* Tech tips from Netcordia
A couple of months ago, Netcordia Founder and CEO Terry Slattery started to share with me technology tips that he has picked up during his 20 years of troubleshooting networks (read his previous tip about root bridge selection). Recently Slattery explained two tips, one for determining routing origins and another to avoid Hot Standby Router Protocol (HSRP) errors.
While Netcordia’s NetMRI product suite uses automation and other features to help IT managers quickly find the source of many problems such as duplex mismatches, Slattery says best practices and some common manual checks can also help network managers optimize performance.
For instance, Slattery explained that routes within routing tables should be periodically checked to determine if there are any that are unknown, rogue or perhaps leftover from a discontinued service or connection. If there is an unidentified route in the routing tables, network managers should find the origin of the route to determine its origin.
To do this, network managers need to use Cisco’s or Juniper’s command-line interface to find the router from which the route was learned, and then telnet to that router and repeat the process. Slattery warns the route may not be visible from all locations in the network and that manual route-origin determination can be tedious and error-prone, but it will help eliminate unnecessary routes.
Secondly, Slattery says HSRP is designed to let two or more routers back each other up on a subnet. If there is a configuration error (a partial configuration or one not completely deleted) on the routers, then they continue to consume internal resources but aren’t fully operational. Routers configured as such are considered in an “initial state,” meaning they are waiting to work but need more or accurate configuration data.
To find such issues manually, Slattery says network managers need to use the “Cisco privileged EXEC command show standby init” to identify HSRP groups in that initial state. Identifying these routers will help network managers ensure the redundancy they had planned to build into the network is actually in place, Slattery says.
Stay tuned for potentially more tech tips from Slattery and others in future Network Optimization newsletters.
