4000 Router Series Layer 2 - LAN Switching Configuration Guide

2. Configure Router B:

# Create VLAN 100.

<RouterB> system-view

[RouterB] vlan 100

[RouterB–vlan100] quit

# Configure Ethernet 2/1 and Ethernet 2/2 as trunk ports, and assign them to VLAN 100.

[RouterB] interface ethernet 2/1

[RouterB-Ethernet2/1] port link-type trunk

[RouterB-Ethernet2/1] port trunk permit vlan 100

[RouterB-Ethernet2/1] quit

[RouterB] interface ethernet 2/2

[RouterB-Ethernet2/2] port link-type trunk

[RouterB-Ethernet2/2] port trunk permit vlan 100

[RouterB-Ethernet2/2] quit

3. Configure Router C:

# Create VLAN 100.

<RouterC> system-view

[RouterC] vlan 100

[RouterC–vlan100] quit

# Configure Ethernet 2/1 and Ethernet 2/2 as trunk ports, and assign them to VLAN 100.

[RouterC] interface ethernet 2/1

[RouterC-Ethernet2/1] port link-type trunk

[RouterC-Ethernet2/1] port trunk permit vlan 100

[RouterC-Ethernet2/1] quit

[RouterC] interface ethernet 2/2

[RouterC-Ethernet2/2] port link-type trunk

[RouterC-Ethernet2/2] port trunk permit vlan 100

[RouterC-Ethernet2/2] quit

Verifying the configuration

After the configurations are complete, Router A detects loops on ports Ethernet 2/1 and Ethernet 2/2

within a loop detection interval. Consequently, Router A automatically shuts down the ports and

generates the following log messages:

[RouterA]

%Feb 24 15:04:29:663 2011 RouterA LPDT/4/LOOPED:Slot=1;

Loopback exists on Ethernet2/1.

%Feb 24 15:04:29:667 2011 RouterA LPDT/4/LOOPED:Slot=1;

Loopback exists on Ethernet2/2.

%Feb 24 15:04:44:243 2011 RouterA LPDT/4/RECOVERED:Slot=1;

Loopback on Ethernet2/1 recovered.

%Feb 24 15:04:44:248 2011 RouterA LPDT/4/RECOVERED:Slot=1;

Loopback on Ethernet2/2 recovered.

# Display the loop detection configuration and status on Router A.

[RouterA] display loopback-detection

Loop detection is enabled.

Loop detection interval is 35 second(s).