> # AAA Service Configuration Options

> AAA configuration in Cisco MDS 9000 Family switches is service based. You can have separate AAA configurations for the following services:

> - Telnet or SSH login (DCNM-SAN and Device Manager login)
> - Console login
> - iSCSI authentication (see the IP Services Configuration Guide, Cisco DCNM for SAN).
> - FC-SP authentication (see "Configuring FC-SP and DHCHAP").
> - Accounting

> In general, server group, local, and none are the three options that can be specified for any service in an AAA configuration. Each option is tried in the order specified. If all the options fail, local is tried.

> Caution | Cisco MDS NX-OS supports user names that are created with alphanumeric characters or specific special characters (+ [plus], = [equal], _ [underscore], - [hyphen] , \ [backslash], and . [period]) whether created remotely (using TACACS+ or RADIUS) or locally, provided the user name starts with an alphabetical character. Local user names cannot be created with all numbers or with any special characters (apart from those specified). If a numeric-only user name or a non-supported special character user name exists on an AAA server, and is entered during login, then the user is denied access.

> Note Even if local is not specified as one of the options, it is tried by default if all AAA servers configured for authentication are unreachable. User has the flexibility to disable this fallback (See section "Configuring Fallback Mechanism for Authentication" topic).

> When RADIUS times out, local login is attempted depending on the fallback configuration. For this local login to be successful, a local account for the user with the same password should exist, and the RADIUS timeout and retries should take less than 40 seconds. The user is authenticated if the username and password exist in the local authentication configuration.

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