Avaya Configuring Data Compression Services Manuel d'utilisateur télécharger pdf (Page 40)

Configuring Data Compression Services

2-10

117352-D Rev. 00

CCP Negotiations

CCP allows the two ends of a PPP connection to negotiate whether to use data

compression and, if so, which algorithm to use. Both WCP and Hi/fn LZS use

CCP to negotiate compression.

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 Hi/fn 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, see

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. You can edit WCP parameters

for compression mode, history size, and buffer size to optimize compression

performance on your network (see “Allocating Compression Memory for WCP

”

on page 3-2

Note:

If one side of a link requests an algorithm that the other side does not

support, traffic over the link continues, but in uncompressed form.

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Avaya Configuring Data Compression Services Manuel d'utilisateur Page 40