Description: An entry in the ATM VC Cross Connect table. This entry is used to model a bi-directional ATM VC cross-connect cross-connecting two end points.

Step-wise Procedures to set up a VC Cross-connect

Once the entries in the pxmAtmVclTable are created, the following procedures are used to cross-connect the VCLs together to form a VCC segment.

(1) The manager obtains a unique pxmAtmVcCrossConnectIndex by reading the pxmAtmVcCrossConnectIndexNext object.

(2) Next, the manager creates a set of one or more rows in the ATM VC Cross Connect Table, one for each cross-connection between two VCLs. Each row is indexed by the ATM interface port numbers and VPI/VCI values of the two ends of that cross-connection. This set of rows specifies the topology of the VCC cross-connect and is identified by a single value of pxmAtmVcCrossConnectIndex.

Negotiated VC Cross-Connect Establishment

(2a) The manager creates a row in this table by setting pxmAtmVcCrossConnectRowStatus to createAndWait(5). The agent checks the requested topology and the mutual sanity of the ATM traffic parameters and QoS Classes, i.e., the row creation fails if: - the requested topology is not supported by the agent, - the traffic/QoS parameter values associated with the requested row are incompatible with those of already existing rows for this VC cross-connect. [For example, for setting up a point-to-point VC cross-connect, the ATM traffic parameters in the receive direction of a VCL at the low end of the cross-connect must equal to the traffic parameters in the transmit direction of the other VCL at the high end of the cross-connect, otherwise, the row creation fails.] The agent also checks for internal errors in building the cross-connect.

The pxmAtmVcCrossConnectIndex values in the corresponding pxmAtmVclTable rows are filled in by the agent at this point.

(2b) The manager promotes the row in the pxmAtmVcCrossConnectTable by setting pxmAtmVcCrossConnectRowStatus to active(1). If this set is successful, the agent has reserved the resources specified by the ATM traffic parameter and QoS Class values for each direction of the VC cross-connect in an ATM switch or network.

(3) The manager sets the pxmAtmVcCrossConnectAdminStatus to up(1) in all rows of this VC cross-connect to turn the traffic flow on.

One-Shot VC Cross-Connect Establishment

A VC cross-connect may also be established in one step by a set-request with all necessary parameter values and pxmAtmVcCrossConnectRowStatus set to createAndGo(4).

In contrast to the negotiated VC cross-connect establishment which allows for detailed error checking i.e., set errors are explicitly linked to particular resource acquisition failures), the one-shot VC cross-connect establishment performs the setup on one operation but does not have the advantage of step-wise error checking.

VC Cross-Connect Retirement

A VC cross-connect identified by a particular value of pxmAtmVcCrossConnectIndex is released by:

(1) Setting pxmAtmVcCrossConnectRowStatus of all rows identified by this value of pxmAtmVcCrossConnectIndex to destroy(6). The agent may release all associated resources, and the pxmAtmVcCrossConnectIndex values in the corresponding pxmAtmVclTable row are removed. Note that a situation when only a subset of the associated rows are deleted corresponds to a VC topology change.

(2) After deletion of the appropriate pxmAtmVcCrossConnectEntries, the manager may set pxmAtmVclRowStatus to destroy(6) the associated VCLs. The agent releases the resources and removes the associated rows in the pxmAtmVclTable.

VC Cross-Connect Reconfiguration

At the discretion of the agent, a VC cross-connect may be reconfigured by adding and/or deleting leafs to/from the VC topology as per the VC cross-connect establishment/retirement procedures. Reconfiguration of traffic/QoS parameter values requires release of the VC cross-connect before those parameter values may by changed for individual VCLs.