Avaya Configuring DLSw Services User Manual download pdf (Page 216)

Configuring DLSw Services

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303523-A Rev. 00

The router holds packets in the assigned priority queue according to how you

configure DLSw protocol prioritization.

Based on the needs of your site, you can configure up to ten queues (Q0 to Q9) for

each DLSw peer. For example, you can assign a separate queue for each filter

criterion, for specific address ranges, or for particular DLSw peers.

When you enable DLSw protocol prioritization, you distribute the available

bandwidth for a configured DLSw peer among its priority queues. The combined

bandwidth of each peer’s queues totals 100 percent.

By default, there are two DLSw priority queues: Q0 receives 60 percent of the

bandwidth and Q1 receives 40 percent.

Nonordered Queues

Although Site Manager numbers the DLSw priority queues, the queue number

hierarchy does not determine priority. You configure both the number of queues

for each DLSw peer and the percentage of bandwidth assigned to each queue. For

example, you can assign 50 percent of available bandwidth to Q3 and 25 percent

each to Q1 and Q0.

The Dequeuing Process

The algorithm for DLSw bandwidth allocation is called weighted dequeuing. With

weighted dequeuing, packets at the front of the protocol prioritization queues

enter a dequeue list and receive a weighted score. Packets with the lowest score

are transmitted first.

By distributing the selection of packets from all queues, weighted dequeuing is

more stable than the algorithms used for circuit-level WAN protocol prioritization.

One goal of weighted dequeuing is to send smaller packets ahead of large packets,

without violating the bandwidth of each queue or depriving large packets. The

algorithm accomplishes this by putting smaller packets ahead of larger packets by

simultaneously considering how long the larger packets have been in the dequeue

list. A large packet accumulates credit (lowering its weighted score) as each

smaller packet gets ahead of it, and eventually the larger packet moves to the front

of the dequeue list.

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Avaya Configuring DLSw Services User Manual Page 216