> # About Vendor-Specific Attributes

> The Internet Engineering Task Force (IETF) draft standard specifies a method for communicating vendor-specific attributes (VSAs) between the network access server and the RADIUS server. The IETF uses attribute 26. VSAs allow vendors to support their own extended attributes that are not suitable for general use. The Cisco RADIUS implementation supports one vendor-specific option using the format recommended in the specification. The Cisco vendor ID is 9, and the supported option is vendor type 1, which is named cisco-avpair. The value is a string with the following format:

>     protocol : attribute separator value *

> Where protocol is a Cisco attribute for a particular type of authorization, separator is `=` (equal sign) for mandatory attributes, and `*` (asterisk) is for optional attributes.

> When you use RADIUS servers to authenticate yourself to a Cisco MDS 9000 Family switch, the RADIUS protocol directs the RADIUS server to return user attributes, such as authorization information, along with authentication results. This authorization information is specified through VSAs.

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