Using Synchronous Leased Lines        19

The following topics are described:

•  "Overview of Leased Line Connections" on page 19-1

•  "Configuration Steps for Leased Line Connections" on page 19-3

•  "Troubleshooting a Leased Line Connection" on page 19-8

  See the Command Line Administrator's Guide for more detailed command descriptions and instructions.

Overview of Leased Line Connections

PortMaster routers support leased line connections using synchronous ports and the PPP protocol. In this configuration, one PortMaster is usually connected to another PortMaster or other router over a leased line where each router uses its own Ethernet address for the serial link-known as IP unnumbered-and the address of the other end is discovered dynamically. In this way, a dedicated high-speed connection is established between two routers located at separate sites. Figure 19-1 shows an example of the leased line connection.  

Leased Line Configuration If you are connecting two networks together for the first time, you should make sure first that the two networks are not overlapping subnets. For more information on network numbers and subnetting, see Appendix A, "Networking Concepts."

In the leased line configuration described in this chapter, the Ethernet address of the PortMaster routers is used as the address for the serial link in a point-to-point unnumbered serial connection. Because the PortMaster relies on an external clock signal, you do not need to set the speed on the synchronous port. The port speed is whatever the carrier sends. If you choose to set a speed, it is used for documentation purposes only. The speed you set is ignored by the PortMaster.

PortMaster synchronous ports support leased line connections from 9600bps to T1 (1.544Mbps) or E1 (2.048Mbps) speeds. Synchronous ports used for leased line connections are configured for PPP operation and can have input and output filters for network security.

Note ¯ The PortMaster also supports numbered IP interfaces on leased lines, but Lucent Remote Access does not recommended this method because it wastes IP address space.

Configuration Steps for Leased Line Connections

To install your PortMaster, follow the instructions in your hardware installation guide. If you need additional help, refer to the troubleshooting chapter of your installation guide. The example in this chapter shows variables in italics. Change these values to reflect your network.

Once you have assigned an IP address to the PortMaster, continue with the following steps:

1. Configure the following settings for the PortMaster in Rome:

a. Global settings (page 19-4)

b. Ethernet interface settings (page 19-4)

c. Synchronous WAN port settings (page 19-5)

1. Configure the following settings for the PortMaster in Florence:

a. Global settings (page 19-6)

b. Ethernet interface settings (page 19-7)

c. Synchronous WAN port settings (page 19-7)

1. Troubleshoot the configuration, if necessary (page 19-8).

Configuring the PortMaster Office Router in Rome

Configuring Global Settings

Once you have configured the global settings shown in Table 19-1, save the configuration by using the following command:  

Command> save all

For more information about global settings, refer to Chapter 3, "Configuring Global Settings."

Configuring Ethernet Interface Settings

Once you have configured the Ethernet interface as shown in Table 21-2, save the configuration using the following command:

Command> save all

For more information on Ethernet settings, refer to Chapter 4, "Configuring the Ethernet Interface."

Configuring Synchronous WAN Port Settings

If you are not sure of the IP address on the other end of the connection, you can set the IP destination to 255.255.255.255 and the PortMaster will attempt to learn the address.

Leave all other settings at their default values. Once you have configured the port S1 as shown in Table 19-3, reset the port and save the configuration using the following commands:  

Command> reset s1 Command> save all

For more information about synchronous ports, refer to Chapter 6, "Configuring a Synchronous WAN Port."

Configuring the PortMaster Office Router in Florence

Configuring Global Settings

Once you have configured the global settings shown in Table 19-4, save the configuration by using the following command:  

Command> save all

For more information about global settings, refer to Chapter 3, "Configuring Global Settings."

Configuring Ethernet Interface Settings

Once you have configured the Ethernet interface as shown in Table 19-5, save the configuration using the following command:  

Command> save all

For more information on Ethernet settings, refer to Chapter 4, "Configuring the Ethernet Interface."

Configuring Synchronous WAN Port Parameters

If you are not sure of the IP address on the other end of the connection, you can set the IP destination to 255.255.255.255 and the PortMaster will attempt to learn the address.

Leave all other settings at their default values. Once you have configured the port S1 as shown in Table 19-6, reset it and save the configuration using the following commands:  

Command> reset s1 Command> save all

For more information about synchronous ports, refer to Chapter 6, "Configuring a Synchronous WAN Port."

Troubleshooting a Leased Line Connection

If you are having trouble with a leased line connection, verify the following:

• Use the following commands to view the PPP negotiation on port S1, if this is the port you are using:

  Command> set console s1 Command> set debug 0x51 Command> reset s1

For information about the interpreting the results of the debug command, refer to "Debugging and Interpreting PPP Negotiation" on page 20-9. Once you have verified that the PPP negotiation is correct, use the following commands to turn off the debug utility:

Command> set debug off Command> reset console

• The error counters should be 0 (zero) except for abort errors. If your counters are
  nonzero, the problem is external to the PortMaster.

  Note ¯ CRC errors will occur if the cable is ever unplugged from the PortMaster.

• Verify that you are using the correct cable and that it is attached securely to the correct port. Not all WAN ports are capable of the same speeds.

• Verify that the DIP switch next to the synchronous port is set to V.35 for Lucent Remote Access cables and that you are plugged into the correct V.35 interface on your CSU/DSU.

• Verify that the CSU/DSU is providing the clock to the PortMaster. The CSU/DSU can generate the clock or receive it from the carrier.

• Verify that the CSU/DSU is configured properly.

• If you have a Cisco router on the other end of your connection, make sure that it is running Cisco's software release 9.14(5) or later and is using PPP encapsulation, not High-Level Data Link Control (HDLC).

• If the framing errors are greater than 0, verify that the router on the other end of the connection is running the PPP protocol.

• If you are still having problems, set the following:

  Command> set debug 0x51 Command> set console s1

Then set the CSU/DSU for local loopback. You should see the following message:

LCP_APPARENT_LOOP

For more information about the interpreting the results of the debug command, refer to "Debugging and Interpreting PPP Negotiation" on page 20-9.

• If the local loopback shows network connectivity in the local router, take the CSU/DSU out of loopback and set line loopback on the remote CSU/DSU. If the remote loopback test does not show network connectivity in the remote router, the problem is either in the configuration of one of the CSU/DSUs or in the line itself.

• When you have finished, use the following commands to turn off the debug utility:

  Command> set debug off Command> reset console

• Contact your carrier to review your configuration and the status of their line.