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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: ATM Wide-Area Networks (was: sell shell accounts?)
On Tue, 23 Jul 1996, Tim Salo wrote: > I am not quite sure how an ATM switch becomes a "packet shredder," or > even what a "packet shredder" is... An ATM switch shreds a 1500 byte IP packet into 29 ATM cells of 53 bytes each. If an ATM has a 5% loss, i.e. 1 in every 20 cells is lost, then 0% of the IP traffic will get through. This is a worst case kind of scenario but I'm sure you can see other scenarios where the 53 byte ATM transport could cause problems. For instance, if the first ATM cell containing a new IP packet gets lost, the switch may continue to transmit the other 28 cells in the packet even though these are now useless garbage data that don't need to be forwarded. The 7 layer model can be useful as an intellectual tool to separate the different mechanisms required to implement networks but it is wrong to assume that arbitrary combinations of layers can operate efficiently and effectively in the real world. Of course, ATM switch vendors are learning how to make their equipment handle IP packets better, and then there is Ipsilon http://www.ipsilon.com RFC 1953 and RFC 1954 Michael Dillon - ISP & Internet Consulting Memra Software Inc. - Fax: +1-604-546-3049 http://www.memra.com - E-mail: [email protected] - - - - - - - - - - - - - - - - -
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