3Com 3CRWX120695A, 3CRWX440095A Configuration Manual page 121

Distributed MAPs and STP
A Distributed MAP is a leaf device. You do not need to enable STP on the
port that is directly connected to the MAP.
If Spanning Tree Protocol (STP) is enabled on the port that is directly
connected to a Distributed MAP, you might need to change the STP
configuration on the port, to allow the MAP to boot.
STP on a port directly connected to a Distributed MAP can prevent the
MAP from booting.
As part of the boot process, a MAP disables and reenables the link on the
port over which the MAP is attempting to boot. If STP is enabled on the
device that is directly connected to the port, the link state change can
cause the port on the other device to leave the forwarding state and stop
forwarding traffic. The port remains unable to forward traffic for the
duration of the STP forwarding delay.
A MAP waits 30 seconds to receive a reply to its DHCP Discover message,
then tries to boot using the other MAP port. If the boot attempt fails on
the other port also, the MAP then reattempts to boot on the first port.
The process continues until a boot attempt is successful. If STP prevents
the other device's port from forwarding traffic during each boot attempt,
the MAP repeatedly disables and reenables the link, causing STP to
repeatedly stop the other device's port from forwarding traffic. As a
result, the boot attempt is never successful.
To allow a MAP to boot over a link that has STP enabled, do one of the
following on the other device:
Disable STP on the other device's port.
Enable the port fast convergence feature, if supported, on the other
device's port. (On some vendors' devices, this feature is called
PortFast.)
If the other device is running Rapid Spanning Tree or Multiple
Spanning Tree, set the port into edge port mode.
MAP Parameters
Table 8 summarizes parameters that apply to individual MAP access
points, including dual-homing parameters. (For information about
parameters for individual radios, see "Configuring a Radio Profile" on
page 147 and "Configuring Radio-Specific Parameters" on page 154.)
MAP Overview 121