[Diffserv-interest] DiffServ over ATM
John Tillberg <John.E.Tillberg@telia.se> Thu, 30 August 2001 15:03 UTC
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From: John Tillberg <John.E.Tillberg@telia.se>
To: "'diffserv-interest@ietf.org'" <diffserv-interest@ietf.org>
Date: Thu, 30 Aug 2001 17:03:50 +0200
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Subject: [Diffserv-interest] DiffServ over ATM
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Hello DiffServers! I'm currently doing some simulations (using Opnet) of IP over ATM where I use WFQ to differentiate between two separate traffic classes on a network with low bandwidth links (2 Mbps). It appears that the WFQ mechanism doesn't have any significant impact on the performance of the network. No matter how I tune the weights, or even if I overload some of the links, I get almost zero delay for both of my queues. However I do get delay on the ATM layer (and I am aware of that I have to map my IP QoS classes onto proper ATM QoS classes). I presume this is because the forwarding speed on the IP layer is much higher than the bandwidth of the network. Hence every (conforming) incoming packet will receive service on the IP layer (i.e. sent down to the lower layers) right away even if there is a state of congestion on the ATM layer. Have I misunderstood the matter? If not: Is this the same case for DiffServ? Does the effect of the IP-packet scheduler get "disabled" in a similar manner when you run DiffServ over ATM? Yours Sincerely John Tillberg ********************************************************************* John Tillberg Telia Research AB Phone: +46 8-713 82 07 Wireless Solutions Fax: +46 8-713 81 49 Vitsandsgatan 9 Mobile: +46 702-43 43 90 SE-123 86 Farsta Email: John.E.Tillberg@telia.se Sweden ******************************************************************** _______________________________________________ Diffserv-interest mailing list Diffserv-interest@ietf.org http://www1.ietf.org/mailman/listinfo/diffserv-interest
- [Diffserv-interest] DiffServ over ATM John Tillberg