Specifications

Spanning Tree Folder
Extreme Networks EAS 100-24t Switch Software Manual
81
NOTE
STP Port Settings window for MSTP mode.
In addition to setting Spanning Tree parameters for use on the switch level, the Switch allows for the
configuration of groups of ports, each port-group of which will have its own spanning tree, and will
require some of its own configuration settings. An STP Group will use the switch-level parameters
entered above, with the addition of Port Priority and Port Cost.
An STP Group spanning tree works in the same way as the switch-level spanning tree, but the root
bridge concept is replaced with a root port concept. A root port is a port of the group that is elected
based on port priority and port cost, to be the connection to the network for the group. Redundant links
will be blocked, just as redundant links are blocked on the switch level.
The STP on the switch level blocks redundant links between switches (and similar network devices).
The port level STP will block redundant links within an STP Group.
It is advisable to define an STP Group to correspond to a VLAN group of ports.
In this window, the following parameters can be configured:
Parameter Description
From Port/To Port A consecutive group of ports may be configured starting with the selected
port.
External Cost (0=Auto) External Cost - This defines a metric that indicates the relative cost of
forwarding packets to the specified port list. Port cost can be set automatically
or as a metric value. The default value is 0 (auto).
0 (auto) - Setting 0 for the external cost will automatically set the speed for
forwarding packets to the specified port(s) in the list for optimal efficiency.
Default port cost: 100Mbps port = 200000. Gigabit port = 20000.
value 1-200000000 - Define a value between 1 and 200000000 to determine
the external cost. The lower the number, the greater the probability the port
will be chosen to forward packets.