IBM 19K5716 Connections to internet service providers (ISPs)

180 IBM ISDN PC Card:User’s Guide

6. Confirm your entries by clicking OK and close the modem window.

Connections to internet service providers (ISPs)

There is no binding standard for ISDN dial-in access to the Internet via Internet

providers. PPP/SLIP protocol variants, fixed or dynamically assigned IP

addresses, static or dynamic DNS and a variety of authentication techniques

make it impossible to set a universally valid Internet access configuration for the

ISDN CAPI Port Device Driver.

For TCP/IP connections using the ISDN CAPI Port Device Driver, you must also

use 32-bit client software (i.e., WWW browsers, FTP clients, etc.) rather than 16-bit

applications for Windows 3.x. Otherwise, no connection to the 32-bit TCP/IP

protocol stack integrated in Windows 95/98 is possible.

Many providers use the ”HDLC” or ”X.75” protocol on the ISDN B channel. Two

protocol variants are used for PPP connections: "PPP over ISDN" in accordance

with RFC 1618 (also known as synchronous PPP), and "PPP modem style" in

accordance with RFC 1162 (also called asynchronous PPP).

Note: Please ask your Internet provider which combination of protocols and

authentication procedures are required for ISDN dial-in access.

Incorrect protocol settings either result in an immediate termination of the

connection or prevent the ISDN connection from being established in the first

place (error message: "The computer you are dialing in to is not answering.").

Setting modem registers for ISDN B-channel protocols and PPP: The virtual

modem ISDN Internet (PPP over ISDN) is set by default to ”HDLC” and ”PPP

over ISDN” according to RFC 1618. If a different configuration is requested by

your Internet provider, you can change the B-channel ISDN protocol by setting

the register "S31":

• S31=0X.75 protocol

• S31=1HDLC protocol (default)

• S31=2V.110 protocol

• S31=7V.120 protocol

The registers ”S41”, ”S42” and ”S43” can also be used to set the B1, B2 and B3

protocol layers individually. However, this is not necessary in most cases.

The PPP protocol variant used can be configured using register "S51":

• S51=0 asynchronous PPP ("modem style", RFC 1162)

• S51=1 synchronous PPP ("PPP over ISDN", RFC 1618)

ISDNmst.fm Page 180 Wednesday, January 15, 2003 9:22 AM