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Re: QoS/CoS in the real world?
At 11:13 AM 7/15/2002 -0400, Art Houle wrote:
That's exactly the right phrase: "We are using QOS to preferentially drop packets...."We are using QOS to preferentially drop packets that represent file-sharing (kazaa, gnutella, etc). This saves us 40Mbps of traffic across our multiple congested WAN links. The trick is to mark packets meaningfully. Also, the WFQ introduces some additional latency at our edge.
When my research customers come to me wanting QoS, I can usually screen out the silly requests from the serious requests by asking "OK how can I tell which packets are less important and should be dropped?"
If they say "someone's packets other than mine" I nod and smile politely.
However, the Access Grid application runs both video and audio. The AG folks can very easily mark the packets for video and audio, and are quite happy to drop video packets in order to get the audio clear. AG users really truly want good audio at the expense of high quality video.
To this point we haven't actually implemented it, but it's a nice option to have in one's back pocket to pull out when it's really needed.
Bill Nickless http://www.mcs.anl.gov/people/nickless +1 630 252 7390
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