Westermo IDW-90 AT - Manual (Page 38)

38 6620-3200
5.1 Using Multilink PPP
To enable Multilink PPP handling within the IDW-90 please enable the B channel protocol
ML-PPP: prot = 31.
ML-PPP may be used with two different authentication protocols during the link estab-
lishment phase:
• PAP (password authentication protocol, RFC 1334)
• CHAP (challenge handshake authentication protocol, RFC 1994) with variants
1. MD5 according to RFC 1321
2. Microsoft Chap according to RFC 2433.
The simpler PAP transmits the user password as clear text over the line, whereas
CHAP uses encryption. Which protocol is actually used depends on:
• the local PC: if the dialup network configuration requests password
encryption only CHAP will be used,
• the remote host configuration: it may (e.g.) allow both PAP and
CHAP, CHAP only etc..
5.1.1 Restrictions on Windows95
The CHAP protocol requires that the local side (PC or TA) responds with the proper,
encrypted password when requested by the remote host. Since Windows95 does not
respond on repeated requests CHAP can be used on the second link only if the TA
knows the password. It must be stored in the TA’s NVRAM:
• Enter “at**chappwd=< password>” to input your password in the TA.
Warning: The input echo is shown in clear text, it should be hidden from
unauthorized persons. Nevertheless, commands as “AT&V1” display the
password as a sequence of asterisks (“*”).
• Enter “AT&W” to store the setting in the TA.
If the password chappwd is not stored on the TA (or is wrong) and remote and/or
local dialup network configuration require password encryption, the second link will be
physically established for a short time, and will then be disconnected. As a consequence
the Multilink option is disabled for the current connection.