Bridging Vlans Across Multiple Switches - Alcatel-Lucent OmniSwitch AOS Release 7 Manual

Configuring VLANs

Bridging VLANs Across Multiple Switches

To create a VLAN bridging domain that extends across multiple switches:
1
Create a VLAN on each switch with the same VLAN ID number (for example, VLAN 10).
2
On each switch, assign the ports that provide connections to other switches to the VLAN created in
Step 1.
3
On each switch, assign the ports that provide connections to end user devices (for example,
workstations) to the VLAN created in Step 1.
4
Connect switches and end user devices to the assigned ports.
The following diagram shows the physical configuration of an example VLAN bridging domain:
Switch B
138.0.0.3
2/2
VLAN 10
VLAN 10
3/8
Switch A
138.0.0.2
In the above diagram, VLAN 10 exists on all four switches and the connection ports between these
switches are assigned to VLAN 10. The workstations can communicate with each other because the ports
to which they are connected are also assigned to VLAN 10. It is important to note that connection cables
do not have to connect to the same port on each switch. The key is that the port must belong to the same
VLAN on each switch. To carry multiple VLANs between switches across a single physical connection
cable, use the 802.1Q tagging feature (see
The connection between Switch C and D is shown with a broken line because the ports that provide this
connection are in a blocking state. Spanning Tree is active by default on all switches, VLANs and ports.
The Spanning Tree algorithm determined that if all connections between switches were active, a network
loop would exist that could cause unnecessary broadcast traffic on the network. The path between Switch
OmniSwitch AOS Release 7 Network Configuration Guide
VLAN 10
2/1
VLAN 10
2/3
2/10
VLAN 10
2/9
VLAN 10
VLAN Bridging Domain: Physical Configuration
"Using 802.1Q Tagging" on page
Bridging VLANs Across Multiple Switches
Switch C
VLAN 10
3/7
VLAN 10
3/9
3/2
VLAN 10
3/1
VLAN 10
Switch D
4-7).
March 2011
138.0.0.4
3/10
VLAN 10
VLAN 10
3/3
138.0.0.5
page 4-11