General operation

When used, the encryption key (sometimes termed "key", "secret key", or "secret") helps to prevent unauthorized intruders on the network from reading username and password information in TACACS+ packets moving between the switch and a TACACS+ server. At the TACACS+ server, a key may include both of the following:

Global key:
A general key assignment in the TACACS+ server application that applies to all TACACS-aware devices for which an individual key has not been configured.
Server-Specific key:
A unique key assignment in the TACACS+ server application that applies to a specific TACACS-aware device.

NOTE:

Configure a key in the switch only if the TACACS+ server application has this exact same key configured for the switch. That is, if the key parameter in switch "X" does not exactly match the key setting for switch "X" in the TACACS+ server application, then communication between the switch and the TACACS+ server will fail.

Thus, on the TACACS+ server side, you have a choice as to how to implement a key. On the switch side, it is necessary only to enter the key parameter so that it exactly matches its counterpart in the server. For information on how to configure a general or individual key in the TACACS+ server, see the documentation you received with the application.