some of my devices are "unreachable" for CS discovery process, although they can be pinged, they can be reached by telnet, they can be polled by SNMP with the correct read community from the LMS server.
Enclosed you will find screenshots of CS and the versions of LMS modules we are using.
Thanks in advance for any hint.
Devices which are unreachable to Discovery cannot be contacted using the SNMP credentials configured in Discovery. Check the credentials you have configured under Common Services > Device and Credentials > Device Discovery. If in doubt, start a packet capture filtering on UDP port 161 traffic to one of the unreachable devices, then start a new Discovery. That will tell you exactly what is being used to contact the device.
Which snmp version is configured on the devices?
Where these devices reachable before?
If yes, you can test the community stored for theses devices by doing an "SNMP Walk" from Device Center, select the device from "Device Selector" and just adding "system" as the "Starting OID"
thank you for the reply. Although e.g. 172.18.18.241 is listed as unreachable after device discovery i will find it in every CW database (DCR, RME, Campus, DFM ...). The credentials in DCR must be correct, because I can successfully snmpwalk, telnet, ping the device from commandline.
So it isn't a severe problem, but discovery takes a lot of time (2h45min) because of many of these "unreachables".
snmpwalk from commandline is different as from Device Center. If you use the Device Center snmpwalk it uses the credentials stored in DCR for that device, you do not have to add them (beside the fact you want to test a specific string). If you have checked the device config you can test the community in DCR with this method. If it fails - there is a task in Device Center to modify credentials, - just retype what should ve correct.
The fact that theses devices are in every LMS application just says they were reachable in the past. If discovery marks these devices as unreachable something must have changed to prevent LMS from contacting the device through snmp.
Usually it is one of these things:
- the community in DCR is wrong
- the community on the device is wrong
- a new or changed ACL/firewall rule does not allow the traffic
- VRF or NAT configuration in the network changed
Please, retype the expected community for one device in DCR and try to snmpwalk to it from Device Center