Topic: General Computer network question

[DavidKlecker]

I have a question for those here who are familiar with computer networks and their setups. I was informed the network I am on was upgraded to 50Mbs. Each computer lab I plug into on this campus gives me only 2Mbs when I run the speedtest.net page. I asked about that and the tech guy told me it's because of all the routers and cabling. Something here doesn't click but my inexperience with this make it hard for me to guess what it is. That is I figured with his response I should be able to go to the building where the server is located and have the least amount of cabling and wires. I still get 2Mbs. My guess here is they have old equipment where the routers don't go higher than 2Mbs, but that's strange since I would have figured if they upgraded to 50Mbs wouldn't that (the routers) be one of the first things anyone would replace?

Any opinions?

[markc]

  All of the above; physical, cabling, routers, etc as well as software can limit your data speed. On the software side I can limit throughput of specific computers while allowing max speed for others. Thus allowing servers with more bandwidth than student's.
  As to what to upgrade? IMHO you would upgrade the cable first and then the other equipment. That is along as the equipment works with the new cabling. As money allows, speed needed and equipment retirement comes into play you can upgrade the equipment as needed.
  Cabling is also generally/can be the most expensive especially if you have to run wire, fiber, IR/microwave towers, etc. Wire is generally not expensive compared to the others but the labor cost of all of the above is very expensive. 


Does that help?
MDC

[vroomfogle]

I'll agree with marck that all those things, especially cable, can slow down the network. 

However, these are internet speeds, not intranet speeds.   You have a lot of routers to slow down a network by that amount, or the cable would have to be rather old.   Cat 5 is capable of 100 Mbs speed, while cat 5e and 6 is capable of Gigabit speeds.    Your network card is a 100 Mbs card at least (unless it's 15 years old) and likely Gigabit if it's less than 3.   That's more than enough to handle internet speeds.

I think it's more likely that you are sharing the total bandwidth, which is 50 Mbps, with a lot more usage.  How many users are on this one internet pipe?

[markc]

 I agree that lots of users can slow down a network. But I very curious about the 2Mbs constant rate. I think they might be limiting the throughput by account group permission or other permissions on the network.
 Also as Matt Hanson said above check the speed of the World Wide Web vs the intra-network speeds. If they are the same then IMHO the accounts are set up that way.
 The limiting of network speeds by accounts can be done for various reasons but it is mainly done to prevent one group from hogging bandwidth needed by other groups. ie scientist need to send data at a specific speed to equipment for it to work properly or to get timely results.
 Some U's have also agreed to limit speeds of their free networks to make pirating, web hosting, video sharing, etc harder. This was done at the request of various companies and agreed to by quite a few U's so they did not have to go to court.
MDC

[DavidKlecker]

I guess this is just my ignorance when it comes to how a network is setup. I have heard from numerous people that the network admins upgraded to a 50Mbs network. Granted I know that this means the whole network cannot retrieve more than 50Mbs per second from the internet but I was under the assumption that on a network with say 200 people, we would share the 50Mbs or perhaps 25Mbs as its available. Thus during the peak periods the bandwidth would be slower, but during the off periods, the bandwidth higher. That's not what I see here though. Here, the bandwidth regardless of what computer I am on is 2Mbs and if I want to download something it's not even .1 Mbs. I don't know if they have old cables or routers but given I heard they spent thousands of dollars on upgrading to a 50 Mbs server something tells me these things such as cables and routers were also a part of that upgrade.

I have a feeling I will ask for a tour of the IT department where I could try in a nice way to pick the brains of the IT guys and see why I can never see the benefits of a 50Mbs network.

Thanks for the insights!

[Guillaume]

ok, lets see...

First the questions :
- is that bytes or bits ( usually in network land we talk in bits ) ?
- is that the internal network ? ( that is the Local Area Network your computer is attached to )
- is that the external link towards the world ? ( that is the DSL/Leased Line/Fiber/SDH/ATM link towards an ISP/Telco)

50Mb ( I assume bits here ) is not a standard for LANs, but you can ( with a given configuration ) have 50Mb of bandwidth out of a 100Mb network ( though in these days of Gigabits networks it's pretty silly to restrict the LAN bandwidth unless you have very serious bottlenecks in it ).

So the 50Mb are probably the external link towards the ISP. And it's most probably either a native IP or an ATM/SDH link.

You have only 2Mb when you run a ADSL speed test... Those tests are unreliable when it comes to SDSL/Leased Line/Fiber links. ( I used it at work where my Net link is made up of several OC-3 ( 155MB SDH fibers ) and it gave me results that were worse than at home ( 8Mb ADSL )...
The best way to make sure is to download a huge file ( I regularly download Solaris OS Images from Oracle... 4gigabytes files downloaded in less than 5 minutes... ) and see how long it takes.

As you assumed the link bandwidth gets divided by the number of people using it, but it's not that easy, there's also usually some quality of service traffic shapping involved. For example one of the mechanism used to avoid having a user use all the bandwidth is to limit the maximum throughput a given connection has. ( 2Mb seems a nice number for that )
Another way is to prioritize traffic. VoIP, Videoconferencing will have a high priority as they need near real time, while file transfer and web will bet low priority, as it doesn't matter if it takes a few more seconds to display a page.

All in all, the IT guys may know why you can't go over 2Mb, and it is probably caused by a traffic shapping system put in place to avoid congestion of the link.