ZyXEL Omni TA 128 User Guide - Page 52

Compression Control Protocol CCP, Multilink PPP

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• ATS87.2 = 1 - Accept PAP/None only. • ATS87.2 = 0 - Accept CHAP/PAP/None (default). Compression Control Protocol (CCP) The ISDN channel can be utilized more effectively when using compression. Compression Control Protocol (CCP) is used by PPP to negotiate compression methods between peers. CCP starts after the PPP reaches the network phase. Both ends must support the same compression method to start packet compression. ZyXEL supports STAC/LZS. Right now STAC/LZS is only supported with single history check mode 0 (none), 3 (sequence) and 4 (extended). Mode 1 (LCB) and mode 2 (CRC) are not supported due to patent limitations. CCP negotiation is described in RFC1962. STAC/LZS is described in RFC1974. The TA will monitor the DTE's activity. If software compression has been negotiated, the TA will automatically disable STAC/LZS compression. Related commands: • AT&K00 - Disable CCP negotiation (default). • AT&K44 - Enable CCP negotiation. Multilink PPP There are two B channels in basic rate ISDN. This offers the possibility of opening multiple simultaneous channels between systems giving users additional bandwidth on demand. Multilink PPP is a method for bundling both B channel into one PPP link for higher throughput. It must be negotiated in the link establish phase by both peers. If Multilink PPP is negotiated successfully, the second link will be dialed after the first link reach network phase. In some countries the directory number is not the same for both channels. For dialing the second B channel with a different directory number, both numbers must be obtained before dialing out unless the peer supports BACP/BAP, which will be described later in this chapter. Multilink PPP is described in RFC1990. 40

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40
•
ATS87.2 = 1
- Accept PAP/None only.
•
ATS87.2 = 0
- Accept CHAP/PAP/None (default).
Compression Control Protocol (CCP)
The ISDN channel can be utilized more effectively when using
compression. Compression Control Protocol (CCP) is used by PPP
to negotiate compression methods between peers. CCP starts after
the PPP reaches the network phase. Both ends must support the
same compression method to start packet compression. ZyXEL
supports STAC/LZS. Right now STAC/LZS is only supported with
single history check mode 0 (none), 3 (sequence) and 4 (extended).
Mode 1 (LCB) and mode 2 (CRC) are not supported due to patent
limitations. CCP negotiation is described in RFC1962. STAC/LZS
is described in RFC1974. The TA will monitor the DTE’s activity.
If software compression has been negotiated, the TA will
automatically disable STAC/LZS compression.
Related commands:
•
AT&K00
- Disable CCP negotiation (default).
•
AT&K44
- Enable CCP negotiation.
Multilink PPP
There are two B channels in basic rate ISDN. This offers the
possibility of opening multiple simultaneous channels between
systems giving users additional bandwidth on demand. Multilink
PPP is a method for bundling both B channel into one PPP link for
higher throughput. It must be negotiated in the link establish phase
by both peers. If Multilink PPP is negotiated successfully, the
second link will be dialed after the first link reach network phase. In
some countries the directory number is not the same for both
channels. For dialing the second B channel with a different
directory number, both numbers must be obtained before dialing
out unless the peer supports BACP/BAP, which will be described
later in this chapter. Multilink PPP is described in RFC1990.