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Data will be transmitted only when the link is in the open phase.
Negotiation details are described in RFC1661.
Feature list
Async to Sync Conversion (external)
PPP uses HDLC-like framing as encapsulation, which can be bit-
oriented or character-oriented. Most ISDN routers use bit-oriented
HDLC framing, also known as synchronous transmission. However,
serial transmission in most personal computers is still character-
oriented, also known as asynchronous transmission. In order for an
ISDN router and PC to communicate, it's necessary to do
asynchronous to synchronous conversion. The omni can be used as a
bridge. Any data from a PC to a ZyXEL TA will be converted from
asynchronous to synchronous form and vice versa. PPP HDLC
framing is described in RFC1662. PPP over ISDN is described in
RFC1618.
Related command:
ATB40 - Async to Sync PPP conversion.
Authentication conversion
After a link is established, it is necessary to authenticate the peer for
security reasons. There are two popular authentication methods. One
is Password Authentication Protocol (PAP) and the other is
Challenge Handshake Authentication Protocol (CHAP). PAP is less
secure because it transmits the username/password in plain text form.
Unlike PAP, CHAP transmits the username/password in coded form.
Some ISPs may support CHAP as the only method for
authentication. For those applications which do not support CHAP,
the omni converts PAP into CHAP. By default, the PAP/CHAP
conversion is always activated, so the authentication from the TA to
PC is always PAP. That means you must configure your software to
accept plain text as password authentication. Do not worry about
password leakage, the TA will send the password out in hashed form
Point-to-Point Protocol (PPP) 45
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