sell shell accounts?

Jim Van Baalen vansax at
Fri Jul 19 21:48:52 UTC 1996

Here is the senario I was thinking about

Case 1

R1 --- R2 --- R3

Case 2

R1 --- SW --- R3

Assume that the wide area segments are the same in both cases and that SW and
R2 are collocated. In case 1 there are 2 router hops between R1 and R3. In case 
2, given a full mesh of PVCs, R1 and R2 are only one hop apart. This does not
imply that the traffic flows any differently relative to the physical paths
taken, but if I do a traceroute I think it will look different. Am I missing 
the point here?


> > If you have full use of the fiber across which you move your packets you
> > can create a mesh of PVCs directly connecting each router thus decreasing
> > the hop count. The same can be done when using an existing cell-relay cloud,
> > but you pay on a per pvc basis so the benefit needs to be weighed against the
> > cost. Of course the packets still flow along the same physical path and in a 
> > wide area network the time in transit will be more significant than the time 
> > to get through the routers.
> > 
> > Jim
> Nope, remember - there is no magic.  Any mesh of PVCs that one makes
> over a switched network must reflect the toplogy of that network, and
> one can set up a matching set of active routing sessions and route
> weights which will cause traffic to flow the same way.
> Yes, the switches are a bit faster and have less to do. Data moves through 
> them in a few ms less per point.  But as you said (and as I said in our
> discussion in NYC), relative to any distance, the speed of light guarantees 
> that you won't notice the difference.
> The question is:  Will there be routers available that can make IP
> routing decisions based on 40-60kroutes and move 2-3 OC3s worth of 
> bidirectional traffic?  The building of the configs to have a routed
> network work the same as a switched ATM one can be automated, but it's
> true that it *can be* easier to see what's going on in a large-scale 
> switched network.
> Avi

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