Re: Help understanding download speeds
You most likely have RADSL via Quest/CenturyLink/whatever they call themselves these days. the "RA" bit means "rate adaptive." That means your speed and effective bandwidth gets dynamically adjusted (down) to compensate for line quality: a poor connection, or lot of noise on the line and you won't have much bandwidth.
Originally Posted by ron ll
Things that you can easily check:
0. Make sure everything plugged into your telephone line that isn't a DSL modem has a DSL filter between it and the phone line. This is absolutely essential. A DSL filter is a little dongle that looks something like this. It gets plugged into the phone jack and the phone/fax machine/other non-DSL modem device gets plugged into it:
1. Plug your computer in at the Network Interface box (should be a grey plastic box somewhere on the side of your house), where the phone line transitions from being Ma Bell's responsibility to being yours. If you get great download speeds there, the problem is likely in your wiring. If it's still sucky, you're pretty much SOL: the problem is in Ma Bell's court. You may have an old noisy line, or noisy mechanical switch. You may be a long, long way from the CO (DSL has a maximum run of 15,000 feet run as the cable flies between the CO and the subscriber's network interface).
Things to look for.
Are you running cat 5e or cat 5 cable (4 twisted pairs, 8 conductors total) from the network interface, or old-school 4 conductor phone wire?
Running old-school will hurt your bandwidth. It's non-twisted pair and that will result in a lot of noise and crosstalk. The reason etherNet supports such high speeds is that the twisted pairs make some sort of electrical engineer/electron magick happen so that doesn't occur.
You might consider pulling new Cat 5e or Cat 6 cable to replace the old 4-conductor stuff.
If you're pulling new cable or already have etherNet cable, make sure it's installed according to spec:
- No untwisted length should be longer than 1/2 inch.
- Minimum bend radius is 4x the cable diameter, c. 1 inch. Bends tighter than that or kinks in the cable cause signal loss and noise.
- Unshielded AC power lines (e.g., Romex) spew RF noise. If you're AC is in ground metal conduit or raceways, you're probably OK, but otherwise:
- Keep your cable as far away from AC wiring as possible (1 foot minimum).
- Don't run cable parallel to AC wiring
- If you have to cross AC wiring, cross at as close to a right angle as possible.
There's an argument to be made for running your cable in ground metal conduit to avoid possible AC interference (not really practical unless the walls are open).
You would not enjoy Nietzsche, sir. He is fundamentally unsound. — P.G. Wodehouse (Carry On, Jeeves)