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Network Programming

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Lecture /

SOHO Network Design

A Network Programming Lecture by Steven Choy

Overview: Network Devices - Examples of home network design - Wired vs. Wireless - Router Configuration - WAN Settings - LAN Settings - Wireless LAN Settings - Network settings

Network Devices and Components

  • Computers/PC - The computers connected to a network must have an OS and a network adapter that supports networking.
  • NIC - known as network interface card, network adapter, network interface controller, or LAN adapter.
It is a computer hardware component designed to allow computers to communicate over a computer network.
It provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses.
  • Wireless Adapter Card
A wireless network adapter allows a computing device to join a wireless LAN.
Wireless network adapters contain a built-in radio transmitter and receiver.
Each adapter supports one or more of the 802.11a, 802.11b, or 802.11g Wi-Fi standards.
  • Broadband modem - It is used to connect the network to the Internet. It can be a DSL modem using a phone line, or a cable modem using the cable internet connection.
  • Router
It is connected between the broadband modem and the network.
This enables multiple devices to connect to the Internet simultaneously.
A router can include the residential gateway, hub/switch, DSL modem, and wireless access point all in one box detailed as a router.
(Diagram: A home network example)
  • Wireless access point - It can be a part of the router
A wireless access point (WAP) is a device that allows wireless communication devices to connect to a wireless network using Wi-Fi, Bluetooth or related standards.
The WAP usually connects to a router, and can relay data between the wireless devices (such as computers or printers) and wired devices on the network.
  • Switch (Ethernet Hub)
It is a central networking hub containing a number of Ethernet port for connecting multiple networked devices together.
This is another piece that can be built-in to a router.
  • Bridge
A bridge is added in a a network to connect two different networks (2 different LANs) together.
A bridge is an interconnection device that operates in the data link layer of ISO OSI model, it can connect different LANs together, but it can also filter the traffic among (between) the LANs. Basically a bridge serves three functions:
(1) Packet forwarding function. A bridge can determine where to forward a packet (towards its destination).
(2) Another important feature of a bridge is the transformation between different LAN frame formats.
(3) A bridge is also required to accommodate the speed differences between LANs.
  • Gateway
A gateway is an interconnection device for the highest layer in the OSI model — the application layer.
They can examine every field of an incoming packet, even its data content, and then take some operations to modify incoming packets.
  • Repeater
A repeater is used to regenerate transmission signals (so that they can travel farther) to extend the length of a LAN. It operates in the physical layer of ISO OSI model. It is usually used when a travelling signal is too weak to travel farther. When a repeater receives a frame, it regenerates the frame and strengthens the signal. A hub is a multi-port form of a repeater. The main advantage of a repeater is its low cost, because its function is simple. But its disadvantage is that if a repeater connects two LANs, the two LANs will actually become one LAN. For example, if a repeater connects two Ethernets, when a station in one of the two LANs sends a frame, all stations in two LANs can read this frame — the two have merged into one. Thus, even though a repeater is the simplest interconnection device, it is not suitable if you want to build separate LANs.

Some examples of home network design

Example 1: A Home Network with Wireless Router
Example 2: A Home Network with Wired Router
Example 3: A Home Network with Wired Router and Wireless Access Point
Example 4: A Wireless Home Network featuring Wi-Fi Connections
Example 5: A Wired Home Network featuring Ethernet Switch
Example 6: Another Home Network Design

Wired vs. Wireless

  • Wired networks are connected via Ethernet cables while wireless networks require no physical connection.
  • A wireless network can be more expensive than a wired network to setup.
  • Wireless routers are more expensive than wired routers and you might also need to buy wireless printer servers or wireless networking cards for computers that don't have them.
  • A wired connection is going to be faster than a wireless connection because data is transfered faster through an Ethernet cable than through the air.
  • Security is an issue when looking at a wired vs. wireless network setup.
  • A wireless network is vulnerable to attacks by computers that can join on to your network.

Router Configuration

1) WAN Settings

  • WAN port - how the router acquires an IP address
  • Many DSL connections require a PPPoE Connection in order to log in to an internet connection.
WAN Port Setting
  • PPPoE (Point-to-Point Protocol over Ethernet) combines the Point-to-Point Protocol (PPP), commonly used in dialup connections, with the Ethernet protocol, which supports multiple users in a local area network. The PPP protocol information is encapsulated within an Ethernet frame.

2) LAN Settings

  • LAN ports: it is about assigning private IP addresses (LAN side IP addresses) to the devices in the LAN.
  • DHCP (Dynamic Host Configuration Protocol) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers configured for a given network.
  • Manual Assignment of IP Address: You can configure the DHCP server to manually assign IP addresses.

3) Wireless LAN Settings

  • You can configure
    • i) whether you want to enable or disable the wireless LAN
    • ii) the name of SSID (or ESS-ID)
    • iii) whether you want to broadcast the SSID to the public
    • iv) whether you want to enable data encryption
    • v) data encryption methods
    • vi) whether you want to limit the access of WLAN by MAC filter
  • ESS-ID stands for Extended Service Set ID. The ESS-ID is the identifying name of a wireless access point. It allows one wireless network to be clearly distinguishable from another.
  • An SSID is the name of a wireless local area network (WLAN). All wireless devices on a WLAN must employ the same SSID in order to communicate with each other.
  • Wireless security setup
  • Wireless MAC filter: You can limit the access to WLAN by MAC filter.

4) Network settings

  • Address Translation Setup
This setting turns the Network Address Translation function on or off.
If this is not used, the network becomes self-contained and no access to the Internet or WAN is possible.
When address translation is used, two scenarios are supported.
IP masquerade:
Communications from LAN side devices to WAN side devices are changed to present the WAN side the IP address of the AirStation's WAN port automatically. Multiple LAN side clients share the single IP address of the WAN port to access the Internet.
Static address translation:
Communications from the LAN side devices to WAN side devices will be sent to a static LAN side IP address.
  • DMZ (Demilitarized Zone)
In computer networks, a DMZ (demilitarized zone) is a computer host or small network inserted as a "neutral zone" between a company's private network and the outside public network. It prevents outside users from getting direct access to a server that has company data. (The term comes from the geographic buffer zone that was set up between North Korea and South Korea following the UN "police action" in the early 1950s.) A DMZ is an optional and more secure approach to a firewall and effectively acts as a proxy server as well. (Source)
The DMZ client will receive all the packets that have an unknown destination when network address translation is performed.
Incoming packets containing no recognizable destination port information will be redirected to the DMZ’s IP address.
  • You can add your own rules for address translation.
  • Packet filter:
  • Some system information about the router

References and Resources

Thanks for Reading

If you would rather like to have this lecture note in printed format, please click the print action link in the top right corner.

If you find any problem in this lecture note, please feel free to tell Steven via steven@findaway.hk.

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Page last modified on March 15, 2010, at 12:19 PM