TrustSec Architecture
The Cisco TrustSec solution establishes clouds of trusted network devices to build secure networks. Each device in the Cisco TrustSec cloud is authenticated by its neighbors (peers). Communication between the devices in the TrustSec cloud is secured with a combination of encryption, message integrity checks, and data-path replay protection mechanisms. The TrustSec solution uses the device and user identity information that it obtains during authentication to classify, or color, the packets as they enter the network. This packet classification is maintained by tagging packets when they enter the TrustSec network so that they can be properly identified for the purpose of applying security and other policy criteria along the data path. The tag, also called the security group tag (SGT), allows Cisco ISE to enforce access control policies by enabling the endpoint device to act upon the SGT to filter traffic.
The following figure shows an example of a TrustSec network cloud.

For information on how to simplify network segmentation and improve security using Cisco TrustSec, see Simplify Network Segmentation with Cisco TrustSec and Policy-Based Software Defined Segmentation and Cisco TrustSec Improve Security White Paper. For a complete list of Cisco TrustSec platform support matrices, see Cisco TrustSec Platform Support Matrix. For a complete list of support documentation available for TrustSec, see Cisco TrustSec. For a complete list of TrustSec community resources, see TrustSec Community. |
TrustSec Components
The key TrustSec components include:
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Network Device Admission Control (NDAC)—In a trusted network, during authentication, each network device (for example Ethernet switch) in a TrustSec cloud is verified for its credential and trustworthiness by its peer device. NDAC uses the IEEE 802.1X port-based authentication and uses Extensible Authentication Protocol-Flexible Authentication via Secure Tunneling (EAP-FAST) as its Extensible Authentication Protocol (EAP) method. Successful authentication and authorization in the NDAC process results in Security Association Protocol negotiation for IEEE 802.1AE encryption. Cisco ISE has CTS Provisioning (EAP-FAST) TLSv1.2 support for switching platforms starting IOSXE 17.1, and for routing platforms starting IOSXE 17.6.
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Endpoint Admission Control (EAC)—An authentication process for an endpoint user or a device connecting to the TrustSec cloud. EAC typically happens at the access level switch. Successful authentication and authorization in EAC process results in SGT assignment to the user or device. EAC access methods for authentication and authorization includes:
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802.1X port-based authentication
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MAC authentication bypass (MAB)
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Web authentication (WebAuth)
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Security Group (SG)—A grouping of users, endpoint devices, and resources that share access control policies. SGs are defined by the administrator in Cisco ISE. As new users and devices are added to the TrustSec domain, Cisco ISE assigns these new entities to the appropriate security groups.
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Security Group Tag (SGT)—TrustSec service assigns to each security group a unique 16-bit security group number whose scope is global within a TrustSec domain. The number of security groups in the switch is limited to the number of authenticated network entities. You do not have to manually configure security group numbers. They are automatically generated, but you have the option to reserve a range of SGTs for IP-to-SGT mapping.
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Security Group Access Control List (SGACL)—SGACLs allow you to control the access and permissions based on the SGTs that are assigned. The grouping of permissions into a role simplifies the management of security policy. As you add devices, you simply assign one or more security groups, and they immediately receive the appropriate permissions. You can modify the security groups to introduce new privileges or restrict current permissions.
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Security Exchange Protocol (SXP)—SGT Exchange Protocol (SXP) is a protocol developed for TrustSec service to propagate the IP-SGT bindings across network devices that do not have SGT-capable hardware support to hardware that supports SGT/SGACL.
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Environment Data Download—The TrustSec device obtains its environment data from Cisco ISE when it first joins a trusted network. You can also manually configure some of the data on the device. The device must refresh the environment data before it expires. The TrustSec device obtains the following environment data from Cisco ISE:
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Server lists—List of servers that the client can use for future RADIUS requests (for both authentication and authorization)
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Device SG—Security group to which the device itself belongs
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Expiry timeout—Interval that controls how often the TrustSec device should download or refresh its environment data
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Identity-to-Port Mapping—A method for a switch to define the identity on a port to which an endpoint is connected, and to use this identity to look up a particular SGT value in the Cisco ISE server.
TrustSec Terminology
The following table lists some of the common terms that are used in the TrustSec solution and their meaning in an TrustSec environment.
Term |
Meaning |
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Supplicant |
A device that tries to join a trusted network. |
Authentication |
The process of verifying the identity of each device before allowing it to be part of the trusted network. |
Authorization |
The process of deciding the level of access to a device that requests access to a resource on a trusted network based on the authenticated identity of the device. |
Access control |
The process of applying access control on a per-packet basis based on the SGT that is assigned to each packet. |
Secure communication |
The process of encryption, integrity, and data-path replay protection for securing the packets that flow over each link in a trusted network. |
TrustSec device |
Any of the Cisco Catalyst 6000 Series or Cisco Nexus 7000 Series switches that support the TrustSec solution. |
TrustSec-capable device |
A TrustSec-capable device will have TrustSec-capable hardware and software. For example, the Nexus 7000 Series Switches with the Nexus operating system. |
TrustSec seed device |
The TrustSec device that authenticates directly against the Cisco ISE server. It acts as both the authenticator and supplicant. |
Ingress |
When packets first encounter a TrustSec-capable device that is part of a network where the Cisco TrustSec solution is enabled, they are tagged with an SGT. This point of entry into the trusted network is called the ingress. |
Egress |
When packets pass the last TrustSec-capable device that is part of a network where the Cisco TrustSec solution is enabled, they are untagged. This point of exit from the trusted network is called the egress. |
Supported Switches and Required Components for TrustSec
To set up a Cisco ISE network that is enabled with the Cisco TrustSec solution, you need switches that support the TrustSec solution and other components. Apart from the switches, you also need other components for identity-based user access control using the IEEE 802.1X protocol. For a complete up-to-date list of the Trustsec-supported Cisco switch platforms and the required components, see Cisco TrustSec-Enabled Infrastructure.