links on the blink (fwd)

Michael Dillon michael at
Thu Nov 9 07:53:35 UTC 1995

On Wed, 8 Nov 1995, Dennis Ferguson wrote:

> to be a bleak prospect.  There comes a point where you just run out of
> router bandwidth, and nothing but more router bandwidth is going to fix
> it, but the bigger bandwidth boxes are no where to be found.

Are you sure that creative ways of using lots of smaller T3 bandwidth 
boxes couldn't solve the problem?

If we assume that bandwidth on the lines is not a problem (no shortages) 
and that T3 routers with smaller routing tables could make effective use 
of the bandwidth, then is it possible to do the following?

In Hypothetica, PA are ABC ISP who has a T1 to Sprint and XYZ ISP who has 
a line to MCI. Both have so-called portable addresses from the swamp and 
thus consume space in the core routing tables. This means that traffic 
from ABC to XYZ travels from Hypothetica to Pennsauken, thence to MCI and 
back to Hypothetica. However, suppose we clean up the swamp by simply 
removing it entirely from all the core routing tables. What then? Every 
provider puts a default route in each core router. This default route 
points to a special router whose job is to just deal with the swamp 
routes and nothing else. In effect we are partitioning the routing tables 
in two. Under this regimen packets from ABC to XYZ travel to Pennsauken, 
then follow the default to Fort Worth and thence to Chicago where the 
swamp router lives. The swamp router uses a separate continental backbone 
to route the traffic back to Fort Worth, back to Pensauken and thence to 
MCI where the traffic takes a similar circuitous route before reaching 

Seems terribly wasteful of bandwidth doesn't it? But if something like 
this can help prevent routers from flapping and if bandwidth is 
avaialbale, perhaps it could work. If the parallel lines carrying "swamp" 
traffic are of lower bandwidth than the main lines and suffer congestion, 
then I suppose ABC could simply renumber to be within Sprint's aggregate 
and be back on the mainline.

In fact, if this really is a viable technical solution, perhaps the 
threat of deployment would cause a rush of renumbering and make it easier 
for NSP's to just say no to swamp addresses.

> seem to be anything to spend the money on which is clearly going to fix
> anything.  I don't think this is a happy state to be in, in fact it sucks,

If you are right, then yes it sucks. Obvoiusly the ATM and OC3 
technologies are right where you have pegged them, but what about 
parallelism using existing DS3 technology? And if this is done, are there
mux/demux boxes that can handle DS3's<->OC3 ? 

> profit motives.  I think we're victims of our having own success creep up
> to and pass the technology when we weren't paying close enough attention,
> and the only thing left to do seems to be to try to play catch-up from
> a position of increasing disadvantage.

One nice side effect is that this may force the video-on-demand folks off 
the Internet and into straight ATM instead. I rather like the future 
scenario where the globe is girdled by an IPng data network and a separate
parallel video/ATM network.

Michael Dillon                                    Voice: +1-604-546-8022
Memra Software Inc.                                 Fax: +1-604-542-4130                             E-mail: michael at

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