Specifications

180 Implementing IBM System Networking 10Gb Ethernet Switches
According to the reference architecture described in Chapter 3, “Reference architectures” on
page 107, the links between AGG1 and AGG2, AGG1 and ACC1, AGG1 and ACC2, AGG2
and ACC1, and AGG2 and ACC2 are point-to-point Layer 3 links. The corresponding VLANs
do not span across the network, so no loops are formed. The STP runs on the
default configuration.
A configuration other than the default configuration is applied only for VLAN 10 and VLAN 20,
which contains the hosts in our topology.
The PVRST and VRRP configuration are consistent, so one access switch (ACC-1) forwards
traffic for VLAN 10 and the other access switch (ACC-2) forwards traffic for VLAN 20. This
configuration provides load balancing between access switches and a more efficient use of
network resources by distributing traffic and processing among different equipment and links.
The per-VLAN roles of the access switches are shown in Table 5-3.
Table 5-3 Per-VLAN roles of the access switches
Run spanning-tree stp <STG number> bridge priority <0-65535> to configure the bridge
priority for a specified VLAN (Example 5-31).
Example 5-31 Bridge priority configuration example
ACC-1#configure terminal
Enter configuration commands, one per line. End with Ctrl/Z.
ACC-1(config)#spanning-tree stp 10 bridge priority 0
ACC-1(config)#spanning-tree stp 20 bridge priority 4096
ACC-1(config)#^Z
ACC-1#
Aug 2 9:57:30 ACC-1 ALERT stg: STG 10, new root bridge
ACC-2#configure terminal
Enter configuration commands, one per line. End with Ctrl/Z.
ACC-2(config)#spanning-tree stp 20 bridge priority 0
ACC-2(config)#spanning-tree stp 10 bridge priority 4096
ACC-2(config)#^Z
ACC-2#
The commands appear under the Spanning Tree section of the configuration:
spanning-tree stp 10 bridge priority 0
spanning-tree stp 10 vlan 10
spanning-tree stp 20 bridge priority 4096
spanning-tree stp 20 vlan 20
For more detailed configuration options for STP (global commands, timers, and ports
parameters), see 5.5, “More information” on page 238.
VLAN PVRST primary
root
PVRST
secondary root
VRRP master VRRP backup
10 ACC-1
priority 0
ACC-2
priority 4096
ACC-1
priority 105
ACC-2
priority 100
20 ACC-2
priority 0
ACC-1
priority 4096
ACC-2
priority 105
ACC-1
priority 100