You can connect a single computer to the Lnet with a direct cable connection. In order to build a wireless network or to connect several devices in a shared apartment or in studios, you will need a separate router.
Routers
You can connect several devices to Lnet by using a router intended for household use. Most routers have a WLAN feature, i.e. a wireless base station, which you can use to connect laptops, mobile phones and tablets to the network.
Check the router’s connections to make sure you connect the device to the network using the port intended for internet connections. The port is usually marked "WAN" (Wide area network) or "Internet" and it is often a blue port.
Router’s LAN ports
Ports with the abbreviation "LAN" (Local area network) are intended for personal devices and they are not connected to the Lnet connection supplied to your apartment i.e. the wall socket. A router provides various services in its local network (LAN) ports, such as the distribution of IP addresses (DHCP), which when offered in the direction of Lnet will mess up the network operations for other users.
A router connected to the network via one of its LAN ports will not operate in the intended manner because your local network will connect directly to the rest of Lnet without the firewall offered by the router. These LAN ports that are meant for your local network use are usually yellow and there are usually several of them next to each other. Connections which are found to have incorrectly connected routers shall be closed
ADSL/VDSL modems are worth avoiding
Please also not that devices intended for ADSL/VDSL connections are not usually designed in a way that they could be used correctly with Lnet because the connection technology is different. DSL routers have been designed in such a way that connections to the outside world take place via the phone line network, and Lnet does not use such connections.
The local network ports of DSL routers are therefore intended for personal devices (LAN). As above, the connection of LAN ports may cause interference to other users of the network, in which case connections thay cause problems shall be closed.
Please note that the colour codes referred to in the text are for reference purposes, because some devices use different colours. Familiarise with the user manual of your device, which will explain which port should be connected to what.
Notes on shared LAN/WAN ports
Some ADSL routers have the possibility to use one network connector for an Internet connection instead of a DSL connection. In this case, one of the ports is usually marked e.g. "LAN/WAN". Such devices can be used with the Lnet, if they have been installed correctly. Unfortunately, the automatic detection of the network connection to be used does not work automatically for many (especially those intended for Elisa connections) devices, and merely connecting the cable is not enough for the device operate correctly.
Connections of example devices
The diagram shows an example of the connectors of a router. The blue connector is the WAN connector intended for network connections, and the yellow cluster of four connectors indicates the LAN connectors intended for the user’s devices.
Wireless networks
When installing a wireless base station, it is worth considering that your wireless network must be encrypted to ensure unauthorised people do not access it. Sharing the Lnet connection to others than the residents of your apartment is in breach of the operating guidelines. The recommended encryption method is WPA2-PSK, and you should choose a password which is difficult to guess. Random letter combinations are good and they can be generated at e.g. random.org. The password only needs to be entered once on personal computers, so a complicated password will not make the use of the network more difficult.
Using a PC as a router
A skilled user can also use a normal PC which has two network interface cards as a router instead of a separate (wireless) router. The function is known in Windows under the name "Internet Connection Sharing" and in Linux under the name "Source NAT".
What can go wrong?
Below is a diagram of the DHCP function between a correctly connected router and computer. A router is connected to the network behind which there is a computer.
- The router requests an IP address to use via its WAN port and Lnet’s DCHP server assigns it an address from Lnet’s address range (86.50.x.x). The router transmits correctly to Lnet. Sections (1) and (2) in the diagram.
- The computer connected to the router’s LAN port requests an IP address and the router responds by assigning an address from its own local network (e.g. 192.168.y.y). In the diagram, sections (3) and (4).
- When the computer connects to the network, the router transmits traffic between the local network and Lnet.
The diagram below shows how the DHCP address distribution fails when the network is connected to the router’s LAN port. This time the router marked in red is connected to the network via its LAN port. The neighbour’s device (computer on the right) tries to connect to the network.
- The computer requests for an IP address. At this stage, it does not know what it is connecting to, so the request is transmitted to all the routers on the network. Section (1) in the diagram.
- Both Lnet’s router and the incorrectly connected red router respond. The device is assigned two IP addresses. Diagram section (2).
- The device randomly uses either of the addresses. If the device tries to use the address provided by the neighbour’s router, its traffic will not be transmitted anywhere because the router does not have Internet access from its WAN port.
- The neighbour’s network does not work and their studies are slowed down.
