Cisco Systems 8600 Series manual ATM Connection Requirements, ForeSight Congestion Control

ATM Connection Requirements

Figure 7-2 ABR VSVD Flow Control Diagram

Forward flow data cells

Source

Node	Node	Node
			Destination
NE	NE	NE

Forward RM cells

RM cell control loop for forward flow data

Backward RM cells

Only the flows for forward data cells and their associated RM cell control loop are shown in this diagram. The flows for backward flow data cells (destination to source) and their associated RM cell control loop are just the opposite of that shown for the forward flow data cells.

NE = Network element

S6156

ForeSight Congestion Control

ForeSight may be used for congestion control across BPX/IGX/IPX switches for connections that have one or both end points terminating on ASI-T3/E3 or BXM cards. The ForeSight feature is a proprietary dynamic closed-loop, rate-based, congestion management feature that yields bandwidth savings compared to non-ForeSight equipped trunks when transmitting bursty data across cell-based networks. The BXM cards also support the VSVD congestion control mechanism as specified in the ATM Traffic Management 4.0 standards.

ATM Connection Requirements

There are two connection addressing modes supported. The user may enter a unique VPI/VCI address in which case the BPX switch functions as a virtual circuit switch. Or the user may enter only a VPI address in which case all circuits are switched to the same destination port and the BPX switch functions as a virtual path switch in this case. The full ATM address range for VPI and VCI is supported.Virtual Path Connections are identified by an * in the VCI field. Virtual Circuit Connections specify both the VPI and VCI fields.

The VPI and VCI fields have significance only to the local BPX switch, and are translated by tables in the BPX switch to route the connection. Connections are automatically routed by the AutoRoute feature once the connection endpoints are specified.

ATM connections can be added using either the Cisco StrataView Plus Connection Manager or a node’s command line interface (CLI). Typically, the Cisco StrataView Plus Connection Manager is the preferred method as it has an easy to use GUI interface. The CLI may be the method of choice in some special cases or during initial node setup for local nodes.

ATM Connections 7-5