Allied Telesis Rapier Switch - Manual (Page 55)

Layer 2 Switching 55
Software Release 2.5.1
C613-02025-00 REV B
Figure 1-4: Port membership of VLANs which belong to different spanning tree instances (on Rapier i Series
switches only).
Configuring STP
By default, the switch has one default STP which cannot be destroyed. In most
situations this default STP will suffice.
By default, all VLANs, and therefore all ports, belong to the default STP. To add
or delete a VLAN and all the ports belonging to it from any other STP, use the
commands:
ADD STP=stpname VLAN={vlan-name|2..4094}
DELETE STP=stpname VLAN={vlan-name|2..4094|ALL}
The default STP is disabled by default at switch start up, and STPs created by a
user are disabled by default when they are created. An STP must be enabled
before STP can be enabled or disabled on particular ports belonging to it. To
enable or disable STPs, use the commands:
ENABLE STP{=stpname|ALL}
DISABLE STP={stpname|ALL}
The Spanning Tree Protocol uses three configurable parameters for the time
intervals that control the flow of STP information on which the dynamic STP
topology depends: the HELLOTIME, FORWARDDELAY and MAXAGE
parameters. All switches in the same spanning tree topology must use the same
values for these parameters, but can themselves be configured with different,
and potentially incompatible time intervals. The parameter values actually
used by each switch are those sent by the root bridge, and forwarded to all
other switches by the designated bridges.
The FORWARDDELAY parameter sets the time, in seconds, used to control
how fast a port changes its spanning state when moving towards the
Forwarding state. The value determines how long the port stays in each of the
Listening and Learning states which precede the Forwarding state. This value
STP A STP B
VLAN 1 VLAN 2 VLAN 3
Port 1
Port 2
Port 3
Port 2 is a member of multiple Spanning Tree Instances (STP A and STP B) because it is a member of
multiple VLANs (VLAN 2 and VLAN 3).
SWITCH12