CSPC 2.7 CDP discovery not working on some devices

[mark.miller]

I'm running CSPC 2.7 and have successfully run a CDP discovery for one of my sites when using the core switches as the seed devices.  I then tried to run a CDP discovery at two additional sites and the only thing that was discovered was the core switch used as the seed device, but nothing else.  There were no failed devices either, it simply failed to discovery any additional ones.  If I re-ran the discovery using a seed device connected to the core switch, I again only discovered the seed device, but not the core switch.  Hop count was set to 15 during all discoveries.

To make sure the collector was working properly, I went back and re-ran a discovery again at my original site via CDP and it again successfully discovered the devices at that site.  I have also restarted the collector an re-run discovery which again, only discovered the seed device.  

Are there any troubleshooting steps that I can follow to determine why the devices are not being discovered?

[taywelch]

Hey Mark, 

Can you check and make sure CDP is enabled in the environment that you are trying to discover?

Thanks, 

Taylor 

[mark.miller]

Taylor,

I checked from the core switch and I can see the following devices via sh cdp neigh

• (2) Routers
• (2) Access Points

I was able to logon to both routers and run sh cdp neigh and see the core switch they are connected to.

thanks.

[taywelch]

Hey Mark, 

Can you run a discovery on just the core switch with the CDP protocol enabled with a hop count of 4?  If this still fails you will need to double check the SNMP credentials on the core switch neighbors. 

Thanks,

Taylor

[mark.miller]

Taylor,

My issue appears to be partly related to SNMP.  I have Enable CLI Discovery enabled in my Discovery Settings, which should allow discovery when SNMP discovery fails.

For my original site, I didn't have SNMP allowed from the collector and it successfully discovered everything via CLI.

For my next site, I had to add the IP address of my collector to the SNMP ACL on the core switch and then it was able to discover everything at the site via CDP.  However, I did not add the collector IP address to either of the router ACLs and they were discovered as were the access points.  The access points should have been discovered regardless because they have no ACLs to prohibit access.

The main difference between the core switches at the sites is that the one that worked are N3Ks and the one that didn't are C3850s.

Even with SNMP prohibited via ACL, should the devices not have been discovered via CLI?  Trying to understand why one site worked versus the other.

thanks.

[taywelch · Accepted solution]

Hi Mark, 

Thank you for the additional details on your issue. CLI discovery is used for other services (Advance services), and the collector does require SNMP for discoveries on all devices. 

Thanks, 

Taylor 

[mark.miller]

Taylor,

Thanks for the explanation.  I don't think it was articulated that well in the documentation which is what caused the initial concern.