Dell Brocade DCX, Configuration Manual

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BigIron RX Series Configuration Guide 957
53-1001810-01
How 802.1x port security works
33
Message exchange during authentication
Figure 123 illustrates a sample exchange of messages between an 802.1x-enabled Client, a
BigIron RX acting as Authenticator, and a RADIUS server acting as an Authentication Server.
FIGURE 123
Message exchange between Client/Supplicant, Authenticator, and Authentication Server
In this example, the Authenticator (the BigIron RX device) initiates communication with an
802.1x-enabled Client. When the Client responds, it is prompted for a username (255 characters
maximum) and password. The Authenticator passes this information to the Authentication Server,
which determines whether the Client can access services provided by the Authenticator. When the
Client is successfully authenticated by the RADIUS server, the port is authorized. When the Client
logs off, the port becomes unauthorized again.
Brocade ’s 802.1x implementation supports dynamic VLAN assignment . If one of the attributes in
the Access-Accept message sent by the RADIUS server specifies a VLAN identifier, and this VLAN is
available on the
BigIron RX device, the client’s port is moved from its default VLAN to the specified
VLAN. When the client disconnects from the network, the port is placed back in its default VLAN.
Refer to
“Configuring dynamic VLAN assignment for 802.1x ports” on page 962 for more
information.
Brocade ’s 802.1x implementation supports dynamically applying an IP ACL or MAC address filter to
a port, based on information received from the Authentication Server.
If a Client does not support 802.1x, authentication cannot take place. The device sends
EAP-Request/Identity frames to the Client, but the Client does not respond to them.
When a Client that supports 802.1x attempts to gain access through a non-802.1x-enabled port, it
sends an EAP start frame to the
BigIron RX device. When the device does not respond, the Client
considers the port to be authorized, and starts sending normal traffic.
RADIUS Server
(Authentication Server)
BigIron Device
(Authenticator)
Client/Supplicant
Port Unauthorized
EAP-Response/Identity
EAP-Request/Identity
EAP-Response/Identity
EAP-Request/MD5-Challenge
EAP-Success
EAP-Logoff
Port Authorized
Port Unauthorized
RADIUS Access-Request
RADIUS Access-Challenge
RADIUS Access-Request
RADIUS Access-Accept