IP Route Profile
The show ip route profile command can be used on a Cisco IOS router to display routing table change statistics. This is especially useful when observing and troubleshooting route flapping.
Note that in order to gather route profile information, you must first enable this feature using the ip route profile global configuration command. This command identifies route flapping over brief time intervals. The sampling interval is a fixed value and is set at 5 seconds. Once activated, it begins to collect and store statistics, which can then be displayed using the show ip route profile command.
The command has no arguments or keywords, but displays something like this:
Router# show ip route profile -------------------------------------------------------------------- Change/ Fwd-path Prefix Nexthop Pathcount Prefix interval change add Change Change refresh -------------------------------------------------------------------- 0 87 87 89 89 89 1 0 0 0 0 0 2 0 0 0 0 0 3 0 0 0 0 0 4 0 0 0 0 0 5 0 0 0 0 0 10 0 0 0 0 0 15 0 0 0 0 0 20 2 2 0 0 0 25 0 0 0 0 0
The output table shows the various types of changes and events that can be detected in a routing table. These include:
- Fwd-path change - This is the total accumulation of Prefix add, Nexthop Change, and Pathcount Change values.
- Prefix add - This counter represents a new prefix that was added to the routing table.
- Nexthop Change - This respresents the change in the next hop of an existing prefix.
- Pathcount Change - This indicates that the number of paths in the routing table has changed for a particular prefix. This is usually the result in the increase in the number of paths that the underlying IGP has discovered.
- Prefix refresh - This indicates a standard routing table maintenance process, no forwarding behavior changes when this takes place.
Now the key to understanding the counters we see for each of these events is lies in understanding the Change/interval column. Each value in this column represents what is known as a "frequency bucket". It shows the number of times an event has taken place within the 5 second interval.
So in the above output, you can see a value of 2 in the Fwd-path change column for the frequency bucket of 20. That means that since the beginning of taking statistics, there were two 5-second time intervals in which this event took place over 20 times.
Another important note is that every time a 5-second time interval elapses without any events taking place, the "0" frequency bucket values are incremented by 1. So it is normal, and indeed desirable to have large counters for the "0" bucket row.
For an example, you can see it in action in the Troubleshooting AD Redistribution lesson.
For more information, search for these two commands in Cisco's official command line reference documentation.
ip route profileshow ip route profile