Operation Manual

Remote Access with NetWAYS/ISDN
20 NetWAYS/ISDN – 3 Remote Access with NetWAYS/ISDN
3 Remote Access with
NetWAYS/ISDN
This chapter explains the basic principles of NetWAYS/ISDN,
and provides detailed information about the features, func-
tions and configuration options.
For complete information about individual commands and
parameters, see the Online Help.
3.1 Throughput Optimization
Each ISDN B channel permits data throughput of 64 kilobits
per second. Because many applications today demand higher
throughput, NetWAYS/ISDN incorporates two efficient com-
pression techniques to make optimum use of the available
bandwidth: header compression and payload data
compression. In ADSL Internet access, data communication
takes place at up to 6 Mbit/s downstream (that is, from the In-
ternet to the user) and up to 640 kbit/s upstream.
Header Compression
Every data packet in network communication has a header
which contains the source and destination addresses. By
compressing this header NetWAYS/ISDN increases the
throughput rate enormously, especially when packet sizes
are small. IPX headers can be compressed from 36 bytes to
as little as 2 bytes. TCP/IP headers can be compressed from
40 bytes to three.
Data Compression
The payload data of the packet can also be compressed for
transmission. NetWAYS/ISDN uses the data compression
standards V.42bis, Stac LZS (RFC 1974) and MPPC (RFC 2118).
These techniques achieve compression ratios of up to 8 to 1,
depending on the data content.
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