Filter
Top Products
274 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring STP related features
8
Configuration example for STP load sharing
Figure 52 shows another example of a STP per VLAN group implementation.
FIGURE 52 More complex STP per VLAN group example
In this example, each of the devices in the core is configured with a common set of master VLANs,
each of which contains one or more member VLANs. Each of the member VLANs in an STP group
runs the same instance of STP and uses the STP parameters configured for the master VLAN.
The STP group ID identifies the STP instance. All VLANs within an STP group run the same instance
of STP. The master VLAN specifies the bridge STP parameters for the STP group, including the
bridge priority. In this example, each of the devices in the core is configured to be the default root
bridge for a different master VLAN. This configuration ensures that each link can be used for
forwarding some traffic. For example, all the ports on the root bridge for master VLAN 1 are
configured to forward BPDUs for master VLAN spanning tree. Ports on the other devices block or
forward VLAN 1 traffic based on STP convergence. All the ports on the root bridge for VLAN 2
forward VLAN 2 traffic, and so on.
All the portss are tagged. The ports must be tagged so that they can be in both a member VLAN
and the member's master VLAN. For example, port 1/1 – and ports 5/1, 5/2, and 5/3 are in
member VLAN 2 and master VLAN 1 (since master VLAN a contains member VLAN 2).
Here are the commands for configuring the root bridge for master VLAN 1 in figure Figure 51 for
STP per VLAN group. The first group of commands configures the master VLANs. Notice that the
STP priority is set to a different value for each VLAN. In addition, the same VLAN has a different
STP priority on each device. This provides load balancing by making each of the devices a root
bridge for a different spanning tree.
PowerConnect(config)#vlan 1
PowerConnect(config-vlan-1)#spanning-tree priority 1
PowerConnect(config-vlan-1)#tag ethernet 1/1 ethernet 5/1 to 5/3
PowerConnect(config-vlan-1)#vlan 201
PowerConnect(config-vlan-201)#spanning-tree priority 2
Member VLANs
2 - 200
Member VLANs
202 - 400
Member VLANs
402 - 600
Member VLANs
3802 - 4000
Root bridge
for master VLAN 1
Root bridge
for master VLAN 201
Root bridge
for master VLAN 401
Root bridge
for master VLAN 3801
FWD 1
FWD 1
FWD 1
BLK 1
BLK 1
5/1
5/2
5/3