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A Crash Course on Network Bandwidth Metrics? 108

Kind of Blue asks: "I work for a small software development company in India, providing development services for a company in UK. We connect to the UK client through VPN; and our correct staff strength is around 13. We are going in for a major upgrade in our internet connection — and owing to the size of the firm, cannot afford the services of a networking expert/consultant. Hence I, a layman, have been asked to look into the matter and decide on the ISP and the bandwidth. I have a vague idea about the required bandwidth — it must be around 512 kbps(remember, it's India I am talking about!) and must be a persistent connection, since we use source control softwares connecting to servers in the UK. There doesn't seem to be a 'networking for dummies' kind of resource on the web. No one seems to talk of network metrics anywhere. So, can Slashdot give me a crash course in what I need to know?"
"Our present ISP gives us a DSL connection of 512 kbps on 1:4 sharing. There are frequent disconnections; and hence loss of work while code check-ins. As we are increasing in strength, I am also looking at more bandwidth. But what bamboozles me is how are these things measured? Will I get a better bandwidth if I take a 512 leased line on 1:2 sharing? When the staff doubles, should I upgrade to a 512 connection on 1:1 sharing or must I take 1 Mbps on 1:4 sharing?(There's a huge price gap between the 2 here in India) In any case, how does one decide the optimum bandwidth required for a bunch of 15 developers on VPN and Source control?"
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A Crash Course on Network Bandwidth Metrics?

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  • by edmudama ( 155475 ) on Thursday September 07, 2006 @05:52PM (#16062847)

    it must be around 512 kbps(remember, it's India I am talking about!) and must be a persistent connection, since we use source control softwares connecting to servers in the UK.

    Have you actually measured how much bandwidth your source control software application consumes? To me that'd be the very first step, before you look into upgrading from one voodoo number to another. Real data is very often the key to good decisions.

    • by Kesch ( 943326 ) on Thursday September 07, 2006 @06:08PM (#16062928)
      Stop calling my numbers voodoo! Libraries of Congress/Fornight is a respected measurment for bandwith and I know many people who like to have their ping times displayed as multiples of the time it takes light to travel from NY to LA (assuming a vacuum of course).
    • by Bastian ( 66383 ) on Thursday September 07, 2006 @07:06PM (#16063229)
      Keep in mind - [i]bandwidth is not the same thing as speed.[/i] If your transfers are small enough that you're never really filling the pipe (as is probably the case if most of what you're doing is talking to a source code control system), then adding bandwidth won't make a bit of difference. It would be like using a box truck to pick up a your groceries.

      For the kinds of usage patterns that source code control systems generate, latency is most likely going to make a bigger difference.

      The classic example is the old saying, "Never under-estimate the bandwidth of a van full of tapes." It's true - the bandwidth of such a system would be incredible compared to what most people are used to working with. It's just that the latency for, say, a connection between Inda and the UK would be measured in days.
      • by shigelojoe ( 590080 ) on Thursday September 07, 2006 @07:15PM (#16063265)
        It would be like using a box truck to pick up a your groceries.

        The internet is not a big truck! It's a series of tubes!
        • by Knara ( 9377 )
          "Re:Measure twice, cut once (Score:2, Informative) by shigelojoe (590080) Alter Relationship on 06:15 PM September 7th, 2006 (#16063265)" mods apparently posting from their senate offices
        • Re: (Score:3, Funny)

          by Bastian ( 66383 )
          The internet is not a big truck! It's a series of tubes!


          Yeah. Tubes. [wikipedia.org]
        • by dramaley ( 20773 ) *

          The internet is not a big truck! It's a series of tubes!

          I like what passes for "Informative" on Slashdot.

      • Re: (Score:1, Funny)

        by Anonymous Coward
        I used to work at a national lab; broadest bandwidth connection between two parts of the facility (until they laid in a dedicated fiber FDDI -- this was early 90's) was a graduate student on a bike with a basket full of tapes. Depending on the student the latency wasn't too bad. Also, student+bike latency was less than automobile latency because there were always parking issues. Transmission errors were few but spectacular -- network collision between packets and free roaming deer made a mess once or twi
      • For the kinds of usage patterns that source code control systems generate, latency is most likely going to make a bigger difference.

        mod parent up. what parent is trying to say is related to the way TCP manages its congestion window. If you're facing high latency in the link to your UK office (which is likely, given the distance metric), the RTT will be high and TCP will slice its congestion window in half -- so even if you were to have "sufficient bandwidth" (whatever that means!), TCP wouldnt let you f
  • Also (Score:5, Funny)

    by Surt ( 22457 ) on Thursday September 07, 2006 @05:52PM (#16062848) Homepage Journal
    Dear slashdot:

    I'm trying to outsource your jobs. However, I don't know all that I need to know. Would you mind providing free training in your spare time for your replacement?

    OTOH: you probably don't need as much speed as you do reliability. I would guess that an unsharing situation will work better for you.

    You might, over the short term, insert an extra hop in your network in front of the ISP hop, and measure avg bandwidth there over the course of a business day. As long as you have enough total bandwidth / second to match your typical usage (allowing for some margin, and expected growth) in a business day, all you'll cope with is some latency.
    • by Aladrin ( 926209 )
      I sense another Ask Slashdot in the making...

      Dear Slashdot, how do I measure bandwidth usage...?

      Seriously, I think that's a pretty basic point and the fact that he didn't bother says a lot about the likelihood of this mission being a success.

      He can't hire a consultant for 1 DAY !! to figure this problem out properly, instead of throwing money at it and hoping it works? Good freaking luck.
      • At the level of issue he's talking about, it might well be hiring a consultant for 2 hours. Heck, we'd do it for two hours, but a local consultant probably costs less for a day.

        My other piece of advice is similar to what I've already seen: Ignore bandwidth, look for reliability. As recently as 2003 we had 4 users in the US on a single 56k line - and really, it was fine if you weren't trying to download big files. But it was a rock solid 56k that didn't lose any packets.

        If you have actual DSL disconnect
    • I'm trying to outsource your jobs. However, I don't know all that I need to know. Would you mind providing free training in your spare time for your replacement?

      I think he should insert two, four, or even eight hops in between his network and the ISP. Actually, maybe it should just be 60 extra hops, since we all know that if you exceed your TTL (stands for "Takes Too Long"), most ISPs will increase your bandwidth to compensate anyway. Go ahead, string up those routers!

    • by sharkey ( 16670 )
      Calm down. He's probably a Sonicwall Tier 2 tech trying to gain the skills needed to jump to a Forum Moderator position.
  • Seems silly to me. (Score:5, Informative)

    by onion2k ( 203094 ) on Thursday September 07, 2006 @06:09PM (#16062937) Homepage
    Unless there are also developers in the UK constantly accessing the code repository there's no good reason to use source control outside of your office. It'll be considerably cheaper to buy a small server with a RAID array, stick Subversion on it, and put it on your network, than it would be to be transfering files all the time. If the company in the UK that you work for insist on having control of the code then write something that syncs diffs between your local repository and the UK nightly/a few times a day/hourly/whatever. 13 coders aren't likely to be checking in more than a couple of megabytes of changes every hour.

    Note: SVN/CVS/SourceSafe/whatever can probably do this already, IANAEIVS (I am not an expert in versioning systems).
    • Re: (Score:2, Informative)

      It usually happens that the company which is outsourcing to India wants all the source code in their own control. The reasons are easy to see: Firstly, they always have the code even if the deal is cancelled midway and Secondly, they can easily see the activity of the developers.
    • by Phrack ( 9361 )
      Your client gets a warm and fuzzy feeling knowing that all of the code resides among his own boxes. For that matter, I've seen outsourcing jobs that required the developer to use Remote Desktop back to the client site so that all source, dev tools and the entire environment were contained on the client machine.

      I'm neither promoting nor denigrating such practices, merely relaying observed behavior.
  • Subversion..... (Score:4, Informative)

    by Anonymous Coward on Thursday September 07, 2006 @06:10PM (#16062939)
    One thing you could look at is to use subversion as your source control system, as it only transfers diffs accrss the network so is very good with low bandwidth connections.
  • Staff levels (Score:1, Informative)

    by Anonymous Coward
    and our correct staff strength is around 13

    So after adding in your incorrect staff, you get a total of?

    How much data are they pushing onto the source control server? Why not just move the source control server to India?

    Contention ratios only help to ensure that you get the full 512Kb/s, it won't increase your reliability I wouldn't think. You will have to increase your total bandwidth size, not just change your contention ratio when you get more staff.

    • by joshetc ( 955226 )
      and our correct staff strength is around 13

      In any case, how does one decide the optimum bandwidth required for a bunch of 15 developers on VPN and Source control?"

      So after adding in your incorrect staff, you get a total of?

      Comon, it says it right there. 13 correct staff + 2 incorrect staff = 15 total staff
  • by Yonder Way ( 603108 ) on Thursday September 07, 2006 @06:14PM (#16062967)
    ...so I will just say what half the other people here are thinking.

    Maybe you can outsource this project to the west since there are plenty of very well experienced people who know this stuff who could use the work.

    I don't hate India or Indians, but it will be a cold day in Hades before I give assistance to a shop whose only purpose in this world is to displace jobs formerly occupied by my neighbors.
      • by SaDan ( 81097 )
        Oh, great. First they take our jobs, now they're taking the employees outright!

        Thanks, but no thanks. India is definately on the list of places I'll never live, regardless of the job market or pay scale.
    • Re: (Score:3, Insightful)

      by Anonymous Coward
      Perhaps we can get together some day and discuss this while we take a ride to Walmart in your Lexus.

      Seriously, I'm not convinced by the economists that our current import/export situation is a good thing, and I've always been a big Buy American advocate, but I find intense irony in the fact that my IT coworkers seem to all think I'm retarded for buying a Ford, but can go on endlessly about outsourcing programming to India.

      I don't know Yonder Way, and maybe this doesn't describe him, but I've always been ama
      • Re: (Score:3, Interesting)

        by Yonder Way ( 603108 )
        "Perhaps we can get together some day and discuss this while we take a ride to Walmart in your Lexus."

        Sorry, I don't make enough to buy one of those. You'll have to pick between my 1981 Ford or my wife's 1984 Dodge "K car".
        • by T-Ranger ( 10520 )
          One of diddnt live up to the second sylable in its name when it came of the assembly line, new. The other is a Ford. Fucked either way, get a horse.
      • I fault the American citizens for their purchasing and voting decisions.

        don't blame "us" - "we're" just the sheep. Blame the criminals who legislated themselves a banking monopoly - that'd be the quasi-public "federal reserve" system.

        Federal Reserve "prints" money to pay for the budget deficit. Printing money (monetary inflation) causes price inflation, and price inflation causes producers of goods to cut corners to keep their costs down, hopefully just a little while longer than their competitor.

        In recen
        • by hab136 ( 30884 ) on Friday September 08, 2006 @02:02AM (#16064573) Journal
          The good news is that the dollar crash will take out the families with "old money" too, and we can return to a more egalitarian economic system. It'll be rough, for a bit, but definitely worth it.

          Nope. Old money families usually own resources, not dollars. If you own a diamond mine worth $3 million today, and the dollar deflates by 100 - now you own a $300 million diamond mine. You've lost nothing. Same with stock, pork futures, or real estate.

          The rich usually stay rich.

          However, your $70k mortgage balance is still only $70k, while the value of the house is now $7 million. Any debt you (or rich people) hold would become trivial to pay off.

          • ...There's a big "but", usually, to try and curb hyper-inflation interest rates are raised. So now your 5% PA mortgate is a 50% PA one. However, if you were smart enough to get into a fixed rate mortgage and there's still time before it converts into a variable rate one you should be a happy camper, if you can feed yourself that is. If you have savings, that 50% interest should come in handy for that too!
            • by hab136 ( 30884 )

              ...There's a big "but", usually, to try and curb hyper-inflation interest rates are raised. So now your 5% PA mortgate is a 50% PA one.

              Not sure what PA is supposed to mean.. per annum?

              Assuming that's what you meant.. most adjustable rate mortgages (ARMs) have both an upper-limit rate and a maximum increase per year. For example, I have a 4.50% ARM that can adjust 1% per year, cap of 12%.

              However, if you were smart enough to get into a fixed rate mortgage and there's still time before it converts into a

              • by geekoid ( 135745 )
                yes, and they are a fools game.

                Like 40 year loans, loans where you only pay interest, unless you ahve a very precise need for one, avoid the,m. Hell avoid 30 year loans and go for 15 year loan.

                BTW, move into a fixed as soon as you can, interest rates are rising very soon, and the housing bubble has popped.
              • In the UK uou can usually only get a fixed rate for a period of up to 5 years, after which you convert back to a variable rate. Of course, at that point you switch to another mortgage and/or renogotiate a new fixed rate (IIRC).
      • by b!arg ( 622192 )
        Perhaps you didn't realize that pretty much every Toyota bought in the U.S. is also built in the U.S.
    • Re: (Score:3, Insightful)

      by Badfysh ( 761833 )
      Since you're not being very helpful, I'll give the guy a hand. Fortunately, I have a lot of time on my hands now that I'm unemployed here in the UK and...

      Actually, forget that.

    • Re: (Score:3, Insightful)

      Quick question: what makes you or your neighbors so damn special that they have more rights (ha!) to hold down a job than some joe schmuck who just so happens to not live within some completely arbitrary geographical boundaries? And if you seriously believe that you "deserve" a job more than someone else, I suggest you emigrate to France and see how that works. Hint: it's not pretty.
      • by sumdumass ( 711423 ) on Friday September 08, 2006 @01:13AM (#16064454) Journal
        What gives then that "right" is more of an issue of fair play.

        You see, his neighbor (in this implied situation) didn't lose his job because he done something wrong, he didn't lose it because some one better came along and could do it more efficiently. He didn't lose it because some produced a product cheaper from a better process. He lost it because some one is exploiting the difference in the econemy between two places.

        If the dollar was the same value everywere and a gallon of milk cost the same in india, china, UK or USA, then the job would never have left the country. But the reality is that we are exploiting third world countries and lessor developed countries because they are lacking the development of econemy that the rest of the world has. We are seeing people working for pennies on the dollar mostly because when converting the penny to the other currency, it is valued more like a dollar.

        Now, the right that is implied is were a company wishes to compete in one location but derive it's labor supply another. We aren't importing the product, just the labor for the product. In the real world, minimum wage laws, unions and trade contracts would place limits on the lowest a company can pay the employee but when outsourcing to other countries, they are getting around this. Imagine the government allowing mexicans to come to america legaly with the intended purpose of working for less then minimum wage at factories were normal workers get $12.00 per hour. It would never last (on a legal basis) but outsourcing is basicly allowing this to happen.

        It might not exactly be a right to work more then a obligation for the company to hire employees in the country that they are set up in and doing business in. If the company wants to set up shop in that arbitary geographical location then let them hire all they want from there. Fireing some one in the location were you make your product, profits and public image in order to exploit the difference in currency or econemy in another location doesn't seem proper. If you think it's ok to screw the people over in the area making the bread and butter for your company then more power to ya. I'll save you a spot in the unemployment line when you find out your job has been replaced by someone doing it for 40 cents an hour because the working conditions and monetary value of the currency in some other country is so different. At least japan decided to make plants in america when the foreign cars cost so much less then american cars because the value of the yen.
        • I read this and presume your are American. I understand what you are saying but your are the only nation can can change this for you. HOW? Buy American. Check the label before you buy. I am in Canada and we cannot produce everything we need because of size. You are big enough to do that but then that D-Link router would cost 119.99 instead of 49.99 and toys would be 3 times the price. Walmart would go out of business. What would a telephone cost if it were made in America? That is a bit centric so let us
          • by geekoid ( 135745 )
            paying the higher prices would be fine because the amount of income that would now be made and kept in America.
            • Good! Now there is 1. You just need to convince another 300 million Americans and the problem is solved.
        • What gives then that "right" is more of an issue of fair play.

          You see, his neighbor (in this implied situation) didn't lose his job because he done something wrong, he didn't lose it because some one better came along and could do it more efficiently. He didn't lose it because some produced a product cheaper from a better process. He lost it because some one is exploiting the difference in the econemy between two places.

          Well, in this case, the person living in the country to which the job was outsourced did

          • Ohh were to begin..

            Well first off, let me begin by saying I agree with most of what your saying. I don't have any issue with buying something manufactured in some other country. Even if it is something that is part of something else assembled in your country. What I have the problem with is farming the jobs out to otherwise equal paying paersons but exploiting the weaknes of thier econemy and still trying to maintain they are A local company.

            If you break it down to the buying power of the persons salery, y
            • The government DID step in. And instead of implementing some sort of system that would tend to balance the standards of living, they have created INCENTIVES for offshoring.

              http://techpolicy.typepad.com/tpp/2004/03/tax_brea ks_for_.html [typepad.com]
              http://www.americanprogress.org/site/pp.asp?c=biJR J8OVF&b=32409 [americanprogress.org]

              These were high up in Google, that's my only endorsement of these sources. It was a hot issue in 2004...
              • Ok, the first post cites the whole reason being a parrot of Kerry in his failed election bid. Now if this actualy made sence, then i would agree but he doesn't state the full story and makes it apear one sided.

                If a company makes money from offshoring, then they are going to be paying taxes were ever they off shore. Why should they be double taxed because they have a presence in america? This is the only fair way to have a mumtinational corperation do business in multiple countries. The tax will just be pass
      • by hab136 ( 30884 )
        Quick question: what makes you or your neighbors so damn special that they have more rights (ha!) to hold down a job than some joe schmuck who just so happens to not live within some completely arbitrary geographical boundaries?

        Joe India may have equal rights to that job.. but people have a vested interest in a) keeping their own job and b) keeping their own economy healthy.

      • by geekoid ( 135745 )
        The same rights that give those companies tax breaks?

        If a company wants to exploit economic imbalance, then they should not get any tax breaks or tax write offs. Then will see outsourcing come to an end.
    • by mgblst ( 80109 )
      For a recent job I had to learn coldfusion. So I went to some sites for help with different problems from time to time, and they were full of questions like this, ranging from how do i get coldfusion to work, to how to do this simple little thing, to can someone get this code to work for me - all from Indians.

      I know there are a lot of great IT people in India, but there are also a lot of crap ones. I take from this that the good ones are employed, and the search for more and more IT programmers is coming up
  • by QuantumRiff ( 120817 ) on Thursday September 07, 2006 @06:17PM (#16062978)
    Will I get a better bandwidth if I take a 512 leased line on 1:2 sharing?

    Yes and No. Right now you are setup on a 512K/s line, shared with up to 4 other customers. This means that if Customer A is using 400k/s, and Customer C is using 100k/s, then customers b and c get to share 12k/s. (without getting into the discussion of prioritizing and QOS, I'm way oversimplifying) Or, depending on the setup, each of you might be setup to only get 128k/s when all of you are using your connection. Now, if its the first case, and you have one other customer that is hogging all your traffic, then you will benifit from moving to a 1:2, or even just getting rid of them on the same circuit. However, the only way to be sure that you have 512k/s if you need it is to make sure you have your own connection, and a garuntee from the ISP. (in the US, these are called "Business class" DSL circuits in many areas) It will be MUCH more expensive.

  • reliability of an internet service is not always dependent on bandwidth used.

    Most times it depends on your ISP and their upstream ISPs' network, quality of service, etc.

    Note: it is possible you are reaching your real bandwidth limit (what the ISP makes available to you) at different times which causes delays resulting in timeouts. Might be volume of traffic over the VPN link or it might be non-VPN traffic to the rest of the internet.

    If you want more bandwidth (hedged bet for the future) and better reliabil
  • When I started my current job the company had minimal bandwidth requirements, a dedicated T1 and only 7 people using the connection. And they all complained about the "slow" connection. Problem was latency. 250ms to the ISP's gateway was typical and often worse. Given that displaying a typical web page involves several DNS lookups and many connections those quarter-seconds added up quick.

    We switched to a new provider (actually had to, the old one was in bankruptcy) and people were stunned by the improved sp
    • Alternatively, implement a local DNS server and put static entries for the remote versioning server. Then have your clients hit the local server with the >2ms ping times.

      Additionally, the local DNS server may help to reduce the amount of bandwidth that is being used by reducing the number of machines that are going out for DNS lookups.
  • Pony up and pay (Score:5, Insightful)

    by TLouden ( 677335 ) on Thursday September 07, 2006 @06:59PM (#16063191)
    You say you can't afford to figure this out with an expert. My response is that you're asking your competition to help you cut your costs so that you can better compete with them.
    Enjoy the answers.
  • by russ1337 ( 938915 ) on Thursday September 07, 2006 @07:04PM (#16063215)
    You could have figured out how much bandwidth you don't have by posting a link to your local server. Being Slashdotted would've shown your ISP you need more bandwith!

    Then; Take the number of connections at your end before your connection was severed, and add that to 'half' the number of connections when your ISP's server/connection maxed out, multiply by the number of toilets in your office, and divide by Pi.
  • That's easy... (Score:2, Informative)

    by solid_liq ( 720160 )
    Why don't you just outsource your development work to the U.S.? Then you won't have to worry about bandwidth.
    • by kv9 ( 697238 )

      Why don't you just outsource your development work to the U.S.? Then you won't have to worry about bandwidth.

      how so? are US - UK pipes free?

  • you've come to the Slashdot community which is mostly Americans to ask us to help you out. Someone who is taking our jobs away from us. I don't think so.
    • How is an Indian doing work for a UK company taking jobs away from the US? If anyone should be annoyed, it's the British.
  • Pricing (Score:3, Insightful)

    by solid_liq ( 720160 ) on Thursday September 07, 2006 @07:10PM (#16063243) Homepage Journal
    "(There's a huge price gap between the 2 here in India) In any case, how does one decide the optimum bandwidth required for a bunch of 15 developers on VPN and Source control?"

    Welcome to the world of business. Are you starting to understand why we charge as much as we do outside of India? It's because we have to support our business infrastructure and still make a profit for all our effort! Don't like it, go back to India. Oh wait...

  • Tell (Score:4, Funny)

    by mattboston ( 537016 ) on Thursday September 07, 2006 @07:13PM (#16063257) Homepage
    your developers to stop downloading porn and illegal music at work.
  • Wait. (Score:2, Insightful)

    by Anonymous Coward
    You're (ostensibly) a professional services shop, seeking to provide (ahem) professional services to another company, over the internet. You plan on using the internet as your delivery method for the services rendered. Now, why on earth would you ask Slashdot for professional services advice? What if your customers instead decided to go it on their own for internet services? While a 13 person shop may be a small company, I refuse to believe that you cannot spend the money necessary to have a PROFESSIONAL co
    • The 'Anonymous Coward' has a pretty good point there. I don't know how much research you've done before posting here, but if you ask me this sort of question exactly slashdot worthy, IMHO. Most developers should be fairly familiar with SVN/CVS/etc to consider those first, and be capable of google searching for such information. It's basic math really, figure out how much bandwidth your application consumes to be useable, then multiply by the number of people that will be using it at the same time, and add a
  • One of the major things to consider is that TCP's performance is also bound by the recieve window size[2]. Since TCP can only send more data as it's ACK'd due to this window, RTT plays a factor.

    So also consider the "bandwidth delay product"[1] to where you're connecting to and compare this to your recieve window size. Consider checkking to make sure increasing your recieve window size won't get you better performance. This needs to be done at the end of the connection that's recieving the data, which for

  • Didn't he have to compile numbers for WEekly Network USage and Annual Network USage?

    • by hab136 ( 30884 )
      Didn't he have to compile numbers for WEekly Network USage and Annual Network USage?

      Nope. The WENUS - Weekly Estimated Net Usage Statistics. Net being gross minus expenses; nothing to do with networking.

      Man, I watched too much of that show..

  • ""There are frequent disconnections; and hence loss of work while code check-ins.""

    Is this the key reason why you need a VPN?
    [BTW, I hope that you are not using MS SourceSafe...]
    Have you considered alternate revision control systems?

    On the (not too expensive) commercial side, I am a fan of Code Co-op, from http://www.relisoft.com/ [relisoft.com]. I've used it with a development team in China a few years ago, and they were definitely worse-off than you. Free trial available for download.
  • first, use the MS network tool fdisk.
    Follow the procedure, you want to do a network latence repair know has 'partitioning'. It splits the bandwidth up among applications accross your hard drive. This will dramatically reduce bandwidth.

    You versioning system is going to be a big drain, I suggest starting with that one.

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