TACACS+ Authenticates one account but no others.

[crbishop111]

I have a large network consisting of around 300 layer 2 switches and 5 ITNs. We have TACACS+ installed and have been using it for authentication for years. Just recently, our TACACS+ has begun getting the following error:

"%SEC_LOGIN-4-LOGIN_FAILED: Login failed [user: XXXXXXX] [Source: xxx.xxx.xxx.xxx] [localport: 22] [Reason: Login Authentication Failed] at 07:54:21 CST Thu Jun 23 2016"

This error occurs on about 80% of the switches on the network, but the other 20% authenticate and log in just fine.

If I use the TACACS+ account we have made for our Cisco Prime server to login to switches, it authenticates on every one. The TACACS+ configurations are identical on all devices, so I don't understand what could be the issue. Why would one TACACS+ user account authenticate just fine, but the others only authenticate on 20% of the network.

Our version of ACS is 5.5

Thanks for any help!

[nspasov]

I am not sure I understand the description of the problem completely. Is the user failing the authentication the same as your Prime user?

Thank you for rating helpful posts!

[crbishop111]

The Prime user account authenticates successfully on every network device. All other individual TACACS+ accounts only succeed on about 20% of the network devices, even though they all have the same TACACS+ configuration.