The Routing Over Large Clouds Mailing List Archive by date

[Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>]

Sam;

> I wouldn't want to get into an argument about the potential performance
> of future cell switches vs future packet switches.  On our network, at
> the moment, with the kit we have, each router hop adds considerable
> latency and may introduce capacity bottlenecks.  To avoid it requires
> either NHRP (non-scaling according to Ohta-san) or some mangling of the
> routing model.

To avoid what?

Please remember that ATM is not a magic.

Regardless of numerous hype, the current bottlenecks, which is,
at the same time, the place to drop packet for TCP throttling,
will continue to be the bottlenecks and packets will be lost.

One way to live with such congestion is prioritization. But, as you
know, we don't have RSVP stabled yet. And, if we have, CSRs work.

> We have 4 MANs centred on Edinburgh, Glasgow, Aberdeen and Dundee. 
> These are to be interconnected in a star based on Edinburgh.  Each MAN
> comprises its own core of arbitrary topology, some pure ATM, some mixed
> ATM and FDDI technology.  Attached to each MAN are a number of campus
> LANs, of the order of a dozen on each MAN, using various technologies
> including ATM.  The Scottish MAN Interconnect in Edinburgh will also
> connect to the SuperJANET ATM network. 

> Now, Ohta-san - is that large? It is not large in the sense of number of
> connected entities (I'd guess 30-40K attached hosts in the catenet) nor
> in complexity of routing.

It is large. Considering that it should be a part of the Internet,
it is as large as the Internet.

But, something constructed with the catenet is not a cloud.

> Thanks for your contribution.  One of the difficulties with switched
> link layers (with attitude or not) is that the you can end up building
> logical meshes on top of physical stars or vice versa.  Design decisions
> interact between the layers.  But you all know that, anyway...

Making something logical only add unnecessary management burden with
no real benefit.

							Masataka Ohta