[aklug] Re: regarding router/switch bandwidth

On Fri, 3 Jun 2011, Christopher Howard wrote:

> I'm not a networking expert, but I've noticed something over time at the
> various home and work networks I've been around. A person would
> intuitively imagine that, if there were x numbers of people
> simultaneously wanting all the bandwidth on a network, that the
> bandwidth would end up being roughly divided between those people.
> However, what actually seems to happen is that the first people to start
> using most of the bandwidth first are the ones who get the most access.
>
> For example, at work: if my coworker beings downloading a set of huge
> files, he gets almost all of the bandwidth until the downloads are
> complete. But if I try to download something right after he starts, then
> I only get a small trickle (a few bytes per second) until his downloads
> are finished.
>
> I was wondering if there was some inherent reason for sort of behavior
> in the design of our whole TCP/IP system. Or is that just the way
> cheaper routers and switches tend to work?

Part of it is standard TCP, and part of it is likely buffer bloat. Most of
the congestion controls we use by default are based on some faulty
assumptions. Luckily, if your primary gateway is a Linux router you can
control some of this with tc.

         --Arthur Corliss
           Live Free or Die
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Received on Fri Jun 3 23:38:46 2011