Networking / Beginners

Troubleshooting PPP

When you use PPP to connect to a remote network, you may encounter problems. These problems can range from no dial tone to a modem misconfiguration or connectivity problems with the remote PPP server. A log is included with your communication device to enable you to monitor the steps in opening a PPP connection and to troubleshoot where the breakdown might have occurred. To enable modem logging in Windows, go to the properties of the modem device in Device Manager and click the Diagnostics tab. On the Diagnostics tab choose the Append To Log option.

When logging has been enabled, you can see the log file after the next attempt to connect to a PPP server. The log file, modemlog_modemname.txt, is stored in the Windows directory by default. It can be viewed using any standard text editor and is appended each time a new connection is attempted.

It demonstrates the layout of the log file and how detailed it can become. Understanding how to read these log files enables you to troubleshoot almost any PPP problem that could occur.

Advantages of PPP over SLIP

PPP offers several advantages over SLIP. First, PPP offers multinetwork protocol support, meaning that it can run with IPX/SPX, TCP/IP, NetBEUI, and AppleTalk while SLIP can be used only with TCP/IP. Any of these protocols can be used, which enables you to connect to multiple types of systems on the remote network through dial-up. The addition of NCPs allows for this functionality in PPP.

In addition, PPP offers the capability to use DHCP. The addition of LCP made options such as this available to PPP. In addition, PPP handles higher-speed links better than SLIP does. This easier use is due to the error-checking capability within the protocol. SLIP does not check datagrams for errors as they pass through the connection.

The following list summarizes the characteristics of PPP:

  • PPP can run with TCP/IP, IPX/SPX, NetBEUI, AppleTalk, or DecNET.
  • PPP can use DHCP.
  • PPP performs error checking and also supports compression.
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