Advanced Networking Features

Motivation

The network capabilities of Linux are not limited to what you have seen so far. This chapter gives you a list of what else you could do, without much details.

List of more Advanced Networking Topics

VLANs

You can run more then one network on the same wire, but to properly separate them there is the possibility of VLANs (IEEE 802.1Q, or often called dot1q ) where networks are separated by a 12 bit VLAN number. So you can have about 4096 different virtual LANs on a cable. Most larger switches support this so you can have different networks on the same switch. On some cables (e.g. interconnects between switchs) you would sent your packets with the VLAN header (tag) included. So called tagged ports. On others, where you have only one station in one particular virtual LAN they are sent untagged. The station does not know about any other VLANs at all.

In order to give a Linux server the option to be directly connected in multiple virtual LANs you would connect them to a tagged port and configure virtual interfaces for each VLAN number that you need to see.

You can configure VLANs in /etc/network/interfaces once the vlan tools are installed:

auto eth0 eth0.1492 eth0.2345
iface eth0 inet static
     address ...

iface eth0.1492 inet static
     address ...

iface eth0.2345 inet static
     address ...

Bonding

When you need a highly available system you want to connect it to 2 different network switches. If one is down you could still be reached via the other. To do this you could setup an active/slave bonding. You would use 2 network cards and with the bonding you define a virtual one that consists of the 2 individual ones.

You can configure bonding in the /etc/network/interfaces