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MultiModemISDN User Guide
S-register: S58
Function: Client-side Authentication Protocol Negotiation
Unit: Decimal ASCII code
Range: n=1 PAP
n=2 PAP between TA and PC; CHAP MD5 between T A and server
n=3 ANY authentication protocol
Default: 1 (PAP)
Description:Sets the client-side authentication protocol to be negotiated during the Link
Control Protocol (LCP) phase of PPP/MLPPP negotiation. Does not
determine which authentication protocol is negotiated if the TA is used on the
server side. S58=1 allows only PAP to be negotiated. S58=2 allows PAP
between the TA and PC and CHAP MD5 between the TA and server. S58=3
allows any authentication protocol. If the server does not allow PAP, set
S58=2 to try CHAP MD5 with the server. If the server doesn’t allow CHAP
MD5 or the PC doesn’t allow PAP, set S58=3 to allow any authentication
protocol that the server requests. MultiLink connections are possible if the
authentication protocol is PAP (S58=1 or S58=3), CHAP MD5 (S58=2 or
S58=3), MS-CHAP (S58=3) and possibly others (S58=3).
S-register: S59
Function: Dynamic Bandwidth Allocation (DBA) Scheme
Unit: Decimal ASCII code
Range: n=0 Disable
n=1 MP+
n=2 PPP
Default: 1 (MP+)
Description:Determines whether Dynamic Bandwidth Allocation (DBA) is disabled or
enabled by the use of a specific scheme (MP+ or PPP). Setting S59=0
disables DBA and as a result disables the Bandwidth-on-Demand and Call
Bumping features. Setting S59=1 (MP+) instructs the TA to negotiate the
MP+ option during the PPP LCP phase. If the MP+ DBA scheme is desired,
but the server does not support MP+, the TA falls back to the PPP DBA
scheme. Due to this fall-back ability, DBA on the client side is always
possible. Setting S59=2 to use PPP instructs the TA to use basic PPP
requests to perform DBA (the most widely accepted scheme). Basic PPP
requests include the LCP Terminate Request command to disconnect a data
channel and instruct the TA to add a second channel by dialing the second
number given in the dial string (or dialing same number if &J1).
If the TA is used as a host, MP+ must be supported by the client also. The
host TA must set S59=1 (MP+). If the TA is used as a host, but either MP+ is
not supported by the client or the host did not set S59=1 (MP+), DBA is not
possible. For example, if the host sets S59=1, but the client does not support
MP+, DBA is not possible. If the host sets S59=2, DBA is not possible. MP+
is required to be negotiated by both the client and host if the host is to
perform DBA. The PPP DBA scheme is the most widely accepted DBA
scheme. This is why the TA falls back to the PPP scheme if MP+ is not
supported, thus allowing DBA to be available at all times (for the client TA).
The second data directory number must be set if using the TA as a host with
MP+ enabled as the DBA scheme. The TA uses the second data directory
number to send to the client as the call-back number to have the client dial to
set up the second data channel (call-back number is sent as a part of MP+
protocol). Due to the ability to send the client a call-back number, it is then
possible to allow the host to perform DBA as well. Since the PPP DBA
scheme cannot instruct the client to call back, we cannot allow the PPP DBA