Brocade Network OS NETCONF Operations Guide v4.1.1 - Manual (Page 372)

340 Network OS NETCONF Operations Guide
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Spanning tree configuration and management
24
Specifying the bridge priority for all xSTP
For any spanning tree mode (STP, RSTP, MSTP, PVST, or Rapid PVST), use this procedure to specify
the priority of the switch. After you decide on the root switch, set the appropriate values to
designate the switch as the root switch. If a switch has a bridge priority that is lower than all the
other switches, the other switches automatically select the switch as the root switch.
The root switch should be centrally located and not in a “disruptive” location. Backbone switches
typically serve as the root switch because they often do not connect to end stations. All other
decisions in the network, such as which port to block and which port to put in forwarding mode, are
made from the perspective of the root switch.
Bridge Protocol Data Units (BPDUs) carry the information exchanged between switches. When all
the switches in the network are powered up, they start the process of selecting the root switch.
Each switch transmits a BPDU to directly connected switches on a per-VLAN basis. Each switch
compares the received BPDU to the BPDU that the switch sent. In the root switch selection process,
if switch 1 advertises a root ID that is a lower number than the root ID that switch 2 advertises,
switch 2 stops the advertisement of its root ID, and accepts the root ID of switch 1. The switch with
the lowest bridge priority becomes the root switch.
The priority range is 0 through 61440 and the priority values can be set only in increments of 4096.
The default priority is 32678.
To specify the bridge priority, perform the following steps.
1. Issue the RPC to configure the node in the
urn:brocade.com:mgmt:brocade-interface namespace.
2. Under the node, include the node from the
urn:brocade.com:mgmt:brocade-xstp namespace.
3. Under the node, include the , , , , or node
element.
4. Under the , , , , or node, include the leaf
element, and specify the bridge priority.