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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!"
MRTG
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.
FLR
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
No.
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.
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
Any decent router or firewall (which you will likely need to purchase or lease anyway.) Will have this capability built in.
m rtg/mr tg.html
Then there's always MRTG
http://people.ee.ethz.ch/~oetiker/webtools/
fslg503-985-8686503-985-8686503-985-8686503-985-8
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.
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 vendor...how 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?"
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.
I think you found the way, but you forgot to include the address for your site.
Slackware: old school feel, new school gear.
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.
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.
Cheers
-b
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.
Lacking <sarcasm> tags,
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.
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.
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.
A hero is someone who knows when to run away. I am a hero. -Trent the Uncatchable
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?
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.
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.
Finally, math books without any of that base 6 crap in them.
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.
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!
SIG: HUP
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.
You speak the truth. Now, for reasons you've so conveniently illustrated, we must blow your ass up with cinematographer-friendly guerilla actions.
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...
matusa
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.
Nathan
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.
"Klaatu, verada, necktie!" -Ash
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)
Free Software: Like love, it grows best when given away.
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!
-Jason
That's it. I'm no longer part of Team Sanity.
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).
If no site can get consistently good bandwidth, then I'd be more likely to blame it on my ISP oversubscribing.
Free Software: Like love, it grows best when given away.
There seems to be some confusion between what a T1 is, and the data rate a T1 can support, as well as how bandwidth is marketed and sold, and wether or not the online "speedtests" mean anything.
... or raise several billion in VC money to build your own Internet to all the sites you want super-fast connections to.
First off, excluding some very odd and sparse cases, from a telco "loop" perspective (the wire and associated hardware involved in providing a T1 from you to the telco's office or remote), a T1 is a T1, regardless of it being frame relay, fractional, point to point, or otherwise. Basically, 1.544Mbps raw data rate. The only thing the telco can tell you is that it is working within acceptable limits, with an acceptably low BER (Bit Error Rate). Nothing more. If it's a non frame relay dedicated T1 (aka point-to-point or "nailed up"), you should see something like 160kBps on a single transfer over an otherwise idle circuit. Frame relay is a totally different ballgame - you run into the circuit's "CIR" - Committed Information Rate (or also referred to as Certified Information Rate on occasion). Basically, it works like this - even though your local loop (wire from you to the telco) supports T1 rates, they're only provisioning your chunk of the frame relay "cloud" to support the bandwidth you purchase. Depending on the provider, it could be a "hard" limit (ie - you'll never get more than that), or a "soft" limit, meaning that you may get more speed if there is sufficient packet bandwidth left, but when it's busy, you'll get choked down to your CIR.
Second immutable fact of the Internet - providers (particularly tier 2 non-backbone providers) will always oversell their bandwidth. Think about it - how do they make any money at it otherwise? It's their bandwidth "sold" to bandwidth "available" ratio that tells you anything about the quality of service you may expect to see from them. It can be virtually anything really. It's similar to the subscriber to modem ratio dialup ISP's keep, or subscriber to bandwidth broadband ISP's keep.I'm not sure what the averages are anymore with the changing scene of broadband right now.
As for testing your speed with one of the online "speed test" sites, take the results with a grain of salt - a very BIG grain. It's only benchmarking the ability for you to transfer data between your location on the Internet to their location on the Internet. Nothing more, nothing less. More oft than not, their results are less than what your circuit (or broadband connection) are configured for, and sometimes, dramatically less. I've seen 256k DSL connections that "felt" as they should speed wise, bench in at dialup speeds using those sites because of bottlenecks beyond their or their provider's control.
A better test of bandwidth, and possibly more importantly connectivity, is to do some basic homework. Ask your provider to provide some traceroute and ping data to some common sites potentially used in your day to day activity - taken at different times of the day, preferrably at the times you're most interested in. Or better yet, ask them if they would let you do the tests yourself from their facility. Choose some sites you frequently visit, business or pleasure, and trace their progress theough the Net. Fewer hops = better speed and reliability overall.
I may catch a little hell for this, but I've found it to be a good general benchmark - download something that is known to be cached at at Akamai cache farm. NAI virus updates used to be a good test. Akamai is generally connected very well, in strategic points through the Internet, and provides at least a benchmark to go from. Downloading from Microsoft is sometimes a decent test, sometimes not, depending on what's downloaded and when. And, no, that wasn't meant to be a troll or flamebait, just a basic fact really.
In all, if it generally looks right, feels right, and provides stable, repeatable performance during the times you need it, it's probably fine. There is no good, clear, black and white method of determining if your "T1" is a "T1".
They may just be shooting you a good deal because they have plenty of bandwidth, and sales prospects are limited because of the economy. Who knows. Just do your homework, limit your exposure to marketdroids and the resultant weasel-words, and go from there.
Remember, for all intents and purposes, the Internet is basically the data version of the public road and highway system. You'll find construction, detours, and bottlenecks regardless of how many 12 lane super-highways exist. You just need to live with it and work within those limits as best you can...
Brad
All bandwidth providers oversell thier available capacity. Almost no one (legitimate) uses all of thier available bandwidth all the time, so usually everything runs together fine. They have to do this to comepete with everyone else. A T1 isn't really a big connection any more and you're probably not going to be an account they bend over backwards for. If you really want to be on a network that isn't oversold, you're going to pay 5 times as much. Worry about response (ping, number of hops in traceroute, etc) times to AT&T @Home customers and DSL customers. At the t1 level if those response times are good, you are doing great. When you move into a DS3 and up connections, the whole sales game changes again.
I have a remote-administered server in a colo in Mountain View, CA. I routinely have transfer rates of 2200 Mbit, for example, when updating via the Red Hat Network.
/dev/null on the system being tested, and watched the graph with MRTG.
Yes, that's about 15 T-1 lines worth of bandwidth - my 1.5 Mb DSL line is always saturated when loading stuff down from it.
So, I wrote a quick PHP script to take a 100k file off the disk, and hurl it at you repeatedly 1000 times, with a mime-type of application/octet-stream. That's a 100 MB file being downloaded by HTTP.
Then, I hit the script with lynx -dump >
In my case, we did get effectively 1.48 Mbit on the T-1 line being tested, which is close enough to satisfy my curiousity.
I'd be happy to perform this test for you... BTW - if you are in North California, I recommend o1.com as an excellent provider!
I have no problem with your religion until you decide it's reason to deprive others of the truth.
That provider declared bankruptcy (doesn't narrow the field of suspects too much I'm afraid) and left California. We now have a T1 split into half voice and half data - ie. half the bandwidth we did before - and everyone is amazed at how fast things became. The real difference is that the round-trip latency is generally more like 20-40ms or an order of magnitude faster than with the previous carrier.
Note: we are with a "smaller company" and are quite happy with the service. I've "been serviced" by the big unnamed telco (Should Be Castrated...) and it has always been terrible. Terrible for home voice, terrible for home DSL, terrible for business voice and terrible for business data. The big guys are doing what they always do - spreading FUD instead of providing good service.
~~~~~~~
"You are not remembered for doing what is expected of you." - Atul Chitnis
Guilty as charged. But with an explanation... I was just assuming he's been getting his 900kbps with remote bandwidth testers (located who knows where) on "untweaked" PC's.
You are correct in that T1's themselves do not use hubs, switchs, and are not ethernet. However, you are not taking into account what happens on the other end of the router once it's out of the provider's loving hands.
You can't just run the T1 into every device on a network, you either have to hub it (Cheap but SLOW) or switch it (More $, but better performance). Take my old High School for example: The district has a seriours cash problem (namely, no money) because we have no city government, they get no city taxes, and they get $0 corporate donations. So they chose to get a T1, but hub the hell out of it. In the English "Computer Lab" alone there were 2, 36 (I believe) port 3 Com hubs. This was the case all over the school, aside from our 1 router, every thing else was hubed, and this was also true for the whole district. As a result, the network worked fine at 6 AM when no one was there and everything was off, but by 10 AM, it dragged bad. It was so horrible that I was actually able to get faster bandwidth using a dial-up.
Request: ECM unit, 1000 km fullerene cable, 1 tactical nuclear weapon. Reason: Birthday party for foreign dignitary.
dslreports.com
FoundNews.com - get paid to blog.,
There really isn't a true way for the end user to tell what rate he is getting with any accuracy.
He would have to wait until the DS3 was full (maybe during peak hours), but the problem with this is that the rest of the internet is congested too, and therefore the speed from dslreports to the end user would not be accurate.
The other problem is, tests such as ftp test (which use 1500 byte packets), give results that have a huge variation. To get any good results you will have to use ftp a huge file (many many MB) so that the transfer can come to steady state.
The only true way to test this is really in a lab scenerio!
Ask the ISP how he gaurantees that the ds3 is not oversubscribed. Is it set up for Qos/Cos, and if so, how is it set up?
Good Luck!
Furthermore, we split the T1 out over a hub with two other tenants in the building. I'm coming through from behind that hub.
Hubs? You actually use hubs? No wonder it seems slow.
Here is a Google cache of the difference between hubs and switchs (basic).
If you're in charge of the network, you need to take some courses. No offence.
One thing that always bugged me was how the Time Domain Multiplex (TDM) formats naming doesn't make a lot of sense. A DS-3 carries 28 T-1's. A DS-3 is sometimes known as a T-3, and maps closely onto an OC-1. The OC naming makes a bit more sense, in that OC-3 is three times the capacity of an OC-1, OC-12 is twelve times, etc.
If the ISP has more than 28 T-1 customers and a single DS-3 (or OC-1) to its provider, then you are all sharing that bandwidth. But if you think about it, at some point you are going to have to share comm. links somewhere upstream, so the fact that an ISP has only a DS-3 is not in itself a concern.
About the only thing you can do is keep an eye on the performance that you get, and ensure that you (1) can achieve peak bandwidth of 1.544 Mbps sometimes, and (2) that your average bandwidth isn't too low. Ask your ISP what average bandwidth you can expect to its provider, and use that as a benchmark. If your average gets too low, then you can complain.
Anybody want a peanut?
All ISPs even the phone company over sell their down stream to upstream. 4:1 is a common ration for business level down stream bandwidth to upstream bandwitdth.* I know of one ISP here that keeps this ratio, and generally uses about 50% of their upstream bandwidth. They are likely to have burstable upstream connections, just in case it gets extra busy.
*Incidentally, consumer level stuff has higher ratios that that, I have heard of dial-up places with ratios closer to 200:1. I doubt broadband ISPs can go much higher than 10:1, but that is just a guess. That ratio is one of the best indicators of service quality, but I doubt you can find a service provier that will tell you theirs.
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
Try Ettercap. It sniffs switched networks through ARP cache poisoning.
Most of those friggn things measure the "time it takes to download a 1 MB image file"
;)
What they don't tell you is that its mostly wholly dependent on the rendering speed of your computer!
Two machines, side by side with different processors, browser versions, video cards, drivers will give wildly differing opinions of the true "speed".
Unless you're doing a lot of hosting on your end of the T1, or you're doing QoS based services (like VoIP) -- go with the local ISP -- the money you spend will be returned to your community and you'll get better support. Not to mention, most of the smaller ISP's do other types of consulting, so you almost always get more bang for the buck.
But take everything I say with a grain of salt, since I own a small local ISP -- not in your area
Old age and treachery almost always overcome youth and skill.
Couple of things, first, all ISPs oversell bandwidth. I am assuming the 'larger' guys meant that the local ISP likely only has a single DS-3 to his upstream provider. Depending on how small he is, this may not be an issue (/all/ providers oversell at some ratio, it just depends on what that ratio is that determines if the provider sucks or not) depending on how many other customers he has, what types of circuits your providers customers' have, and what type of customer they are (business vs. residential), etc. Obviously there are other factors too.. if your provider suddenly grows and doesn't increase its upstream capacity, thats an issue.
/most/ circuit IDs from /most/ telcos is something like XX.AAAA where AAAA is frequently what your concerned about to determine the circuit type, but the format of the CID depends on your telco (there are many guides out on the internet at decyphering these to determine what type of service they are, or you could call your telco and they could tell you.. maybe.. if your good.. heh)). The CID should be on the smartjack..
/can/ be, without having to deal with other provider's networks being congested, etc (the traffic in this case will be local to your provider's network, so if thats congested then um.. that sucks).. You should get somewhere around ~192KB/s.. if its slightly less don't worry about it, there is some overhead involved, etc.. When you do this be sure you only have /one/ machine connected to test (or you can verify there is nothing else that is generating traffic that is going over that circuit, etc... don't assume.. check. (there are many, many, many tools to do this..) to see whats hitting the ethernet interface of your router (its a lot easier to check if you have access to your router, as you can just do a show int on a cisco to get traffic statistics, etc).
Now, on to determine if you have a 'real' T1. Many providers tend to sell frame relay service as a 'T1'. While its true that the circuit itself from the telco to your place of business is a T1 (unless you have say 56k DDS service, etc), after your traffic hits the telco's switch, it transverses their frame relay network, and eventually gets sent to the frame host on your provider's network. This can suck for many reasons, however the biggest one is that the provider can get away with purchasing a CIR that is less than 1.5 mbps (like 768kbps), and just have it be able to burst up to 1.5. This can suck a whole lot if the telco's frame network is congested, and you can never burst, and/or you constantly want to use more than the CIR etc..
You can tell what kind of circuit it is by quite a few ways, if its installed and you have access to the router you can simply check the encapsulation on the T1 (if its set to frame relay, its a frame circuit, if its set to PPP or HDLC its a point to point circuit), you can also tell by the format of the circuit id (the first part of
If you have a frame circuit they should be charging you quite a bit less than a point to point T1, especially if the CIR is low (the lower the CIR the less expensive generally). Point to point T1s are preferible in almost all cases unless your worried about cost.
So now that you've determined the type of circuit you have, you can check what speeds your getting. Its usually best to do as other people have mentioned and download (and UPLOAD too.. you should check both speeds) from an FTP server on the provider's network. This will give you the most accurate picture of how fast your connection
You should also do a separate test to a major site.. You could download the 1.4.0 Java SDK from Sun for instance (that should give you a decent speed). Don't worry if this is somewhat lower than 192KB/s, as that can be caused by congestion in a network inbetween you and sun that has nothing to do with your provider, etc.. If its consideribly lower than that speed consistantly (and other sites with bandwidth to spare yield the same results), then I would contact your provider about it. It could be that your provider doesnt have enough upstream capacity, or about a billion other things, but they might be able to tell you any known issues, or that the problem isn't them and/or tell you the current utilization levels of their upstream circuits.. heh
testing your outbound traffic is going to be a bit harder (mostly a problem with finding people who will take great gobs of your data).
P2P networks with a juicy set of files to transfer are a pretty good way of doing that.
If you can watch the raw traffic as it goes to your DSU, then you should even be able to factor in the bandwidth that your building-mates are using, too.
Free Software: Like love, it grows best when given away.
True, but he's not so much asking slashdot if anyone works at his ISP; he's asking how to check up on his ISP. I'll bet there's someone in his LUG who could tell him. I know who in my LUG I'd direct that question to...
I assume you're talking about ethernet (which uses hubs).
Your T1 goes to your DSU/CSU, then to your Router, which probably has an ethernet jack on the back of it. Now, ethernet is 10 or 100Mbit, but since a T1 is only 1.544Mbit, 10 will do fine. Also, at a mere 1.544Mbit, the overhead of ethernet due to collisions is practically nonexistant, certainly not enough to affect the overall performance that you see in internet bound communications.
Now, if you're running bunches of local stuff over the same 10Mbit hubbed ethernet, you may see severe performance issues, and this would probably be solved quite nicely by a switch (as local traffic will be forwarded only locally, internet traffic will be forwarded only to the internet router).
Dude...you almost had it. If you had included a link to a webserver running on your network in your post, half a million /. drones would have clicked it.
Then all you have to do is monitor the traffic between your gateway and your webserver. Presto! Instant T1 validation.
"Don't blame me, I voted for Kodos!"
Ask him the "Certified Internet Rate". A full T-1 line delivers 1.5 MB/S through 24 separate channels, each channel is responsible for 128K. For instance, the T-1 where I work is separated into 12 circuits for internet (768kbps) and 12 for voice. My CIR is 700 kbps down, 256 up. That means I can download something at a guaranteed minimum of 700 kbps, and I can upload something at a guaranteed 256 kbps.
He cannot, by law, lie about the CIR. If he does, the company he works for gets major fragmentation from the shit that hits the fan. I can sell T-1 service all day long, but if all 24 channels only amount to a CIR of 1 MBPS, I'm hardly competitive with companies who are selling my T-1 lines with 1.4 Mbps CIR.
BTW, why are you getting a T-1 line? Are you splitting it for both voice and data, or is it pure data. A number of clients I've consulted for in the past really only needed a cable or dsl connection for their uses (basically, web collaboration and surfing).
There's no way to answer the question you asked. But, maybe you should be asking a different question: Am I getting what I'm paying for?
/. earlier in the thread, and see if you're satisfied with the results.
There's no way to tell from the outside how much bandwidth the provider has sold, and they're not going to tell you. All you can do is, use any of the lovely tools touted by the great geeks of
Probably best way to do it is, find a few sites that you can get high throughput to (>1 Mbps) on off-peak times. Monitor those connections at peak and off-peak times for a week or so. If there's a big difference for *all* the sites, chances are your ISP is not giving you a big enough slice of the pie. If it drops for some and not others, you're looking at other parts of the internet getting bogged down. Even this is far from a perfect test, but it can rule out ISP bottleneck.
Don't you wish your girlfriend was a geek like me?
You have a TRUE T1 if you have.. a T1!
If you have constant 1.5Mbps between you and your ISP, tha'ts a T1.
And that's ALL A t1 is.
That's it.
It's just a line.
How much upstream bandwidth your ISP has is another issue. How much upstream bandwidth THEIR isp has is another issue as well, and so on, and soforth.
The best way to tell is to see what they will put down in writing.
Best thing is to ask for certain maximum latencies to certain points outside their network... that's the best bet..
Put the remote CSU/DSU in loopback mode, use a line tester on your end. It should tell you 1544000 bits/sec exactly. Or am I misunderstanding the question?
Aaargh. Serves me right for being lazy in my explanation...
What I was getting at is that if you just take a default configuration of your networking, and try to do bandwidth measurements with a remote "bandwidth tester" over a "public" network that has all sorts of hops between you and the test-server, you're likely to get not-so-good performance, and that 900Kbps is not a terribly bad number. As I said before, it depends partly on what doodads might be between the testing PC and the server (inclusive of the equipment on both ends). Poorly configured client PC's over a high-latency network can take a 1.5 Mbps connection and make it look like 400 Kbps...
You can, of course, run a test on a quiet and private network, with all the networking parameters tuned to optimal to get full utilization of your bandwidth.
This touches on some of the issues.
*sigh*
Those who test by FTPing large files and watching the transfer rate, should understand these limitations (kindly explained to me by J.Spencer Love).
I had a similar problem trying to host a large-bandwidth video clip. It turned out the bandwidth of my 10Mbps line did not saturate at all (in fact, it was utilized at mere 5%), so neither did the trans-Atlantic connection. The bottleneck was the internal buffer in client and server software.
This also means you may not need that much bandwidth to push the speed of your FTP/TCP-based tasks to its limit.
17779 eligible voters in a district, 17779 'vote' as one. This is Russia.
Does anyone know of a company that has a faster network than Savvis (savvis.net)?
They've got SLA agreements that I have never seen beaten for on network latency.
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
Write up a short story that says your company uses Linux because they hate Microsoft. Then, place that story as an HTML page on a a webserver on that T1. Submit the story to Slashdot. (don't worry, it'll get posted.)
If you're not getting enough hits to it from Slashot, put a small Flash animation on the page. This will infuriate the users, they'll bitch about it and cause more people to hit your site.
If your server catches fire, then your T1 is up to speed.
Shouldn't be too hard. Walk up to your PBX, open it up, you should see lots of cards. A few on the lower shelf might be labeled something like TMDN64, TIE, you get the picture. Pull them out one by one to see which one might have the span in question.
ftp://ftp.src.uchicago.edu/pub/OpenBSD/3.1/src.tar .gz
:)
The math is simple. 1540 Kbit / 8 = 192.5 KByte.
If the line is empty, and you dont get ~ 190-200K, you dont have a full T1
I don't understand the logic behind that. I think of T1 as a speed, not a product. If he is on a shared DS-3, but always gets 1.5 and up down, 24 hours a day, then who cares?
Finally, math books without any of that base 6 crap in them.
To be specific, if you want to know if you have a T1 line, as others have pointed out, get it in writing from your ISP. If you want to know what your total throughput is on average, do you want to know the "real world condition" throughput, or the to-backbone throughput? If you just want to make sure you're getting fairly close to normal bandwidth(and not avery bit you can just cause), check out a web-based bandwidth meter. It's not super accurate, but it's not bad. Check out www.toast.net. They've got multiple test sites, so you can get an average based on proximity to your location, etc. If you really want to maximize the accuracy of your results, you'll want to be the only computer on the line, and check your MTU, TTL, etc. settings, just for the hell of it(though it might be overkill for a test that's this loose to begin with).
--Not to be worried, Pitr fix.
If you're going to transfer files to see what you're "true" speed is then you should use TFTP instead of FTP.
FTP uses TCP acknowledgements (to make sure packets are sent reliably) which eat up bandwidth. TFTP uses UPD which doesn't check to see if packets were lost. TFTP isn't 100% accurate, but it is much closer than FTP.
"A plan fiendishly clever in its intricacies"- Homer Simpson
sh int s0
This will show you info like your line quality, errors and the rate of the bits going accrss it. 9 out of 10 times your T1 will operate full capacity, the big question is what kind of network and peering does your provider has. Are they over subscribed?
IE. My cable modem can do 27 mbps, but RoadRunner doesn't have the capacity to handle that.
The peice of cooper that terminates at your site will almost always be the same wire that all the T-1 providers will provide. It's just depends which cage on the other side of the wire you hooked into.
zin
-ZiN-
Isn't the more important question: Is the bandwidth meeting your needs? Are you getting it for a good or at least fair price? If it's meeting your needs and you can't do better elsewhere, does it really matter if you're getting every bit of bandwidth that's possible?
If you're starting to strain the limits, then a simple bandwidth meter should be able to tell you how much is being used, at which point it would be pretty obvious if you're getting what you're told.
It's hard to say for sure because there are too many variables to calculate. What you can do is measure over a period of time and then take a best guess at whether or not you're getting reasonable throughput for the price.
But that's just MHO.
My advice, having done it before.
There is no such thing as overselling. He is selling you a T1 to his network. You will get precisely that. Everything else, you can tlak all you want about whether it's "Good" or not... or oversold or not... but when it comes down to it, you need something you can put on paper, in the contract.
Find out who your ISP is connected to, and how. Get them to make certain latency guarantees to certain points outside their network. None of this is exact science... so decide what the level of service you are willing ot pay for is and then ask for it, come to some agreement. Don't just leave it hanging. I mean, okay, if it's really really cheap, and he says "Well it's good right now" go ahead and gamble.... if you want.
There is simply no easy, clear way to define it. ISPs are not overselling when they get a T3 and then sell 60 T1's... they weren't offering you a T1 to their upstream... if you wanted that, you would just go to their upstream directly, and get a better deal.
A T1 is not a Lan. It is a point to point link. If you want to see what's going across your T1, you should first check the various counters that your router provides. As for capacity testing, get a box on the other side of the link that you can do load testing with and poll that.
"We returned the General to El Salvador, or maybe Guatemala, it's difficult to tell from 10,000 feet"
Comment removed based on user account deletion
You need to first figure out if you are buying a T1 link with Internet access, or are purchasing Internet access as T1 speeds.
It may seem subtle, but there is a big difference. In the first you have a 1.544 Mb/s link (either a true T1, FrameRelay or rate limited connection of some type) to the ISP. They in turn allow you access to their backbone connection. Here your ISP guarantees 1.5MB/s to their POP, but not necessarily to the Internet.
In the second you purchase a link (perhaps a T1) and Internet access at a set minimum bitrate. Your ISP guarantees that you get from your site to the Internet at 1.5MB/s. Once past their backbone router though, they aren't responsible for performance.
Also realise that you will never achieve that throughput for payload data. Each 1500 byte packet has a significant amount of wrapper data for all the lower protocols (IP,TCP,Link).
As far as your ISP's claim that they aren't overselling their T3, I don't believe them. I've never encountered a provider that didn't oversell their backbone. I'm not saying it isn't possible.
For testing: All you can really test is your link speed from you to your ISP. If they have an FTP server, transfer a large file and time the throughput. Once you get to the Internet all bets are off for throughput testing.
A comprehensive program of throughput testing and ping times from servers across the net at many different times of the day would reveal your maximum Internet throughput, but you never can tell exactly what could be causing any slowdown.
If you suspect your link is slower than it should be, ask whoever owns the local loop to run a circuit test, this will usually be the local telco. Tell them you need a local data loop tested for noise compliance because you are getting low throughput. They should do this for free as basic troubleshooting.
Article X: The powers not delegated... by the Constitution...are reserved...to the people
For all that switch cares, that router is another machine to speak with. Darn switch is just gunna forward it to where the MAC says to, pure and simple. If that be the router, it go to the router, if the server it be, there go ye (eh, so the rhyme is horrible, you get the picture).
A switch isolates collision domains, and only forwards packets to where they need to go (hence accomplishing the collision domain isolation). Basically, that means that the comps talking to the server (and sucking up mucho bandwidht doing so, as it's a full speed LAN connection not limited by the T1) won't interfere with the other peeps talking to the border router that's limited in speed by the T1.
This is the purpose of a switch (bridge), and it does this well.
Actually, a T1 is MORE than your average small school needs. The problem is all the idiots running P2P software and downloading warez all day long to their home directory. In terms of casual web browsing (especially in an educational environment, where cache hits tend to be frequent due to numerous students looking for the same info to complete an assignment), you can put hundreds or even thousands of simultaneous users on a T1. Web browsing is a very bursty activity; most of the time there's no traffic flowing over the line (while the person is reading the page).
Furthermore, SDSL coverage is spotty and rare compared to T-1. Standard DSL distance limitations apply, and the local teleco has to have some fairly new equipment. For businesses (the main consumers of T-1s), SDSL pricing is far higher than for residential. T-1s tend to be more expensive (though not by much), but the level of service with a T-1 is generally much higher than that of a DSL line, which makes for a much more convincing business case.
In short, SDSL is *NOT* "exactly like T1 without the extra costs ".
ftp uses tcp, which has a lot of overhead. In reality, a good rule is to divide by 10, and if your getting that, your doing damn good.
Lawyers, MBA's, RIAA? A jedi fears not these things!
Still using a T1? We used those ages ago, upgraded a bit since then.
We tested our T1 by sending it out to destroy a small village. It turned out that it wasn't water proof, and was quickly stopped.
We are up to the T1000 now, just about to send it on it's first test to. The lawyers couldn't do anything about them humans reverse engineering our model T101 CPU, even when threatened with the DMCA. So we hope this will sort them out.
What the competitors are telling you is that this particular provider has a DS3 circuit that has basically 45 Mb/s of throughput. In other words it can support 29.22 T1 users running at full throttle. In reality if you are using your full bandwidth then you are not!!! VERY IMPORTANT HERE!!! If your T1 is loaded then the routers on each end are dropping packets since they don't have very big buffers. This causes packets to be retransmitted, messages to be sent requesting TCP connections throttle down, timeouts, etc. Remeber that the real goal is how many WWW pages, email messages, FTP files, etc. that you can move. It is NOT how many bits per second you can send! If you are running at about 90% capacity then you can consider the line MAXED out. The same thing goes for your provider on his DS3 line.
If you throw in the burstyness of TCP/IP traffic your traffic really maxes out bouncing around somewhere between 65% and 90% of its max rated load. When you add in the fact that people like to have headroom and the size steps between T1 and T3 or partial T3 nobody uses their max bandwidth all of the time. This is something that your provider uses to his advantage by selling more than 29.22 T1's. In reality that provider may have 1000 dial up customers, many more DSL customers, people with dedicated 56K connections, and maybe even some old ISDN connections on top of the other T1's that he has sold. It is fairly safe for a provider to oversell a connection somewhere between 5x and 20x. Especially if you consider that people that have DSL's usually leave them on but don't use them for that many hours in the day. Headroom is defined as being prepared for the slashdot effect!
You need to figure out if your provider speciallizes in retail (home) customers or business customers. If it is home customers then his load will spike in the evening when poeple get home from work and on the weekend. If it is business customers then his load will spike during business hours. Also consider if your provider is hosting very much traffic beyond home users personal WWW pages. If he is then that is bandwidth that is not available to resell.
The only real way to tell is to look at your provider's router logs. Don't just look at averages for a day! Look at averages generated at least every hour over the course of at least a week so you can see when his network (which you will be a part of) loads up. If he consistantly stays below 80% of his upstream bandwidth and will upgrade his upstream connection if it passes that then you are fairly safe. On the other hand if he routinely pushes his max then that is exactly what his competitors are warning you about! If he loads up then everyone downstream from him will slow down as that will become the bottleneck.
Another thing to consider is that it sounds like he has a single DS3 upstream connection. Ask him if that is true and if he has any plans to become multi-homed. This has two major advantages over a single fat pipe: redundancy and load balancing. If he connects to two or more of the backbone providers then the traffic can most likely pick the shortest route to its destination while still having the other one available if one of the DS3 lines goes down. I'm sure the people @ /. have more than one connection if they are served from their business. It is more likely that they are hosted by a large hosting company that is already multi-homed though. A final thing to ask is if this provider does any traffic shaping. This can throttle users that are consuming more than their fair share. But if you are paying for a T1 you should get all of it. Sometimes though a customer will have a partial T1 (this requires a full T1 connection from their site to the provider though) and get to use any excess if it is available.
This is what I used to do for a living so I know a little bit about what I'm talking about! Once again his logs can tell you if he has oversold his service as his competitors suggest. But put some value on a provider that has more than one connection to the upstream Internet regardless of how large their single pipe is. If you want to have some fun ask him how much an OC196 would cost. 8-)
Regards, Tres
Restore America: Dr. Ron Paul for President!
... 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.
I can't imagine that poisoning their system performance falls within ethical use of my connection...
What's this Submit thingy do?
I've done T1 maintainence and provisioning for a VERY LARGE telcom.
From your question it appears you are probably not in a position to know.
Or at least not in one where you can test for yourself.
If you are behind a 'hub' as you say you are then you do not have access to your CSU/DSU, or your smartjack.
You leave more questions than you ask.
My first question is if you know your Access Provider Circuit ID. The second is as others have asked, who are you getting the service from?
Have you talked to your vendor?
Is your vendor also your provider?
In the end _if_ you cannot access the equip. yourself directly, all you can do is trust your vendor and pay them to test.
If your into pain, and simply unable to trust anyone, check out the folks at www.gl.com. The have some nifty PC based T1 testing systems.
However if you are interested in a T1 speed every once in a while (say when you need to download the latest OS patches, stream media, etc..) and the rest of the time is casual web surfing and email then get something from a local provider.
Going with the big boys you will most likley get directly connected to a larger pipe (T3) and will probably not run out of BW when you need it. But you will PAY for that privledge. This is no garuntee of service, just that you will most likley get more BW when needed. I have a major provider, UUnet, and it is a Frame T1, it bounces sporadicaly. I also have a local provider that has a T3, their like is rock solid compared to UUnet. So it is a crap shoot as to what you will get.
Most small buisness do not need that much BW. When I sell BW, it is metered and the clients know that they can burst up to a T1, but it is unrealistic of them the expect 24/7 T1 speeds at a discounted rate.
~Sean
um, he also said he's splitting it out between two other companies and sharing the bandwidth.
I don't know of any effective way to test this, because packets sent over TCP are a very unreliable meter, unless you have a connection at both ends and are only sending network traffic between two endpoints. Rerouting, packet loss, packet queuing delays, bad routing tables, slow machines or network connectors, dirty lines, and any number of other factors could skew the results.
It's possible to get a rough estimate of bandwidth, nonetheless, but it's not easy if you're splitting the line. If you know no other computer is online and running through the hub you should get close to peak performance, but it's still tough to say if you're getting shortchanged because of external factors.
Think about a brand new house. When you lay out how many amps of electrical service to 'buy' from the electric utility and in terms of the power panel that you install, you don't ask 'what if every outlet in the house was maxed out?' but rather, what is a realistic maximum utilization for the size of the house and the major electrical appliances? The same thinking goes into designing your neighborhood substation and out to your multi-state and international chunks of the grid. Whereas everyone flushing the toilet during the superbowl/world cup halftime won't 'take down' the water system, everyone in a state turing on every electrial appliance in their houses (and firing up all the industrial uses, too) could take down the electrical grid. Yet, with some crafty engineering (peaker plants, pump storage) the system still works with this supply/demand model.
What are the plusses and minuses of the analogy? On the down side, network traffic tends to be less predictable and more 'spikey' than electric demand. On the plus side, too much network use just bogs things down, but too much electrical demand blows the breakers (at various scales).
So does it really matter if an ISP 'realistically' 'oversells' their pipes? Your house/business is on an 'oversold' electrical network, and for most of us, it works pretty damn well. Perhaps it comes down to a realistic expectation of degree of performance.
...even though many of the other answers are correct in their own ways. This is the one that counts.
Say you live in an affluent neighborhood on the shores of Lake Washington in Seattle. Many of your neighbors are Microsofties who compete with each other on who can say their home has the highest bandwidth (hell, they look down their noses at any coworker who has only 220-volt electric service). They don't use all that bandwidth on a continuous basis. But they get great download times as long as the other end is fast. Your provider serves all these sites and has only enough backbone access to handle 50% of the bandwidth he promises if they all use it at once.
Now imagine your brother lives in a seedier section of town where all his neighbors are running pr0n sites in their spare bedrooms. He uses a telco provider which has the system wired to handle 90% of what they promise. But his neighbors use near 100% of their T1s 18 hours a day.
The result: The massively oversold ISP gives you better bandwidth than the not-oversold telco gives your brother.
You can test for this in any number of ways (lots of suggestions have been posted). But you still don't know the answer to the really important question: Am I getting what I'm paying for?
The reason: Suppose the kids of the MS employees one day discover P2P file-swapping, how to replace their overpriced OSes with Linux, and how they can make MP3s of every CD they own, set up an Icebox server, and listen to their music anywhere, anytime. All of a sudden, they are using all of that bandwidth which was just a status symbol for their parents.
The real question for an ISP is how fast do they realize this is happening and add capacity to their backbone connection to prevent bottlenecks. The only way to know is to watch your actual throughput over time and see how it holds up. It's easier for a telco to do it, sure. But whether they do or not is unclear until you have lived with them for a while.
I have a very long story about how my small ISP was bought out by a backbone provider who then bought out a telco. In the end, I practically had to maintain their router network myself by hand.
You can ask all your prospective providers how they monitor and how often and how quickly they respond to bottlenecks (do so, they may give you better service if they know you care). But ultimately careful monitoring of your throughput (particularly as you come to use your whole T1) is the only way to know for sure.
I buy Internet access for my small business the same way I buy phone service (local and long distance). Once a year, I ask for bids (including from my current provider). The telcos tell me their competitors will give me poorer quality service. I tell them that's been the exact opposite of my experience. If I don't get the service I've been promised, I go elsewhere. You're only bound by a contract if the other guy lives up to his side of the agreement.
If you really care about the degree to which you are getting your money's worth, monitor constantly, ask for bids regularly, and don't be afraid to switch providers. I have been constantly amazed by how much better my service is (and how much less I'm paying) as a direct result of doing this.
By the way, if the telco telling you the small guys don't deliver is Qwest, laugh in their faces.
Eternal vigilance only works if you look in every direction.
A few basics first. A full T1 will allways run at full T1 speeds. This can be tested by measuring bandwidth between your end and your provides's end of the T. The concern the more expensive providers bring up is oversubscribing (or overselling), That is, is your PROVIDES's pipe to the backbone fat enough to carry full load from all of his customers pipes to the backbone without throttling.
The only real way to measure that, is to pump data between your end and a large sample of servers that are NOT on his network simultainiously. The sample must be large enough that congestion on their end won't significantly affect your results (since no provider can do much about other people's feeds). 100-1000 would be enough (since the load on any individual end network would be less than a dial-up connection's worth). The hard part here is that you can only be 'pretty sure' unless you could get all of his customers to flood his net at the same time. Normally, the best you can do is repeat the test several times and try to test during your best guess of peak traffic hours.
a more subtle sign of potential trouble is dropped packets. In the above test, a few spefcific targets dropping packets is not a problem (their network is likely the problem). However, if all of the connections are showing dropped packets, and especially if the drops come in 'waves', it's a sign that your feed is being throttled to relieve congestion on your provider's uplink.
There are other considereations as well. One that comes to mind is your provides's router capacity. It doesn't matter if your T1 is up to speed and his uplink can handle it if his router bogs down and introduces excessive per packet latency.
Those effects can be measured by using ping, or (where not filtered) UDP echo packets. Here, the idea is to send many short packets to see if his router can make it's routing decisions fast enough. traceroute can be helpful here as well. You'll be interested in the time your provider's router takes for it's hop.
Pathchar - It sends multiple ICMP Packages of diferent sizes to diferent hosts and it shows you how much bandwidth you get. Don't confuse with throughput...
Install it and give it a try. It's the smartest tool that I have used so far.
hehe. For the next 5 years anyway.
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
How do you think those 'channels' are used? You think your TCP session is limited to a single DS0 because your ISP has a T1? That would mean only 64Kbps per TCP session.
I'm not sure what you mean though.. I'm fairly certain that's not what you meant.
Routers use a T1, usually, as a single channel. The fact that's it's channelized is irrelevant, all channels are used equally in round-robin fashion, usually.
The T1 appears as a single point-to-point interface on the router.
Oh, of course, it doesn't HAVE to, and you could be using a channelized T1 as aseveral fractional connections to different locations.. but that's another story.
The insinuation was that TCP cannot make full (or mostly full) use of the bandwidth available to it, and that multiple connections are required in order to get full utilisation. This is not true.