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How Necessary Is Qos?

Discussion in 'Other Linksys Equipment' started by DocLarge, Mar 8, 2006.

  1. DocLarge

    DocLarge Super Moderator Staff Member Member

    I came across this link on broadband reports regarding Qos and thought this might be of interest to others. The overall point was this, is it necessary under 100% bandwith usage?


  2. NateHoy

    NateHoy Network Guru Member

    No, QoS is not necessary if you never use 100% of your bandwidth.

    That's a big, fat, ugly "IF".

    That "if" exists in the magical fantasy fairyland where all connections can be upgraded at a whim, at no expense, and we never have any real-world limitations like that nasty speed of light everyone keeps griping about, and the laws of physics applying to the amount of data that can be put through an extruded bit of metal or glass, not to mention the bean counters down in accounting mumbling on about being able to make more money than is spent in a given time period... ;)

    In the real world, more and more users are starting to use services like BitTorrent, VoIP, streaming music, and you-name-it. As the capacity of a network expands, the possibilities it opens up almost guarantees that the network will be overloaded (if someone suddenly discovers that a cool high-bandwidth application works due to the recent upgrade, they'll start using it and tell all their friends).

    In that same real world, copper and fiber optics cost real money. Where does this money come from to keep network capacity above 100% of demand all the time, when demand is growing?

    Enter QoS. My P2P applications are very tolerant of delays, as I don't worry too much about delays in getting my Linux distros, etc, off P2P. I leave them overnight, and they are waiting for me the next morning. If I was in a hurry, I'd pay for HTTP premium download, or order the CD's overnight.

    Email, similarly, can take its sweet time. Ideally, it should be delivered in real time. But if a router gets overstressed from people doing VoIP and streaming media, then email can find a different, slower route, or sit in a router buffer for a few extra seconds while the priority stuff whizzes by.

    My web browsing can tolerate a delay of a second or two and I won't have too much problem. My VoIP, on the other hand, MUST have bandwidth all the time, or it's unuseable.

    QoS, if applied correctly, is simply a way of taking the peaks and valleys of useage and maximizing the experience for everyone while not spending money on ineffective upgrades. Lower priority services suffer small delays to make room for higher priority services, so the stuff you need in real time gets there on time, and the stuff you don't need in a huge hurry takes a few more seconds.

    There are companies that will offer you unlimited bandwidth, or as close to it as you can handle. It'll cost you a few thousand a month, or more, but you can have your very own gigabit pipe into the 'net. For people who want $50 a month connectivity and still demand streaming media, VoIP, and P2P, their service providers have to make compromises to make a profit. And QoS is a pretty good compromise, as long as it isn't used to "de-optimize" a competitor's product (as in the recent allegations between Comcast and Vonage, for example).

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