The Internet’s Communications Protocols
By Charles Miller
To better understand some of the subtle problems you might experience but not even notice with your Internet connection or your Local Area Network (LAN) at your house, it is useful to know how some of the Internet’s communications protocols were designed to work. In the 1960s when the United States Defense Department was funding research into the development of a new way for the military to communicate, they had some requirements that were rather odd, yet were deemed appropriate for the times.
The engineers working on the Pentagon’s Advanced Research Projects Agency Network (Arpanet) set out to create a communications grid that was non-hierarchal and survivable. The thinking at the time of the cold war was that the system needed to survive wartime conditions and continue to function, so the Internet communications protocols were designed from the beginning to be robust and extremely fault-tolerant. Any time there is a disruption big or small (big as in a devastating earthquake in a major city, or small as in radio frequency interference in your house from your microwave oven), the Internet communications protocols will try over and over again to route around the interference to get the message through. This approach has proven to be most efficient, but it also has a dark side.
The unintended consequence of this fault tolerance in Internet communications protocols is that a lot of problems can exist that untrained people won’t recognize. Badly installed cables or incorrect router configurations do not automatically bring all communications to a halt, because the whole system was designed to avoid just that. No matter how haphazard or sloppy the installation is, Ethernet cables will often still transmit data, albeit at lower speeds. Have you ever heard anyone complain that his or her Internet is slow?
Not long ago I was called to troubleshoot a client’s Local Area Network. The electrician who installed the Ethernet cable had run it from one side of the house to the other by taking the cable up to the roof then around the perimeter of the house. The problem with this particular case was that the layout of the cable on the roof unintentionally formed the shape of a folded dipole antenna. The unshielded Ethernet cable was doing a great job of picking up stray radio frequency (RF) signals, such as local taxis’ CB radios, Radio Havana, and other interference.
Improperly installed Ethernet cables can be the cause of excessive packet loss inside your LAN. Some of your data packets are always going to be lost in transit, but you can help mitigate this by doing everything possible to eliminate packet loss inside your house. If some of your data packets are being lost somewhere between Los Angeles and Dallas, well, there is nothing you can do about that. However, if you are losing data packets because of faulty wiring or a misconfigured router in your house, you could do something about that.
So, before blaming Telmex, Megacable, or your computer for being “so slow” you should have a qualified technician examine your home network.
Charles Miller is a freelance computer consultant, a frequent visitor to San Miguel since 1981 and now practically a fulltime resident. He may be contacted at 415 101-8528 or email FAQ8 (at) SMAguru.com.