Configuring a Leased Line

• Your Cisco  1700 router hardware is correctly installed according to the Cisco  1700 Router Hardware Installation Guide that came with the router.

• Your Cisco  1700 router is using multilink Point-to-Point Protocol (PPP).

• Your Cisco  1700 router is using dynamic IP and IPX routing, in which IP Routing Information Protocol (RIP) resolves IP routes, and IPX RIP and IPX SAP dynamically resolve IPX routes and services.

Before you begin configuration, be aware of the following:

• You need to enter the commands in the order shown in the task tables.

• The values shown in italic are examples. You should substitute the values shown with values that are appropriate for your network.

• You should be familiar with Cisco  IOS software and its conventions.

Step	Task	Router Prompt	Command
1 .	Enter configuration mode.	Router#	configure terminal
2 .	Configure the router to show the date and time of all debug messages. This command is optional, but recommended if you use debug commands to troubleshoot your configuration.	Router(config)#	service timestamps debug datetime msec
3 .	Configure the router to show the date and time of all log messages. This command is optional, but recommended if you use the verification steps described in this guide. This feature is enabled for all the example command output shown in this guide.	Router(config)#	service timestamps log datetime msec
4 .	Configure the router to use subnet zero for interface addresses and routing updates.	Router(config)#	ip subnet-zero
5 .	Disable the IP Domain Name System (DNS)-based host name-to-address translation on the router.	Router(config)#	no ip domain-lookup
6 .	Enable IPX routing and configure the router with an IPX address.	Router(config)#	ipx routing 0000.0caa.1111

Step	Task	Router Prompt	Command
1 .	Specify a password to prevent unauthorized access to the router.	Router(config)#	enable password <1700user>
2 .	Configure the router with a host name, which is used in prompts and default configuration file names. For PPP authentication, the host name entered with this command must match the username of the central-site router.	Router(config)#	hostname 1700

Step	Task	Router Prompt	Command
1 .	Enter configuration mode for the Fast Ethernet interface.	1700(config)#	interface fastethernet0
2 .	Configure this interface with an IP address and a subnet mask. This interface must have an IP address assigned in order for the serial interface to be configured for IP unnumbered routing.	1700(config-if)#	ip address 10.1.1.1 255.0.0.0
3 .	Enable IPX routing on this interface, assign the IPX network number, and configure the interface for IPX SAP encapsulation.	1700(config-if)#	ipx network 100 encapsulation sap
4 .	Configure a secondary IPX network on this interface that uses the default NetWare encapsulation.	1700(config-if)#	ipx network 100 encapsulation novell-ether secondary
5 .	Enable the interface and the configuration changes you have just made on the interface.	1700(config-if)#	no shutdown
6 .	Exit configuration mode for this interface.	1700(config-if)#	exit

Step	Task	Router Prompt	Command
1 .	Enter configuration mode for the serial interface.	1700(config)#	interface serial0
2 .	Add a description of this interface to help you remember what is attached to it.	1700(config-if)#	description leased line to headquarters
3 .	Enable IP routing on this interface without assigning an IP address.	1700(config-if)#	ip unnumbered FastEth0
4 .	Enable IPX routing on this interface and assign an IPX network number.	1700(config-if)#	ipx network AAAA
5 .	Configure this interface for PPP encapsulation.	1700(config-if)#	encapsulation PPP
6 .	Enable this interface and the configuration changes you have just made on the interface.	1700(config-if)#	no shutdown
7 .	Exit configuration mode for this interface.	1700(config-if)#	exit

Step 2 Confirm that the "Serial0 is up, line protocol is up" message (shown in bold in the example) appears in the command output.

1700# show interface ser0
Serial0 is up, line protocol is up
   Hardware is PowerQUICC Serial
   Description: leased line to headquarters
   Interface is unnumbered. Using address of FastEthernet0 (10.1.1.1)
   MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
   Encapsulation PPP, loopback not set, keepalive set (10 sec)
   LCP Closed
.
.
.

Step 3 If you see the message shown in the example command output, continue configuration by re-entering global configuration mode.

Table 4-1: Leased Line Problems and Suggested Actions

Line State	Possible Cause	Suggested Actions
Serial x is down, line  protocol is down.	The router is not sensing a carrier detect (CD) signal due to one of the following reasons: Telephone company problem, such as the line is down or not connected to the DSU/CSU. Faulty or incorrect cabling of the router. Local DSU/CSU hardware failure. Local router hardware failure.	Following are some steps you can take to isolate the problem: Check the LEDs on the external DSU/CSU for CD activity. Refer to the Cisco  1700 Router Hardware Installation Guide to confirm that your router is correctly installed using the correct cables. Contact the telephone company. Connect the leased line to another port, if possible. If the connection come up, there is a hardware failure. Contact your Cisco reseller.
Serial x is up, line  protocol is down.	Possible causes for this line state are Local or remote router misconfigured. The remote router is not sending keepalive packets. Problem with the leased line. The serial clock transmit external is not set on the DSU/CSU. Local or remote DSU/CSU hardware failure. Router hardware failure.	Following are some steps you can take to isolate the problem: Perform DSU/CSU loopback tests. During local loopback, enter the show  interface  ser0 command. If the line protocol is shown as up, there might be a problem with the telephone company, or the remote router is down. Refer to the Cisco  1700 Router Hardware Installation Guide to confirm that your router is correctly installed using the correct cables. Connect the leased line to another port, if possible. If the connection come up, there is a hardware failure. Contact your Cisco reseller.
Serial x is up, line  protocol is up (looped).	The possible cause is that a loop exists in the circuit. The sequence number in the keepalive packet changes to a random number when a loop is first detected. If the same random number is returned over the line, a loop exists.	Following are some steps you can take to isolate the problem: Use the write  terminal privileged EXEC command to display any instances of the loopback command. If the router has been configured with the loopback command, enter the no  loopback command to remove the loop. Check to see if the DSU/CSU is configured in manual loopback mode. If it is, disable manual loopback. Reset the DSU/CSU. If you are unable to isolate the problem, contact the telephone company for help with troubleshooting.
Serial x is administratively down, line protocol is up.	The possible causes for this state are The serial interface has been disabled with the shutdown  interface configuration command. Different interfaces on the router are using the same IP address.	Following are some steps you can take to isolate the problem: Use the show  configuration privileged EXEC command to display the serial port configuration. If "shutdown" is displayed after "interface Serial0," use the no  shutdown interface configuration command to enable the interface. Use the show interface privileged EXEC command to display the IP addresses for all router interfaces. Use the ip  address interface configuration command to assign unique IP addresses to the router interfaces.