AAA Protocols : RADIUS and TACACS+



Networks need to be protected against any unknown access. In other words, network administrators need to control the users that can access to the network. They need to check who they are, what are they allowed for and what did they do. These three questions are the main explanation of AAA (Authentication, Authorization, Accounting). There are some protocols are used for this purposes. The two common ones are TACACS+ and RADIUS. In this lesson we will see, TACACS vs RADIUS.

Authentication : Who are you?
Authorization : What do you allowed to do?
Accounting : What did you do?

There is also another AAA protocol called “Diameter” that we will talk about later. Here, we will focus on RADIUS and TACACS+.

RADIUS is the abbreviation of “Remote Access Dial-In User Service” and TACACS+ is the abviation of “Terminal Access Controller Access-Control System”. As you see, it is better to use abbreviations and you will always come across the abraviations not the whole name.

You can find the main differences between RADIUS and TACACS+ in the below table. In the following RADIUS and TACACS+ lessons, we will discuss these AAA Protocols and their characteristics detaily.



Generally these two protocols are used at the same time in the networks if we compare tacacs vs radius. Because, the have their own common duties and all of these duties are very common for a network.

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