Checking the Connection between Routers

You can check that the connection between routers is active by performing the following tasks:

• Use MONITOR to determine whether a link is active
• Run an Echo or Ping test to determine whether a remote router or services are reachable
• Use PPPTRACE to monitor the PPP protocol exchanges that occur during PPP data-link establishment
• Use MONITOR and the consoles to monitor the error counters

This topic contains the following sections:

• Determining Whether a LAN or PPP WAN Link Is Active
• Determining Whether a Remote Router Is Reachable over a PPP WAN Link
• Monitoring PPP Packet Exchanges
• Monitoring Communications Equipment
• Monitoring Error Counters

Determining Whether a LAN or PPP WAN Link Is Active

To determine whether a link is active, load MONITOR and follow this path:

Select LAN/WAN Information > interface you want to view

Under Generic Statistics, look at the Total Packets Sent and Total Packets Received counters. The link is active if these counters are increasing.

Determining Whether a Remote Router Is Reachable over a PPP WAN Link

To determine whether a remote router is reachable, you can run an Echo test. To run an Echo test, load PPPCON and follow this path:

Select PPP Interfaces > interface you want to view > PPP Echo Test

The following information is displayed:

• Interface Name---Symbolic name used by the Link Support Layer^TM (LSL^TM ) software to refer to this interface.
• Interface---Interface index used by SNMP to refer to this interface. This is the same as the board number assigned by the LSL to this interface.
• Echo Test Results---Displays the results for the Echo test. Displays None if the test has not been run, Success if the test is successful, Failure if the test fails, and In Progress if the test is in progress.
• Current Call Destination---Displays the PPP WAN call destination name if the interface is connected to a PPP peer or None if the local interface is not connected. To select the WAN call destination, press Enter to display a list of destinations, select a destination and press Enter again.
• Number of Echo Test Iterations---Number of times the Echo test is repeated. The default is 1. To specify a different number, press Enter and type a new number.
• Echo---Press Enter on this field to perform the Echo test.

Monitoring PPP Packet Exchanges

You can determine the location of a failure point by capturing PPP packet exchanges. To do this, load PPPTRACE and complete the following steps:

1. From the Available Options window, select Configuration.

2. Select Capture Device.

   Select whether you want to capture the data to RAM or to Disk. If you select Disk, specify the filename in the Disk Filename field.

3. Press Esc to go back to the Available Options window.

4. Select Real-Time Monitor to view and capture the PPP protocol exchanges.

   The Real-Time Monitor window is displayed.

5. Press F7 to begin capturing the information.

   Press F7 when you want to end the capture.

   You can also use the following keys:

   F2 ---Displays the statistics for the next interface.

   F3 ---Toggles the display between raw mode (no decode of any PPP frames) and decode mode (PPP frames fully decoded).

   F5 ---Toggles the display between Hex and ASCII.

   F6 ---Enables you to freeze and resume the continuous display of data.

   F8 ---Selects the next interface.

   F9 ---Selects the preceding interface.

6. Establish the call.

   If you are testing outgoing calls, use CALLMGR on the local router to initiate the call. If you are testing incoming calls, use CALLMGR on the remote router to initiate the call.

7. Press F7 to stop the capture when the desired data has been sent.

8. Press Esc to return to the PPPTRACE menu.

9. Select Playback to view the captured data at your convenience.

   The captured data might show one of the following problems:

   • Failure to negotiate LCP options---Shown by the LCP Config-Reject or the LCP Config-NAK packet. Check the LCP negotiated parameters in PPPCON and make sure that the maximum and minimum MRU values are set within the negotiable range between routers. For more information, see Viewing Negotiated Options Configuration for a PPP WAN Link.
   • Failure to authenticate a user---Shown by the LCP Authentication Config-Reject packet and the LCP PAP NAK packet or the LCP CHAP Fail packet. An LCP Config-NAK packet might also appear, but it does not indicate a problem with authentication. Look at the system console for messages. Check that authentication is enabled at the calling end, and make sure that both sides are using the same authentication method. Also, confirm that the Remote System ID and the Password parameters at the receiving end are set to the same value as the Local System ID and the outbound Password parameters at the calling end. For more information, see Viewing Authentication Configuration for a PPP WAN Link.
   • Failure to negotiate NetWare^® Core Protocol^TM (NCP^TM ) options---Shown by the NCP Config-Reject and the NCP Config-NAK packet. Ensure that the interface is bound to the same protocol on both sides. Use CALLMGR to find out which network protocol is used to make the call, then use PPPCON to check whether the same protocols are bound to the interfaces at both ends.

   Figure 9 shows a sample PPP packet exchange.

Figure 9
Real-Time Monitor Capturing PPP Packet Exchanges

Monitoring Communications Equipment

Monitoring your communications equipment can help you identify the source of some common problems with your local modem or data circuit-terminating equipment (DCE) device, including the following:

• The modem or DCE does not answer incoming calls.
• The modem or DCE does not initiate outgoing calls.
• The modem or DCE initiates outgoing calls but does not successfully connect.

If the modem or DCE device cannot answer an incoming call or cannot initiate an outgoing call, you might need to reset it. Before resetting the device, check the following information:

• If the modem cannot answer incoming calls, check the AA (Auto Answer) light on your device. If it is off, reset the modem by using PPPCON or cycling the power.
• If the modem cannot answer incoming calls or initiate outgoing calls, use PPPTRACE to capture and decode modem or DCE device dialogs. Look at the send and receive exchanges to determine whether it is responding to the command properly (see the next section, Capturing Modem/DCE Device Dialogs ). If the modem does not respond properly, reset it by using PPPCON or cycling the power.

If the modem or DCE device can initiate an outgoing call but cannot connect, you might need to change the settings or the hardware. To determine your course of action, check the following information:

• Use PPPTRACE to capture and decode modem or DCE device dialogs. Look at the dial command to determine whether the correct phone number for the remote modem was used. If the number is incorrect, use NIASCFG to change the number.
• Use MONITOR to look at the serial signals. If data set ready (DSR) or data carrier detect (DCD) are off, the modem cannot connect. Check the cable between the router and the modem. If the cable is properly connected, try another modem. If this does not resolve the problem, enable the Simulate DSR On parameter. Load NIASCFG and follow this path:

  Select Configure NIAS > Protocols and Routing > Network Interfaces > Physical Options

Capturing Modem/DCE Device Dialogs

To capture and decode modem or DCE device dialogs, load PPPTRACE and complete the following steps:

1. From the Available Options window, select Configuration.

2. Select Capture Device.

   Select whether you want to capture the data to RAM or to Disk. If you select Disk, specify the filename in the Disk Filename field.

3. Press Esc to go back to the Available Options window.

4. Select Real-Time Monitor to view and capture the modem or DCE device dialog.

   The Real-Time Monitor window appears.

5. Press F7 to begin capturing the modem or DCE device dialog.

   Press F7 when you want to end the capture.

   You can also use the following keys:

   F2 ---Displays the statistics for the next interface.

   F5 ---Toggles the display between Hex and ASCII.

   F6 ---Enables you to freeze and resume the continuous display of data.

   F8 ---Goes to the next interface.

   F9 ---Returns to the preceding interface.

6. Establish the call.

   If you are testing outgoing calls, use CALLMGR on the local router to initiate the call. If you are testing incoming calls, use CALLMGR on the remote router to initiate the call.

7. Press F7 to stop the capture when the desired data has been sent.

8. Press Esc to return to the PPPTRACE menu.

9. Select Playback to view the captured data at your convenience.

   You can expect to see the response OK or an echoed command for each initialization string sent to the modem. If the modem does not respond, check the power and cable connections.

   Figure 10 shows a sample modem dialog.

   Figure 10
   Real-Time Monitor Capturing a Modem Dialog
   

Viewing Modem/DCE Serial Signals

To monitor the serial interface signals raised by the modem or the DCE device, load MONITOR and follow this path:

Select LAN/WAN Information > interface you want to view

Under the specific board's statistics section, look for serial interface signals such as DTR, DSR, RTS, CTS, and DCD (1=on, 0=off).

Resetting a Modem or DCE Device

To reset the modem or DCE device, load PPPCON and follow this path:

Select PPP Interfaces > interface you want to view > PPP Reset Modem > Reset Modem

The following information is displayed on the PPP Reset Modem window:

• Interface Name---Symbolic name used by the LSL to refer to this interface.
• Interface---Interface index used by SNMP to refer to this interface. This is the same as the board number assigned by the LSL to this interface.
• Reset Modem Results---Displays None if the test has not been run, Success if the modem reset correctly, Failure if the modem did not reset correctly, and In Progress if the test is in progress.
• Reset Modem---Pressing Enter on this field resets the modem or DCE device.

Monitoring Error Counters

Error counters are monitored to make sure they are not increasing rapidly, because a rapid increase indicates a problem. You can monitor error counters for PPP interfaces in the following ways:

• By using MONITOR to view counters such as Checksum Errors, Send and Receive Packet Errors, and interface-specific errors. To view these counters, load MONITOR and follow this path:

  Select LAN/WAN Information > interface you want to view

• By using PPPCON to view the following PPP counters:
  • Bad Address Fields
  • Bad Control Fields
  • Bad FCS Values
  • Packets Too Long

  To view these counters, load PPPCON and follow this path:

  Select PPP Interfaces > interface you want to view > PPP Error Statistics

• By using IPXCON to view the following IPX counters:
  • Too Many Hops
  • Header Errors
  • Unknown Sockets
  • Decompression Errors
  • Malformed Requests
  • Compression Errors
  • Open Socket Failures
  • Maximum Sockets

  To view these counters, load IPXCON and follow this path:

  Select IPX Information > Detailed IPX Information

• By using TCPCON to view the following TCP/IP counters:
  • IP Errors
  • IP Address Errors
  • Unknown Protocol Errors
  • Local Errors
  • Reassembly Failures Detected
  • Fragmentation Failures Detected

  To view these counters, load TCPCON and follow this path:

  Select Statistics > IP > More IP Statistics

• By using ATCON to view the following AppleTalk counters:
  • Bad DDP Length
  • Bad DDP Checksum
  • No Route Found
  • Too Many Hops

  To view these counters, load ATCON and select Packet Statistics.