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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: value of co-location
> > I'm also curious about the value of co-location. Using a fast packet > > service (Frame Relay, SMDS, or ATM) allows your on-site router to > > communicate directly with a router of another ISP. There's no need to > > purchase another router to place at the co-location site. Why incur the > > additional cost? > > To avoid having to use any of the fast packet services you mentioned? > Or to allow you to use routers, which you know about, instead of being > dependent on the random characteristics of switches the telephone > company bought? > > Not using either of the last two fast packet services, in particular, will > also yield 30% more useful bandwidth from a T3 circuit. This all by itself > may make up for the co-location costs and the cost of a router. Actually, the overhead for IP over SMDS is more like 40%, if I remember correctly, because of all the headers (8 byte SNAP, 32 byte SMDS) on top of the ATM cell tax (5 out of 53 on cell headers, average 1/2 a cell wasted at the end of the packet which occurs about ever 5 or 6 cells), figured on the observed Internet average packet size of ~220 bytes a couple years ago. What's the average packet size now? I think the overhead on DS-3 ATM/SMDS is worse than on OC-3, if I recall correctly, because the DS-3 PLCP is so wasteful as well. Someone should redo these calculations more accurately. So, if the fast packet based access to NAPs is priced at ~40% less, *and* the ATM switches perform as well as the FDDI switches, then it is a don't care. -- Jim
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