SNMPv3 and End Host Discovery:
ENA may not be able to discover all end host information from devices being managed via SNMPv3, due to a lack of support for VLANs in the SNMP agent of the device. Only end hosts (MACs) on default VLANs are discovered. This is a known limitation in several device agents, including Cisco.
A lack of end-host information can have the following impacts:
- maps may not be able to accurately determine uplink connections between layer 2 switches and layer 3.
- End Host Configuration Changes may not be detected.
You can configure some newer SNMPv3 Cisco devices to provide VLAN information using SNMPv3 contexts. For example, the following command configures a device to automatically create an SNMPv3 context for each VLAN:
snmp-server group mygroup V3 auth context vlan- match prefix read
myread write mywrite notify mynotify
For older Cisco devices you can explicitly configure a context for each VLAN, for example:
snmp-server group mygroup v3 noauth context vlan-99
Consult the device documentation on which command is appropriate for a particular device.
When you have configured these devices, ENA will use SNMPv3 contexts to extract VLAN host information.
You can change the vlan- prefix by setting snmpVlanContextPrefix in entuity_home\entuity.cfg, for example:
If a device does not support SNMPv3 contexts, then to access the VLAN host information you could manage the device using SNMPv2.