Establishing Adjacencies on a Broadcast Link
On broadcast links, each IS receives packets sent by the DIS, minimizing the amount of traffic that needs to be generated to maintain the adjacencies and databases. The DIS has the responsibility of flooding the LSPs to all connected systems running Integrated IS-IS. The adjacencies with the other routers are maintained by the DIS, which sends out Hellos every 3.3 seconds, three times the speed of other routers. This is to ensure the integrity of the adjacencies by identifyin..
Troubleshooting Dial-on-Demand Routing (DDR) Issues in IGRP
Dial-on-demand routing is very common when the ISDN or similar dialup links are used as a backup link. When the primary link goes down, this backup link comes up. IGRP starts sending and receiving updates on this link as long as the primary link is down. Two ways exist for using the dialup links as a backup for the primary link: • Using the backup interface command • Using floating static routes with a dialer list that defines interesting traffic The first m..
Catalyst Configuration File Management
For complete system recovery, make sure that you have a copy of each Catalyst's configuration file stored somewhere other than on the Catalyst itself. If anything happens to the Catalyst Supervisor module, you might not be able to recover the configuration file. It is a crime to have to rebuild the entire configuration file from scratch during a system outage when it is easy to create a backup on a network accessible machine. Through TFTP, you can store your configuration fi..
Logging Router Syslog Messages in Different Files
To disable router syslog messages from inundating your local system logfiles, use the following commands: local7.info /var/log/rtrlog *.err;kern.debug;auth.notice;mail.crit;local7.none /var/log/syslog *.notice;kern.debug;auth.info;mail.crit;local7.none ..
The most common reasons for failed dial backup calls are incorrect dial strings and PPP authentication problems. You can easily diagnose both of these problems with this command: Router1#debug ppp authentication Here is another useful command for diagnosing problems with dialer configurations: Router1#debug dialer When you use CHAP authentication with PPP, as we have done throughout this chapter, it is relatively easy to debug most common problems. We like to use the debu..
