3Com 3C15500 - Network Director User Manual page 509

Key Concepts 505
VLAN, two VLAN-based IP interfaces are created on a Layer 3 switch:
192.168.50.1/255.255.255.0 for VLAN ID 2 and
192.168.51.1/255.255.255.0 for VLAN ID 3.
Figure 261 below shows another example. The Switches are connected
by 802.1Q tagged links. Using the 802.1Q tagged links, the Layer 3
switch, Switch D, can tell Switches A, B and C which VLAN the packets
are destined for. All switches at the end of the links receive traffic for all
VLANs. Traffic on each VLAN is switched at Layer 2 via Switch D, and
routed at Layer 3 to other VLANs via Switch D. For example, traffic from
VLAN 1 on Switch A is switched to VLAN 1 on Switch B via Switch D.
Traffic from VLAN 1 on Switch C to VLAN 2 on Switch C is routed at Layer
3 through Switch D.