Internet Draft
GSMP Working Group                                        Avri Doria
Internet-Draft                             Kenneth Sundell, Ericsson
Expiration Date: August 1999                        17 February 1999

            Addition of Partition Id to the GSMP header

                  <draft-doria-gsmp-partition-id-00.txt>


Status of this Memo

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Copyright Notice

Copyright (C) The Internet Society (1999).  All Rights Reserved.


Abstract
A set of modifications to the GSMP protocol are proposed in order
to allow the GSMP to support partitioning of physical switch
resources into separate virtual switches.

Overview
The use of the GSMP can be expanded by introducing the use of
switch partitions.  One way to do is to allow for multiple
instances of GSMP to run in both the switch and in the
controllers.  A physical switch could be divided into separate
partitions by means of a separate (non GSMP) management interface
according to the policy of the administration that controls the


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switch.  That is, the GSMP would have no involvement in creating
the partitions. Each switch controller that established adjacency
with a switch partition would be limited to control of its
assigned partition(s).

This proposal includes the minimal set of changes that need to be
made to the GSMP to support switch partitions.  Essentially it is
necessary to identify which switch partition GSMP messages belong
to.  Support of partitions can be achieved by making 2 changes to
the protocol.

O Additon of a partition identifier to the standard GSMP message
header.
O Changes to the Adjacency message format.

1.     Addition of a partition identifier to the standard GSMP
 message header
A partition identifier needs to be added to the GSMP message
header that is prepended to all GSMP messages other then the
adjacency message.
An 8 bit field can be cut out of the transaction id to be used for
the partition id.  This would leave 24 bits for the transaction id
which should be enough for most any switch.  It would also allow
for backward compatibility.

 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      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Partition ID |                  Transaction Identifier       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
   ~                    Message Body                 ~
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


2.     Changes to the Adjacency message

2.1  Changes to message format
To support multiple switch partitions, a change also needs to be
made to the adjacency protocol.
Each instance of [switch controller, switch partition] pair will
need to satisfy its own adjacency negotiation and heartbeat.  It
is, therefore, necessary that the partition information should be
exchanged in the adjacency protocol.  In the simplest form, each
controller and partition would only be able to achieve adjacency
if they both used the same pre-set partition id.  On the other
hand, it is often desirable for a switch to assign partitions

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based on the identity of the controller or some other
administrative policy.  And finally, especially in case where
adjacency is being re-established after a fault, the controller
might need to request access to a specific partition.
The following fields need to be added to message 10 to support
switch partitions:

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  |     Timer     |M|   Code      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          Sender Name                          |
+                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                               |                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
|                         Receiver Name                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Partition ID | PType | PFlag |      PCode     |  Unused      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         Sender Port                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                        Receiver Port                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Sender Instance                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                      Receiver Instance                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where:
Partition Id is the Partition Identifier which is either requested
by the Controller or Assigned by the Switch

PType is the type of partition being requested.  In this version
there is only one type:
   1 Fixed Partition

PFlag would be used to indicate whether this is a request
occurring after a fault or a new request.  This flag indicates
that switch state should not be reset after synchronization.
    1 New Adjacency
    2 Recovered Adjacency
        (other flags TBD if needed)

PCode would indicate the type of request:
   1 Partition ID request from controller
   2 Partition ID assigned by switch
   3 Partition Unavailable ­ Response sent by switch when
partition requested by controller is unavailable.
      (other codes TBD if needed)




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2.2  Changes to the Loss of Synchronization section
The section of Loss of Synchronization should be changed to read
as follows:

If after synchronisation is achieved, no valid GSMP messages are
received in any period of time in excess of three times the value
of the Timer field announced in the incoming adjacency protocol
messages, loss of synchronization may be declared.

The preferred procedure for a switch to use when it looses
synchronisation with its active controller is to attempt to
establish synchronization with (one of) its backup controller(s).
However, in this preferred approach, it must not reset its state
until it achieves synchronization with a backup controller. This
means that if, before achieving synchronization with a backup
controller, it regains synchronization with its original
controller and PFlag is set, it may continue the original session
(and cease attempting to establish synchronization with a backup
controller). If synchronisation with the original session is
regained it is the responsibility of the controller to ensure
consistent state between the switch and controller.

Additionally if the PFlag is set, and a redundant controller
establishes synchronization, then the switch may continue the
original session.  If synchronization with the original session is
regained it is the  responsibility of the redundant controller to
ensure consistent state between the switch and controller.

2.3  Changes to Adjacency State Table
Additionally, the adjacency state tables in the GSMP would need to
be changed so that  wherever the Peer Identifier was either set or
checked, the TransactionId would be checked as well. That is, the
tests in the GSMP V2 specification[Newman98] would need to be
changed to the following:

O The state tables use the following Boolean terms and operators:

     a)  The Sender Instance in the incoming message matches the
        value stored from a previous message by the "Update Peer
        Verifier" operation.

     b)  The Sender Instance, Sender Port, Sender Name and Sender
        Partition ID fields in the incoming message match the
        values stored from a previous message by the "Update Peer
        Verifier" operation.

     c)  The Receiver Instance, Receiver Port, Receiver Name and
        Receiver Partition ID fields in the incoming message match
        the values of the Sender Instance, Sender Port, Sender
        Name and Sender Partition ID currently sent in outgoing
        SYN, SYNACK, and ACK messages.


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References

Newman, P, Edwards, W., Hinden, R., Hoffman, E. Ching Liaw, F.,
Lyon, T. and Minshall, G., "Ipsilon's General Switch Management
Protocol Specification," Version 1.1, RFC 1987, August 1996.

Newman, P, Edwards, W., Hinden, R., Hoffman, E., Ching Liaw, F.,
Lyon, T. and Minshall, G., "Ipsilon's General Switch Management
Protocol Specification," Version 2.0, RFC 2397, March 1998.


Authors' Contact

Avri Doria
+1 401 458 2490
avri@apocalypse.org

Kenneth Sundell
+46 8719 9880
etxkens@etxb.ericsson.com



























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