Avaya Configuring Data Compression Services Bedienungsanleitung PDF herunterladen (Seite 40)

Configuring Data Compression Services

3-2 114061 Rev. A

If either side of the link speciﬁes PPC, both sides of the link use PPC.

Maximizing Throughput

Each side of the link has both a compression and decompression history and a

lookup table. The compression and decompression histories maintain a record of

data that has already traveled across the network. The lookup tables maintain

pointers to redundant strings and the offset and length tokens that replace each of

those strings.

You can specify either 8 KB or 32 KB of local memory to maintain a compression

history.

If the link uses software compression with a history of 8 KB, each end of the link

allocates 8 KB of memory for compression, 16 KB for the compression lookup

table, and 8 KB for decompression, or 32 KB. If the link uses a compression

history of 32 KB, each end of the link allocates 32 KB of memory for

compression, 64 KB for the compression lookup table, and 32 KB for

decompression, for a total of 128 KB. Hardware compression entails similar

requirements.

If you select different values for history size for the two sides of the link, 8 KB

becomes the history size for both sides of the link.

8 KB History Size

In general, 8 KB histories are appropriate for Frame Relay and X.25, when you

have large numbers of VCs and need to be conservative when you allocate

memory to each of them.

32 KB History Size

For PPP, with only one circuit per line, you may want to use a 32 KB history.

You may want to allocate a 32 KB history size for links with speeds higher than

64 Kb/s to improve throughput. The compressor can ﬁnd a data pattern match up

to three times faster using a 32 KB history than an 8 KB history.

Site Manager: Compression Mode parameter: page A-2 (line); page A-6 (circuit interface)

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Avaya Configuring Data Compression Services Bedienungsanleitung Seite 40