Demand-Dial Routing
Demand-Dial Routing |
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The following tools, which enable you to gather additional information about the source of your problem, are included with Windows 2000.
If a demand-dial connection attempt fails, the demand-dial interface is left in an unreachable state. A Windows 2000 router records the reason why the connection failed through the unreachability reason. You can troubleshoot further based on the information in the unreachability reason.
To check the unreachability reason
The following are reasons why the demand-dial interface is left in an unreachable state:
When a demand-dial interface is configured, a port is selected. A port is a hardware or software channel that represents a single point-to-point connection. Ports are grouped by type such as analog phone ports, ISDN B-channel ports, and VPN ports such as PPTP and L2TP.
While you might configure a demand-dial interface to use a specific port, you are also configuring the demand-dial interface to use a port type. If the specific port is not available when the connection needs to be made, the Routing and Remote Access service attempts to use another port of the same type. For example, if you have two modems and you configure a demand-dial interface to use a specific modem and that modem is in use when the demand-dial connection needs to be made, the calling router uses the other modem automatically.
The Routing and Remote Access snap-in allows you to configure more demand-dial interfaces for a given port type than there are actual ports. For example, you can configure multiple demand-dial interfaces that are all configured to use the same modem port. If that modem port is in use when the demand-dial connection needs to be initiated and there are no other ports of that port type available, the connection attempt fails and the unreachability reason is recorded.
Event logging is the recording of events in the Windows 2000 system event log. Event logging is typically used for troubleshooting or for notifying network administrators of unusual events.
On the Event logging tab on the properties sheet of an answering router, there are four levels of logging. Select Log the maximum amount of information and try the connection again. After the connection fails, check the system event log for events logged during the connection process. After you are done viewing events, select the Log errors and warnings option on the Event logging tab.
The Routing and Remote Access service supports the logging of authentication and accounting information for demand-dial and remote access connections when Windows accounting is enabled. This logging is separate from the events recorded in the system event log. You can use the information that is logged to track demand-dial and remote access usage and authentication attempts. Logging is especially useful for troubleshooting remote access policy issues. For each authentication attempt, the name of the remote access policy that either accepted or rejected the connection attempt is recorded.
The authentication and accounting information is stored in a configurable log file or files stored in the SystemRoot\System32\LogFiles folder. The log files are saved in IAS 1.0 or IAS 2.0 format. IAS 2.0 format is database–compliant, meaning that any database program can read the log file directly for analysis.
You can configure the type of activity to log (accounting or authentication activity) and log file settings from the properties of the Remote Access Logging folder in the Routing and Remote Access snap-in.
Network Monitor is a packet capture and analysis tool that you can use to view the traffic sent between demand-dial routers during the connection establishment process and during data transfer. Network Monitor does not interpret the compressed or encrypted portions of demand-dial traffic.
The proper interpretation of the PPP connection establishment traffic with Network Monitor requires an understanding of PPP protocols described in "Remote Access Server" in this book. Network Monitor captures can be saved as files and sent to Microsoft support for analysis.
Tracing records the sequence of programming functions called during a process to a file. Enable tracing for remote access or demand-dial components and try the connection again. After you are done viewing the traced information, reset the tracing settings back to their default values.
The tracing information can be complex and very detailed. Most of the time, this information is useful only to Microsoft support professionals, or to network administrators who are very experienced with the Routing and Remote Access service. The tracing information can be saved as files and sent to Microsoft support for analysis.
For more information about PPP tracing, see "Remote Access Server" in this book.