Avaya Configuring Frame Relay Services Bedienungsanleitung PDF herunterladen (Seite 61)

Frame Relay Overview

117376-C Rev. 00

2-31

Using Traffic Shaping with Data Compression

Traffic shaping occurs at the VC level; compression, at the driver level. Shaping

therefore occurs before compression, which compromises effective compression

because only the precompressed traffic is shaped: the compressed traffic is not

shaped. WCP compresses data at the rate it receives it, which with traffic shaping

is the CIR. It is therefore unrealistic to expect a high compression throughput for

data that originates from a site that also uses traffic shaping.

Using Traffic Shaping Effectively

You can use traffic shaping at one or both ends of a link, but you must use

compression at both ends of a link. It makes sense to use traffic shaping at a

central site, where you have a T1 line that sends data to remote sites with 64 KB

line rates, and the goal is to control the flow of traffic and avoid flooding the

remote sites. But if the CIR is equal to the line rate, which could well be the case

at the remote site with 64 KB line rates, there is no need to use traffic shaping.

Using Compression Effectively

You can use compression effectively in the case of the 64 KB site which does not

use traffic shaping. You can also compensate for the throughput cost associated

with using compression and traffic shaping at the central site by taking into

account characteristics of compression and traffic shaping, and fine-tuning traffic

shaping parameters.

• When you configure traffic shaping, take into account the compression ratio

you want to achieve.

• If you set the B

equal to the B

, the router doubles the amount of traffic it

attempts to send and, when you enable compression, compresses that amount

of traffic, because WCP compresses data at the rate it receives it.

• If you also set the Congestion Method parameter to throttle, the router will

queue traffic if congestion occurs, and thus prevent exceeding the CIR.

• Congestion may occur if compression histories are not in sync, and WCP has

to resend packets. If WCP retransmits many packets, it may exceed the CIR.

1 2 ... 56 57 58 59 60 61 62 63 64 65 66 ... 239 240

Keine Kommentare

Avaya Configuring Frame Relay Services Bedienungsanleitung Seite 61