175 lines
3.7 KiB
HTML
175 lines
3.7 KiB
HTML
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>Queues and Queueing Disciplines explained</TITLE
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>Chapter 9. Queueing Disciplines for Bandwidth Management</TD
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>9.1. Queues and Queueing Disciplines explained</H1
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><P
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>With queueing we determine the way in which data is <EM
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>SENT</EM
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>.
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It is important to realise that we can only shape data that we transmit.</P
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><P
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>With the way the Internet works, we have no direct control of what people
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send us. It's a bit like your (physical!) mailbox at home. There is no way
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you can influence the world to modify the amount of mail they send you,
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short of contacting everybody.</P
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><P
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>However, the Internet is mostly based on TCP/IP which has a few features
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that help us. TCP/IP has no way of knowing the capacity of the network
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between two hosts, so it just starts sending data faster and faster ('slow
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start') and when packets start getting lost, because there is no room to
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send them, it will slow down. In fact it is a bit smarter than this, but
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more about that later.</P
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><P
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>This is the equivalent of not reading half of your mail, and hoping that
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people will stop sending it to you. With the difference that it works for
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the Internet :-)</P
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><P
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>If you have a router and wish to prevent certain hosts within your network
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from downloading too fast, you need to do your shaping on the *inner* interface
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of your router, the one that sends data to your own computers.</P
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><P
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>You also have to be sure you are controlling the bottleneck of the link.
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If you have a 100Mbit NIC and you have a router that has a 256kbit link,
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you have to make sure you are not sending more data than your router can
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handle. Otherwise, it will be the router who is controlling the link and
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shaping the available bandwith. We need to 'own the queue' so to speak, and
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be the slowest link in the chain. Luckily this is easily possible.</P
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>Queueing Disciplines for Bandwidth Management</TD
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>Simple, classless Queueing Disciplines</TD
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