Wed Mar 2 00:06:19 EST 2011

eth0.1 vs eth0:1

802.1Q VLAN (eth0.1) vs alias (eth0:1).

An alias can be used to attach a second IP address to a single
interface, while a VLAN is an encapsulated ethernet connection based
on packets tagged with an extra identifier[1].

To enable VLAN support, issue:

# modprobe 8021q

To create a new interface for VLAN ID 11, issue:

# vconfig add eth0 11
# ifconfig eth0.11 up
# tcpdump -i eth0.11

[1] http://en.wikipedia.org/wiki/IEEE_802.1Q