Brocade Mobility Access Point System Reference Guide (Supporting software release 5.5.0.0 and later) - Manual (Page 92)

82 Brocade Mobility Access Point System Reference Guide
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17. Select the Enable option within the 802.1x supplicant (client) feature to enable a username
and password pair to be used when authenticating users on this port. Select the Show option
to display the password being typed in the Password field.
18. Select the Spanning Tree tab.
Spanning Tree Protocol (STP) (IEEE 802.1D standard) configures a meshed network for robustness
by eliminating loops within the network and calculating and storing alternate paths to provide fault
tolerance.
STP calculation happens when a port comes up. As the port comes up and STP calculation happen,
the port is set to Blocked state. In this state, no traffic can pass through the port. Since STP
calculations take up to a minute to complete, the port is not operational there by effecting the
network behind the port. Once the STP calculation is complete, the port's state is changed to
Forwarding and traffic is allowed.
Rapid Spanning Tree Protocol (RSTP) (IEEE 802.1w standard) is an evolution over the standard STP
where the primary aim was to reduce the time taken to respond to topology changes while being
backward compatible with STP. PortFast quickly changes the port state from Blocked to
Forwarding toallow traffic while the STP calculation occurs.
Multiple Spanning Tree Protocol (MSTP) provides an extension to RSTP to optimize the usefulness
of VLANs. MSTP allows for a separate spanning tree for each VLAN group, and blocks all but one of
the possible alternate paths within each spanning tree topology.
If there is just one VLAN in the access point managed network, a single spanning tree works fine.
However, if the network contains more than one VLAN, the network topology defined by single STP
would work, but it is possible to make better use of the alternate paths available by using an
alternate spanning tree for different VLANs or groups of VLANs.
A MSTP supported deployment uses multiple MST regions with multiple MST instances (MSTI).
Multiple regions and other STP bridges are interconnected using one single common spanning tree
(CST)
MSTP includes all of its spanning tree information in a single Bridge Protocol Data Unit (BPDU)
format. BPDUs are used to exchange information bridge IDs and root path costs. Not only does this
reduce the number of BPDUs required to communicate spanning tree information for each VLAN,
but it also ensures backward compatibility with RSTP. MSTP encodes additional region information
after the standard RSTP BPDU as well as a number of MSTI messages. Each MSTI messages
conveys spanning tree information for each instance. Each instance can be assigned a number of
configured VLANs. The frames assigned to these VLANs operate in this spanning tree instance
whenever they are inside the MST region. To avoid conveying their entire VLAN to spanning tree
mapping in each BPDU, the access point encodes an MD5 digest of their VLAN to an instance table
in the MSTP BPDU. This digest is used by other MSTP supported devices to determine if the
neighboring device is in the same MST region as itself.
Max Reauthenticate Count Configures the number of times an attempt is made to reauthenticate a controlled port. When
exceeded, the controlled port is set as unauthorized.
Maximum Request Configures the number of times an attempt is made to authenticate with the EAP server before
returning an authentication failed message to the device requesting authorization using the
controlled port.
Quiet Period Configures the duration in seconds where no attempt is made to reauthenticate a controlled
port. Set a value from 0 - 65535 seconds.
Reauthentication Period Configures the duration after which a controlled port is forced to reauthenticate. Set a value from
0 - 65535 seconds.