DCX is running v6.4.3c. Search FOS Admin and Command Guides for TACACS config info.
Before anyone states TACACS+ is not supported with DCX see this tidbit which doesn't provide
any detail on any necessary config steps within the DCX:
first of all, NOS manuals are for foundries. if you want to do something to DCXes and other brocades, you should be looking for FOS manuals.
then, TACACS+ is only supported starting from 7.1, so you have to upgrade your 6.4.3c a little bit.
Fabric OS Administrator’s Guide
Slight correction. NOS is the operating system for our VDX portfolio. Not quite sure what the 'foundries' refers too, but wanted to point this out.