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Thread: LAN bandwith question

  1. #1
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    LAN bandwith question

    Guys,

    I have ADSL connection for my LAN and when more than one PC are connected to Internet they obviously distribute the 256k bandwith between them. My question is... is there a way to control or put a limit of bandwith to any of these PCs? Because for example the less important PCs sometimes are using almost of the kbs of the bandwith and my main PC only have some kbs to browse AO, download things, etc. in Internet. I want to give a limit of kbs to the rest of the PCs, is there a way to do that?, do i need a determined program to accomplish this or this can't be possible?

    Thanks in advance.

  2. #2
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    Accomplishing this is fairly difficult. AFAIK, you have to use "traffic shaping" - this is available as hardware or software. I have heard of it mostly being used in either hardware firewalls or completely dedicated hardware.

    I believe that Linux 2.4 has kernel support for it, but I have no idea how to set it up (there must be some tools). I think you have to separate traffic into different classes and give them their own policies.

  3. #3
    AO übergeek phishphreek's Avatar
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    OK...

    There are many ways to do this, like Slarty said.

    Here is how I did it. I have a switch coming from my firewall and my PCs all get plugged into the switch. From the switch I have a hub going to everyone elses PCs. They all have to share the speed of the hub, where the switch is way faster!

    I have since changed them all to switches, but I have 5 users on and it is still fast as hell.
    You just have to limit peoples P2P network usage and disable as much upload as possible.
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  4. #4
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    On *nix, the obvious choice is AltQ. It allows you to assign packet/connections to diffrent priority queues...

    On openbsd's firewall (pf, -current), it's even integrated with the filtering rules...

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  5. #5
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    Originally posted here by phishphreek80

    Here is how I did it. I have a switch coming from my firewall and my PCs all get plugged into the switch. From the switch I have a hub going to everyone elses PCs. They all have to share the speed of the hub, where the switch is way faster!

    This is not necessarily true, if you have a 100Mbps hub and a 100Mbps switch, the effective throughput is still only 100Mbps because your uplink is still the bottleneck. Your machine on a 100Mbps port is still fighting with everyone else on the hub with the same 100Mpbs port. What a switch does do is reduce the amount of traffic seen on ports that are not directly part of an ethernet session.

    Although it is certainly possible that there may be a minimal impact to performance, this is definately not any way to try to shape traffic patterns. There is simply not enough control. replacing hubs with switches is by all means an effective method of reducing unwanted traffic on the network, but definately will not allocate more bandwith to yourself, especially when you are only talking about a 256k pipe.

    This type of traffic shapinng needs to be done at an Internet choke point somewhere in your network. Which usually means a router or firewall. There are many products that have this capability, such as cisco routers, Checkpoint's Floodgate, F5, and just about any type of content switch along with the "freeware" solutions others have mentioned. One of the more commonly used industry terms for this is QOS , so you will probably be able to find more info on a google search.

    You will most likely not be able to do anything like this on any type of home/SOHO router firewall. At least none that I have seen. As always, I am happy to provide more info or help in any way I can. I am keeping this message as brief as possible so I don't put people to sleep, but let me know if you need anything else.

  6. #6
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    Dark,

    I agree with Invictus that you probably wont be able to do any type of QOS on a soho router/firewall. If you have a few extra bucks to spend, you can go with a Cisco router. Cisco supports CAR (Committed Access Rate). CAR allows you to partition your network into multiple priority levels. This will allow you to give a specific amount of bandwidth to your second pc, and the rest to your primary pc.
    Heres a link to read up on it.

    http://www.cisco.com/en/US/products/...0800c60db.html
    Os1LaYr5

  7. #7
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    Dark,

    I suggest you 2 method

    1- using rate limit within your end users terminals

    2- using QoS (IntServ & DiffServ) to prioritize streaming on your ingress (you can give a color to packets based on source IP). This will allow you to guarante a minimum throughput for the each classes of traffic. Streams will behave a bit like UBR & VBR in ATM world.

    Hope this can help
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  8. #8
    Interesting, I thought a Switch would solve everything... hahaha but good call on the QOS, I suppose if you want better speed for your networking that equals $$ gawd... I wish everything wasnt so damn expensive
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  9. #9
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    Hubs are a Layer 1 device and therefore no better than a repeater except they have more than 1 port...whereas...most switches are layer 2 devices and can build a database containing port to hardware address information (Unless you are using layer 3 which is IP or layer 4 which is TCP (Very expensive)).

    What this means is that with a layer 1 device you cannot seperate the collision domains, this means it is slower. With a layer 2 device you can seperate the collision domains once the device has learnt the hardware address, primarily means it only sends information down the 1 port and not all of them ( However a broadcast still has to go to all ports, the only way around this is to set up a VLAN).

    Make sense.....doh...probably not.

    but just incase you are wondering what layers I am on about....

    The OSI (Open Systems Interconnect)...

    Layers as follows:-

    7: Application
    6: Presentation
    5: Session
    4: Transport
    3: Network
    2: Data Link (Includes MAC Sublayer and LLC Sublayer)
    1: Physical

    Back to your question. Yes you can. There are firewalls that can provide you with this. ISA server is an example. You can create bandwith policy and apply them to the pc's at home. One draw back is that you need to be running Win2k Server with SP1. You might wonder how do you get ISA and Win2k server. Well .. if you have enough experience you already know that if you look in the right places you can find anything. (Im not saying do something illegal)
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