A new stdaddr draft is forthcoming shortly. This other conversation is of interest, though. We're arguing about 100Mb/s interconnect technology as if we all planned to keep using it for some significant period. That's not so. Two years from now it'll be 622Mb/s or it'll be a dead concept. PMTUD matters, and TCP MSS (therefore IP MTU) matters because it will dictate the frame rate to the routers and the end hosts. Bytes are cheap, frames cost.
Paul, with all due respect, there is a lot of apparent need and demand for 100mbps interconnects, one could argue that 100 100mbps interconnects are better than 3 or 4 622mbps interconnects. I think 100 interconnects are at least as likely in 2 years as 4 622mbps interconnects. Since most of the customers connecting up to these interconnects will be by devices with MTUs of 1500 (frame, T-1, switched 10 and 100mbps interconnects), and all of the network below these interconnected sites are 1500 MTU and smaller. I know of maybe 100 sites around the globle that can currently send FDDI MTUs in the 4000 range.a By contrast good esitmates show about 10 million dialup users connected via termial servers which have ethernet interfaces. In terms of total users FDDI users would be well below .001%. In terms of total revenues FDDI users would be well below 1%. Basied on these numbers, my recommendations to NAP/MAE builders would be to build based on 100mbps switched ethernet, with the option to interconnect FDDI. To make the FDDI worth while there would have to be at least two networks attached that had routers co-located (or virtually co-located), with DS-3 rate connections, and those two networks would each need at least one DS-3 rate customer each. Assuming this is the case the upgrade to FDDI is a relatively simple thing. Comparing the cost of 100mbps switched ethernet, to the 100 mbps switched FDDI, there is about 30% to 50% difference per port on the switch, and greater than that on the router. Prices on switched ethernet are dropping much faster than those of FDDI, because the price point is below the level at which a technology is only used where speed is the only factor. Speaking of interfaces and speed, I see Cisco now has a OC-3 packet interface that will do raw packets via HDLC or PPP at OC-3 rates via SONET. That seems much nicer than the ATM AIP card. You could build a fairly nice backbone with a dual attached mesh of OC-3 routers. -- Jeremy Porter, Freeside Communications, Inc. jerry@fc.net PO BOX 80315 Austin, Tx 78708 | 1-800-968-8750 | 512-339-6094 http://www.fc.net