I cannot add the new NE to my eSight topology and thus cannot monitor the device.
"The NE already exists"
After the NE has been added to eSight it was removed. After this operation the NE cannot be added to eSIght again because the ip address and mac-address are already stored in eSight database. The solution is to restart the server to clear all data from previous operations and then attempt to add the device again.
This failure occured becaus ethe NE has been added to eSight in the past.