Conference netcad::hub_mgnt

2551.0. "ThinWire legacy and migration to structured wiring" by THEPUB::JRS (John SHADE - 'Attila the Nun') Mon Jul 24 1995 08:09

I'd like to describe a real situation at a customer site, and then ask for help
in coming up with a solution based on NPBU products. The description is
somewhat simplified, but it captures the gist of the problem.

The customer has a four-floor building, with a DEMPR on each floor (8 ThinWire
segments per floor). There's a also a small FDDI ring on the ground floor.
All the DEMPRs and the FDDI ring are connected into a DECnis (which acts like a
bridge, not a router).

With the advent of a few powerful Alphas, the customer (who is primarily a DEC
shop) is concerned about the bandwidth of the current infrastructure, and is
thinking in terms of structured cabling. Their immediate concern, however, is
to provide a dedicated 10Mb/s to each of the existing ThinWire segments.

A PORTswitch 900CP (16 THINWIRE ports) would seem to be a good idea, but there
are only 6 Ethernet LANs available on the hub backplane. Nevertheless, if we
add a DECswitch 900EF, we can then bridge those six LANs onto FDDI (running
vertically in the building).

Is this the best solution? Can anyone think of alternatives? Any ideas when the
6 Ethernets in a backplane limit might be lifted?

Thanks,

-John

    Your solution sound like exactly what I would propose.  From your
    proposed configuration, expanding the infrastructure to multiple FDDI
    rings and dedicated ethernets would be a matter of incremental costs as
    opposed to major capital dollars being expended as the customer needs
    to upgrade the network.
    
    IMO, of course
    
    Brian Pituley
    NPC, Calgary
    

    Sounds like overkill to me.  If you already have the DECNIS in the
    basement on FDDI, just insert two L602 cards (Dual-port Ethernet) cards
    and attach some ThinWire MAU's to each port, and you have a dedicated
    Ethernet to each DEMPR.  
    
    Later, as the workgroups grow, I would upgrade each DEMPR site to a
    HUB900, and feed FDDI to it.  The DECNIS is more powerful and has more
    port capacity than you need for a while.  (I assume it's a 600)
    
    JR

Thanks for the replies.

RE: .2 - I maybe didn't express myself very well in the base note, but the
DECnis already has L602 cards. What the customer wants is dedicated Ethernet to
each DEMPR *port*.

I'm still not convinced that we have a solution that compares favourably to, for
example, a 3COM solution based on LANplex2500 (modular Ethernet PMDs) with,
later, a CELLplex switch in place of the DECnis (evolution to ATM). 

-John