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How to Test Your T1?

Cliff posted more than 12 years ago | from the ensuring-your-bandwidth-pipe-works-as-advertised dept.

The Almighty Buck 488

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!"

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4 letters (4, Informative)

Anonymous Coward | more than 12 years ago | (#4166996)


Re:4 letters (3, Informative)

mosch (204) | more than 12 years ago | (#4167065)

Even better, Cricket [] . It has a much saner config than MRTG, especially if you start monitoring more than one or two routers.

3 letters (5, Interesting)

Khan (19367) | more than 12 years ago | (#4167205)

S.L.A. (Service Level Agreement)
If said small provider is telling the truth, then he won't have a problem signing one. I've found in my area that the big guys are the bullshiters when it comes to SLA's.

Re:4 letters (5, Funny)

The Bungi (221687) | more than 12 years ago | (#4167213)

The first post is (Score:5, Informative)

From an Anonymous Coward...

...ok Satan, you can take me now.

Man was I wrong! (5, Funny)

Anonymous Coward | more than 12 years ago | (#4167214)

I thought I had a T1 but it kept asking if I had seen John Conner, turns out I got a T1000! Word to the wise NEVER shop with Cyberdine!

first post (-1, Troll)

Anonymous Coward | more than 12 years ago | (#4167000)


fp! (-1, Troll)

Anonymous Coward | more than 12 years ago | (#4167001)

first post muthafuckas!

T1 is THE SUCK (-1, Offtopic)

SuicideTroll (604972) | more than 12 years ago | (#4167002)

I'lL KiLL Myself if THIS IS ModdED DoWN

Re:T1 is THE SUCK (-1, Offtopic)

Anonymous Coward | more than 12 years ago | (#4167019)

Please, mod it down! MOD IT DOWN!

Re:T1 is THE SUCK (0)

Anonymous Coward | more than 12 years ago | (#4167099)

If only all the other stupid fucks that post inane shit would do the same.

First? (-1)

CmdrTaco (troll) (578383) | more than 12 years ago | (#4167005)


First one! (-1, Troll)

Anonymous Coward | more than 12 years ago | (#4167006)

First Post! Woohoo!

If you can't tell the difference... (-1, Troll)

Anonymous Coward | more than 12 years ago | (#4167009) probably doesn't matter?

Packet Sniffer? (1, Insightful)

XBL (305578) | more than 12 years ago | (#4167010)

Maybe you could use a packet sniffer and see if you are getting other stuff on your line. If you are, then it's not a true T1.

Re:Packet Sniffer? (2, Informative)

krich (161944) | more than 12 years ago | (#4167042)


If their upstream is overselling the DS-3, that will not dump extraneous traffic over the T-1 connection they have bought. It will simply lower the effective bandwidth.

And as to why he should care... because he's *paying* for T-1, not some fraction thereof.

asdf (-1, Offtopic)

Anonymous Coward | more than 12 years ago | (#4167011)

Stupid topic...stupid

w00k! (-1, Offtopic)

Anonymous Coward | more than 12 years ago | (#4167014)

first w00k!

Re:w00k! (-1, Offtopic)

Anonymous Coward | more than 12 years ago | (#4167041)

I salute you sir.

A Full T1 is ... (5, Offtopic)

Cytlid (95255) | more than 12 years ago | (#4167015)

24 channels of 64 kbits apiece. We sell T1s to customers, and if one of them wanted a util to test their bandwidth (the full 1.544 mbit) they could download a file from an ftp right at our pop. Or, have them ping flood you... use something like mrtg to graph the results, etc.

PNIG FLOD SI TEH R0X0R!!! (-1, Offtopic)

Saturday Night Palsy (604905) | more than 12 years ago | (#4167128)

ME nad my kr3w test T!z allteh tiem with teh HAX0re57 skr1p7x !!!! yuo wlil nevar serviev !!!

Re:A Full T1 is ... (3, Insightful)

Anonymous Coward | more than 12 years ago | (#4167168)

None of those methods will work. Ping flood point-to-point will always max out the pipe. It doesn't test the effective bandwidth that you have to the public internet or other backbone providers. The same goes for FTP'ing a file from their POP. The true way to test is to download 100 files from 100 different machines on the internet and tally up the total bytes/sec. If you don't come up to 192k/s during peak hours, you're getting screwed.

Fuck. (-1)

Anonymous Coward | more than 12 years ago | (#4167017)

There's people starving and this fuckwad is upset because he's getting the exact data rate he wants but can't get the right alphabet soup marked on his paper so he's having a "gay-guy-doesn't-like-the-wallpaper" wrist flapping hissy fit?!

Jesus. How about a "I can't find a job, so what do I eat first? The cardboard boxes or my leather shoes?"

Re:Fuck. (-1, Troll)

Anonymous Coward | more than 12 years ago | (#4167137)

You presumptious bastard, starving people in Africa don't have cardboard boxes or leather shoes.

Look at you going off on your selfish "I care about 1st world poverty but don't realize starving people in the rest of the world don't have a street to beg on or a hospital to sleep in"

The best test (0)

Anonymous Coward | more than 12 years ago | (#4167022)

1. Start stopwatch
2. Find XXX password site
3. Use aforementioned password
4. D/L 100Gigs of pr0n
5. Stop stopwatch
6. Do the math (1, Offtopic)

unicron (20286) | more than 12 years ago | (#4167025) [] is the only site you'll EVER need for that purpose. Just go to the tools section. It will tell you your up and down, how it compares to other types of connections, and you can enter what city you live in and your ISP so that it can compare your speeds between other people all over the country with every type of connection. It's really an awesome, quick little tool, go check it out. (3, Informative)

Pyrrus (97830) | more than 12 years ago | (#4167046)

umm, it's a nice and useful site, but as the
author said, he wants to know if it's a true T1
vs, oversold DS3, which is not nessicarily
detectable by a bandwidth meter (3, Informative)

unicron (20286) | more than 12 years ago | (#4167144)

He said he's getting 300-900 Kbps average, so I think he answered his own question. If I purchased a T1, that shit better never drop below 1.2 or 1.3 Mbps, and even that would piss me off.

And while that page is great, the only real accurate test would be throughput on his router. (5, Insightful)

PurpleFloyd (149812) | more than 12 years ago | (#4167217)

He said he's getting 300-900 Kbps average, so I think he answered his own question. If I purchased a T1, that shit better never drop below 1.2 or 1.3 Mbps, and even that would piss me off.
Remember that speed on the 'net is influenced by many other factors: you could have an OC-192 like the big telecoms, but if you're downloading from someone's FTP site connected with a 2400 bps modem, then you will only ever get the bandwidth of the slowest link in the chain (in this case, 2400 bits per second). What the guaranteed bandwidth on a T1 specifies is that you'll always have a line that is capable of 1.544 MBPS transfer from one end to the other. (1)

eggnet (75425) | more than 12 years ago | (#4167177)

umm, it's a nice and useful site, but as the
author said, he wants to know if it's a true T1
vs, oversold DS3, which is not nessicarily
detectable by a bandwidth meter

Yes, it is. If you get your 1.3-1.5 megs of throughput all the time, you're not oversubscribed.

lay down a fair and square framework. (1)

zoftie (195518) | more than 12 years ago | (#4167029)

If ISP is a business, it will try to squeeze most out of T1. If you host stuff it might be good.
Otherwise getting business ADSL/Cable/Wireless would be better idea. Having your own T1 linked to Backbone is reallly nice idea, if the sharing parties don't abuse it. Its only around 150k downstream , think of it that way.

Its best to put switch that would have traffic counter on the ports so if someone is abusing
the T1, everyone else would be able to see that.
Setup a mail script to query switch/router, and send daily mails to respective parties.

ISP built in Bandwidth meter. (2, Offtopic)

josquint (193951) | more than 12 years ago | (#4167031)

I've noticed with a few of our local smaller broadband companies that they will have a diagnostic bandwidth meter on their website. []

The advantage to that is there is no 'internet traffic' delay to speak of because its basically a direct connection from one end of the line to the other. They've found it to be an invaluable diagnostic tool for tech support.

I'm guessing not to many larger companies are going to do this, that and "fixing" the meter to their advantage is always a possibility :)

Re:ISP built in Bandwidth meter. (0)

Anonymous Coward | more than 12 years ago | (#4167148)

That's not going to detect if they are oversubscribing their link.

T1->ISP = Full T1
T1->ISP->The Internet(TM) = Possibly fractional if the internet connection is oversubscribed and that is what is being asked here.

FTP (3, Offtopic)

damien_kane (519267) | more than 12 years ago | (#4167032)

You should have an account on their FTP server, if not get one, and then upload a large file (>10MB) to the server. Record the speed.
Download said file, record the speed.
Rinse, Lather, Repeat, average the speeds. Since the T1 is straight to him, you should get ~~1.5Mbps (192KB/s).
Make sure you do this while you're not using your T1 for anything else.

If you want to test your seppd relative to the whole net, try getting a friend on a T1 to give you access, and try the tests against his server, you should get similar results if your boxes are near each other (on the network I mean, not across the street)

Re:FTP (4, Informative)

Julian Plamann (449854) | more than 12 years ago | (#4167175)

Better yet... download the ~10MB file _while_ uploading a second ~10MB file. Since a full T1 is full duplex, both inbound and outbound transfers should be at or near 1.544mbps.

Ahh, but what about stat mux? (2, Informative)

Anonymous Coward | more than 12 years ago | (#4167182)

The problem is that your ISP may be doing statistical multiplexing, which is fancyspeak for oversubscribing their DS3 and then hoping that everybody doesn't use it all at once. That is, they have 45 Mbps coming in and they sell (say) 50 T1 lines * 1.5 Mbps = ~75 Mbps to customers. Now the chances are pretty good that not all 50 of those lines will be saturated all the time, so most customers will see good bandwidth most of the time. However, if everybody jumped on their FTP server all at once, then the 45 Mbps would have to split 50 ways and customers would be getting less than 1 Mbps. The problem is you wouldn't know it unless you were testing your bandwidth to your ISP 24/7 (which renders your T1 pretty useless), and even if they aren't stat muxing today, that doesn't prevent them from starting tomorrow.

The only real way to know is to ask your ISP exactly how many customers are using that DS3, and hope they're telling the truth.

But wait, what if your ISP's ISP is oversubscribing *their* DS3.... :)

Testing Bandwidth (3, Funny)

dattaway (3088) | more than 12 years ago | (#4167033)

Suck up some usenet binaries and put some pr0n on your webserver. Shouldn't take too long.

Re:Testing Bandwidth (1, Funny)

Anonymous Coward | more than 12 years ago | (#4167117)

Suck up some usenet binaries and put some pr0n on your webserver. Shouldn't take too long.

Better yet, you should have including a link to your webserver in your ask slashdot submission

Easy... (3, Funny)

Anonymous Coward | more than 12 years ago | (#4167034)

if your penis grew 2 inches after having the line installed, it's a T1. If you only gained about an inch, you're getting ripped.


Re:Easy... (2)

Bingo Foo (179380) | more than 12 years ago | (#4167149)

So that's what all those emails I've been getting are advertizing!

Re:Easy... (0)

Anonymous Coward | more than 12 years ago | (#4167212)


Tis soo soo true..

well.. (0)

Anonymous Coward | more than 12 years ago | (#4167035)

..get a connection which is half as fast as your T1 should be. If you notice that it's slower your T1 is a T1.
It's easy as that ;-)

this really is a stupid question (0, Troll)

cp5i6 (544080) | more than 12 years ago | (#4167038)

honestly if the speed looks about right... then that really is good enough. just try downloading some files for an OC-12 site like MS and see how fast you get for down speeds and upload to like a university account and see how fast it is. Does it really matter that yer piggy backing on a DS-3 line?

Re:this really is a stupid question (0)

Anonymous Coward | more than 12 years ago | (#4167070)

Downloading from a remote site that you do not control isn't a valid comparison.

Example is that MS uses OC-48's (not OC-12's as the prior post stated) however they are load balanced ACROSS THE GLOBE. You have no guarantee that you are getting to a particular server in a particular area.

Also, being piggy backed on a DS-3 rather than a full T-1 does make a difference, not technically, but contract and business wise. If they are lying to you about your connection what else are they lying to you about?

To fully test your line... (-1, Troll)

Anonymous Coward | more than 12 years ago | (#4167039)

Download some grits to your pants... if they arrive hot, then you have a full T1.

That is a really really stupid question. (0, Flamebait)

Anonymous Coward | more than 12 years ago | (#4167047)

First of all, you probably have a t1, I have no doubt about that. A t1 is a t1 is a t1, there is no questions about that. If you have a t1 then I am sure that you could transfer 1.544mbps over that line to the other side. Now, after you get past the point directly on the other side that is an entirely different question, AND ONE THAT YOU DIDN'T ask. Unless you have that t1 connected to somewhere with so much aggregate bandwidth that you're head will spin I seriously doubt that you will ever get every single kbps that a T1 is good for. If you can sustain 200kb/s downloads or get close, then you have just about all you're going to get.

Re:That is a really really stupid question. (0)

Anonymous Coward | more than 12 years ago | (#4167136)

If you can sustain 200kb/s downloads or get close, then you have just about all you're going to get.

I can get that and better from my cable line so i think it will have to be somethign better than this to tell if he has a true T1.

Re:That is a really really stupid question. (0)

Anonymous Coward | more than 12 years ago | (#4167204)

I am sure that you can burst higher than ~200k/s on your cable and YOU HAVE NO IDEA HOW leased lines work. Your cable could bog down to less than 56k speeds in some situations. The whole concept of T1s is that that bandwidth between the two points is FIXED, and unvariable. Bandwidth downstream can fluctuate wildly, but still you are an idiot for thinking a T1 could provide faster speeds.

Re:That is a really really stupid question. (1)

JM_the_Great (70802) | more than 12 years ago | (#4167163)

if you can't sustain 200Kb/s you're getting ripped, if you can sustain 200KB/s you're defying math :)

A T1 should do ~192KB/s or 1.544Mb/s.

Sorry to nitpick :)

Re:That is a really really stupid question. (1)

ianster (605032) | more than 12 years ago | (#4167194)

Won't a T1 handle 193KB/s? 1544000 bits divide by 8 = 193,000 bytes or 193KB....

MRTG (3, Informative)

indiigo (121714) | more than 12 years ago | (#4167050)

Any decent router or firewall (which you will likely need to purchase or lease anyway.) Will have this capability built in.

Then there's always MRTG rtg/mr tg.html

Simple, thanks to Open Source (0)

Anonymous Coward | more than 12 years ago | (#4167052)

download WonderShaper from It has the built-in capability to test T1s and T3s for bandwith, throttling, retries, drops, and runt packet stats.


Anonymous Coward | more than 12 years ago | (#4167053)

that's right! linux sux and linus is nothing more than an egotistical maniac.

Why do i say such things? SHIT! Linus...Linux...he named an OS after PATHETIC!!!

LINUX IS DEAD, THE PENGUIN IS DEAD, AND I WISH LINUS WOULD DIE OF EBOLA (but i would settle for anthrax or west nile)

Some clarity is in order (1)

dvanduzer (563848) | more than 12 years ago | (#4167055)

Are you asking how to make sure you're getting a full T1 worth of transport to your ISP, or are you asking how to tell if the ISP is overselling their upstream bandwidth? If the latter, the answer is yes. The problem is if the upstream load of your ISP peaks out. Any ISP you go with is "oversubscribed". The problem is if your ISP is peaking to their upstream. A more appropriate comparison to make is the level of diversity and redundancy of the upstream.

Getting a T1 or getting a "T1"? (5, Insightful)

toybuilder (161045) | more than 12 years ago | (#4167057)

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.

Not sure I understand your you? (5, Interesting)

dillon_rinker (17944) | more than 12 years ago | (#4167059)

Cytlid has a good point - you get a T-1 from the phone company (or a reseller/CLEC) and it either IS a T-1 or it IS NOT.

I suspect that you're asking how you can tell whether or not your ISP is selling 50 million T-1 lines when he himself only has a T-3 connection with the rest of the world.

I think the simplest way is to ask. Talk to the sales engineers who work for the larger guys - tell them "Ok, you're trying to scare me away from a smaller can I prove for myself how he's configured?" Ask the small guy "This looks like a really good deal...can you demonstrate to me I'll get X level of performance?"

Re:Not sure I understand your you? (2)

tupps (43964) | more than 12 years ago | (#4167167)

I would ask the ISP to show you detailed info on there outbound bandwidth and the current performance. Also ask about what there upgrade policy is as well. A lot of people work on keeping there links at 80% utilisation and upgrade when they go above that. This applies to the small guys as well as the big guys. The advantage is if you go with the big guys and a couple of people have sudden jumps in there bandwidth it is not going to make as big a difference to your throughput as it will with the little guys.

Welp. (5, Informative)

!ramirez (106823) | more than 12 years ago | (#4167061)

Well, usually, you're buying a T1 from your location to the ISP or hosting company or whoever. 99 times out of 100, you're going to have a full T1 from your place to theirs (ie: 24 channels of 64kbps, or 1.544kbps). The 1% is most likely going to be some unscrupulous ISP; I've heard stories, but never seen a T1 sold to a customer that wasn't a full on "T1".

Now, as for your bandwidth, that's a different story. It is accepted practice to have oversubscription on your network; ISPs simply don't have the money to provide a full, balls-to-the-wall, 1.544mbps connection to the net for every single one of their customers. Local loop charges for simply a T1 from their office to yours starts at around $200 (in Alabama), and that's only if you use a CLEC. The bandwidth is what you're wondering about, and quite frankly, without having someone in the know inside your ISP, you will *never* find out how oversubscribed they are. What you pay above and beyond local loop charges are bandwidth access charges; you're actually paying for internet access at that point. Roughly analogous to paying for a phone line (local loop), then paying for dialup internet service (the T1, in this analogy).
Basically, unless you're buying a DS3 (44.762mbps) or above, you will never ever get committed, 100% full bandwidth on demand all the time.

pathchar, pathload, pathrate (1)

wuchang (524603) | more than 12 years ago | (#4167066)

Van Jacobson's pathchar can measure this. ar/ Another variant that measures available bandwidth was just presented at SIGCOMM 2002... Couples periodic packet trains with queuing delay analysis. Does a binary search over a range of periods to zero in on the bandwidth. Run the tool continually and look for the maximum.

well, one way (5, Funny)

joekool (21359) | more than 12 years ago | (#4167067)

I think you found the way, but you forgot to include the address for your site.

Re:well, one way (2, Informative)

SiMac (409541) | more than 12 years ago | (#4167104)


Rule #1. EVRYTHING IS OVERSOLD (5, Informative)

philzama (582467) | more than 12 years ago | (#4167071)

Its just a matter of how much it is over sold. If the "Big Guys" are try to tell you they dont over sell they are lying. Everyone does, playing the averages are how this bussiness works. Ask to see some MRTG graphs of thier gateways b/w. See if thier heads are bonking against the top very often. BTW chances are that the small isp will treat you very well while the super available mega corp sales man soon be replaced with a touch tone menu. Ask for refrences and call them.

Actually... (0)

Anonymous Coward | more than 12 years ago | (#4167124)

I'm pretty sure the first rule is you do not talk about fight club.

Re:Actually... (2)

rakslice (90330) | more than 12 years ago | (#4167196)

You speak the truth. Now, for reasons you've so conveniently illustrated, we must blow your ass up with cinematographer-friendly guerilla actions.

How to tell.. (0)

Anonymous Coward | more than 12 years ago | (#4167076)

Easy. Click here [] .

Thank god for Microsoft.

There's only one reliable tool... (1)

Clownburner (257523) | more than 12 years ago | (#4167079)

A line tester will tell you if you've got a physical T1 but can't tell you how much upstream bandwidth is available. Unless the provider is willing to give you SNMP read access to their network (uh, yeah, right, that'll happen), MRTG isn't going to be very helpful either.

The best and most reliable tool for hop-by-hop bandwidth determination we've found is PCHAR:

Join a LUG (1, Offtopic)

dillon_rinker (17944) | more than 12 years ago | (#4167080)

I learned all I know from other members of my LUG. What I didn't know I could ask.

You can't. (3, Interesting)

brooks_talley (86840) | more than 12 years ago | (#4167081)

There is no way for you to determine whether the small guy is overselling his uplink without getting into his data center and doing an audit of his equipment -- something he'd have to be crazy to allow (*I* don't want a T1 from someone who lets potential customers do that!).

However, as other people have noted, after installation it's fairly easy to measure the bandwidth you're actually seeing. Telltale signs of oversold uplinks are things like vastly better performance at 3am than 3pm.

All in all, it's not necessarily a bad thing to have a (slightly) oversold uplink, as long as it is constantly monitored and upgraded if/when end users' aggregate usage is more than 75% for any length of time.


Overselling (1)

martoQ (572166) | more than 12 years ago | (#4167085)

As it was stated 24 channels at 64k a peice for a T1. Now if this is point to point, I am not aware of how he is "overselling" his bandwidth. You simply cannot do that in a point to point as the cross connects from CO to CO are directly routed. Now if it was frame-relay, then thats a different story because then you have to worry about how much CIR you purchased. CIR is commited information rate, basically how much traffic is guranteed that will not be marked discard eligable. Once a packet is marked DE, it potentially can be dropped due to congestion in the frame switch thus it goes deep with FECN and BECN, etc.

Overall to me it sounds like he is feeding you a line.

But if you REALLY wanted to test, I suppose you could look into a TBird but then you would need to contacts in the local terminal to run head to head with you.

If your ISP is overselling (5, Informative)

overshoot (39700) | more than 12 years ago | (#4167087)

then that variable 300-900 kbps is exactly what you'd see. The problem isn't between you and your ISP (which is what you'd be testing with line meters etc.) but with the ISP->backbone connection.

The real test, frankly, is to get bandwidth from someone with heavy-duty backbone connection (e.g. AT&T) and just plain hammer it with mondo file transfers scattered across the day. If your transfer times are varying with Net traffic periods, your ISP is the bottleneck.

You might be able to get similar information cheaper by doing repeated traceroutes and logging the delay between the ISP and the next router up, which would indicate the queueing delay at the ISP's routers.

Over selling not inherently evil... (4, Insightful)

srvivn21 (410280) | more than 12 years ago | (#4167089)

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.

No. (1, Informative)

Anonymous Coward | more than 12 years ago | (#4167090)

MRTG doesn't test jack $hit. You have to measure between your serial router and the upstream network at the ISPs side. See if they will install netiq qcheck, and measure udp streaming.

fool (0)

Anonymous Coward | more than 12 years ago | (#4167092)

I don't think you really understand the difference between a T1 and allocated bandwidth. Just be happy it is up and that you are getting good latency. A few tools you may use are: traceroute, ping, and ftp.

I would have thought this type of question would have been asked about 5 years ago. Guess things don't change much.

It's a myth (4, Informative)

ZoneGray (168419) | more than 12 years ago | (#4167093)

It's an old ISP myth. Everybody "oversells" their connections at some point in the stream. In the early days, this sort of thing was an issue, a small ISP would but a certain upstream bandwidth (usually one or two connections) and then sell pieces of it until they had sold more downstream than they had upstream. In practice, it worked well, since few people ever use their maximum bandwidth constantly. A few were fastidious about buying upstream bandwidth in exact proportion to what they sold downstream. They mostly went out of business or were bought by Verio.

Today, few ISP's actually have upstream bandwidth equal to what they've sold downstream. And it gets even more complicated when you consider that there are usually multiple routes out of an ISP, some of which can be easily overloaded, others less so, depending on where the traffic is destined.

The only worthwhile measure is a subjective one. Can you get 1.5Mb throughput on ANY site? On some sites but not others? Do you think you're going to get better service from somebody else? There's no exact answer as to whether you're getting your money's worth; experienced net admins have used a several connections over time, and usually know within a day or two whether they're on a good one or not.

Re:It's a myth (2)

Jason Earl (1894) | more than 12 years ago | (#4167183)

Well said. My take would be to go with whoever is cheapest, and switch if you don't feel you are getting your money's worth. Setup MRTG (or whatever) to monitor your router, and then keep track of your traffic. If it appears that you are topping out before your 1.5Mb (especially at busy times of the day), then complain.

Otherwise pocket the dough and be happy.

Check the CSU/DSU (5, Informative)

Sierran (155611) | more than 12 years ago | (#4167101)

The T1 will terminate in a box (or in a card in the router) called the CSU/DSU (something service unit/data service unit). This is the device that allocates the 24 channels of 64Kbps (mentioned earlier in the thread). If the CSU/DSU is a separate box, you can probably do this from its management interface; otherwise, if it's an integral one that's inside a router or on a card in the router, you'll need to get onto the router's mgmt interface.

First of all, if you have *the whole T1* then you should have control of the CSU/DSU and the router at your end. Accept no substitutes. If the guy is, in fact, splitting a T1's worth of bandwidth off a DS-3 (say) then you should (at the least) have monitoring privileges on the router and DSU, either via web, SNMP, or telnet.

As mentioned earlier, the DSU should show that your connection to the line is using 24 x 64Kbps channels, for a total of 1.544Mb/sec (minus a few k for channel overhead gives you 1536). ALL of those channels should be coming out your end of the CSU/DSU.

If you have control of the router, then you might try (again, as mentioned earlier) ping-flooding the router at the other end of the T1 and checking how many packets/sec get through, then multiplying by your packetsize. That should give you a reasonably close answer.

If the guy isn't bullshitting you, then he should have no problem giving you read access to the SNMP MIB on the router and letting you watch traffic - if you can access this, you can run bandwidth monitors like MRTG.

Good luck.

SLA (0)

Anonymous Coward | more than 12 years ago | (#4167103)

Any T1 you get from anyone is going to be oversold. What matters is the speed specified in your SLA. If it says you're getting a 1.54MBPS T1, then that's the bandwidth they
have to provide to you. That doesn't mean though, that they have to have 1.54MBPS x the number of T1s they have sold worth of bandwidth, because not everyone is going to have thier T1 pegged 24/7. If your SLA specifies that you're going to get a certian speed, I wouldn't worry about it. Get the better deal, if they don't hold up thier end of the bargian, you get a refund...

Very easy (0)

Anonymous Coward | more than 12 years ago | (#4167108)

Just set up a site that could somehow be submitted as a Slashdot story, wait for the Slashdot effect to bring wrath to your server, and look at your MRTG graphs while it lasts. :)

Forgive the trolling, but this has to be said (4, Funny)

AntiTuX (202333) | more than 12 years ago | (#4167116)

3 things:
1. tell your boss to fire you, and hire someone with clue.
2. you have a router, use it, dipshit.
3. see #1 and #2.

Jesus christ, do you think the router's there just to look at?

Re:Forgive the trolling, but this has to be said (4, Funny)

Jonny Ringo (444580) | more than 12 years ago | (#4167153)

But what about those holes in the router?
sales guy: yeah, those are speed holes.. oh and a I almost forgot here's you free bread sticks

Re:Forgive the trolling, but this has to be said (2)

unicron (20286) | more than 12 years ago | (#4167208)

Louie: Should I shoot him gangland style or execution style?

Fat Tony(whimsical): Listen to your heart.

Big Guy vs. little guy (2)

truesaer (135079) | more than 12 years ago | (#4167120)

One of the interesting things I picked up on at my last job, is that service from the LEC tends to be better than other companies. For example, an Ameritech line is often faster than Broadwing (even though Broadwing is having Ameritech install the circuit anyway...). There are two potential reasons for this....Either they are screwing with their competitors lines, which wouldn't be a surprise, or they have better peering relationships with various backbones and other providers. The quality of peering relationships is important, and not something that is easy to determine.

TTCP (1, Interesting)

Anonymous Coward | more than 12 years ago | (#4167129)

I've had good luck testing T1's with TTCP on pc's at each end. Also, TTCP is available on Cisco 3500 switches as an undocumented command as well as on Cisco routers with certiain (Enterprise) feature sets.

Use "bing" (4, Informative)

Nurf (11774) | more than 12 years ago | (#4167131)

Ooops... bumped the submit button by accident last time. :-P
Bing [] works well for symmetric links. It's not much use for DSL lines, but for true symmetric lines it's pretty accurate.

It will check the bandwidth between two IPs, as long as the one IP is in the path to the other from your machine.

Why care? (0)

Anonymous Coward | more than 12 years ago | (#4167138)

If you're having such a hard time finding any way to discern a real T1 from an oversold DS-3, maybe you simply shouldn't care?

Overselling (1)

p7 (245321) | more than 12 years ago | (#4167139)

Transfer speed websites will likely not help you in this case. The problem you are worried about is an oversold DS3 connection (The maximum bandwidth they accept and route to the internet is greater than the bandwidth of their DS3.) To find out if this is happening would require you to set up a sustained transfer to a site just beyond your ISP. Then if you spotted a drop in you bandwidth you could attribute that to other customers maxing out the ISPs DS3. A two minute transfer to a site x number of hops beyond your ISP will only tell you that somewhere along the line something slowed down your transfer, but that could be the other site slowing down. If you have a contract guaranteeing the bandwidth, stick with the little guy. You obviously haven't experienced terrible performance from this connection or you would have checked up before the big guys planted the seed of doubt.

Don't Hub, Use a Switch (1)

Bloodmoon1 (604793) | more than 12 years ago | (#4167152)

While I have no advice to find your T1's speed, I have a suggestion to improve it. Take the hub that you and the other two occupants share, sell it, and spend the money plus whatever else it takes to buy a switch. Hubs devide up the bandwidth, so you're probably getting around 1/3 the speed you could be getting, switches don't. They only forward data to the appropiate computer/network, where as a hub broadcasts it to every device on all connected networks barring a switch/router somewhere down the line. Add a switch and you will see a great improvment.

Re:Don't Hub, Use a Switch (4, Informative)

MonMotha (514624) | more than 12 years ago | (#4167219)

T1s don't use hubs, or switches. They aren't ethernet.

As was mentioned in an earlier post, a T1 uses something called a DSU/CSU to manage the 24 BLines on your T1. This is sometimes built into a router, on a card in a router, or an external device running to some sort of high speed serial line (not always HSSI though) that can be linked to your router.

You can check the settings on this DSU/CSU to make sure you have a full T1 and not a fractional (all 24 channels is a full T1, less than 24 is fractional), but that won't help with finding oversubscription at the other end. There's really no easy way to check that, but if you never notice, who cares? Just make sure you get an SLA for the bandwidth you expect (usually the full 1.544Mb/sec on a T1) and if you at any time are unable to get that due to oversubscription by your ISP (all of them do it, some more than others though), you are entitled to compensation (often a partial refund or even being paid).

You're behind a hub? You ain't got a T1. (3, Interesting)

toybuilder (161045) | more than 12 years ago | (#4167154)

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.

Ahem. From this, it looks like you're really just buying Internet access with a "T1" rate. 900kbps is almost as good as you're going to get on a T1. Maybe upto 1.1Mbps or so, tops. You have to allow for protocol overhead, latency of all equipment between you and the "other side", and congestion that may or may not exist.

Everybody shares bandwidth (1)

cprice (143407) | more than 12 years ago | (#4167156)

In my experience all vendors, big or small, 'oversell' themselves. Remember, all salesmen are liars, have no souls and will all burn in eternal hellfire... They will try to spin you a yarn to try and differentiate their products where there really are no differences. I would say that if you regularly see 900Kbytes/s and have uptime in excess of 99.99%/year, that you are doing well with your T-1 line (not considering the cost of your line).

Hmmm... probably hard to tell... (1)

prozach (91711) | more than 12 years ago | (#4167165)

Honestly I think unless you have access to some FTP server or something like that just on the other side of their DS-3 you will have no reliable way to tell for sure. Yes, you could run a bandwidth meter like DSL reports or something like that but unless there is no congestion between you and the server running the test you may not get accurate results. In otherwords, you may have slow link somewhere in between that would make it hard to check how fast your connection actually is. The only sure fire reliable way to test is to run a check from your site to something just on the other side of your provider(your providers provider) if you can find out where they buy their uplink from.
You could have a T1 while your provider has a T3 or something but maybe they sold 100 T1's with that T3 uplink. (a T3 is 40-some T1's) so you may never get close to T1 during peak traffic hours. (But it may appear you have a full T1 during off hours) Unless you show up and ask for a tour of their co-lo or office I think you'll just have to take their word for it that they own enough bandwidth to cover your needs.

Say they get their uplink from WorldCom, if you could find a server on the WorldCom/UUNet backbone where you could download a large file and check the speed during peak hours it might give you an idea. (Just incase it is WorldCom, has a mirror site on the UUNet backbone)

Good Luck...

Pound the upstream (2)

autocracy (192714) | more than 12 years ago | (#4167174)

Nail their upstream with pings... really big ones, down the pipe as fast as you can, right into the closest provider from them (their gateway on the other side). Then use (guess what) MRTG to meter the bandwidth. Reason for doing it this way is that almost any method that rates a download will come out on the conservative side because of network overhead, and you get to measure both upstream and downstream at once. Just play nice about how you this, massive ping floods can be taken the wrong way!

Smartbits... (1)

umask077 (122989) | more than 12 years ago | (#4167176)

If you can get a smart bits and want to test a point to point connection its the best way. You can probably rent one from GE Capitol. They cost around 40k to buy so there not trivial but they are the best method of testing. It however requires access to both sides of the network to do properly.

the quick and EZ AnalogX tool (0, Offtopic)

mozkill (58658) | more than 12 years ago | (#4167178)

its not the answer, but for people who like a basic bandwidth meter for their system, go to the analogx site and get Netstat Live...

Unbelievable... (0, Offtopic)

nochops (522181) | more than 12 years ago | (#4167185)

I really can't believe this.

A few days ago I post a good story abount how the new terrorist database system keeps crashing, and get rejected:
2002-08-23 20:52:48 Terrorist database often crashes (articles,news) (rejected)

But somehow, this makes it onto slashdot...

On the other hand, I don't wanna get off topic so why don't you just do like everyone else, and get MRTG and set it to SNMP to your router and get the interface statistics directly.

CIR (2)

J4 (449) | more than 12 years ago | (#4167186)

What commited information rate are you paying for? It's possible can get more effective sustained throughput with a fractional T
with a higher CIR than a full T with lower.
The full T will have higher burst speed.

What does it matter? (1)

greymond (539980) | more than 12 years ago | (#4167198)

Are you really inerested in some kind of bragging rights to say "yeah I have a T1 look at me" or are you more concerned with bandwidth. If it's thebandwidth it won't matter if its from a split DS-3 or a true T1 as long as your speed is what you need and expect. Besides you could get a DSL line running at 1.7mbs and it would be just as good considering a T1 runs at 1.5mbs anyway.

But I guess i'm just being logical here and forgetting the corporate thinking of:

more expensive = better

I'll tell you exactly how (3, Funny)

matusa (132837) | more than 12 years ago | (#4167200)

I run the network for the dorm here. I know that we have 1.544Mbps full duplex on both T1s because of...

P2P software. Yessir, these suckers are fully saturated at all times as the year goes on =)

Seriously though, the way I've tested is get a machine a few hops away, and start moving as many bits as you can. I use RRDtool to track everything, and it works quite excellently. I have multiple graphs, which collect data using SNMP directly from the routers...


Does it really matter? (3, Informative)

gblues (90260) | more than 12 years ago | (#4167202)

A DS-3 is essentially a T-1 on steroids. Instead of only having 24 64k channels, a DS-3 has 672 64k channels.

So if the ISP is selling you 24 channels of the DS3 and calling it T1, then you're getting a T1. Quitcherbitchin.


Lies, damned lies, and statistics. (5, Informative)

Stephen Samuel (106962) | more than 12 years ago | (#4167209)

It all depends on where you want your T1 bandwith to go TO. Unless your local guy is guaranteeing you a specific bandwidth to the local backbone, there's nothing wrong with him (slightly) over-subscribing a DS-3. That sort of stuff is being done all over the net.. Mostly based on the fact that hardly anybody comes close to running their pipe full out 24/7.

This even applies to phone lines.. That's why It's sometimes hard to get a call through on Mothers' day. The phone companies provision to handle 99%+ of the volume spikes, and mothers' day can consistently make it into that last percentile. Even so... handling 99% of the traffic spikes still comes to far less than one circuit for every two subscribers.

To test if your T1 is really a T1, you can try setting up for an FTP (or whatever) session with your buddies... Change things to make sure that you've each got the route to the other going through the first hop on your T1. As long as that router doesn't icmp-redirect the traffic, (in which case your measured bandwidth will be more in line with local ethernet traffic) you should be able to get a good estimate as to the raw bandwidth of your 'last mile'. (it'll actually be the lesser of your uplink speed and your downlink speed minus a little bit)

The next hop would be to set up a transfer with something inside of your ISP's primary network. (did they give you a web site on one of their systems, etc??). That'll allow you to test for local bandwidh bottlenecks and give you a theoretical maximum to the outside world.

The last link check would be to find a machine on a fast network that's not on your local ISP's but is (topologically) close. Try doing traceroutes to nearby universities.. See if you can find one that doesn't put you through 3 different ISPs. Then try and transfer data from/to them and see how fast it goes.

You'd be best to try connections to a few semi-local sites. Otherwise it'll be hard to tell if a low bandwidth reading is the fault of your ISP, or the server's ISP.

It's pretty much useless to check bandwidth to random (distant) sites. Once you get a site that's a reasonable ways away (topologically or geographically), then you run into the vagraties of internet traffic (see the article earlier this week about 'net quakes)..

BTW: When I speak of being topologically close, this is different from geographically close. I remember one case where getting a packet to a machine not more than 100 feet away (but on another ISP) sent traffic from Vancouver, down the coast to Silicon Valley and back. Needless to say, ping times stank. In that case we were geographically close, but topographically distant.

THere would be two times to test these transfer speeds: Low time (e.g. 4am) and prime time (Last time I peeled apart ISP traffic stats, traffic peaks were around 8-9pm for home traffic and about 4PM and 9AM for commercial traffic)

Over selling a T-1 is a subjective measurement (1)

old7 (564621) | more than 12 years ago | (#4167216)

I worked for a small ISP (40,000 subscribers) for 5+ years. The best method to tell if it is over subsrcibed to to run bandwidth tests at various times during the day and night and compare. Of course you need to also look at the price that you are currently paying and compare that with what everyone else is quoting.

If you are happy with the price that you are paying and the service/bandwidth that you are getting then stay where you are. If you are unhappy then go shopping.

Even the national providers oversell there Internet service. They just do it on a different scale.
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