SNMP community names are similar to passwords. SMS Network Discovery uses community names to gain access to routers that are SNMP devices. Gaining access to a router informs Network Discovery about the other routers and subnets linked to the first router. Network Discovery can get information only from an SNMP device for which you have specified a community name.
Each SNMP device can have its own community name, but usually the same community name is shared among several devices. If you do not know the community names used by the SNMP devices in your network, ask your network administrator.
Most SNMP devices have a default community name of "public" (in addition to any others they have). If you do not know any other community names, you can use "public". However, some organizations delete "public" from their devices' lists of community names as a security precaution.
Configure Network Discovery
Network Discovery Overview