Avaya Configuring Data Compression Services Manual de usuario descargar pdf (Pagina 37)

Data Compression Overview

117352-B Rev. 00

2-9

In Figure 2-1, negotiations begin when PPP establishes a link. CCP uses the same

configuration and network control protocol negotiations that the Link Control

Protocol (LCP) uses to establish a link.

For Stac LZS, CCP also provides the following:

• History reset request messages

• Request acknowledgment messages

These messages help to synchronize the receipt and transmission of the

compression and decompression history after a packet is lost. WCP does not use

these messages.

For an explanation of LCP negotiations, refer to Configuring PPP Services.

WCP Negotiations

WCP allows two ends of a PPP, frame relay, or X.25 connection to negotiate

compression.

Frame relay and X.25 use WCP to negotiate whether to use data compression, and

which algorithm to use. (PPP uses CCP and WCP to negotiate this information.)

As with PPP, if one side of a link requests an algorithm that the other side does not

support, traffic continues, but in uncompressed form. All three WAN protocols use

WCP to negotiate options such as compression mode, history size, and buffer size.

Each side of a link running data compression has a compressor, a decompressor, a

compression history, and a retransmission buffer. When you configure

compression, you can edit WCP parameters for compression mode, history size,

and buffer size to optimize compression performance on your network.

Data Transmission

For PPP links using WCP, Network Control Protocol (NCP) negotiations and

WCP negotiations occur simultaneously. When PPP, NCP, and WCP negotiations

are complete, data transmission using compression begins.

For PPP links using Stac LZS, data transmission using compression begins when

CCP and NCP negotiations are complete.

For frame relay and X.25 links, data transmission using compression begins when

WCP negotiations are complete.

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Avaya Configuring Data Compression Services Manual de usuario Pagina 37