NEC INTELLIGENT L2 SWITCH N8406-022A - Manual (Page 52)

Spanning Tree Protocol 52
Figure 8 Two VLANs on one instance of Spanning Tree Protocol
In the following figure, VLAN 1 and VLAN 2 belong to different Spanning Tree Groups. The two instances of
spanning tree separate the topology without forming a loop, so that both VLANs can forward packets between the
switches without losing connectivity.
Figure 9 Two VLANs on separate instances of Spanning Tree Protocol
VLAN participation in Spanning Tree Groups
The following table shows which switch ports participate in each Spanning Tree Group. By default, server ports
(ports 1-16) do not participate in Spanning Tree, even though they are members of their respective VLANs.
Table 11 VLAN participation in Spanning Tree Groups
VLAN 1 VLAN 2
Switch 1 Spanning Tree Group 1
Port 17 Spanning Tree Group 2
Port 18
Switch 2 Spanning Tree Group 1
Port 17 Spanning Tree Group 2
Port 18
Configuring Multiple Spanning Tree Groups
This section explains how to assign each VLAN to its own Spanning Tree Group on the switches 1 and 2.
By default, Spanning Tree Groups 2-31 are empty, and Spanning Tree Group 1 contains all configured VLANs
(except VLAN 4095) until individual VLANs are explicitly assigned to other Spanning Tree Groups. Except for the
default Spanning Tree Group 1, which may contain more than one VLAN, Spanning Tree Groups 2-32 may contain
only one VLAN each.
NOTE: Each instance of Spanning Tree Group is enabled by default.