Nortel Networks 450 manual Vlans Spanning Multiple Untagged Switches

Using the BayStack 450 10/100/1000 Series Switch

Because there is only one link between the two switches, the Spanning Tree Protocol (STP) treats this configuration as any other switch-to-switch connection. For this configuration to work properly, both switches must support the 802.1Q tagging protocol.

VLANS Spanning Multiple Untagged Switches

Figure 1-22 shows VLANs spanning multiple untagged switches. In this configuration switch S2 does not support 802.1Q tagging and you must use a single switch port on each switch for each VLAN.

For this configuration to work properly, you must set spanning tree participation to Disabled (the STP is not supported across multiple LANs).

VLAN 1

VLAN 2

S1	BayStack 450-24T
Untagged ports	Untagged ports
S2	Non-802.1Q
	tagging switch

BS45016A

Figure 1-22. VLANs Spanning Multiple Untagged Switches

When the STP is enabled on these switches, only one link between each pair of switches will be forwarding traffic. Because each port belongs to only one VLAN at a time, connectivity on the other VLAN is lost. Exercise care when configuring the switches to ensure that the VLAN configuration does not conflict with spanning tree configuration.

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