific to the input port or the output port.  ATM cells arrive at
   the switch from an external communication link on incoming virtual
   paths or virtual channels at an input port. ATM cells depart from the
   switch to an external communication link on outgoing virtual paths or
   virtual channels from an output port. Virtual paths on a port or link
   are referenced by their virtual path identifier (VPI). Virtual
   channels on a port or link are referenced by their virtual path and
   virtual channel identifiers (VPI/VCI).

Top      ToC       Page 4 
   A virtual channel connection across a switch is formed by connecting
   an incoming virtual channel to one or more outgoing virtual channels.
   Virtual channel connections are referenced by the input port on which
   they arrive and the virtual path and virtual channel identifiers
   (VPI/VCI) of their incoming virtual channel. A virtual path
   connection across a switch is formed by connecting an incoming
   virtual path to one or more outgoing virtual paths. Virtual path
   connections are referenced by the input port on which they arrive and
   their virtual path identifier (VPI).  In a virtual path connection
   the value of the VCI in each cell on that, connection is not used by
   the switch and remains unchanged by the switch.

   GSMP supports point-to-point and point-to-multipoint connections. A
   multipoint-to-point connection is specified by establishing multiple
   point-to-point connections each of them specifying the same output
   branch. A multipoint-to-multipoint connection is specified by
   establishing multiple point-to-multipoint trees each of them
   specifying the same output branches.

   In general a virtual channel is established with a certain quality of
   service (QoS). A rich set of QoS messages is introduced in this
   version of the protocol. However, implementation or operation of GSMP
   without any of the messages defined in Section 9, "Quality of service
   messages," is permitted.  In this case each virtual channel
   connection or virtual path connection may be assigned a priority when
   it is established. It may be assumed that for virtual connections
   that share the same output port, an ATM cell on a connection with a
   higher priority is much more likely to exit the switch before an ATM
   cell on a connection with a lower priority if they are both in the
   switch at the same time. The number of priorities that each port of
   the switch supports may be obtained from the port configuration
   message.

   GSMP contains an adjacency protocol. The adjacency protocol is used
   to synchronize state across the link, to negotiate which version of
   the GSMP protocol to use, to discover the identity of the entity at
   the other end of a link, and to detect when it changes.


2. GSMP Packet Encapsulation

2.1 ATM Encapsulation

   GSMP packets are variable length and for an ATM data link layer they
   are encapsulated directly in an AAL-5 CPCS-PDU [I.363] with an
   LLC/SNAP header as illustrated:

Top      ToC       Page 5 
    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               LLC (0xAA-AA-03)                |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
   |                   SNAP (0x00-00-00-88-0C)                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         GSMP Message                          ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Pad (0 - 47 octets)                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +               AAL-5 CPCS-PDU Trailer (8 octets)               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   (The convention in the documentation of Internet Protocols [RFC1700]
   is to express numbers in decimal. Numbers in hexadecimal format are
   specified by prefacing them with the characters "0x".  Data is
   pictured in "big-endian" order. That is, fields are described left to
   right, with the most significant octet on the left and the least
   significant octet on the right. Whenever a diagram shows a group of
   octets, the order of transmission of those octets is the normal order
   in which they are read in English. Whenever an octet represents a
   numeric quantity the left most bit in the diagram is the high order
   or most significant bit. That is, the bit labeled 0 is the most
   significant bit. Similarly, whenever a multi-octet field represents a
   numeric quantity the left most bit of the whole field is the most
   significant bit. When a multi-octet quantity is transmitted, the most
   significant octet is transmitted first. This is the same coding
   convention as is used in the ATM layer [I.361] and AAL-5 [I.363].)

   The LLC/SNAP header contains the octets: 0xAA 0xAA 0x03 0x00 0x00
   0x00 0x88 0x0C. (0x880C is the assigned Ethertype for GSMP.)

   The maximum transmission unit (MTU) of the GSMP Message field is 1492
   octets.

   The virtual channel over which a GSMP session is established between
   a controller and the switch it is controlling is called the GSMP
   control channel.  The default VPI and VCI of the GSMP control channel
   for LLC/SNAP encapsulated GSMP messages on an ATM data link layer is:

      VPI = 0
      VCI = 15.

Top      ToC       Page 6 
2.2 Ethernet Encapsulation

   GSMP packets may be encapsulated on an Ethernet data link as
   illustrated:

    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Destination Address                      |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                         Source Address                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Ethertype (0x88-0C)       |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                                                               |
   ~                         GSMP Message                          ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Sender Instance                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Receiver Instance                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Pad                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Frame Check Sequence                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Destination Address
             For the SYN message of the adjacency protocol the
             Destination Address is the broadcast address
             0xFFFFFFFFFFFF. (Alternatively, it is also valid to
             configure the node with the unicast 48-bit IEEE MAC address
             of the destination. In this case the configured unicast
             Destination Address is used in the SYN message.) For all
             other messages the Destination Address is the unicast 48-
             bit IEEE MAC address of the destination. This address may
             be discovered from the Source Address field of messages
             received during synchronization of the adjacency protocol.

   Source Address
             For all messages the Source Address is the 48-bit IEEE MAC
             address of the sender.

   Ethertype
             The assigned Ethertype for GSMP is 0x880C.

Top      ToC       Page 7 
   GSMP Message
             The maximum transmission unit (MTU) of the GSMP Message
             field is 1492 octets.

   Sender Instance
             The Sender Instance number for the link obtained from the
             adjacency protocol.  This field is already present in the
             adjacency protocol message. It is appended to all non-
             adjacency GSMP messages in the Ethernet encapsulation to
             offer additional protection against the introduction of
             corrupt state.

   Receiver Instance
             The Receiver Instance number is what the sender believes is
             the current instance number for the link, allocated by the
             entity at the far end of the link.  This field is already
             present in the adjacency protocol message. It is appended
             to all non-adjacency GSMP messages in the Ethernet
             encapsulation to offer additional protection against the
             introduction of corrupt state.

   Pad
             The minimum length of the data field of an Ethernet packet
             is 46 octets.  If necessary, padding should be added such
             that it meets the minimum Ethernet frame size. This padding
             should be octets of zero and it is not considered to be
             part of the GSMP message.

   After the adjacency protocol has achieved synchronization, for every
   GSMP message received with an Ethernet encapsulation, the receiver
   must check the Source Address from the Ethernet MAC header, the
   Sender Instance, and the Receiver Instance.  The incoming GSMP
   message must be discarded if the Sender Instance and the Source
   Address do not match the values of Sender Instance and Sender Name
   stored by the "Update Peer Verifier" operation of the GSMP adjacency
   protocol. The incoming GSMP message must also be discarded if it
   arrives over any port other than the port over which the adjacency
   protocol has achieved synchronization.  In addition, the incoming
   message must also be discarded if the Receiver Instance field does
   not match the current value for the Sender Instance of the GSMP
   adjacency protocol.


3. Common Definitions and Procedures

   GSMP is a master-slave protocol. The controller issues request
   messages to the switch. Each request message indicates whether a
   response is required from the switch and contains a transaction

Top      ToC       Page 8 
   identifier to enable the response to be associated with the request.
   The switch replies with a response message indicating either a
   successful result or a failure. There are five classes of GSMP
   request-response message: Connection Management, Port Management,
   State and Statistics, Configuration, and Quality of Service.  The
   switch may also generate asynchronous Event messages to inform the
   controller of asynchronous events.  Event messages are not
   acknowledged by the controller. There is also an adjacency protocol
   message used to establish synchronization across the link and
   maintain a handshake.

   For the request-response messages, each message type has a format for
   the request message and a format for the success response.  Unless
   otherwise specified a failure response message is identical to the
   request message that caused the failure, with the Code field
   indicating the nature of the failure. Event messages have only a
   single format defined as they are not acknowledged by the controller.

   Switch ports are described by a 32-bit port number. The switch
   assigns port numbers and it may typically choose to structure the 32
   bits into subfields that have meaning to the physical structure of
   the switch (e.g. slot, port). In general, a port in the same physical
   location on the switch will always have the same port number, even
   across power cycles. The internal structure of the port number is
   opaque to the GSMP protocol. However, for the purposes of network
   management such as logging, port naming, and graphical
   representation, a switch may declare the physical location (physical
   slot and port) of each port. Alternatively, this information may be
   obtained by looking up the product identity in a database.

   Each switch port also maintains a port session number assigned by the
   switch. A message, with an incorrect port session number must be
   rejected.  This allows the controller to detect a link failure and to
   keep state synchronized.

   Except for the adjacency protocol message, no GSMP messages may be
   sent across the link until the adjacency protocol has achieved
   synchronization, and all GSMP messages received on a link that does
   not currently have state synchronization must be discarded.

3.1 GSMP Packet Format

   All GSMP messages, except the adjacency protocol message, have the
   following format:

Top      ToC       Page 9 
    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    | Message Type  |    Result     |     Code      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Transaction Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                          Message Body                         ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Version
             The version number of the GSMP protocol being used in this
             session. It should be set by the sender of the message to
             the GSMP protocol version negotiated by the adjacency
             protocol.

   Message Type
             The GSMP message type. GSMP messages fall into six classes:
             Connection Management, Port Management, State and
             Statistics, Configuration, Quality of Service, and Events.
             Each class has a number of different message types. In
             addition, one Message Type is allocated to the adjacency
             protocol.

   Result
             Field in a Connection Management request message, a Port
             Management request message, or a Quality of Service request
             message is used to indicate whether a response is required
             to the request message if the outcome is successful. A
             value of "NoSuccessAck" indicates that the request message
             does not expect a response if the outcome is successful,
             and a value of "AckAll" indicates that a response is
             expected if the outcome is successful.  In both cases a
             failure response must be generated if the request fails.
             For Sate and Statistics, and Configuration request
             messages, a value of "NoSuccessAck" in the request message
             is ignored and the request message is handled as if the
             field were set to "AckAll". (This facility was added to
             reduce the control traffic in the case where the controller
             periodically checks that the state in the switch is
             correct. If the controller does not use this capability,
             all request messages should be sent with a value of
             "AckAll.")

Top      ToC       Page 10 
             In a response message the result field can have three
             values: "Success," "More," and "Failure". The "Success" and
             "More" results both indicate a success response. The "More"
             result indicates that the success response exceeds the
             maximum transmission unit of the data link and that one or
             more further messages will be sent to complete the success
             response. All messages that belong to the same success
             response will have the same Transaction Identifier. The
             "Success" result indicates a success response that may be
             contained in a single message or the final message of a
             success response spanning multiple messages.

             The encoding of the result field is:

                  NoSuccessAck:  Result = 1
                  AckAll:        Result = 2
                  Success:       Result = 3
                  Failure:       Result = 4
                  More:          Result = 5.


             The Result field is not used in an adjacency protocol
             message.

   Code
             Field gives further information concerning the result in a
             response message. It is mostly used to pass an error code
             in a failure response but can also be used to give further
             information in a success response message or an event
             message. In a request message the code field is not used
             and is set to zero. In an adjacency protocol message the
             Code field is used to determine the function of the
             message.

   Transaction Identifier
             Used to associate a request message with its response
             message. For request messages the controller may select any
             transaction identifier. For response messages the
             transaction identifier is set to the value of the
             transaction identifier from the message to which it is a
             response.  For event messages the transaction identifier
             should be set to zero. The Transaction Identifier is not
             used, and the field is not present, in the adjacency
             protocol.

   The following fields are frequently found in GSMP messages. They are
   defined here to avoid repetition.

Top      ToC       Page 11 
   Port
             Gives the port number of the switch port to which the
             message applies.

   Port Session Number
             Each switch port maintains a Port Session Number assigned
             by the switch. The port session number of a port remains
             unchanged while the port is continuously in the Available
             state and the link status is continuously Up. When a port
             returns to the Available state after it has been
             Unavailable or in any of the Loopback states, or when the
             line status returns to the Up state after it has been Down
             or in Test, or after a power cycle, a new Port Session
             Number must be generated.  Port session numbers should be
             assigned using some form of random number.

             If the Port Session Number in a request message does not
             match the current Port Session Number for the specified
             port, a failure response message must be returned with the
             Code field indicating, "Invalid port session number."  The
             current port session number for a port may be obtained
             using a Port Configuration or an All Ports Configuration
             message.

   Any field in a GSMP message that is unused or defined as "reserved"
   must be set to zero by the sender and ignored by the receiver.

   It is not an error for a GSMP message to contain additional data
   after the end of the Message Body. This is to support development and
   experimental purposes. However, the maximum transmission unit of the
   GSMP message, as defined by the data link layer encapsulation, must
   not be exceeded.

   A success response message must not be sent until the requested
   operation has been successfully completed.

3.2 Failure Response Messages

   A failure response message is formed by returning the request message
   that caused the failure with the Result field in the header
   indicating failure (Result = 4) and the Code field giving the failure
   code. The failure code specifies the reason for the switch being
   unable to satisfy the request message.

   If the switch issues a failure response in reply to a request
   message, no change should be made to the state of the switch as a
   result of the message causing the failure. (For request messages that
   contain multiple requests, such as the Delete Branches message, the

Top      ToC       Page 12 
   failure response message will specify which requests were successful
   and which failed. The successful requests may result in changed
   state.)

   If the switch issues a failure response it must choose the most
   specific failure code according to the following precedence:

       Invalid Message

       Failure specific to the particular message type (failure code
           16). (The meaning of this failure is dependent upon the
           particular message type and is specified in the text defining
           the message.)

       A failure response specified in the text defining the message
           type.

       Connection Failures

       Virtual Path Connection Failures

       Multicast Failures

       QoS Failures (QoS failures are specified in Section 9.7.)

       General Failures

   If multiple failures match in any of the following categories, the
   one that is listed first should be returned. The following failure
   response messages and failure codes are defined:

   Invalid Message

       3:  The specified request is not implemented on this switch.
               The Message Type field specifies a message that is not
               implemented on the switch or contains a value that is not
               defined in the version of the protocol running in this
               session of GSMP.

       5:  One or more of the specified ports does not exist.
               At least one of the ports specified in the message is
               invalid. A port is invalid if it does not exist or if it
               has been removed from the switch.

       4:  Invalid Port Session Number.
               The value given in the Port Session Number field does not
               match the current Port Session Number for the specified
               port.

Top      ToC       Page 13 
   Connection Failures

       8:  The specified connection does not exist.
               An operation that expects a connection to be specified,
               either a virtual channel or a virtual path connection,
               cannot locate the specified connection. A virtual channel
               connection is specified by the input port, input VPI, and
               input VCI on which it arrives. A virtual path connection
               is specified by the input port and input VPI on which it
               arrives.

       9:  The specified branch does not exist.
               An operation that expects a branch of an existing
               connection to be specified, either a virtual channel or a
               virtual path connection, cannot locate the specified
               branch.  A branch of a virtual channel connection is
               specified by the virtual channel connection it belongs to
               and the output port, output VPI, and output VCI on which
               it departs. A branch of a virtual path connection is
               specified by the virtual path connection it belongs to
               and the output port and output VPI on which it departs.

       18: One or more of the specified input VPIs is invalid.

       19: One or more of the specified input VCIs is invalid.

       20: One or more of the specified output VPIs is invalid.

       21: One or more of the specified output VCIs is invalid.

       22: Invalid Class of Service field in a Connection Management
               message.
               The value of the Class of Service field is invalid.

       23: Insufficient resources for QoS Profile.
               The resources requested by the QoS Profile in the Class
               of service field are not available.

   Virtual Path Connections

       24: Virtual path switching is not supported on this input port.

       25: Point-to-multipoint virtual path connections are not
               supported on either the requested input port or the
               requested output port.
               One or both of the requested input and output ports is
               unable to support point-to-multipoint virtual path
               connections.

Top      ToC       Page 14 
       26: Attempt to add a virtual path connection branch to an
               existing virtual channel connection.
               It is invalid to mix branches switched as virtual channel
               connections with branches switched as virtual path
               connections on the same point-to-multipoint connection.

       27: Attempt to add a virtual channel connection branch to an
               existing virtual path connection.
               It is invalid to mix branches switched as virtual channel
               connections with branches switched as virtual path
               connections on the same point-to-multipoint connection.

   Multicast Failures

       10: A branch belonging to the specified point-to-multipoint
               connection is already established on the specified output
               port and the switch cannot support more than a single
               branch of any point-to-multipoint connection on the same
               output port.

       11: The limit on the maximum number of point-to-multipoint
               connections that the switch can support has been reached.

       12: The limit on the maximum number of branches that the
               specified point-to-multipoint connection can support has
               been reached.

       17: Cannot label each output branch of a point-to-multipoint tree
               with a different label.
               Some early designs, and some low-cost ATM switch designs,
               require all output branches of a multicast connection to
               use the same value of VPI/VCI.

       28: Only point-to-point bidirectional connections may be
               established.
               It is an error to attempt to add an additional output
               branch to an existing connection with the bidirectional
               flag set.

       13: Unable to assign the requested VPI/VCI value to the requested
               branch on the specified point-to-multipoint connection.
               Although the requested VPI and VCI are valid, the switch
               is unable to support the request using the specified
               values of VPI and VCI for some reason not covered by the
               above failure responses. This message implies that a
               valid value of VPI or VCI exists that the switch could

Top      ToC       Page 15 
               support. For example, some switch designs restrict the
               number of distinct VPI/VCI values available to a point-
               to-multipoint connection. (Most switch designs will not
               require this message.)

       14: General problem related to the manner in which point-to-
               multipoint is supported by the switch.
               Use this message if none of the more specific multicast
               failure messages apply.  (Most switch designs will not
               require this message.)

   General Failures

       2:  Invalid request message.
               There is an error in one of the fields of the message not
               covered by a more specific failure message.

       6:  One or more of the specified ports is down.
               A port is down if its Port Status is Unavailable.
               Connection Management, Connection State, Port Management,
               and Configuration operations are permitted on a port that
               is Unavailable. Connection Activity and Statistics
               operations are not permitted on a port that is
               Unavailable and will generate this failure response. A
               Port Management message specifying a Take Down function
               on a port already in the Unavailable state will also
               generate this failure response.

       15: Out of resources.
               The switch has exhausted a resource not covered by a more
               specific failure message, for example, running out of
               memory.

       1:  Unspecified reason not covered by other failure codes.
               The failure message of last resort.

   The following failure response messages are only used by the Label
               Range message.

       29: Cannot support requested VPI range.

       30: Cannot support requested VCI range on all requested VPIs.

   The following failure response messages are only used by the Set
               Transmit Cell Rate function of the Port Management
               message.

       31: The transmit cell rate of this output port cannot be changed.

Top      ToC       Page 16 
       32: Requested transmit cell rate out of range for this output
               port.


4. Connection Management Messages

   Connection management messages are used by the controller to
   establish, delete, modify and verify virtual channel connections and
   virtual path connections across the switch. The Add Branch, Delete
   Tree, and Delete All connection management messages have the
   following format for both request and response messages:

    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    | Message Type  |    Result     |     Code      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Transaction Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Port Session Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Input Port                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |M|Q|B|C|      Input VPI        |          Input VCI            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Output Port                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x x x x|      Output VPI       |          Output VCI           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Number of Branches       |       Class of Service        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Input Port
             Identifies a switch input port.

   Flags

        M: Multicast
             The Multicast flag is used as a hint for point-to-
             multipoint connections in the Add Branch message. It is not
             used in any other connection management messages and in
             these messages it should be set to zero. If set, it
             indicates that the virtual channel connection or the
             virtual path connection is very likely to be a point-to-
             multipoint connection. If zero, it indicates that this
             connection is very likely to be a point-to-point connection
             or is unknown.

Top      ToC       Page 17 
             The Multicast flag is only used in the Add Branch message
             when establishing the first branch of a new connection. It
             is not required to be set when establishing subsequent
             branches of a point-to-multipoint connection and on such
             connections it should be ignored by the receiver. (On
             receipt of the second and subsequent Add Branch messages
             the receiver knows that this is a point-to-multipoint
             connection.) If it is known that this is the first branch
             of a point-to-multipoint connection this flag should be
             set. If it is unknown, or if it is known that the
             connection is point-to-point this flag should be zero. The
             use of this flag is not mandatory. It may be ignored by the
             switch.  If unused the flag should be set to zero. Some
             switches use a different data structure for point-to-
             multipoint connections than for point-to-point connections.
             This flag avoids the switch setting up a point-to-point
             structure for the first branch of a point-to-multipoint
             connection which must immediately be deleted and
             reconfigured as point-to-multipoint when the second branch
             is established.

        Q: QoS Profile
             The QoS Profile flag, if set, indicates that the Class of
             Service field contains a QoS Profile Identifier.  If this
             flag is zero, it indicates that the Class of Service field
             contains a Priority or a Scheduler Identifier.

        B: Bidirectional
             The Bidirectional flag applies only to the Add Branch
             message. In all other Connection Management messages it is
             not used. It may only be used when establishing a point-
             to-point connection.  The Bidirectional flag in an Add
             Branch message, if set, requests that two unidirectional
             virtual channels or virtual paths be established, one in
             the forward direction, and one in the reverse direction. It
             is equivalent to two Add Branch messages, one specifying
             the forward direction, and one specifying the reverse
             direction. The forward direction uses the values of Input
             Port, Input VPI, Input VCI, Output Port, Output VPI, and
             Output VCI as specified in the Add Branch message. The
             reverse direction is derived by exchanging the values
             specified in the Input Port, Input VPI, and Input VCI
             fields, with those of the Output Port, Output VPI, and
             Output VCI fields respectively. Thus, a virtual connection
             in the reverse direction arrives at the input port
             specified by the Output Port field, on the VPI/VCI
             specified by the Output VPI and Output VCI fields. It
             departs from the output port specified by the Input Port

Top      ToC       Page 18 
             field, on the VPI/VCI specified by the Input VPI and Input
             VCI fields.

             The Bidirectional flag is simply a convenience to establish
             two unidirectional virtual connections in opposite
             directions between the same two ports, with identical
             VPI/VCIs, using a single Add Branch message. In all future
             messages the two unidirectional virtual connections must be
             handled separately. There is no bidirectional delete
             message. However, a single Delete Branches message with two
             Delete Branch Elements, one for the forward connection and
             one for the reverse, may be used.

        C: Congestion Indication
             The Congestion Indication flag, if set, requests that cells
             on this connection be marked if congestion is experienced.
             If this connection passes through a queue that the switch
             considers to be congested, the Congestion Experienced bit
             will be set in the Payload Type field of the cell header of
             all cells on the connection. GSMP does not specify the
             algorithm or any threshold by which the switch decides when
             a queue is congested.

   Input VPI
             Identifies an ATM virtual path arriving at the switch input
             port indicated by the Input Port field.

   Input VCI
             Identifies an ATM virtual channel arriving on the virtual
             path indicated by the Input VPI field at the switch input
             port indicated by the Input Port field. For virtual path
             connections the Input VCI field is not used.

   Output Port
             Identifies a switch output port.

   x: Unused

   Output VPI
             Identifies an outgoing virtual path departing from the
             switch output port indicated in the Output Port field.

   Output VCI
             Identifies an outgoing virtual channel departing on the
             virtual path indicated by the Output VPI field from the
             switch output port indicated in the Output Port field. For
             virtual path connections the Output VCI field is not used.

Top      ToC       Page 19 
   Number of Branches
             In a success response message and a failure response
             message, gives the number of output branches on a virtual
             channel connection or a virtual path connection after
             completion of the requested operation.  (A point-to-point
             connection will have one branch, a point-to-multipoint
             connection will have two or more branches.) If the switch
             is unable to keep track of the number of branches on a
             virtual path connection or a virtual channel connection it
             must respond with the value 0xFFFF meaning: "number of
             branches unknown".  This field is not used in the request
             message.

   Class of Service
             This field can contain either a QoS Profile Identifier, a
             Priority, or a Scheduler Identifier.  If the QoS Profile
             flag in the Flags field is set, the Class of Service field
             contains a QoS Profile.  If the QoS Profile flag in the
             Flags field is zero, and the value of the Class of Service
             field is greater than or equal to 0x100, the Class of
             Service field contains a Scheduler Identifier.  If the QoS
             Profile flag in the Flags field is zero, and the value of
             the Class of Service field is less than 0x100, the Class of
             Service field contains a Priority. (Values of Scheduler
             Identifier less than 0x100 are interpreted as priorities.)
             The Class of Service field is only used in the Add Branch
             and Move Branch messages.

             A QoS Profile Identifier is an opaque 16-bit value. It is
             used to identify a QoS profile in the switch which
             specifies the Quality of Service required by the
             connection. QoS profiles are established by a mechanism
             external to GSMP.

             A Scheduler Identifier is an alternative method of
             communicating the QoS requirements of a connection. The
             Scheduler Identifier is defined in Section 9, "Quality of
             Service Messages."

             A Priority specifies the priority of the connection for Add
             Branch and Move Branch messages that choose not to use a
             QoS profile, or the QoS capabilities defined in Section 9,
             "Quality of Service Messages." The highest priority is
             numbered zero and the lowest priority is numbered "Q-1"
             where "Q" is the number of priorities that the output port
             can support. The ability to offer different qualities of
             service to different connections based upon their priority
             is assumed to be a property of the output port of the

Top      ToC       Page 20 
             switch. It is assumed that for virtual path connections or
             virtual channel connections that share the same output
             port, an ATM cell on a connection with a higher priority is
             much more likely to exit the switch before an ATM cell on a
             connection with a lower priority, if they are both in the
             switch at the same time. The number of priorities that each
             output port can support is given in the Port Configuration
             message.

   For all connection management messages, except the Delete Branches
   message, the success response message is a copy of the request
   message returned with the Result field indicating success and the
   Number of Branches field indicating the number of branches on the
   connection after completion of the operation. The Code field is not
   used in a connection management success response message.

   The failure response message is a copy of the request message
   returned with a Result field indicating failure and the Number of
   Branches field indicating the number of branches on the connection.

   Fundamentally, no distinction is made between point-to-point and
   point-to-multipoint connections. By default, the first Add Branch
   message for a particular Input Port, Input VPI, and Input VCI will
   establish a point-to-point virtual connection.  The second Add Branch
   message with the same Input Port, Input VPI, and Input VCI fields
   will convert the connection to a point-to-multipoint virtual
   connection with two branches. (For virtual path connections the Input
   VCI is not required.) However, to avoid possible inefficiency with
   some switch designs, the Multicast Flag is provided. If the
   controller knows that a new connection is point-to-multipoint when
   establishing the first branch, it may indicate this in the Multicast
   Flag.  Subsequent Add Branch messages with the same Input Port, Input
   VPI, and Input VCI fields will add further branches to the point-to-
   multipoint connection. Use of the Delete Branch message on a point-
   to-multipoint connection with two branches will result in a point-
   to-point connection. However, the switch may structure this
   connection as a point-to-multipoint connection with a single output
   branch if it chooses. (For some switch designs this structure may be
   more convenient.) Use of the Delete Branch message on a point-to-
   point connection will delete the point-to-point connection. There is
   no concept of a connection with zero output branches. All connections
   are unidirectional, one input virtual path or virtual channel to one
   or more output virtual paths or virtual channels.

   GSMP supports point-to-point and point-to-multipoint connections. A
   multipoint-to-point connection is specified by establishing multiple
   point-to-point connections each of them specifying the same output
   branch.  (An output branch is specified by an output port and output

Top      ToC       Page 21 
   VPI for a virtual path connection and by an output port, output VPI,
   and output VCI for a virtual channel connection.) A multipoint-to-
   multipoint connection is specified by establishing multiple point-
   to-multipoint trees each of them specifying the same output branches.

   The connection management messages apply both to virtual channel
   connections and virtual path connections. The Add Branch and Move
   Branch connection management messages have two Message Types. One
   Message Type indicates that a virtual channel connection is required,
   and the other Message Type indicates that a virtual path connection
   is required. The Delete Branches, Delete Tree, and Delete All
   connection management messages have only a single Message Type
   because they do not need to distinguish between virtual channel
   connections and virtual path connections. For virtual path
   connections, neither Input VCI fields nor Output VCI fields are
   required. They should be set to zero by the sender and ignored by the
   receiver. Virtual channel branches may not be added to an existing
   virtual path connection.  Conversely, virtual path branches may not
   be added to an existing virtual channel connection.  In the Port
   Configuration message each switch input port may declare whether it
   is capable of supporting virtual path switching (i.e. accepting
   connection management messages requesting virtual path connections).

   The connection management messages may be issued regardless of the
   Port Status of the switch port. Connections may be established or
   deleted when a switch port is in the Available, Unavailable, or any
   of the Loopback states. However, all connection state on an input
   port will be deleted when the port returns to the Available state
   from any other state, i.e. when a Port Management message is received
   for that port with the Function field indicating either Bring Up, or
   Reset Input Port.

4.1 Add Branch Message

   The Add Branch message is a connection management message used to
   establish a virtual channel connection or a virtual path connection
   or to add an additional branch to an existing virtual channel
   connection or virtual path connection. It may also be used to check
   the connection state stored in the switch. The connection is
   specified by the Input Port, Input VPI, and Input VCI fields. The
   output branch is specified by the Output Port, Output VPI, and Output
   VCI fields. The quality of service requirements of the connection are
   specified by the Class of Service field. To request a virtual channel
   connection the Virtual Channel Connection (VCC) Add Branch message
   is:

      Message Type = 16

Top      ToC       Page 22 
   To request a virtual path connection the Virtual Path Connection
   (VPC) Add Branch message is:

      Message Type = 26

   If a VPC Add Branch message is received and the switch input port
   specified by the Input Port field does not support virtual path
   switching, a failure response message must be returned indicating,
   "Virtual path switching is not supported on this input port."

   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields; or the virtual path connection specified
   by the Input Port and Input VPI fields; does not already exist, it
   must be established with the single output branch specified in the
   request message. If the Bidirectional Flag in the Flags field is set,
   the reverse connection must also be established.  The output branch
   should have the QoS attributes specified by the Class of Service
   field.

   For the VCC Add Branch message, if a virtual path connection already
   exists on the virtual path specified by the Input Port and Input VPI
   fields, a failure response message must be returned indicating,
   "Attempt to add a virtual channel connection branch to an existing
   virtual path connection." For the VPC Add Branch message, if a
   virtual channel connection already exists on any of the virtual
   channels within the virtual path specified by the Input Port and
   Input VPI fields, a failure response message must be returned
   indicating, "Attempt to add a virtual path connection branch to an
   existing virtual channel connection."

   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields; or the virtual path connection specified
   by the Input Port and Input VPI fields; already exists, but the
   specified output branch does not, the new output branch must be
   added.  The new output branch should have the QoS attributes
   specified by the Class of Service field.

   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields; or the virtual path connection specified
   by the Input Port and Input VPI fields; already exists and the
   specified output branch also already exists, the QoS attributes of
   the connection, specified by the Class of Service field, if different
   from the request message, should be changed to that in the request
   message.  A success response message must be sent if the Result field
   of the request message is "AckAll".  This allows the controller to
   periodically reassert the state of a connection or to change its
   priority. If the result field of the request message is
   "NoSuccessAck" a success response message should not be returned.

Top      ToC       Page 23 
   This may be used to reduce the traffic on the control link for
   messages that are reasserting previously established state. For
   messages that are reasserting previously established state, the
   switch must always check that this state is correctly established in
   the switch hardware (i.e. the actual connection tables used to
   forward cells).

   If the output branch specified by the Output Port, Output VPI, and
   Output VCI fields for a virtual channel connection; or the output
   branch specified by the Output Port and Output VPI fields for a
   virtual path connection; is already in use by any connection other
   than that specified by the Input Port, Input VPI, and Input VCI
   fields, then the resulting output branch will have multiple input
   branches. If multiple point-to-point connections share the same
   output branch the result will be a multipoint-to-point connection. If
   multiple point-to-multipoint trees share the same output branches the
   result will be a multipoint-to-multipoint connection.

   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields, or the virtual path connection specified
   by the Input Port and Input VPI fields, already exists, and the
   Bidirectional Flag in the Flags field is set, a failure response must
   be returned indicating: "Only point-to-point bidirectional
   connections may be established."

   It should be noted that different switches support multicast in
   different ways. There will be a limit to the total number of point-
   to-multipoint connections any switch can support, and possibly a
   limit on the maximum number of branches that a point-to-multipoint
   connection may specify.  Some switches also impose a limit on the
   number of different VPI/VCI values that may be assigned to the output
   branches of a point-to-multipoint connection. Many switches are
   incapable of supporting more than a single branch of any particular
   point-to-multipoint connection on the same output port. Specific
   failure codes are defined for some of these conditions.

4.2 Delete Tree Message

   The Delete Tree message is a connection management message used to
   delete an entire virtual channel connection or an entire virtual path
   connection. All remaining branches of the connection are deleted. A
   virtual channel connection is specified by the Input Port, Input VPI,
   and Input VCI fields. A virtual path connection is specified by the
   Input Port and Input VPI fields. The Output Port, Output VPI, and
   Output VCI fields are not used in this message. The Delete Tree
   message is:

      Message Type = 18

Top      ToC       Page 24 
   If the Result field of the request message is "AckAll" a success
   response message must be sent upon successful deletion of the
   specified connection. The success message must not be sent until the
   delete operation has been completed and if possible, not until all
   data on the connection, queued for transmission, has been
   transmitted. The Number of Branches field is not used in either the
   request or response messages of the Delete Tree message.

4.3 Verify Tree Message

   The Verify Tree message has been removed from this version of GSMP.
   Its function has been replaced by the Number of Branches field in the
   success response to the Add Branch message which contains the number
   of branches on a virtual channel connection after successful
   completion of an add branch operation.

      Message Type = 19 is reserved.

   If a request message is received with Message Type = 19 a failure
   response must be returned with the Code field indicating: "The
   specified request is not implemented in this version of the
   protocol."

4.4 Delete All Message

   The Delete All message is a connection management message used to
   delete all connections on a switch input port. All connections that
   arrive at the specified input port must be deleted. On completion of
   the operation all dynamically assigned VPI/VCI values for the
   specified port must be unassigned, i.e. there must be no virtual
   connections established in the VPI/VCI space that GSMP controls on
   this port. The Input VPI, Input VCI, Output Port, Output VPI, and
   Output VCI fields are not used in this message.  The Delete All
   message is:

      Message Type = 20

   If the Result field of the request message is "AckAll" a success
   response message must be sent upon completion of the operation. The
   Number of Branches field is not used in either the request or
   response messages of the Delete All message.  The success response
   message must not be sent until the operation has been completed.

   The following failure response messages may be returned to a Delete
   All request.

         The specified request is not implemented on this switch.

Top      ToC       Page 25 
         One or more of the specified ports does not exist.

         Invalid Port Session Number.

   If any field in a Delete All message not covered by the above failure
   codes is invalid, a failure response must be returned indicating:
   "Invalid request message." Else, the delete all operation must be
   completed successfully and a success message returned. No other
   failure messages are permitted.

4.5 Delete Branches Message

   The Delete Branches message is a connection management message used
   to request one or more delete branch operations. Each delete branch
   operation deletes a branch of a virtual channel connection or a
   virtual path connection, or in the case of the last branch of a
   connection, it deletes the connection. The Delete Branches message
   is:

      Message Type = 17

   The request message has the following format:

    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    | Message Type  |    Result     |     Code      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Transaction Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Reserved            |      Number of Elements       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                    Delete Branch Elements                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Number of Elements
             Specifies the number of Delete Branch Elements to follow in
             the message. The number of Delete Branch Elements in a
             Delete Branches message must not cause the packet length to
             exceed the maximum transmission unit defined by the
             encapsulation.

   Each Delete Branch Element specifies an output branch to be deleted
   and has the following structure:

Top      ToC       Page 26 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Port Session Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Input Port                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Error |      Input VPI        |          Input VCI            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Output Port                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x x x x|      Output VPI       |          Output VCI           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Error
             Is used to return a failure code indicating the reason for
             the failure of a specific Delete Branch Element in a Delete
             Branches failure response message.  The Error field is not
             used in the request message and must be set to zero.  A
             value of zero is used to indicate that the delete operation
             specified by this Delete Branch Element was successful.
             Values for the other failure codes are specified in Section
             3.2, "Failure Response Messages."

             All other fields of the Delete Branch Element have the same
             definition as specified for the other connection management
             messages.

   In each Delete Branch Element, either a virtual channel connection is
   specified by the Input Port, Input VPI, and Input VCI fields; or a
   virtual path connection is specified by the Input Port and Input VPI
   fields. The specific branch to be deleted is indicated by the Output
   Port, Output VPI, and Output VCI fields for virtual channel
   connections and by the Output Port and Output VPI for virtual path
   connections.

   If the Result field of the Delete Branches request message is
   "AckAll" a success response message must be sent upon successful
   deletion of the branches specified by all of the Delete Branch
   Elements. The success response message must not be sent until all of
   the delete branch operations have been completed. The success
   response message is only sent if all of the requested delete branch
   operations were successful. No Delete Branch Elements are returned in
   a Delete Branches success response message and the Number of Elements
   field must be set to zero.

   If there is a failure in any of the Delete Branch Elements a Delete
   Branches failure response message must be returned. The Delete
   Branches failure response message is a copy of the request message
   with the Code field of the entire message set to, "Failure specific

Top      ToC       Page 27 
   to the particular message type," and the Error field of each Delete
   Branch Element indicating the result of each requested delete
   operation. A failure in any of the Delete Branch Elements must not
   interfere with the processing of any other Delete Branch Elements.

4.6 Move Branch Message

   The Move Branch message is used to move a branch of an existing
   connection from its current output port VPI/VCI to a new output port
   VPI/VCI in a single atomic transaction. This operation occurs
   frequently in IP switching, every time a flow is switched from hop-
   by-hop forwarding to a dedicated virtual channel.  The Move Branch
   connection management message has the following format for both
   request and response messages:

    0                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    | Message Type  |    Result     |     Code      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Transaction Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Port Session Number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Input Port                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Flags |        Input VPI      |           Input VCI           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Old Output Port                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x x x x|    Old Output VPI     |        Old Output VCI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        New Output Port                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |x x x x|    New Output VPI     |        New Output VCI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Number of Branches      |       Class of Service        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The VCC Move Branch message is a connection management message used
   to move a single output branch of a virtual channel connection from
   its current output port, output VPI, and output VCI, to a new output
   port, output VPI, and output VCI on the same virtual channel
   connection. None of the other output branches are modified.  When the
   operation is complete the original output VPI/VCI on the original
   output port will be deleted from the connection.  The VCC Move Branch
   message is:

Top      ToC       Page 28 
      Message Type = 22

   For the VCC Move Branch message, if the virtual channel connection
   specified by the Input Port, Input VPI, and Input VCI fields already
   exists, and the output branch specified by the Old Output Port, Old
   Output VPI, and Old Output VCI fields exists as a branch on that
   connection, the output branch specified by the New Output Port, New
   Output VPI, and New Output VCI fields is added to the connection and
   the branch specified by the Old Output Port, Old Output VPI, and Old
   Output VCI fields is deleted. If the Result field of the request
   message is "AckAll" a success response message must be sent upon
   successful completion of the operation. The success response message
   must not be sent until the Move Branch operation has been completed.

   For the VCC Move Branch message, if the virtual channel connection
   specified by the Input Port, Input VPI, and Input VCI fields already
   exists, but the output branch specified by the Old Output Port, Old
   Output VPI, and Old Output VCI fields does not exist as a branch on
   that connection, a failure response must be returned with the Code
   field indicating, "The specified branch does not exist."

   The VPC Move Branch message is a connection management message used
   to move a single output branch of a virtual path connection from its
   current output port and output VPI, to a new output port and output
   VPI on the same virtual channel connection. None of the other output
   branches are modified.  When the operation is complete the original
   output VPI on the original output port will be deleted from the
   connection.  The VPC Move Branch message is:

      Message Type = 27

   For the VPC Move Branch message, if the virtual path connection
   specified by the Input Port and Input VPI fields already exists, and
   the output branch specified by the Old Output Port and Old Output VPI
   fields exists as a branch on that connection, the output branch
   specified by the New Output Port and New Output VPI fields is added
   to the connection and the branch specified by the Old Output Port and
   Old Output VPI fields is deleted. If the Result field of the request
   message is "AckAll" a success response message must be sent upon
   successful completion of the operation. The success response message
   must not be sent until the Move Branch operation has been completed.

   For the VPC Move Branch message, if the virtual path connection
   specified by the Input Port and Input VPI fields already exists, but
   the output branch specified by the Old Output Port and Old Output VPI
   fields does not exist as a branch on that connection, a failure
   response must be returned with the Code field indicating, "The
   specified branch does not exist."

Top      ToC       Page 29 
   If the virtual channel connection specified by the Input Port, Input
   VPI, and Input VCI fields; or the virtual path connection specified
   by the Input Port and  Input VPI fields; does not exist, a failure
   response must be returned with the Code field indicating, "The
   specified connection does not exist."

   If the output branch specified by the New Output Port, New Output
   VPI, and New Output VCI fields for a virtual channel connection; or
   the output branch specified by the New Output Port and New Output VPI
   fields for a virtual path connection; is already in use by any
   connection other than that specified by the Input Port, Input VPI,
   and Input VCI fields then the resulting output branch will have
   multiple input branches. If multiple point-to-point connections share
   the same output branch the result will be a multipoint-to-point
   connection. If multiple point-to-multipoint trees share the same
   output branches the result will be a multipoint-to-multipoint
   connection.




(page 29 continued on part 2)

Next RFC Part