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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: MCI [ATM overhead]
At 03:09 PM 3/21/96 +0800, Vadim Antonov wrote: > ... (as ATM does not handle >levels of overcommitment found in IP backbones now). > > >--vadim > > Vadim; I think that statement, as I interpret it, could only apply if you are running IP over a rate-controlled ATM backbone (either CBR or VBR QoS). Nobody in their right mind does that if they have an alternative. ATM responds to "overcommitment", if you mean "excess offered load", by shedding that load either in the middle of the backbone at the bottleneck if you are running IP over UBR or at the edge of the network if you are running a proprietary ABR. IP routers respond to excess offered load by shedding that load in the middle of the backbone, since IP router QoS is essentially the same as ATM UBR. In this sense, with ATM you have two choices for handling overcommit- ment (if your ATM switch vendor has a proprietary ABR) but with routers you have only one. --Kent
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