Intel ER8100STUS - Express 8100 Router, Reference Manual

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Reference.bok : Chapter02 11 Wed Apr 22 10:58:08 1998
11
Point-to-Point Protocol (PPP)
Leased Lines Links
Multilink PPP
The Intel Express 8100 Router implements PPP Multilink facilities which allow
multiple PPP links between two sites to be used as a single route. A PPP Multi-
link allows links to added dynamically (for bandwidth-on-demand) or statically
and has almost the combined bandwidth of the individual links.
PPP Multilinks are described in Chapter 6 “PPP Multilinks”, p. 39 .
Data Compression
Data compression
Data compression is available when communicating over PPP links, to improve
the throughput.
Both routers over the PPP link must support and be configured for PPP data com-
pression for data compression to be used.
Compression algorithm
used
The compression algorithm implemented in the Intel Express 8100 Router is
based on the Stac* algorithm developed by Stac Electronics Inc. Typical com-
pression rates of 4:1 are achieved for text data.
Requirements for use
The devices at both end of the PPP link must implement the Compression Con-
trol Protocol (CCP) and use the same compression algorithm.
Data compression is negotiated by the CCP whenever the link is established. If
the device over the PPP link does not support the CCP or the same compression
algorithm, compression cannot be used over the link.
Link speeds
Data compression can be used on combined link speeds of up to 256 kbps (for
example compression can be used on one PPP link of 256 kbps or on two PPP
links of 128 kbps). The delays involved with compressing the data make it im-
practical to use at higher link speeds.
Data Encryption
Introduction
The Intel Express 8100 Router offers encryption/decryption of data being trans-
mitted over PPP and Frame Relay links. This offers security in case of intercep-
tion by an unauthorized source.
Note
Data encryption is only available in certain models of the Intel Express
8100 Router which are not available in some countries.
Encryption algorithm
used
The data encryption algorithm implemented in the Intel Express 8100 Router is
Blowfish with a variable length encryption key (up to 144 bits) with 16 rounds
(encryption steps). The algorithm is used in Cipher Block Chaining (CBC) mode