Dell PowerEdge M420 Configuration Manual page 858

VLAN Routing
VLAN routing is required when the switch is used as a layer 3 device. VLAN
routing must be configured to allow the switch to forward IP traffic between
subnets and allow hosts in different networks to communicate.
In Figure 30-1 the PowerConnect switch is configured as an L3 device and
performs the routing functions for hosts connected to the L2 switches. For
Host A to communicate with Host B, no routing is necessary. These hosts are
in the same VLAN. However, for Host A in VLAN 10 to communicate with
Host C in VLAN 20, the PowerConnect switch must perform inter-VLAN
routing.
Figure 30-1. Inter-VLAN Routing
PowerConnect Switch
L2 Switch
L2 Switch
` ` `
Host A
Host C
Host B
VLAN 10
VLAN 20
Loopback Interfaces
When packets are sent to the loopback IP address, the network should be able
to deliver the packets as long as any physical interface on the switch is up.
There are many cases where you need to send traffic to a switch, such as in
858
Configuring Routing Interfaces