Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!HP-SDE.SDE.HP.COM!wunder
From: wunder@HP-SDE.SDE.HP.COM (Walter Underwood)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: IP over ISDN and Satellite?
Message-ID: <8904271800.AA11963@hp-ses.sde.hp.com>
Date: 27 Apr 89 18:00:39 GMT
References: <4947@ditmela.oz>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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   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