PPP Setup for Leased Sync Line

How to set up a Lucent router to connect  to another router on a leased line via Point To Point Protocol (PPP) using its ethernet for the serial link and dynamically discovering information of the other router.. Make sure the CSU/DSU is providing an external clock source.  The following examples give the commands to accomplish this.

Change addresses to match yours.

Configuring Unit at HQ:

Command> set ether0 address 172.16.1.1
Command> set netmask 255.255.255.0
Command> set ipxnet AC100100
Command> set ipxframe ethernet_802.3   { or whatever you are using

Command> set s1 network hardwire
Command> set s1 destination 172.16.2.1 
Command> set s1 netmask 255.255.255.0
Command> set s1 ipxnet AC100101
Command> set s1 protocol ppp
Command> set s1 routing on
Command> set s1 mtu 1500
Command> save all
Command> reset s1

Configuring Unit at remote site:

Command> set ether0 address 172.16.2.1
Command> set netmask 255.255.255.0
Command> set ipxnet AC100200
Command> set ipxframe ethernet_802.3   { or whatever you are using

Command> set s1 network hardwire
Command> set s1 destination 172.16.1.1
Command> set s1 netmask 255.255.255.0
Command> set s1 ipxnet AC100101
Command> set s1 protocol ppp
Command> set s1 routing on
Command> set s1 mtu 1500
Command> save all
Command> reset s1

If you have a connection  problem, the following two commands display  the PPP negotiations. The Configuration Guide has a  section on interpreting the following debug.
 

Command> set console
Command> set debug 0x51

To turn the debug off use the following commands:

Command> set debug 0  or  set debug off
Command> reset console

If you put the CSU/DSU into local loopback or the remote CSU/DSU into loopback while debug 0x51 is set, you should see LCP_APPARENT_LOOP messages displayed.

Information For Troubleshooting

CHECK ERROR COUNTERS FIRST ON CSU/DSU

 The CSU/DSU error counter should display all zeros.  If errors are incrementing this could be an indication of a hardware problem unrelated to the Lucent IRX (TM) router.  Verify that the CSU/DSU, modem and line cables are securely attached and that  known good cables are being used.  Beaware that a few abort errors from plugging & unplugging cables is normal..

There have been three instances on a sync line where the abort counter on a CSU/DSU connected to an IRX router increments:

  1. CSU/DSU is either misconfigured or is defective and needs replacement
  2. An open pair was found on the TelCo wiring.
  3. The Cisco router at the other end was running release 9.14(2). This Cisco IOS version has a known bug which has a 1's assertion problem.  It is recommended to install IOS version 9.14(5) or later. As of this update Cisco is on IOS version 12.X.  Contact Cisco technical support for any questions regarding this issue.

If the framing errors on the IRX are greater than 0 and the other router is not an IRX, make sure it is using PPP encapsulation not High Level Data Link Control (HDLC).

If  errors persist on the CSU/DSU and all other items mentioned above have been checked, refer the problem to the local telephone company providing the line to check for errors on the line.