Sunday, 14 Jul 2024

Compare TACACS+ and RADIUS


Are you looking for robust security protocols to control access into your networks? Look no further! In this article, we will compare two widely used security protocols: TACACS+ and RADIUS. Understanding the differences between these protocols will help you make an informed decision and choose the one that best suits your needs.

Background Information

Before we dive into the comparison, let’s learn a little about TACACS+ and RADIUS. Cisco has been supporting RADIUS since February 1996 and continues to enhance it with new features and capabilities. On the other hand, TACACS+ was developed by Cisco to meet the evolving market demands. It was designed to scale as networks grow and adapt to new security technologies.



RADIUS uses UDP, while TACACS+ uses TCP. TCP offers several advantages such as a connection-oriented transport and immediate indication of server crashes or stops. TCP is also more scalable and adaptable to network size and congestion.

Packet Encryption

RADIUS only encrypts the password in the access-request packet, leaving the rest of the packet unencrypted. TACACS+ encrypts the entire packet for more secure communication.

Authentication and Authorization

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RADIUS combines authentication and authorization, making it difficult to decouple the two. TACACS+ follows the AAA architecture, allowing separate authentication solutions while using TACACS+ for authorization and accounting.

Multiprotocol Support

TACACS+ offers multiprotocol support, whereas RADIUS does not support certain protocols like ARA, NetBIOS, NASI, and X.25 PAD connection.

Router Management

TACACS+ provides more flexibility for router management and terminal services by allowing control over which commands can be executed on a router. RADIUS lacks this feature.


Interoperability can be an issue with RADIUS due to various interpretations of the RFCs. However, Cisco implements most RADIUS attributes, guaranteeing better interoperability as long as vendors implement the same attributes.


TACACS+ and RADIUS generate different amounts of traffic due to their inherent differences. TACACS+ generates more traffic but provides additional features like command authorization and accounting, which RADIUS does not support.

Device Support

The table below shows TACACS+ and RADIUS AAA support by device type for selected platforms. Please refer to the product release notes for complete information.

Device Support

Frequently Asked Questions

Q: Which protocol is more secure, TACACS+ or RADIUS?
A: Both TACACS+ and RADIUS offer security features. However, TACACS+ provides a higher level of security by encrypting the entire packet.

Q: Can RADIUS be used for router management?
A: RADIUS is not as useful for router management as TACACS+ because it does not allow users to control which commands can be executed on a router.

Q: Does TACACS+ support multiprotocol?
A: Yes, TACACS+ offers multiprotocol support, allowing it to handle various protocols.

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In conclusion, both TACACS+ and RADIUS are widely used security protocols, but they differ in several key aspects. TACACS+ offers better security, router management capabilities, and multiprotocol support. On the other hand, RADIUS has its advantages, such as easier interoperability. Assess your network requirements and choose the protocol that best aligns with your needs.

For more information about TACACS+ and RADIUS, visit the Eireview website.


  • RADIUS Support
  • TACACS/TACACS+ Support / Authentication Protocols
  • Requests for Comments (RFCs)
  • Cisco Technical Support & Downloads