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Shotgunning Ethernet Connections? 40

Posted by Cliff from the 100-Mbps+100-Mbps=200-Mbps? dept.
Jon Bardin asks: "I am currently living in a dorm at the University of South Florida. The dorms come wired straight to the Internet and my connection is pretty zippy, because I have seen 2 megabytes per second download speed. I was wondering if there was a way, with the new fancy 2.4 Linux kernel, that I could shotgun at least two of the eight ethernet ports in my suite together, as to effectively double or quadruple my download speed. It doesnt have to be a Linux solution either its just all this talk about the fancy TCP/IP stack and firewalling has me thinking about things. The ethernet ports are configured by DHCP and are reasonably static... I got a new IP when I got back from winter break. so any help would be greatly appreciated." This question gets asked a lot. I wasn't quite sure if this was possible for the 2.2.x kernels, but I figure it might be time to ask this now that 2.4 has been released.
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Shotgunning Ethernet Connections? More

Shotgunning Ethernet Connections?

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  • He probably means megaBYTES. Ives seen alot of computers on universitys transfer at upwards of 12megs a second. Thats BYTEs, not bit.
  • What are you talking about. It would take 11 T1's running at 100% (192KiloBYTES/sec) to get that kind of speed. Not a couple. I also have hit 1megaBYTE with my cable modem, and my friend has hit that much UPSTREAM with it uncapped.

    "Anyone with this kind of bandwidth has to keep it pretty saturated to pay for it. I'm a heavy downloader, but I *never* *never* *never* max out the 330k/s theoretical limit on my cablemodem. "

    First of all. Thats not alot of bandwith, thats about 1/3rd of a T3, a T3 is nothing now days. My local ISP has a OC12. OC48s are not uncommon, particular at universities and datacenters. Even OC192s. OC48 is only around 150K a month, affordable for places that need the bandwith like Yahoo or whatever. T3 is around 20-30K now days. T1 you can even get below 1K a month. And obviously you are not a heavy downloader, I get way more than that all the time. I get 500K from fast sites like Real.com, Mp3.com, Adobe.com, Microsoft.com,etc..
  • Id like to know where you can get both Mediaone and @home. I have never heard of such things. Getting two cable companies i the same place that both offer cable modem (In Portland,Ore you used to have a choice between Paragon and TCI, but no longer). Also, doubling up cable modems should work with two cable modems for the same company. Friend does it with his. The limit on your cable modem are at the router. Thus two of them, should almost double your speed. At least upload speed, since upload is typically capped way below download. My friend is on the same NODE as me, and thus same router, and we have both got 1Meg a second at the same time. Thus, if I had two, i could of maybe got that 2megs by my self. I wouldnt get a second cable or DSL for the downstream, my downstream is fine, but for the limited upstream. I used to have a limit of 125KiloBYTES up, but now @Home is limiting it to 16KiloBYTES max by the end of January.

  • ... anyone who has a connection capable of sustaining a 2MB/sec per user connection has at *least* dual or triple t1's ...

    Uh two or three T1's ain't jack anymore, especially those on Internet2 where connections can and do range from OC3 to OC48. Even for those not on Internet2, ds3's and OC3's are commonplace.

    To answer the original poster, yes it is indeed possible. Routers routinely utilize multiple equal cost paths on a per-packet, per-flow, or per-destination (there are more too) basis depending on the switching method chosen. I don't see why hosts can't do this either. In fact some probably already do with the proper configuration.

    -B
  • Actually yes they do, for outbound traffic. I set up routers to do this all the time. If you choose per-destination or per-flow (which ospf does natively on Cisco boxen for equal cost paths) you can achieve bi-directional results since two flows will have different source addresses*. This assumes of course that each interface has its own unique IP address. This won't improve performance for a single connection, but if you do lots of network transactions at once this will improve throughput, assuming that the single ethernet connection was the bottleneck.

    Etherchannel will also work, if it is supported on your network.

    -B

    * This depends on your software. Some hosts will fill in the source address of the outbound interface (such as Cisco routers), and some will always use the same one.

  • Last century, when I was in school (1997), our only choice for a constant connection to the university network was a 19.2kbps connection that came in over the phone line. A single room could only have a single connection. You ran standard phone line into a Gandalf brand 'modem' device that the dorms provided and then ran a serial cable into your machine. You configured the corresponding com port on the box as a modem, and you were done. The big problem was that it was a hardwired connection to the dialup servers (e.g. telnet connection), not an IP connection, so you had to run a SLIP client on the box you were connecting to to get an IP stack on your machine.

    So, 4 rooms (8 folks) ran phone line through the hall and put all 4 connections into one linux box, and then ran 10baseT to all 4 rooms. They would get anywhere from 50-70kbps throughput, which was pretty good for an 'always-on' connection at the time.

    Out of the 6 folks in the 4 rooms, 3 of them played doom/quake amongst themselves all the time (not using the uplink), the other two didn't use the connections, so the 6th guy (who put it all together) had the entire downstream bandwidth to himself.

  • How possible is it that the campus routers/firewalls/multiplexers/whatever are set to limit the amount of bandwidth any one port can use at a time? If that's the case, then by using two ports, he would be doubling his bandwidth. Now this has me thinking about doing something similar to the machines in my dorm room.....
  • This is normally called "EtherChannel" in cisco-speak. It's usually implemented at the adaptor level and requires that you be connected into a switch that supports it. I'm not sure about support under Linux or other free unixes but the card manufactures support it under windows. Intel has support for it- I believe they call it "Adaptor Teaming".


    One caveat about bonding multiple connections -- unless you're doing something like MultilinkPPP that "sprays" packets out you're not going to see a bandwidth increase on a single connection just by adding multiple pipes. In other words, if you have 2 T1's to the internet you're not going to see 2x1.5Mb/s on a single connection. By default a cisco router will load balance on a srcdst ip basis over each link.

  • Assuming he means 2MegaBITS/sec... It's possible (and likely) that the campus network is limiting bandwidth at the switch and aggregating ports would help. It is hoarding, but it'd be a fun excercise to get it to work.
  • While not exactly the same thing, I have maintained 1 MegaBYTE (not bit) / second while downloading off my cable modem. Only twice mind you (and from Adobe), but it is possible.
    ------------------------------------
  • Maybe he is connected to switch and running a full-duplex connection on the port.

    Couldnt that give him a true 2MByte/s (20Mbit) connection?

    In that case it is resonable for him to increase that lousy :-) bandwidth with another NIC.
  • ....yes, the 2.4 kernel will do that happilly, but no, it probably won't help, and gak, many of us hate you for having so much bandwidth and yet wanting more.
  • Am i missing something here ? Is that theoretical speed your own limited speed or theoretical max speed for cable modem ?

    Im cable subscriber to finnish cable co called HTV which is no doupt suckiest ever even compared to @home in us. (=)) but still ive seen download speeds like >600kb/s. Well most of the time im happy if i even get 30-50kb/s but for example, if i happen to download new linux iso from funet i expect to see that 600kb/s. The top score ive got was from Edome (finnish game server/community website) and speed was 760kb/s !!! Thats double of your theoretical speed.

    And you know what. My isp has said that theoretical speed of our cable modems is 30MB/s. Thats like 3000kb/s (ofcourse its slower than that but lets stick in theory) but 10MB ethernet cards and the fact that line is shared with others in the same segment restricts that quite much..
    --

  • Well, you probably wont ready this anymore but lets say that you do.. What i meant is that cable, the cable that actually comes from isp and connects to my ethernet is shared. I didnt mean that ethernet is shared. Next you go on babling about ethernet speed. Yes, i know what you meant but you fail to mention that the actual protocol puts restrictions to it too. Lets say for example tcpip network. Every package has a header that is size of n. Then you send 1000 packages. Now you have 1000 packages size of n in your network and that is limiting the actual speed of bytes transfered from host to another. Throw this scenery to network with other machines doing transfers, bandwidth is shared/downsized (in this example im talking about the ether).
    --
  • Indeed.. I was running a linux box on a school network (it was for the class.. sadly I don't run one anymore 'cause I have no spare computers for it) and ran the 'bing' program..

    basically it can check the bandwidth of a connection.. Due to overhead, I was only able to pull something like 6.5MB over a 10MB (I think.. bit and byte has me confused when I'm talking about communications) ethernet connection.
    -since when did 'MTV' stand for Real World Television instead of MUSIC television?
  • It's not hard to imagine. Here at school we're connected by an OC12 and triple DS3s, in addition to a smattering of slow stuff (T1, DSL, serial, frame drops, etc). It doesnt help me much tho, because the geniuses here on campus have decided to route all of the student (resnet) connections over a single one of those DS3s (traffic for 12,000 ppl), then deny there's a slowdown. They don't maintain their DNSs properly, and the campus mailhost is on the ORBS list as an open relay.

    Yes, bandwidth is a drug. I miss it horribly when I go home to a cable modem.

    I want my, I want my, I want my gig-base-T...

    -dave
  • I've got a dual homed Windows2000 computer, with one NIC going to my @home cable modem, the other going to my DSL router. Although it doesn't load balance automatically, I can manage my routing tables to specify which interface to use. For example, I specify which interface to use for the IP addresses of each ISP's news server (they restrict access to their own netblocks), so I can download simultaneously from each, which adds up to a lot of bandwidth.

    When I want to play games, I add a route entry for the server I connect to, specifying to use my DSL, since it has lower latency and packetloss. My default route is over the cablemodem, so if I want a fast download, I don't have to specify anything.

    I doubt it would work the same way on the university LAN question due to their setup, but it works great for my purposes.

    It could probably be used in the multiple cablemodem/DSL question above, although I don't think the bultin Internet Connection Sharing could utilize the same thing and provide it to your LAN. Probably a third party app could do it, though. It would certainly work for the one computer, though, since it's basically what I'm doing.
  • I don't know the specifics, but one of my friends has piggybacked 2 cable modems by removing the eeprom (or whatever) and setting the serial number to the same on both modems. He gets 2 megabytes/sec off shaw@home. Just to say it can be done.
  • what AOL don't let you get your own ./ account? you have to post as anonymous? or did somebody higher on the food chain steal your bandwidth? knives kill trolls too. ;)
  • yes that is a bad example there are laws against stealing private property. you have a point. only if there is a rule about bandwidth per person. other wise... the is NO right or EQUAL rights to a service that is provided to all on a first come first serve basis. what about the kids with no computers in the dorm do they still have that "right" to the service? should the school provide computers in the dorms for them? some of you sick monkeys would think so. to each his own to the best of his abilities!
  • what do you suppose is the "proper" amount of bandwidth that every student "should" have? people like you are the problem, winterstorm. you tell everyone else what they can and can't do but offer no real solutions to anything. if a person takes the time and effort to learn how to get more bandwidth. they should be able to do what they like with it. the lazy stupid people can keep to the slow dial-ups, they do less damage that way. reward effort, learning and initiative!! personal freedom and responsibility! screw you lazy socialist losers!

  • That's multihoming and I'm pretty sure you have to get your ISP's to do special things if you want it to work the way you describe. Just using two default routes, you'd be able to have more connections at their max bandwidth, but you wouldn't get twice the bandwidth on a single connection. (Of course, I'm probably wrong.)

    Aaron Plattner

  • adding a second line will free you.

    Um, no. The man will just have his jackboots at both of your necks.

    Of course, if your college's network is like the network I manage, not all of those 8 network ports at the faceplate in your dorm room are patched into the switch at the other end. I mean, if you and your roommate are the average case (only using 2 of the 8 ports), why should Network Services pay for 4 times as many hubs/switches just to have a bunch of live outlets gathering dust behind cheap dorm furniture?

    You'll need to make friends with someone who can get to the patch panel and make sure those outlets are active before you can find out that they aren't any use because the bottleneck is that your school only has a single T1 line.

  • Your ethernet connection so can not be your bottleneck. 10Mbit ethernet = 1.25MB/s (1MB/s at the assumed 80% efficiency of ethernet) 100Mbit ethernet = 12.5MB/s (10MB/s at the assumed 80% efficiency of ethernet) and now theres gigabit ethernet! Your bottlenecks are elsewhere.
  • Actually I cant get both medione and @home but I can get @home and Knowlogy cable modem service, both are offered in my area (Augusta, Georgia a.k.a. "The a$$ end of the south.") along with DSL and DirectPC. How exactly does your friend double up his cable modems? Does he run a special program like those that can be run with 2 dial up modems? Does he use ethernet card teaming? I'm just not sure of exactly how to get it to work.
  • With all of the discussion of shotgunning multiple ethernet cards to increase bandwidth on a university LAN, I was wondering if something similar might be possible by combining the bandwidth of 2 cable modems each on a seperate service (ie one on @home the other on Media One or what not) and a dsl modem. Could a computer be setup as a proxy that would contain multiple ethernet cards for the incoming cable/dsl connections and pump all the data out of a 4th ethernet card to the rest of the network? Could this work? Any links to info or help would be appreciated.
  • Ethernet is a shared medium. In other words, all those ports go to the same place, and share the same aggregate bandwidth.

    Now, if you're on switches (probably) and you were downloading from different places on different ports, you could probably get an improvement. However, I don't think it would improve things using all ports to download from the same port on the hub, because they still have to share the bandwidth incoming. This would depend on what the switch is using for uplink.

    So, while it might be possible, I don't think it would do any good.
  • Nope. There's still only 10Mb/s incoming. He would still only be able to transfer 1MB/s in either direction. If he gets a 2MB/s download, he must be on 100baset ethernet or faster.
  • No.. they don't.
    It's possible to do Etherchannel, wher statistically you get more throughput, but only when dealing with a mmultitude of hosts... most etherchannel devices/configurations use the last 4 byhtes of the mac address to determine which port to use.

    If you are hooknig a computer up to a plain old pair of network connections, you could balance out bound traffic over them.. but there's nothing you could do about incoming, and both ports would still require separate IP addresses.

  • Just a note.. usually capital 'B' refers to 'Byte' and small 'b' refers to 'bit'.. so you're backwards.

    10Mbps ethernet isn't just capped because it's shared; the 10Mbps is the signalling rate of the medium... when bits are clocked onto the wire, tehy are clocked on at exactly 10Mbps... but there are rules governing frame sizes, minimum inter-frame gaps, etc.....so it's impossible for 2 hosts (like you and a router) on 10Mbps ethernet to use the full 10Mbps, no matter what.

  • Both sides have to support it.
    It doesn't increas bandwidth to one place, only across multiple hosts, as it uses the last 4 digits of a mac address to balance traffic over the ports.

    it's good for a server on a lan.. if there's a router in front of it before anything else, you'll only end up using one port anyway.

    Similar to EQL, but not the same. in EQL, you actually get double the throughput.
  • And if I take the time and effort to learn how to get into someone else's car, I should be able to do what I like with it, too?

    You think this is a bad example? The bandwidth the uni/dorms have isn't HIS to monopolise. He is actively taking resources away from other students who have an EQUAL right to the bandwidth as he does (it's not a matter of him being 'enterprising' to get around limitations).

  • You're not being limited by ethernet. You're being limited by the built-in "fairness" of TCP: when there is a limited supply of bandwidth, TCP limits its packet rate to share the bandwidth equitably. Adding a second ethernet connection won't do anything to change that: what you need is to work around the semantics of TCP.

    In other words, either open two TCP connections (remember back when Netscape used to open four connections at once to speed stuff up?) or hack your TCP implementation to be more aggressive.

    And no, I'm not going to tell you how to do that.

  • Bastard. When I was there we fought over the few dialup lines that had 14.4.

    But to answer the question, I doubt the bottleneck is the 10BaseT between your machine and wherever the main line comes in. If you really are getting 2 megabytes per second, it's possible. Maybe you're better off begging for a 100BaseT connection. Or go get a job with Academic Computing, Engineering Computing, or some other place on campus with better bandwidth.

  • Holy goatsex, Batman! I think you must be downloading of your university's LAN and not the internet proper because anyone who has a connection capable of sustaining a 2MB/sec per user connection has at *least* dual or triple t1's and probably more. Anyone with this kind of bandwidth has to keep it pretty saturated to pay for it. I'm a heavy downloader, but I *never* *never* *never* max out the 330k/s theoretical limit on my cablemodem.

  • Yes you can. (Score:3)

    by h2odragon ( 6908 ) on Wednesday January 24, 2001 @12:38PM (#483723) Homepage
    Assuming that you're not simply increasing your bandwidth to an upstream bottleneck, as mentioned by others, then you can do what you want.

    In 2.2 and later, using the iproute2 [freedom.org] interface, you can route traffic through multiple interfaces and connections will go through in a semi-equalized fasion. "ip route add default nexthop via <addr> dev <device>", and repeat for as many interfaces as you have.

    This causes new connections to choose one or the other interfaces, a single connection's traffic goes through one or the other but not both. This is in 2.2 without the DiffServ [icawww1.epfl.ch] patches; patched 2.2 and stock 2.4 can make both interfaces be used equally instead of on a per connection basis with the equalize keyword on the ip command.

  • This kid IS the BottleNeck? (Score:3)

    by winterstorm ( 13189 ) on Wednesday January 24, 2001 @01:50PM (#483724)

    You asked, "Where is the BottleNeck?" Clearly this kid is trying to be the bottleneck. What antisocial technohuckstering! Gobbling up all the available bandwidth is just plain irresponsible. Why should other people suffer because this kid wants to download his pr0n/mp3s/vcds a little faster.

    Its clear that this kid can't figure out how to load balance network devices on his own, can't understand why it doesn't make any difference when done on ethernet, and doesn't care to consider the impact he'll have on those who share his bandwidth if he is succesful. I believe the correct answer to a question of the type the kid posed is, "Sorry, can't help you. Maybe you should think a little more before go ahead with that."

  • Where's the BottleNeck? (Score:3)

    by InitZero ( 14837 ) on Wednesday January 24, 2001 @12:33PM (#483725) Homepage

    I can't believe that your bottleneck is the ethernet connection itself. You say that you've topped out at two megabytes per second but I think you probably meant two megabits per second. That's a big difference.

    For just a moment, let's assume you were right and the NIC in your box or your port is slowing you down. I agree with ATS [slashdot.org] that chances are you won't see a speed increase by adding a port since you're probably going to be hitting the same hub/switch. If you've got a 100mbps NIC and connection and are just hitting 2Mbps (or even 2MBps for that matter), your connection is the the bottleneck. The problem is further up stream.

    Chances are, the university's internet connection is your bottleneck. Ask your college how phat a pipe they've got and work the math back from there.

    The only other situation I can see where adding another port would help you is if the dorm ports are bandwidth limited at the switch. If that's the case, The Man might have his jackboot on your neck. If that's the case, adding a second line will free you.

    The technical details of this quest are best left to the student.

    InitZero

  • It's pretty sad, reading these "ask slashdot" articles, where it's really a simple question and everyone posts a bunch of crap that doesn't even try to answer the question.

    From the linux 2.4.0 configuration options:

    Bonding driver support
    CONFIG_BONDING
    Say 'Y' or 'M' if you wish to be able to 'bond' multiple Ethernet Channels together. This is called 'Etherchannel' by Cisco, 'Trunking' by Sun, and 'Bonding' in Linux.

    If you have two ethernet connections to some other computer, you can make them behave like one double speed connection using this driver. Naturally, this has to be supported at the other end as well, either with a similar Bonding Linux driver, a Cisco 5500 switch or a SunTrunking SunSoft driver.

    This is similar to the EQL driver, but it merges Ethernet segments instead of serial lines.

    If you want to compile this as a module ( = code which can be inserted in and removed from the running kernel whenever you want), say M here and read Documentation/modules.txt. The module will be called bonding.o.

    There, at least one answer. I feel better now. Too bad I don't "reload" early in the day and post right away (meaning this will never get moderated up). Such is the way of slashdot.

    Also, I should mention that I recently installed a HP2512 ethernet switch (you can find it on HP's web site....), and it had an option to connect up to four lines in parallel to another switch, for 400 Mbit/sec between the two. They have their manuals and even instructional training course material on-line, so you can learn quite a bit about it if you want.

  • Wait a minute.... (Score:5)

    by hansendc ( 95162 ) on Wednesday January 24, 2001 @12:39PM (#483727) Homepage
    <TONGUE IN CHEEK>
    This is yet another demonstration of how broadband is like a drug. The more of it you get, the more of it you want. For instance, all of those slow AOL users don't want any more. But give them one hit of cable modem, and they go nuts.

    You get 2 MEGABYTES/sec!!!!!! AND you want more!!!! My suggestion: stop now while you still can, broadband almost has you in its clutches. Once it gets hold, it never lets go. Run, run for your life, run while you still can.
    </TONGUE IN CHEEK>

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