Avaya Configuring Data Compression Services Manuel d'utilisateur télécharger pdf (Page 54)

Configuring Data Compression Services

3-4

117352-E Rev 00

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. When you make this choice, be aware that you are allocating more

memory than the History Size parameter value indicates.

Table 3-1

lists the amount of memory required for 8 KB and 32 KB history sizes.

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.

Hardware compression has similar requirements (see “History Size with

Hardware Compression” on page 3-5).

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 conserve memory for 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 also 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.

Table 3-1. Memory Allocation for Software Compression History

Memory Requirements 8 KB History Size 32 KB History Size

Compression history 8 KB 32 KB

Lookup table 16 KB 64 KB

Decompression history 8 KB 32 KB

Total memory required 32 KB 128 KB

1 2 ... 49 50 51 52 53 54 55 56 57 58 59 ... 107 108

Pas de commentaire

Avaya Configuring Data Compression Services Manuel d'utilisateur Page 54