| Title: | FDDI - The Next Generation |
| Moderator: | NETCAD::STEFANI |
| Created: | Thu Apr 27 1989 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2259 |
| Total number of notes: | 8590 |
We were "this close" to selling and implementing a FDDI LAN for a
customer when someone suggested an Ethernet switch (e.g.Kalpana) with
multiple legs could accomplish the same virtual throughput at a
fraction of the cost. I am now tasked with writing a document detailing
pros and cons. Any general suggestion, comments?
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 418.1 | KONING::KONING | Paul Koning, NI1D | Mon Dec 16 1991 13:19 | 16 | |
"same throughput" -- well, that depends on what you measure. The Kalpana switch has a total throughput of about 70 Mb/s, I believe, which is in the same order of magnitude as FDDI. (FDDI is 100 Mb/s, of course, minus a few for overhead, leaving about 95-98 for actual use.) However, with Ethernet attachments your per-station throughput is only 10 Mb/s. Conversely, with FDDI it can be as high as the total throughput. With current software and typical adapters, you'll probably get more like 30 to 60 Mb/s, which is still a LOT more than Ethernet. So the question is: do you require more than 10 Mb/s for any given station? If so, go FDDI. If you only require the higher total capacity but are satisfied with 10 Mb/s or less per station, then Ethernet is indeed a solution and is likely to be less expensive. paul | |||||
| 418.2 | exit | WLW::WLW::SEITZ | The system is a Network | Wed Dec 18 1991 11:04 | 9 |
Another question I pose to customers considering the "switch" approach
is distance. With an FDDI backbone, you can put the 10/100 bridge very
close to the Ethernet LAN being bridged. This reduces the length of the
Ethernet which increases its overall performance characteristics.
The Kalpana requires all Ethernet segments to converge at one point
which typically lengthens the Ethernet.
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