links on the blink (fwd)

Thu Nov 9 09:19:32 UTC 1995

Michael Dillon <michael at memra.com> wrote:

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

There are hard architectural limits on the number of core routers in
the defaultless backbone.  Backbone has to have a relatively small
number of BGP speakers, to avoid severe routing information propagation
problems.

There _are_ "creative ways", see for example SprintLink presentations
on NANOG, the planned "3-dimensional grid" backbone topology (it allows
to grow the aggregate capacity to about OC-3).  However, you inevitably
run into capacity limitation of LAN interconnects.  Then, there's a
problem with load balancing, as it generally cannot be done with exterior
protocols which have to select a single path.  (And there's no easy
way to do per-destination load distribution on a large scale).

It's only a kludge to survive until (and if) somebody will build real
central-office routers.

>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 ?

There are boxes which can *statically* mux/demux OC-192 to DS-3s.
Synchronous muxes is not a high technology, being basicallly decorated
shift registers.

>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.

That already happened.  I would rather see things going in opposite
deirection.  (For VOD applications ATM is adequate, as it only demultiplexes
big pipes from VOD servers into small access pipes; there's no backwards
data flow, and no statistical multiplexing).

However, the utility of VOD is very questionable, as the basic need to see
the movie quite adequately and cheaply satisfyed by low-tech video rentals.
It is not a "killer application", definitely.  Video telephony and distributed
computing network can be such applications but they beg for symmetrical IP
connectivity.

--vadim