AAA (Cisco Device and ISE Specific)

When discussing AAA (Authentication, Authorization, and Accounting) in the context of ISE (Identity Services Engine) and Cisco devices, it’s essential to understand that AAA is a framework for intelligently controlling access to computer resources, enforcing policies, auditing usage, and providing the information necessary to bill for services. These processes are crucial for network security and management. As a product offered by Cisco, ISE provides a centralized, comprehensive solution to these needs. Here’s a detailed breakdown of each component within AAA:


Authentication is verifying the identity of a user or device attempting to access a system. It’s the first step in the AAA framework, ensuring that only authenticated users or devices can access network resources. Authentication can be based on something the user knows (like a password), something the user has (such as a smart card or a token), something the user is (utilizing biometrics), or a combination of these for multi-factor authentication.

In the context of ISE and Cisco devices, ISE acts as a centralized authentication server that supports multiple authentication protocols (e.g., RADIUS, TACACS+). It allows network devices to verify the identity of users or devices by checking credentials against a database, which could be internal to ISE or external sources like Active Directory.


Once authentication is successfully completed, authorization determines what resources the authenticated user or device is allowed to access and what operations they are permitted to perform. Authorization is policy-based; administrators can define policies that specify access levels and permissions for different users or devices.

ISE plays a key role in authorization by enabling administrators to create and manage policies centrally. These policies can be very granular, controlling access based on various attributes such as user role, device type, location, and time of access. ISE dynamically applies these policies across the network, ensuring that users or devices only have access to the resources necessary for their roles.


Accounting involves tracking the activities of users and devices on the network and recording this information for billing, auditing, and reporting purposes. This includes details about when users or devices access the network, the duration of each session, what resources were accessed, and any changes made during the session.

ISE facilitates detailed accounting by collecting and logging this information, allowing administrators to monitor network usage, identify potential security breaches, and comply with regulatory requirements. The data collected can also be used for capacity planning, network analysis, and billing purposes.

ISE and Cisco Devices Integration

Cisco devices, such as routers, switches, and firewalls, are configured to communicate with ISE using protocols like RADIUS or TACACS+. When a user or device attempts to access the network, the Cisco device forwards the authentication request to ISE. ISE then authenticates the user or device, determines the appropriate access level based on predefined policies, and communicates this information back to the device, which enforces the access controls.

The integration of ISE with Cisco devices provides a robust, scalable, and flexible solution for managing access to network resources. It simplifies the administration of network policies, enhances security by ensuring only authorized access, and provides valuable insights into network usage and behavior.

In summary, AAA in the context of ISE and Cisco devices forms a powerful framework for securing and managing network access. By centralizing the functions of authentication, authorization, and accounting, ISE helps organizations to enforce security policies, comply with regulatory requirements, and optimize their network resources.

What about Microsoft Windows AD (Common)

In the context of AAA (Authentication, Authorization, and Accounting) and its application to network security and management, especially when considering ISE (Identity Services Engine) by Cisco, Windows Active Directory (AD) and AD accounts and groups primarily fit into the Authentication and Authorization phases. Here’s how they integrate into each phase:

Authentication Phase

Windows Active Directory (AD) is a directory service developed by Microsoft for Windows domain networks. It is primarily used for authenticating and authorizing users and computers within a Windows domain. In the Authentication phase, when a user attempts to access the network, their credentials (such as username and password) are checked against the information stored in AD. If the credentials match, the user is authenticated and allowed to proceed. In the context of ISE, it can integrate with AD to use it as an external identity store. This means that ISE can query AD to verify users’ credentials when authentication requests are made.

Authorization Phase

After a user is authenticated, the Authorization phase determines what resources they can access and what operations they can perform. AD groups play a crucial role in this phase. Groups in AD are used to collect user accounts, computer accounts, and other groups into manageable units. Administrators can assign permissions and rights to a group instead of to individual users, making it easier to manage access controls.

In ISE, after a user is authenticated using AD credentials, ISE can retrieve the user’s group memberships from AD. These group memberships can then be used in the authorization policies to determine the level of access and permissions the user should have on the network. For example, members of an “IT Administrators” group in AD might be granted broader access to network resources and capabilities than members of a “Standard Users” group.

Integration Summary

  • In the Authentication phase, Windows AD provides a centralized and secure repository for user credentials and identity information. ISE leverages this by allowing administrators to use AD as an identity source for authenticating users and devices on the network.
  • In the Authorization phase, AD accounts, especially groups, are used to define and manage access levels and permissions. ISE can use information about a user’s group memberships in AD to make dynamic authorization decisions, ensuring that users have appropriate access rights based on their roles and responsibilities.

This integration showcases how ISE, in conjunction with Windows AD, provides:

  • A comprehensive solution for managing access to network resources.
  • Enforcing security policies.
  • Only authenticated and authorized users and devices can access sensitive information and systems.