Avaya Configuring WAN Lines Services Instrukcja Użytkownika Pobierz pdf (Strona 148)

Configuring WAN Line Services

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308648-14.00 Rev 00

Setting Buffer Credits for MCE1

The BCC uses the Transmit Buffer Use Credits, Receive Buffer Use Credits,

Transmit Queue Length, and Receive Queue Length parameters to regulate

performance of the multichannel T1 and E1 device drivers.

The device driver software allocates frame buffers to all logical lines evenly;

however, the software will allocate more buffers to some logical lines temporarily

to absorb a short burst of traffic without dropping frames. The device driver

software accounts for most network scenarios by default and offers the highest

level of service possible given the amount of global packet buffer memory

available to it. However, not all networks are the same. You can use the buffer use

credit and queue length parameters to customize the relative priority between

logical lines.

Nortel Networks recommends that you do not change the default settings of these

parameters, however, without careful consideration of the traffic flow in and out of

the T1/E1 logical lines.

One reason you might want to change the default settings of these parameters is to

change the relative priority of some logical lines over others. If, for example, you

notice a high incidence of transmit drop frames due to transmit clipping, there are

several approaches you can take.

The first approach is to use priority queuing on each logical line to prioritize

traffic. Or, you can upgrade the routing engine to the maximum memory allotment

and increase the global buffer memory to 16 megabytes.

If transmit clip frames persist and you want to prioritize logical lines, you can set

the Transmit Queue Length parameter to a value approximately 25% higher than

the value of your most critical logical lines. See “

Setting the Transmit Queue

Length” on page 7-50 for more information.

Note:

These parameters are not supported on the ASN.

Caution:

You can affect router performance severely by over-allocating buffer

credits.

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Avaya Configuring WAN Lines Services Instrukcja Użytkownika Strona 148