North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Topological significance of transport technologies [Was: Re:
Agreed.. the distinction between the two layers is becoming somewhat more and more vague by the day, especially with companies like Ipsilon and with Cisco's integration of eclipse switching and/or the RSM into the Catalyst.. how the two layers interact is really the only importance to the IP packet. rob > > At 05:00 PM 07/01/97 -0700, Robert Bowman wrote: > > >layer 2 vs. layer 3 > > > >tis like comparing a motorcyle to an automobile--both get you places > >but in fairly different ways > > > > I shouldn't be contributing to this thread, but what the hell. > > Its not really Layer 2 vs. Layer 3, its how to integrate the > two layers and make it work. Mike O'Dell is fond of saying, > "Pure Layer 3 routed networks are dead," and I can understand > his point, although I don't necessarily agree with it. I do > understand, and I think its important for everyone else > to understand the point here. > > Yes, they both get you there, but the pertinent summary to be > drawn from this comparison is that 'you' are the IP packet, > and you really don't care what the mode of transport is (e.g. > frame-relay, leased point-to-point lines, ATM). Each provide > a pipe. Some have more intrinsic flexibility than others (e.g. > virtual circuits) and therefore represent a significant reason > to employ a specific technology over another, given pricing, and > geographic availability. > > Again, IP packets don't really care if it's a motorcycle, an > airplane, or an automobile (unless its a Harley :-). > > It should also be noted that some technologies, such as > frame-relay are used only in *topologically significant* > places, ie. customer aggregation, for precisely these > reasons. In some networks, frame-relay is used for > customer aggregation, fast-ethernet is used in the PoP, > and ATM is used in the wide-area (just an example). > > - paul >
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