Configuring Data Compression Settings 135Data Compression TablesA Data Compression Table describes a table of values assigned for eachcharacter during a call using data compression techniques. The defaultvalues in the table are constantly being changed to ensure the mostefficient throughput possible. Each table uses a dictionary to assign thesevalues.Dictionary size is the amount of memory available for data compressiontable entries. Entries into the table are codes devised for redundant data.Then data is packed into these shorter data units, called code words, andunpacked by the receiving device. Possible dictionary sizes are in Table 30.Table 30 Dictionary SizesThe RAS 1500 uses an 11-bit, or 2048-entry dictionary, but can reduce itssize to accommodate a remote modem that uses a 9- or 10-bit dictionary.As the dictionary fills, the RAS 1500 deletes the oldest unused strings.Configuring Data CompressionThe MNP level 5 Disabled setting allows V.42 compression only (for usewhen transferring compressed files). MNP-5 compression is not usefulwhen transferring files that are already compressed because it tends toadd data to the transmission so that throughput over the link degrades.Table 31 shows the commands used to configure data compressionmethods:Table 31 Data Compression CommandsBits Entries9 51210 102411 2048Action CommandDisable compression AT&K0Auto Enable compression AT&K1 (Default)Enable compression AT&K2MNP Level 5 Disabled AT&K3
