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How to Test Your T1?
lawpoop asks: "We have a T1 line for our building with a local ISP. Right now, we're looking for competitive bids from different companies. The local guy is offering a good price, but the larger guys are saying he may be overselling the T1 service through a DS-3. He swears he's not. So, how do I tell? The sales guys say 'There's bandwidth meters on the web,' but they fail to mention exactly how I can tell if I have a true T1. I've tried a half-dozen bandwith meters on various websites, and the results are highly variable. We've gotten 300-900 Kbps. Each site has disclaimers as to internet traffic, time of day, etc. Furthermore, we split the T1 out over a hub with two other tenants in the building. I'm coming through from behind that hub. How can I tell for certain that I'm getting a full T1? A service tech with a line tester? Any dead-on bandwith meters? What would an oversold T1 read out to be as compared to a true T1? If the larger guys are trying to scare me to their service with stories of oversold T1s, I need to know that they aren't doing it also!"
If you're getting T1 service, it should be possible to borrow a CSU/DSU, put it in remote-loopback, and make sure you have a full T1 of bandwidth. Or, if you own the router, you can just look at the statistics...
If you're talking about getting ISP service with "T1" equivalent bandwidth, that's a different story. You wouldn't be able to tell if the guy has "oversubscribed" you unless you find other buyers of the sevice and generate enough traffic to load down the DS-3.
To prevent getting burned, make sure your SLA clearly states the bandwidth you are expecting, and the means by which that is measured.
An ISP that I know fairly well (*cough* work for *cough*) oversells bandwidth. They use mrtg (as has been suggested elsewhere) and any time a network segment reaches 80% utilization at any point in the day, three days in a row, that segment is upgraded.
Seems to work quite well to me, but maybe I'm biased. Try an get a conference with the techs (see if you can talk to their network monitoring team) and see if they employ a similar practice.
That's it. I'm no longer part of Team Sanity.
The point of testing an FTP download to the T1 providers POP is to test the LINE, not the other guys lines as you suggested by going to 100 other servers. What the person is interested in is the bandwidth provided on his "T1".
... why do you really care? If you're getting the service you need, why bother? If you're satisfied with the current bandwidth and ping times through your T1, why buy something more expensive even if it is faster/less congested/has blinkity blinky florbs?
All reasonably priced providers will sell you shared capacity. And overselling is (usually) a question of what the other customers are doing and at what point your upwards link is going to get upgraded. You'll never get full bandwidth connectivity to the providers peering point for yourself unless you're willing to pay through the nose.
But do you really need that or are you satisfied? If you're satisfied, spending more is a waste of money, wether or not your current provider is using IP over avian carrier to connect you.