Troubleshooting guide

BSR Troubleshooting Guide
5-94
Resolving PPP Link Over SONET Failures
This section discusses how to troubleshoot a problem Point to Point Protocol
(PPP) link on the POS module.
Follow these steps to troubleshoot the PPP link:
1. To check the link state and running information about the PPP link, use the
show ip interface brief command in Privileged EXEC mode, as shown in the
following example:
RDN#show ip interface brief
2. To display the PPP packets that the Packet Over SONET (POS) module sends
and receives, use the debug ppp packet command in Interface Configuration
mode, as shown in the following example:
RDN(config-if)#debug ppp packet
3. Review the debug ppp packet command output and identify the cause of the
problem. To turn the PPP debugging function off, use the no debug ppp
packet command.
The debug ppp packet command output reveals if the PPP link is up or down
and if low-level packet dumps are occurring.
4. If the PPP link is down, check for the following:
• Network Control Protocols (NCPs) that are supported on either end of a
PPP connection.
• Loops that exist in the PPP internetwork.
• Sections that are (or are not) properly negotiating PPP connections.
5. When there is no active link between local and remote devices, use the debug
ppp fsm command in POS Interface Configuration mode.
RDN(config-if)#debug ppp fsm
The command output will show the network activity between the local and
remote devices.