Thanks, Thomas, for the additional information (my original question had been answered by a link).

>Any transmission line (cable having impedance) must be terminated in a restive load equal to its characteristic impedance to provide the maximum transfer of power. If this is not done there will be a reflection of power which can produce heat as an example, with power amplifiers. This can cause breakdown of cable or equipment at worst and reduced efficiency as a minimum.

I understand that especially for computer networks there is another, grave, potential problem: the reflected energy will turn up as a false signal.

I am giving CNAp courses (Cisco Network Academy program), and the question turned up there.

>Thank you for your question - it has been a while since I thought of such things. It is so nice to know there is something else in life besides programming and computers. :) Perhaps that is why I play flamenco guitar.

In my case, we are still talking about computers - but the computer networks are way off my previous (and still current) life as a computer programmer! (My studies, OTOH, were related to computer hardware - but not too much about networks, either).

I was all very sudden. In July, a certain Tuesday, an old friend from the city of Santa Cruz told me (and another friend) about this networking course (which they wanted to start teaching in Cochabamba). On Sunday, we flew off to Buenos Aires, Argentina, for the instructor-training course.

Hardly enough time to review the course materials, which we were supposed to read beforegetting to Buenos Aires.

Before that, I had heard the name, "Cisco", only in passing.

The CNA is the largest "e-learning" offering in the world, with more than 200,000 students worldwide. Quite surprising for an offering which seems to fit only a certain vertical market (you wouldn't want to take a 4-semester course on computer networks to fix the computer network at your home).

Hilmar.