VLAN without an alias?

Felipe Alfaro Solana felipe.alfaro at gmail.com
Tue Sep 19 04:45:17 UTC 2006

> > So, I don't know how to assign/process traffic for a specific VLAN
> > without using subinterfaces (that is, using vconfig). Why do you want
> > to assign VLAN traffic to a physical interface instead of using
> > subinterfaces?
> Whoa careful, the "why" question will turn into the "why don't you.."
> question soon :)
> If all traffic needs to be tagged with a given vlan id, then it should be
> possible for all traffic using eth0 to be tagged with that vlan id.

I don't understand.

If you want _all_ traffic to get tagged with the same VLAN ID, the
only thing you need to do is configuring the switch port in access
mode and attach it to the correct VLAN. In Cisco IOS you will use
something like this:

# config terminal
# interface FastEthernet 0/23
# switchport mode access
# switchport access vlan 23

This will configure port 23 in the switch in access mode and into VLAN 23.

Else, you are targeting several VLANs using a single NIC. In this
case, you configure the switch port in trunking mode

# config terminal
# interface FastEthernet 0/23
# switchport mode trunk

and every VLAN is (usually) on a different network, so I don't see how
you plan on sending traffic to different networks using eth0. Usually
there is a 1-1 map of VLAN-network so, in the end, you have one
subinterface (related to eth0) for each VLAN.

Am I missing something?

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