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Router

Most computers connect to a wired network through ethernet cables. However, there is only one ethernet outlet in the modem. Therefore, even though a modem is able to facilitate addressing more than one computer, it is unable to connect to more than one computer.

You will need to connect a router to the ethernet output of the modem.

If your modem already provides DHCP and NAT, then you would have to choose between using the DHCP/NAT from the router or from the modem. Some modems have a slot for a wireless transmission card to allow the modem to function both as a wireless router and a modem. In that case, there would be no need to choose.

First try using the wireless router's DHCP/NAT.

If you are attempting run a web/file/game server that is visible to the public world-wide internet, it would be helpful for you to get a router that has a DDNS client built-in.

Which router should you get?
If you live in the United States, the fastest public internet access speed affordable to middle-class consumers is about 12 mbs (million bits per second). Therefore, unless you live in Japan, South Korea or Switzerland (or one of the locations selected for Google's ultra-broadband) there is no point in getting a 1 gbs (billion bits per sec) speed. Even if you live in a region with ultra-broadband, most web-sites in the US can barely deliver 1 mbs to you. You most likely have the miserly 760 kbs semi-broadband asymmetric DSL. Asymmetric means, your outgoing speed is about a third to a half of your incoming speed.

Most, if not all, wireless routers include five physical sockets for ethernet too -
  • One, called the WAN socket, is to be used for connecting the router to the public internet through the modem. The WAN socket is also used in large enterprises to connect multiple LANs to form a wide area network (WAN).
  • Four, called the WAN sockets, are for connecting computers and devices within the private LAN to the router.
Some routers even have USB sockets to let you share printers or USB devices.

Some routers have gigabit ethernet connection. Ethernet is a wired connection. Having gigabit ethernet sockets means the router is able to transmit at maximum 1 billion bits per second through those sockets.

You should get a router with gigabit ethernet if your intention is to share within the LAN at home or private WAN in the office
  • game servers
  • file servers
  • web servers
You would connect your file/web/FTP/game servers to the router through the gigabit ethernet sockets and not by wireless.

However, if your intention is to perform such sharing for use over the public internet, make sure you live in a location with ultra-broadband - otherwise don't bother to get routers with gigabit ethernet.





2.4 GHz or 5 GHz transmission router?
The signals transmitted through ethernet and wireless is not digital but analogue. Digital signals cannot be transmitted efficiently. All cell phones, television, radio transmission has to be carried by analogue transmission signals. In older broadcast radio, analogue voice signals are modulated into a carrier analogue signal. Modulation is by varying the carrier signal by frequency or phase. Nowadays, digital messages are modulated into these analogue carriers as well.

There are two standard frequencies used in carrier signals for wireless routers - 2.4 GHz and 5 GHz. These are not the speeds of message transmission but the frequency of the radio signal that the antennae of wireless equipment is tuned into.

There are four wireless standards that has come to accepted use, of which 802.11b/g has the most widespread use.
  • 802.11a (IEEE 802.11a-1999) max message speed of 54 mbs using 5 GHz carrier.
  • 802.11b (IEEE 802.11b-1999) max message speed of 11 mbs using 2.4 GHz carrier.
  • 802.11g (IEEE 802.11g-2003) max message speed of 54 mbs using 2.4 GHz carrier.
  • 802.11n (IEEE 802.11n-2009) allows transmission over multiplexed channels using either/both 2.4 GHz and 5 GHz carriers.
802.11n is said to be able to achieve maximum message speed of 600 mbs on a 5 GHz carrier. A 802.11n capable router may interfere with the transmission of other 2.4 GHz transmission equipment when operated at 2.4 GHz transmission mode without the constraints of 802.11g specifications.

Some 802.11n capable routers can be operate at both 802.11n/5 GHz and 802.11g/2.4 GHz simultaneously. For others, you have to choose to operate it at either 802.11g/2.4 GHz and 802.11n/5 GHz during router configuration.

Despite promulgated limits of 600 mbs in 802.11n technology, currently commercially available affordable 802.11n capable routers probably operate within the constraints of 100 mbs or 144 mbs max speed, resulting in a sustained average speed of 35 - 40 mbs or 55 - 60 mbs respectively.

5 GHz transmission is less susceptible to interference experienced in the crowded bandwidth of 2.4 GHz transmission. But, it is more susceptible to being absorbed/deflected by solid objects like walls and floors, obviously due to its shorter wavelength.

The choice of either 802.11g or 802.11n wireless routers depends on whether you already have 802.11n capable wireless transceivers in your computers and whether the router can operate simultaneously at 802.11n and 802.11g in an environment that has a mix of 802.11n and 802.11g transceivers.


Continue to next page Network Address Translation (NAT)





There is an impression among consumers about digital being superior to analogue. People say, throw away your analogue televisions or cell phones to buy digital ones with the belief digital technology is superior to analogue technology.

Actually, the advanced so-called digital technologies ride on advanced analogue technologies. Without the technological progress in the underlying analogue technologies, the digital facade would not be possible. At high speeds, digital signals morph into analogue signals and it becomes very difficult to decipher/recover such digital signals. The trick then is to encode digital message into the variability of an analogue signal.

Advances in digital interpretation of analogue signals made it possible to squeeze more digital messages into the same analogue bandwidth. Digital-heads like to argue that digital interpretation is the reason why digital technology is superior to analogue, unaware that digital interpretation in analogue signals is in the purview of analogue engineering.



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