rfc1987.txt

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Network Working Group                                P. Newman, Ipsilon
Request for Comments: 1987                           W. Edwards, Sprint
Category: Informational                              R. Hinden, Ipsilon
                                                    E. Hoffman, Ipsilon
                                                 F. Ching Liaw, Ipsilon
                                                       T. Lyon, Ipsilon
                                                   G. Minshall, Ipsilon
                                                            August 1996



       Ipsilon's General Switch Management Protocol Specification
                              Version 1.1





Status of this Memo

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


Abstract

   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 point-to-multipoint connection; manage switch ports;
   request configuration information; and request statistics.



















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Table of Contents

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

   2. GSMP Packet Format..............................................4

   3. Connection Management Messages..................................7
      3.1 Add Branch Message.........................................11
      3.2 Delete Branch Message......................................12
      3.3 Delete Tree Message........................................13
      3.4 Verify Tree Message........................................13
      3.5 Delete All Message.........................................14
      3.6 Move Branch Message........................................14

   4. Port Management Message........................................16

   5. Statistics Messages............................................20
      5.1 VC Activity Message........................................20
      5.2 Port and VC Statistics Messages............................23
          5.2.1 Port Statistics Message..............................26
          5.2.2 VC Statistics Message................................26

   6. Configuration..................................................26
      6.1 Switch Configuration Message...............................27
      6.2 Port Configuration Message.................................28
      6.3 All Ports Configuration Message............................32

   7. Event Messages.................................................33
      7.1 Port Up Message............................................35
      7.2 Port Down Message..........................................35
      7.3 Invalid VPI/VCI Message....................................35
      7.4 New Port Message...........................................35
      7.5 Dead Port Message..........................................36

   8. Adjacency Protocol.............................................36
      8.1 Packet Format..............................................36
      8.2 Procedure..................................................39

   9. Failure Response Messages......................................41

   References........................................................43
   Security Considerations...........................................43
   Authors' Addresses................................................43








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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 point-to-multipoint 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. 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
   channels at an input port. ATM cells depart from the switch to an
   external communication link on outgoing virtual channels from an
   output port. Virtual channels on a port or link are referenced by
   their virtual path and virtual channel identifiers (VPI/VCI). 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.

   In general a virtual channel is established with a certain quality of
   service (QOS). Unfortunately this is an ill defined and changing
   concept as new ideas make their way into hardware. For this version
   of the GSMP protocol it is assumed that each virtual channel
   connection may be assigned a priority when it is established. It may
   be assumed that for 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 port of the switch
   supports may be obtained from the port configuration message.

   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 sub-fields that have meaning to the physical structure of
   the switch (e.g. shelf, slot, port). In general, a port in the same
   physical location on the switch will always have the same port



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   number, even across power cycles. The internal structure of the port
   number is opaque to the GSMP protocol. However, by looking up the
   product identity in a database, network management tools may discover
   the partitioning of the port number and the physical meaning of the
   sub-fields.

   Each switch port also maintains a port session number assigned by the
   switch. A connection management message or a port management message
   with an incorrect port session number must be rejected.  This allows
   the controller to detect a link failure and to keep state
   synchronized. 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, its port session number will have
   changed.  Port session numbers should be assigned using some form of
   random number.

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


2. GSMP Packet Format

   GSMP packets are variable length and are encapsulated directly in an
   AAL-5 CPCS-PDU [I.363] with an LLC/SNAP header 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               LLC (0xAA-AA-03)                |               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
   |                   SNAP (0x00-00-00-88-0C)                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         GSMP Message                          ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Pad (0 - 47 octets)                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +               AAL-5 CPCS-PDU Trailer (8 octets)               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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   (The convention in the documentation of Internet Protocols [rfc1700]
   is to express numbers in decimal and to picture data 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.

   The maximum transmission unit (MTU) of the GSMP message is 1500
   octets.

   The default virtual channel for LLC/SNAP encapsulated messages is:

      VPI = 0
      VCI = 15.

   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
   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 four classes of GSMP
   request-response message: Connection Management, Port Management,
   Statistics, and Configuration. 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.

   Except for the adjacency protocol message, no GSMP messages may be
   sent across the link until the adjacency protocol has achieved