62 Chapter 2: Medium-Sized Switched Network Construction
Example 2-7 shows how to verify the STP protocol for a given VLAN.
In this example, the statement Spanning tree enabled protocol rstp indicates that switch
X is running PVRST+, the Cisco RSTP implementation.
Switch X is the root bridge for VLAN 30. Its priority of 24606 is derived from the sum of
the assigned priority of 24576 and VLAN 30. The MAC address of switch X, which is
00d0.047b.2800, is appended to the priority, 24606, to make up the bridge ID.
As the root bridge for VLAN 30, all the interfaces of switch X are designated ports in the
forwarding state.
If all the switches in a network are enabled with the default spanning-tree settings, the
switch with the lowest MAC address becomes the root bridge. However, the default root
bridge might not be ideal because of traf?¬?c patterns, the number of forwarding interfaces,
or link types.
Before you con?¬?gure STP, select a switch to be the root of the spanning tree. This switch
does not need to be the most powerful switch, but it should be the most centralized switch
on the network. All data ?¬‚ow across the network occurs from the perspective of this switch.
Pages:
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113