IS IT REALLY FULLY MESHED (Was Re: sell shell accounts?)

Fri Jul 19 22:54:28 UTC 1996

The point of discussion orginated as a question about a fully
meshed network in AGIS.

IMHO.  When all you do is connect ATM PVCs point-to-point between routers
you do not, even remotely, have a fully meshed ATM cloud.  

If AGIS onstructed this way [*Please I am not saying they are*],
then there is only a series of routers which use ATM in between for 
    (a) go fast point-to-point or
    (b) lower price-per-megabit point-to-point
    (c) all of the above.

The topology would look like this.  And it is exactly as Avi indicates
a perfect match for the router-only network topology.

   R1 --(ATM PVC)-- R2 --(ATM PVC)-- R3

If however, it is truly a cloud with routers at the edges, the
topology can be described like this:

   R1 --(PVC R1,R2)--( ATM CLOUD  )--(PVC R1,R2)-- R2
   R1 --(PVC R1,R3)--( ATM CLOUD  )--(PVC R3,R2)-- R2
                     ( ATM CLOUD  )--(PVC R1,R3)-- R3
                     ( ATM CLOUD  )--(PVC R2,R3)-- R3

Using this approach, then the ATM interface card in each router
has a path to all other routers, then it is fully meshed.  
HOWEVER, THIS ASSUMES that 
    (1) a series of ATM switches is used to create
        a physical cloud capable of touching all the routers.
    (2) That the PVCs are provisioned accordingly.

I have observed a growing number of network providers calling
themselves "...ATM based..." who are only purchasing point-to-point
PVC service from a carrier.  Until you purchase a PVC from each
router to all others in your network, it is not fully meshed.  
Even then, it is the routers which are managing the mesh unless you
also own the ATM switches in between.

..mike..

Mike Trest,  ATMNET          Voice:  619 643-1805
5440 Morehouse Drive         Fax:    619 643-1801
San Diego, CA USA 92121      Pager:  619 960-9070