smart@ditmela.oz (Robert Smart) (04/26/89)
What is being done about IP connectivity using some of the new communication capabilities. Perhaps satellite isn't so new. Of course it isn't very suitable for IP in its raw form. But I would thing it could be used in cooperation with low speed terestrial links. For example instead of a T1 terestrial link (which is very expensive in Australia) you could link two points with a 56Kb terestrial link plus a T1 satellite link. The idea would be to use the low speed link for all small packets (or big packets when the link is free maybe) and use the satellite for big packets. This would use the satellite for file transfers or bulk data from computer to terminal, but allow interactive traffic to have usable echo characteristics. Has anyone tried anything like this? ISDN is also interesting. I presume you could link your ISDN to many other ISDN sites simultaneously but at low speed using the signalling channel (running something like IP over X.25). Then when you get a significant amount of data going to some destination you would start making connections using the 64Kb data channels. The idea (preferably) would be to use as many data channels as possible while still leaving some lines free at each end for telephone users. Not trivial but not conceptually difficult. Is anyone working in this area? Bob Smart, <smart%ditmelb.oz.au@uunet.uu.net> or <uunet!munnari!ditmelb!smart>
wunder@HP-SDE.SDE.HP.COM (Walter Underwood) (04/28/89)
For example instead of a T1 terestrial link (which is very expensive in Australia) you could link two points with a 56Kb terestrial link plus a T1 satellite link. The idea would be to use the low speed link for all small packets (or big packets when the link is free maybe) and use the satellite for big packets. "The future is now" as someone used to say. The routing algorithms in cisco gateways have been able to do this for a while. When Uniforum was in DC, HP had a 56Kbit satellite link and a 9.6 terrestrial link in parallel between two cisco gateways. We could watch the CSU/DSUs and see the small packets go over the terrestrial and the large packets go over the satellite. This trick does require the right balance of links. The BW and delay of the two links should work out so that the boundary between large and small is in the mid-size for IP packets (200 bytes?). If the boundary is wrong (anything over 2000 bytes goes over the satellite), then you'll end up with an idle link. wunder