talking of and to gateways and bridges


Jon Crowcroft (jon@Cs.Ucl.AC.UK)
Sat, 21 Mar 87 17:12:29 +0000


We at UCL witness an interesting problem. Because it is
regarded as AOK for gateways to talk to each other using unreliable IP,
and gateways don't reassemble, only a minimal amount of info
can get between gateways at any one go.

The internet has got so large now, that when a reasonable percentage
of sites are up, we disappear off the end of routing updates, and go
unreachable.

Why not get the gateways to reassemble packets destined for them (ie when
they are acting as hosts/end points after all),
I hear you cry? Nope, cos thats just a short term
fix til there are more than (say) 1500 bytes worth of update.

Why not use a transport protocol between IP and EGP/GGP/IGP/RIP etc? Yes,
but which one. Well, there's TCP/RDP/ and who knows how many transaction
protocols out there waiting to pounce. [This may also make your
routing algorithms cleaner.]

Well, use the same one as you use for talking management to your gateway from
your hosts for now, like TCP. Surely it's not beyond the wit of
gatewayfarers to put TCP into their boxes, since half of them
build TCP terminal concentrators already.

Our attitude to manageing MAC Bridges ~like~ the DEC LAN Bridge
100, is to put a separate management network (eg V24 or V35/
RS422 lines or whatever) in the ether/coax/fibre bundle, and use that
to talk telnet/tcp blah into the Bridge. That's no solace to
people with proprietry stuff in the Bridge, but I think it's
the way things will go.

Next years answer is: use ECMA ROS
over REX, because it's gonna be a standard, and I am
a biased European.

Jon



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