Avaya Configuring DLSw Services User Manual download pdf (Page 219)

Using DLSw Prioritization

303523-A Rev. 00

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Tuning DLSw Protocol Prioritization

This section explains how congestion control and queue depth affect DLSw

prioritization results for your network. The sections “Customizing the Default

Queue Configuration” and “Customizing Specific DLSw Peer Queues,” later in

this chapter, show how to use Configuration Manager to configure these values.

DLSw Priority Queues and Congestion Control

Because the router cannot clip DLSw traffic without breaking the DLSw session,

DLSw protocol prioritization includes an internal congestion control feature to:

• Temporarily save overflow packets in memory until the appropriate priority

queue can handle them

• Notify DLSw to stop and start the flow of packets

There must be sufficient memory available for congestion control to prevent

clipping. The less the congestion, the better the queue performance.

Queue Depth

Using Site Manager parameters, you configure the maximum queue buffers and

the percentage of bandwidth for each queue.

Queue depth is the configurable number of packets that each DLSw priority queue

can hold. The default value is 50 packets, regardless of packet size.

When you set the queue depth, you assign buffers that hold the packets in the

DLSw queues. To determine whether there are enough buffers for the DLSw

traffic flow on your network, examine the following protocol prioritization

statistics that the router keeps for each DLSw priority queue:

• DLSw HiWater Packets Mark -- The greatest number of packets that have

been in each queue.

• DLSw Congestion Control Count -- The number of packets that the router has

discarded from each queue. The router discards packets from full priority

queues.

Generally, if a queue’s Congestion Control Count is high, and its HiWater Packets

Mark is close to or equal to its queue depth, you have not assigned enough buffers

to that queue.

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Avaya Configuring DLSw Services User Manual Page 219