3Com WX2200 3CRWX220095A Switch User Manual

MAP Overview 181
If only 3COMWX is defined in DNS, the MAP contacts the WX with an IP
address returned for 3COMWX.
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 port of the other device.
Enable the port fast convergence feature, if supported, on the other
device 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.