Chapter 2 Network configuration 61Using the BayStack 420 10/100/1000 SwitchBecause there is only one link between the two switches, the Spanning TreeProtocol (STP) treats this configuration as any other switch-to-switch connection.For this configuration to work properly, both switches must support the 802.1Qtagging protocol.VLANS spanning multiple untagged switchesFigure 18 shows VLANs spanning multiple untagged switches. In thisconfiguration, Switch S2 does not support 802.1Q tagging and you must use asingle switch port on each switch for each VLAN.For this configuration to work properly, you must set spanning tree participationto Disabled (the STP is not supported across multiple LANs).Figure 18 VLANs spanning multiple untagged switchesWhen the STP is enabled on these switches, only one link between each pair ofswitches will be forwarding traffic. Because each port belongs to only one VLANat a time, connectivity on the other VLAN is lost. Exercise care when configuringthe switches to ensure that the VLAN configuration does not conflict withspanning tree configuration.VLAN 1S1S2VLAN 2BayStack 420Untagged portsNon-802.1Qtagging switch10005EA
