Subject: (FRNETMIB) A Cross-Connect Model for the FR/ATM PVC Service IWF MIB

From: "Ken Rehbehn" <[email-masked]>
Date: Mon, 24 May 1999 00:22:23 -0400

The next draft is being prepared for the FR/ATM PVC IWF MIB.  In this
draft, we must deal with the open issue of how this cross-connect MIB
is utilized by the RFC 1604 and RFC 2515 technology-specific MIBs
(TSM).

This is a proposal Orly and I have produced for dealing with the
problem.

Each TSM has a table of PVC endpoints (indexed by ifIndex and logical
link address (DLCI or VPI/VCI).  Typically, two endpoints are
cross-connected via a technology-specific cross connect table.  The
introduction of the FR/ATM MIB creates the need to have multiple
cross-connect tables.  As an example, an ATM PVC endpoint might be
connected to either:

    1) another ATM PVC endpoint via the atmVcCrossConnectTable, or

    2) a frame relay PVC endpoint via the frAtmIwfConnectionTable.

This issue is not restricted to the case of frame relay to ATM
interworking.  An implementation supporting the ATM Forum Circuit
Emulation Service (CES) is another example of an ATM VPI/VCI that is
not cross-connected via the atmVcCrossConnectTable.

Currently, the implicit assumption is made that all PVC endpoints are
cross-connected via a single cross-connect table.  To change this
restriction, one new object is required for each PVC endpoint rows, in
both the ATM and Frame Relay Service MIBs. The object (named
xxxIwfKind, where xxx == atmVcl or frPVC) serves to identify the
cross-connect table associated with the PVC endpoint.  I propose that
use of an OID value that matches the OID of the IWF MIB cross-connect
table that applies (e.g., (1.3.6.1.2.1.10.45.1.2) for the FR/ATM IWF
MIB frAtmIwfConnectionTable (assumes the FR/ATM PVC IWF MIB will be
planted at { transmission 45 }).  A value of zero (or noSuchObject)
indicates cross-connection via the technology-specific cross-connect
table.  Such an approach readily supports standards-based and
vendor-specific cross-connects.

Each TSM contains an existing object that contains an index into the
cross-connect table.  In the case of the ATM MIB, the cross-connect
index might point into one of several cross-connect tables.  I propose
we use these existing cross-connect objects to contain the index into
the FR/ATM MIB cross-connect table.

The ATM MIB has an object called AtmConnKind.  It enumerates a number of
different connection cases and, as a side-effect, points to the correct
cross-connection table.  We should consider adding an enumeration to this
list for generic IWF cross-connection where the actual cross-connection
table is identified in the atmVclIwfKind object.

The example at the end of this email shows how a frame relay PVC
endpoint is cross-connected to an ATM PVC endpoint.  The AtmConnKind object
is ignored in this example.

Review and comments are needed.

Cheers,
Ken Rehbehn

---------------------------------------------------------------
Ken Rehbehn                              Phone: +1-301-296-2325
Visual Networks                            Fax: +1-301-296-2302
2092 Gaither Rd                EMail: [email-masked]
Rockville, MD  20850              http://www.visualnetworks.com

== == == == == ==  == == == == == == == == == == == == == == == ==

Example Cross-Connect using the FR/ATM PVC IWF MIB
--------------------------------------------------

ASSUMPTIONS:

    o  Frame Relay PVC is DLCI 16 on ifIndex 123

    o  ATM PVC is VPI.VCI 45.98 on ifIndex 987

    o  The FR/ATM IWF MIB OID root is assigned by IANA to
       { transmission 45}

    o  All xxxAdminStatus objects reflect an "up" status

    o  No errors in activation for any PVC segment so that
    xxxOperStatus can reflect an "active" status

Step 1 - Create the frame relay PVC endpoint

a)  Agent receives management request to create a row in
frPVCEndptTable for the frame side

b)  system creates the row in frPVCEndptTable with the following
defaults:

    -  initialize frPVCEndptConnectIdentifier to zero

    -  initialize frPVCIWFKind to 0.0

    -  initialize the remaining columns as needed for DLCI 16
    on ifIndex 123

Step 2 - Create the ATM PVC endpoint

a)  agent receives management request to create a row in atmVclTable
for the ATM side

b)  system creates the row in atmVclTable with the following defaults:

    - initialize atmVclCrossConnectIdentifier to zero

    - initialize atmVclIWFKind to 0.0

    - initialize the remaining columns as needed for VPI.VCI
    45.98 on ifIndex 987

Step 3 - Create the FR/ATM cross-connect

a)  manager requests a new cross-connect index value by reading
frAtmIwfConnectionIndexNext from the agent

b)  agent receives GET request for frAtmIwfConnectionIndexNext
and responds with the next available value (9901 - Hey, its a big
switch)

c)  manager requests a new cross-connect row entry using the value
9901 as the index

d)  agent receives SET request to create the frAtmIwfConnectionTable
row entry (note:  the frame relay and ATM PVC endpoints MUST exist and
be specified as part of the index fields for the row)

e)  system creates a row in frAtmIwfConnectionTable for the following
indices:

    - frAtmIwfConnectionIndex of 9901

    - frAtmIwfConnAtmPort of 987

    - frAtmIwfConnVpi of 45

    - frAtmIwfConnVci of 98

    - frAtmIwfConnFrPort of 123

    - frAtmIwfConnDlci of 16

f)  system establishes the appropriate connection descriptor for the
IWF (specified by manager in the SET for the row) and assigns it to
frAtmIwfcOnnectionDescriptorIdx

Step 4 - Point the frame relay PVC endpoint row to the FR/ATM
cross-connect row (Note:  The system may perform these actions as a
side-effect of Step 3)

a)  system sets frPVCEndptConnectIdentifier to 9901

b)  system sets frPVCIWFKind to (1.3.6.1.2.1.10.45.1.2) to point to
the FR/ATM
PVC IWF cross-connect table

Step 5 - Point the ATM PVC endpoint row to the FR/ATM cross-connect
row (Note:  The system may perform these actions as a side-effect of
Step 3)

a)  system sets atmVclCrossConnectIdentifier to 9901

b)  system sets atmVclIWFKind to (1.3.6.1.2.1.10.45.1.2)

Step 6 - Manager signals activation by issuing a SET for the
frAtmIwfConnAdminStatus object using the value of "up"

Step 7 - Agent receives SET request for frAtmIwfConnAdminStatus and
executes internal system mechanisms to activate each PVC segment and
the IWF cross-connect.  The successful activation permits the agent to
respond with "active" when a GET request is received for the following
fields:

    - frAtmIwfConnAtm2FrOperStatus

    - frAtmIwfConnFr2AtmOperStatus

    - atmVclOperStatus (Note: there is no comparable FRS MIB object)

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