need this feature, choose TACACS+. For more information on the differences between TACACS+ and RADIUS, see Cisco's document ID 13838 (http://www.cisco.com/en/US/tech/tk59/tech nologies_tech_note09186a0080094e99.shtml) Chapter 26: Authentication in Cisco Devices Nexus switches seem to be more geared toward open standards. For example, in NX- OS, RADIUS is enabled by default while TACACS+ must be enabled with the feature tacacs+ command. To use a security server, you must configure server groups. Server groups are logical groups of servers that can be referenced with a single name. You can use default server groups or create your own custom groups. Default RADIUS and TACACS+ server groups TACACS+ servers are defined globally in a router with the tacacs-server command. You define where to find a TACACS+ server with the host keyword: tacacs-server host 10.100.100.100 A hostname can be used, provided that you have configured DNS on the router. You can also list multiple servers, in which case they will be referenced in the order in which they appear: tacacs-server host 10.100.100.100 tacacs-server host 10.100.100.101 The router will query the second server in the list only if the first server returns an error or is unavailable. A login failure is not considered an error. Many installations require a secure key to be sent with the query. This key, which functions like a password for the server itself (as opposed to the user being authenti- cated), is configured through the tacacs-server command with the key keyword: tacacs-server key Secret The password will be stored in the configuration as plain text unless you have the password-encryption service enabled. With the password encrypted, the password line ends up looking like this: tacacs-server key 7 01200307490E12 In NX-OS, all of these steps can be combined into one command. Here, I create both servers with one command each: NX-7K-1-Cozy(config)# tacacs-server host 10.100.100.100 key Secret NX-7K-1-Cozy(config)# tacacs-server host 10.100.100.101 key Secret RADIUS ser