Example 2: Parallel Links With Vlans; A, February; Figure 2-2 Example 2: Parallel Links With Vlans - Nortel Web OS Switch Software Application Manual

Web OS 10.0 Application Guide

Example 2: Parallel Links with VLANs

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Figure 2-2 Example 2: Parallel Links with VLANs

The following items describe the features of this example:
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Example 2 shows how it is possible, through the use of VLANs, to create configurations
where there are multiple links between two switches, without creating broadcast loops.
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Two Alteon Web switches are connected with two different Gigabit Ethernet links. With-
out VLANs, this configuration would create a broadcast loop, but the STP topology reso-
lution process resolves parallel loop-creating links.
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To prevent broadcast loops, port 7 is on VLAN 10 and VLAN 22, port 8 is on VLAN 32
and VLAN 109. Both switch-to-switch links are on different VLANs and, thus, are sepa-
rated into their own broadcast domains.
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Ports 1 and 2 on both switches are on VLAN 10; ports 3 and 4 on both switches are on
VLAN 22; Ports 5 and 6 on both switches are on VLAN 32; port 9 on both switches are on
VLAN 109.
n
It is necessary to turn on Spanning Tree Protocol (STP) on at least one of the switch-to-
switch links or, alternately, turned on in both switches. STP Bridge Protocol Data Units
(BPDUs) will be transmitted out both Gigabit Ethernet ports and interpreted by the switch
that there is a loop to resolve.
n
Spanning Tree is VLAN-aware.
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48 Chapter 2: VLANs
Web Switch
10/100/10000 Mbps Ethernet Server Switch
1 2 3 4 5
TX RX TX RX TX RX TX RX TX RX
Gigabit Ethernet Port 7
VLAN #10, VLAN #22
Web Switch
10/100/10000 Mbps Ethernet Server Switch
1 2 3 4 5
TX RX TX RX TX RX TX RX TX RX
6 7 8
Data
Link
TX RX TX RX TX RX
Gigabit Ethernet Port 8
VLAN #32, VLAN #109
6 7 8
Data
Link
TX RX TX RX TX RX
Gigabit
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Power Console
Gigabit
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Power Console
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212777-A, February 2002