Aug 20

Multiple trap receivers with the same community string on Cisco Wireless Controllers

Recently my monitoring team ask me to update 1,300+ Wireless LAN Controllers (WLC) with three new SNMP trap receivers, all with the same community string. On the WLC, it asks you for a community string and an IP address. It can be found under Management –> SNMP –> Trap Receivers then click on “New”. If you have ever tried adding multiple trap receivers with the same community string, the WLC will give you an error and state that you cannot have multiple trap receivers with the same community string.

In Cisco Prime Infrastructure (PI) and Cisco Wireless Controller System (WCS) there are templates to push this configuration out to the WLC’s. In PI and WCS, under Configure –> Controller Template Launchpad –> Management you will find the Trap Receiver template, click on “New”. In PI and WCS, it asks you for a Template Name and an IP address of the trap receiver. Remember the WLC asked for Community String and IP address.

I created three templates in PI, one for each trap receiver, each with a unique template name. I then created a template group. Configure –> Controller Template Groups –> From the top right drop down box, select “Add Config Group”, then click “Go”. I was able to select all three of my trap receiver templates and then all of my controllers and push this configuration out. In less then 20 minutes, all of my WLC’s had received the new configuration with the three new trap receivers.

After manually testing a few WLC’s, I found that the community field had the name of the PI template, not the community string. The PI template did not ask for a community string, so it make sense that it didn’t have the correct community string.

After some digging and talking to Cisco; I found that even though the WLC asks you for a community string, that field does nothing. My monitoring team confirmed that they were receiving traps without a community string attached from the WLC’s.

I have found Cisco PI to be a very powerful piece of software for managing Cisco Wireless networks. In this case of updating the configuration on over 1,300 devices, PI saved me weeks of work.

Have you run into this same problem?
Please share a time when you used a management tool like PI to save you hours or days of work!!!

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