T1 Issues

[fcairforce]

At work we got a T1 line. Me and some friends tried to set it up. The guy who installed the line put his laptop on it and had t1. amazingly enough, we tried for 3 hours and got nil. We have a linksys router, but thats not exactly the problem. When the computer is connected to the router, we detect network connection (still no internet, but closer). To set up the router, we must connect the modem directly to the pc. when I did that, the pc said the other end of the line was disconnected and the modem did not detect a connection either, but again, when the router was in between, all three detected a connection. Any suggestions? We were using regular rj-45 cables, should we be using db-9? what is the difference? At any rate, any suggestions would be helpful!

 

[bchur83]

Do you have a static IP or DHCP on the T1? Have you tried a crossover cable between the CSU/DSU and the computer?

 

[fiji]

At work we got a T1 line. Me and some friends tried to set it up. The guy who installed the line put his laptop on it and had t1. amazingly enough, we tried for 3 hours and got nil. We have a linksys router, but thats not exactly the problem. When the computer is connected to the router, we detect network connection (still no internet, but closer). To set up the router, we must connect the modem directly to the pc. when I did that, the pc said the other end of the line was disconnected and the modem did not detect a connection either, but again, when the router was in between, all three detected a connection. Any suggestions? We were using regular rj-45 cables, should we be using db-9? what is the difference? At any rate, any suggestions would be helpful!

db9 is serial port

rj-45 is the connector for standard NIC, its like rj-11 (phone connectors) but bigger


only time ive used db9 in networking, is with a rj-45/db9 adaptor, using a rollover cable, to configure a cisco router

 

[fcairforce]

in the very short amount of time it took you to reply (Thank You); I discovered the T1 is now working.

don't really know what DHCP is, but I don't think so.
ditto for the static IP, we may, but i don't know

for my next question.....
The other day, I downloaded a 76mb file with cable internet with speeds up to 500kb/s

I was under the impression T1 was faster
With the T1 internet, the same server gave me only a whopping 62kb/s for a download time of 20 minutes!!!!
Cable got done in 2--am i missing something?????

 

[fcairforce]

oh, yeah, I have NO IDEA what CSU/DSU is
embarrased and not exactly a networking god

I do know what a crossover cable is though!!

 

[fiji]

in the very short amount of time it took you to reply (Thank You); I discovered the T1 is now working.

don't really know what DHCP is, but I don't think so.
ditto for the static IP, we may, but i don't know

for my next question.....
The other day, I downloaded a 76mb file with cable internet with speeds up to 500kb/s

I was under the impression T1 was faster
With the T1 internet, the same server gave me only a whopping 62kb/s for a download time of 20 minutes!!!!
Cable got done in 2--am i missing something?????

T1 is 1.544 Mbps upload AND download

while cable speeds vary, but my cable is 3Mbps download/ 256 Kbps upload


but for the download speed, its probably not the T1, but maybe server load or whatnot

 

[fcairforce]

so T1 really has slower download speeds than cable?
if so, how fast can I expect to top out at on a great server?

 

[bchur83]

A CSU/DSU is basically a bridge between Fiber Optic lines (your T1), and another medium (ethernet in your case). In essense a T1 is slow as far as speed, but it is able to hold a larger load without slowing it down. With 3Mb/s Cable, one user can get 3Mb/s DL, but if another user starts downloading, it will split the speed between the two, so each will get around 1.5Mb/s DL. With a T1, you are able to hold a more steady speed, even with multiple users. So if you are downloading at 1.544Mb/s, and someone else starts downloading, you will both be able to hold around 1.544Mb/s even though you are both using the same connection. A T1 can handle the load better without degrading your speed. I hope that helps a bit.

 

[AMD Phreak]

It also depends on how the CSU/DSU is configured. Most of the time, buisnesses will set up their voice and data lines off of T-1 circuits. This allows them to bring in one line, T-1, which can be broken into 24 POTS or voice lines, or channels. I think if i remember correctly, each channel is 64k in size. Depending on if they want to use this for data as well, determines if they decide to allocate some of the channels for data, and they can from there determine the bandwidth they choose to allocate. Just because someone has a T-1 connection, doesnt mean they are running at 1.5mbps. You could have a T-1 line running into the building but have it configured so that the bandwidth is knocked down, so that it can be used for other purposes.

On another note.......
A T-1 is a full buisness class data connection. It has a SLA and garunteed uptime. A DSL "t-1" or Cable "T-1" is NOT a T-1. These services do not have any garuntee on their uptime, or what not. This is why the true t-1 can provide dedicated bandwith amongst all concurrent connections. You pay around 600-1000/mo for 768k to 1.5m services. The only lower cost option for this type of services is a SDSL line, which is very similar to T-carriers.

 

[fcairforce]

Thanks.
I guess what you are telling me is the max download speed I could ever get is 1.5mb/s.

 

[mtnbikerjerry]

A CSU/DSU is basically a bridge between Fiber Optic lines (your T1), and another medium (ethernet in your case). In essense a T1 is slow as far as speed, but it is able to hold a larger load without slowing it down. With 3Mb/s Cable, one user can get 3Mb/s DL, but if another user starts downloading, it will split the speed between the two, so each will get around 1.5Mb/s DL. With a T1, you are able to hold a more steady speed, even with multiple users. So if you are downloading at 1.544Mb/s, and someone else starts downloading, you will both be able to hold around 1.544Mb/s even though you are both using the same connection. A T1 can handle the load better without degrading your speed. I hope that helps a bit.

Yes that about somes it up. I would have gave nearly the same explanation myself.

In some cases. For example I have setup T1's myself when I had worked for Qwest Communications, integrating a Cisco 3600 series router with the older AIU DB-15. DB-9 is a 9 pin, much like RS-232. (Pins 1 through 8 rolled the opposite way in order...)

I have setup and interfaced with classic Frame Relay with BECN, FECN etc at a Pacfic Bell central office, BECN/FECN basically congestion notification, telling the router to send out less packets etc. (If you have a router that supports DE mode). The sad part is you needed more equipment to get this working right past your CSU/DSU. Usually the carrier sends out a signal for test from central office equipment, to your local loop, and back to opposite end if the company has another T1 drop. (Then it is up to the customer, router to router loop testing... ping usually, bandwidth analysis)

There are newer T1's (D4 with B8ZS) that just only connect via BNC or an RJ-45 from a CSU/DSU allowing for stackable DSX-3 backplaning into a DSX to STS/OC-N carrirer. In essence, the lack of an RJ-11 cable. Nortel makes these newer configuraions, and so does Cisco who bought out Cerrent a long time ago, which was the Cerrent 454 which is now the Cisco ONS 15454. On the back of this ONS 15454, you can slide in T1 card modules over OC-48 fiber. You can have T1 BNC cables to an NIU and to the customer CSU(usually T1 device), and set up everything via a java gui on the central office side.

Or sometimes I have seen T1's staggered off a Nortel OC-192 with a T1 shelf with integrated NIU's running to seperate CSU/DSU's right there all in one shot. Hook in your TTC T-Bird and verify loop up and loop down codes.

Its cools stuff.

But more than likely T1 is on 100 percent of the time, with the exception of grooms (network migrations to newer equipment) or fiber hot cuts (Rolling traffic counter clock wise on the other 4 BLSR fiber optic ring, which effects all lower circuts, DS3's and T1's) and that is the only time you will see a T1 down. At times there were advanced notifications sent out when a T1 would experience disruption. For example, AOL is a customer of Qwest, and has many OC-48 connects, it will cost Qwest up to a 1 million an hour if service is not restored.

 

[AMD Phreak]

Thanks.
I guess what you are telling me is the max download speed I could ever get is 1.5mb/s.

Correct. I forgot to add in factors like burst rate and what not too. You could be aloud a 1.5mbps burst, but, depending on your SLA, this could actually not happen at times due to congestion.

 

[Mr.Guvernment]

so T1 really has slower download speeds than cable?
if so, how fast can I expect to top out at on a great server?

yes but the thing is with your T1

put 10 people on your cable line - watch it crawl
put 10 people on your T1 line - watch it work fine

Also in your neighrborhood - the more people who got cable the slower u will go - the T1 is likely a dedicated line right to your ISP.

we just got a T1 into our home office i maxed it out @ 178KB and i am in south america and the server was in Europe!