Cisco WS-C2950SX-48-SI Configuration Manual page 248

Example VLAN Trunk Configurations
Figure 11-3 Parallel Trunk Configuration after Configuring VLAN Traffic Load-Sharing
VLANs 10, 20, 30, 40, 50, and 60: port-VLAN priority 32 (blocking)
Catalyst 4000
1/1
VLANs 10, 20, 30, 40, 50, and 60: port-VLAN priority 32 (forwarding)
Figure 11-3
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 shown in
from all the VLANs, as shown in the following example:
Switch_1> (enable) 04/21/1998,03:15:40:ETHC-5:Port 1/1 has become non-trunk
Switch_1> (enable) show spantree 1/1
Port
--------- ----
1/1
Switch_1> (enable) show spantree 1/2
Port
--------- ----
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
Switch_1> (enable) show spantree 1/2
Port
--------- ----
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
Switch_1> (enable)
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
11-18
Trunk 2
Switch 1
1/2
Trunk 1
shows that both trunks are utilized when the network is operating normally. If one trunk link
Vlan Port-State
-------------
1 not-connected
Vlan Port-State
-------------
1 learning
10 learning
20 learning
30 learning
40 forwarding
50 forwarding
60 forwarding
1003 not-connected
1005 not-connected
Vlan Port-State
-------------
1 forwarding
10 forwarding
20 forwarding
30 forwarding
40 forwarding
50 forwarding
60 forwarding
1003 not-connected
1005 not-connected
Chapter 11 Configuring VLAN Trunks on Fast Ethernet and Gigabit Ethernet Ports
Catalyst 4000
Switch 2
1/1
1/2
Figure 11-3, STP reconverges to use Trunk 2 to forward traffic
Cost Priority Fast-Start
----- -------- ----------
19 32 disabled
Cost Priority Fast-Start
----- -------- ----------
19 32 disabled
19 32 disabled
19 32 disabled
19 32 disabled
19 1 disabled
19 1 disabled
19 1 disabled
19 32 disabled
19 4 disabled
Cost Priority Fast-Start
----- -------- ----------
19 32 disabled
19 32 disabled
19 32 disabled
19 32 disabled
19 1 disabled
19 1 disabled
19 1 disabled
19 32 disabled
19 4 disabled
Group-method
------------
Group-method
------------
Group-method
------------
—
Release 8.1
78-15486-01