5-27
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 5 Configuring Ethernet VLAN Trunks
Example VLAN Trunk Configurations
Switch_1> (enable)
show spantree 1/2
Port Vlan Port-State Cost Priority Fast-Start Group-method
--------- ---- ------------- ----- -------- ---------- ------------
1/2 1 blocking 19 32 disabled
1/2 10 blocking 19 32 disabled
1/2 20 blocking 19 32 disabled
1/2 30 blocking 19 32 disabled
1/2 40 forwarding 19 1 disabled
1/2 50 forwarding 19 1 disabled
1/2 60 forwarding 19 1 disabled
1/2 1003 not-connected 19 32 disabled
1/2 1005 not-connected 19 4 disabled
Switch_1> (enable)
Figure 5-4
shows the network after you configure VLAN traffic load sharing.
Figure 5-4
Parallel Trunk Configuration After Configuring VLAN-Traffic Load Sharing
Figure 5-4
shows that both trunks are used when the network is operating normally; if one trunk link
fails, the other trunk link acts as an alternate forwarding path for the traffic previously traveling over the
failed link.
If Trunk 1 fails in the network that is shown in
Figure 5-4
, STP reconverges to use Trunk 2 to forward
traffic from all the VLANs, as shown as follows:
Switch_1> (enable) 04/21/1998,03:15:40:DISL-5:Port 1/1 has become non-trunk
Switch_1> (enable)
show spantree 1/1
Port Vlan Port-State Cost Priority Fast-Start Group-method
--------- ---- ------------- ----- -------- ---------- ------------
1/1 1 not-connected 19 32 disabled
16749
Switch 1
Switch 2
Trunk 1
VLANs 10, 20, and 30: port-VLAN priority 1 (forwarding)
VLANs 40, 50, and 60: port-VLAN priority 32 (blocking)
Trunk 2
VLANs 10, 20, and 30: port-VLAN priority 32 (blocking)
VLANs 40, 50, and 60: port-VLAN priority 1 (forwarding)
1/1
1/2
1/1
1/2