Catalyst 4500 Series Switch Software Configuration Guide, IOS XE 3.7.xE and IOS 15.2(3)Ex

MKA Policies

You apply a defined MKA policy to an interface to enable MKA on the interface. Removing the MKA policy disables MKA on that interface. You can configure these options:

• Policy name, not to exceed 16 ASCII characters.
• Confidentiality (encryption) offset of 0, 30, or 50 bytes for each physical interface.
• Replay protection. You can configure MACsec window size, as defined by the number of out-of-order frames that are accepted. This value is used while installing the security associations in the MACsec. A value of 0 means that frames are accepted only in the correct order.

Note MKA is not supported in the Virtual Switching System (VSS) mode.

Virtual Ports

You use virtual ports for multiple secured connectivity associations on a single physical port. Each connectivity association (pair) represents a virtual port, with a maximum of two virtual ports per physical port. Only one of the two virtual ports can be part of a data VLAN; the other must externally tag its packets for the voice VLAN. You cannot simultaneously host secured and unsecured sessions in the same VLAN on the same port. Because of this limitation, 802.1X multiple authentication mode is not supported.

The exception to this limitation is in multiple-host mode when the first MACsec supplicant is successfully authenticated and connected to a hub that is connected to the switch. A non-MACsec host connected to the hub can send traffic without authentication because it is in multiple-host mode. We do not recommend using multi-host mode because after the first successful client, authentication is not required for other clients.

Virtual ports represent an arbitrary identifier for a connectivity association and have no meaning outside the MKA Protocol. A virtual port corresponds to a separate logical port ID. Valid port IDs for a virtual port are 0x0002 to 0xFFFF. Each virtual port receives a unique secure channel identifier (SCI) based on the MAC address of the physical interface concatenated with a 16-bit port ID.

MACsec

A Catalyst 4500 series switch running MACsec maintains the configuration files that show which ports on a member switch support MACsec. The stack master performs these functions:

• Processes secure channel and secure association creation and deletion.
• Sends secure association service requests to the stack members.
• Processes packet number and replay-window information from local or remote ports and notifies the key management protocol.
• Sends MACsec initialization requests with the globally configured options to new switches that are added to the stack.
• Sends any per-port configuration to the member switches.

A member switch performs these functions:

• Processes MACsec initialization requests from the stack master.
• Processes MACsec service requests sent by the stack master.
• Sends information about local ports to the stack master.

MACsec, MKA, and 802.1X Host Modes

You can use MACsec and the MKA Protocol with 802.1X single-host mode, multiple-host mode, or Multi Domain Authentication (MDA) mode. Multiple authentication mode is not supported.

Single-Host Mode

MACsec in Single-Host Mode with a Secured Data Session shows how a single EAP authenticated session is secured by MACsec using MKA.

Figure 45-1 MACsec in Single-Host Mode with a Secured Data Session

Multiple-Host Mode

In standard (not 802.1X-2010) 802. multiple-host mode, a port is open or closed based on a single authentication. If one user, the primary secured client services client host, is authenticated, the same level of network access is provided to any host connected to the same port. If a secondary host is a MACsec supplicant, it cannot be authenticated and traffic would no flow. A secondary host that is a non-MACsec host can send traffic to the network without authentication because it is in multiple-host mode. See .

Figure 45-2 MACsec in Standard Multiple-Host Mode - Unsecured

We do not recommend using multi-host mode because after the first successful client, authentication is not required for other clients, which is not secure.

MKA Statistics

Some MKA counters are aggregated globally, while others are updated both globally and per session. You can also obtain information about the status of MKA sessions.

This is an example of the show mka statistics command output:

For description of the output fields, see the command reference for this release.

Default MACsec MACsec Key Agreement Configuration

MACsec is disabled. No MACsec Key Agreement (MKA) policies are configured.

Configuring an MKA Policy

To create an MKA Protocol policy, perform this task. Note that MKA also requires that you enable 802.1X.

This example configures the MKA policy relay-policy :

Let's say that we configure an MKA policy as follows:

We observe the following:

• The payload starting from the SA (source MAC address) + 50 bytes offset is encrypted.
• Replay protect is YES with a window size of 1000. If the frame received has a packet number (PN) of 1020, for example, all frames with a PN of 20 to 1020 can come out of order (i.e, frame with PN 900 can come first and frame with PN 800 can come later). However, if a frame with a PN of 1021 is received first, followed by a frame with a PN of 20, the frame with PN of 20 is dropped. In this scenario, the expected PN is 1022 and the window size is 1000, so the acceptable PN number is anything greater than or equal to (expected PN - window size) = 22. So, any frame with PN < 22 is dropped.

To apply the MKA protocol default policy on an interface, use the mka default-policy interface configuration command. This command also enables MKA on the interface if no MKAs were applied.

When we configure the MKA default policy, all the values in the policy (such as confidentiality, offset, and replay protection) take the default values. For example,

• Confidentiality offset is 0—Encrypts the payload that is immediately after the SA (source MAC address).
• Replay protect is YES with window size 0—Frames cannot come out of order.

Configuring MACsec on an Interface

To configure MACsec on an interface with one MACsec session for voice and one for data, perform this task:

This is an example of configuring and verifying MACsec on an interface:

Configuring Cisco TrustSec Credentials on the Switch

To enable Cisco TrustSec features, you must create Cisco TrustSec credentials on the switch to use in other TrustSec configurations.

To configure Cisco TrustSec credentials, perform this task:

To delete the Cisco TrustSec credentials, enter the clear cts credentials privileged EXEC command.

This example shows how to create Cisco TrustSec credentials:

Note Before you configure Cisco TrustSec MACsec authentication, you should configure Cisco TrustSec seed and non-seed devices. For 802.1X mode, you must configure at least one seed device, that device closest to the access control system (ACS). See this section in the Cisco TrustSec Switch Configuration Guide:

http://www.cisco.com/en/US/docs/switches/lan/trustsec/configuration/guide/trustsec.html

Configuring Cisco TrustSec Switch-to-Switch Link Security in 802.1X Mode

You enable Cisco TrustSec link layer switch-to-switch security on an interface that connects to another Cisco TrustSec device. When configuring Cisco TrustSec in 802.1X mode on an interface, follow these guidelines:

• To use 802.1X mode, you must globally enable 802.1X on each device.
• If you select GCM as the SAP operating mode, you must have a MACsec encryption software license from Cisco.

Note MACsec is supported on the Catalyst 4500 series switch universal k9 image. It is not supported with the NPE license or with a LAN Base service image.

If you select GCM without the required license, the interface is forced to a link-down state.

To configure Cisco TrustSec switch-to-switch link layer security with 802.1X, perform this task:

	Command	Purpose
Step 1	configure terminal	Enters global configuration mode.
Step 2	interface interface-id	Enters interface configuration mode.
Step 3	cts dot1x	Configures the interface to perform NDAC authentication.
Step 4	sap mode-list mode1 [ mode2 [ mode3 [ mode4 ]]]	(Optional) Configures the SAP operation mode on the interface. The interface negotiates with the peer for a mutually acceptable mode. Enter the acceptable modes in your order of preference. Choices for mode are: gcm-encrypt —Authentication and encryption Note Select this mode for MACsec authentication and encryption if your software license supports MACsec encryption. gmac —Authentication, no encryption no-encap —No encapsulation null —Encapsulation, no authentication or encryption Note If the interface is not capable of data link encryption, no-encap is the default and the only available SAP operating mode. SGT is not supported.
Note Although visible in the CLI help, the timer reauthentication and propagate sgt keywords are not supported. However, the no propagate sgt keyword is supported (refer to Step 5 in the next section).
Step 5	exit	Exits Cisco TrustSec 802.1X interface configuration mode.
Step 6	end	Returns to privileged EXEC mode.
Step 7	show cts interface [ interface-id | brief | summary ]	(Optional) Verifies the configuration by displaying TrustSec-related interface characteristics.
Step 8	copy running-config startup-config	(Optional) Saves your entries in the configuration file.

This example shows how to enable Cisco TrustSec authentication in 802.1X mode on an interface using GCM as the preferred SAP mode:

Configuring Cisco TrustSec Switch-to-Switch Link Security in Manual Mode

If your switch does not have access to an authentication server or if 802.1X authentication is not needed, you can manually configure Cisco TrustSec on an interface. You must manually configure the interface on each end of the connection.

When manually configuring Cisco TrustSec on an interface, consider these usage guidelines and restrictions:

• If no SAP parameters are defined, neither encryption nor MACsec Encapsulation are performed.
• If you select GCM as the SAP operating mode, you must have a MACsec Encryption software license from Cisco. If you select GCM without the required license, the interface is forced to a link-down state.
• These protection levels are supported when you configure SAP pairwise master key ( sap pmk ):

– SAP is not configured—no protection.

– sap mode-list gcm-encrypt gmac no-encap —protection desirable but not mandatory.

– sap mode-list gcm-encrypt gmac— confidentiality preferred and integrity required. The protection is selected by the supplicant according to supplicant preference.

– sap mode-list gmac —integrity only.

– sap mode-list gcm-encrypt —confidentiality required.

– sap mode-list gmac gcm-encrypt —integrity required and preferred, confidentiality optional.

To manually configure Cisco TrustSec on an interface to another Cisco TrustSec device, perform this task:

This example shows how to configure Cisco TrustSec authentication in manual mode on an interface:

Cisco TrustSec Switch-to-Switch Link Security Configuration Example

This example shows the configuration necessary for a seed and non-seed device for Cisco TrustSec switch-to-switch security. You must configure the AAA and RADIUS for link security. In this example, ACS-1 through ACS-3 can be any server names and cts-radius is the Cisco TrustSec server.

Seed Device Configuration:

Non-Seed Device: