Cisco Systems 8600 Series manual Traffic Shaping for CBR, VBR, and UBR, Configuration

Traffic Shaping for CBR, VBR, and UBR

Traffic Shaping for CBR, VBR, and UBR

With the introduction of traffic shaping for CBR, VBR, and UBR, the user has the option to provide traffic shaping for these connections types on the BXM. Previously, only ABR utilized traffic shaping. Traffic shaping involves passing CBR, VBR, or UBR traffic streams through VC queues for scheduled rate shaping.

Traffic shaping is performed on a per port basis. When traffic shaping is enabled, all traffic exiting the port (out to the network) is subject to VC scheduling based on the parameters configured by the user for the connection.

Figure 7-22shows an example of traffic shaping. In this example, port 1 is configured to perform traffic shaping. Note that all the ATM cells regardless of class of service pass through the VC queues before leaving the card when traffic shaping is enabled. In the example, port 2 is not configured for traffic shaping, and only the ABR traffic with FCES (flow control external segment) passes through the VC queues.

Figure 7-22 Traffic Shaping Example

Traffic shaping enabled

Port 1

CBR Qbin

VBR Qbin

ABR/UBR Qbin

VC queues

CBR

VBR

UBR

ABR

No traffic shaping

Port 2

ABR/UBR Qbin

VBR Qbin

CBR Qbin

ABR

ABR (with FCES)

UBR

VBR

CBR 12150

Configuration

Traffic shaping is disabled by default. The cnfport command is used to enable and disable the function on a per port basis. No connections should be enabled on the port prior to changing the port traffic shaping parameter. If there are existing connections when the port is toggled, then these connections will not be updated unless the card is reset, connections are rerouted, a switchcc occurs, or the user modifies the connection parameters.

ATM Connections 7-37