Re: Response to anti-bridge comments


Norman Kincl (kincl%hplnmk@hplabs.HP.COM)
Mon, 30 Mar 87 10:29:13 PST


                                                         At the moment, 256
   kbps of this capacity connects a set of five Vitalink Translan IIIs as a
   star with the hub at Piscataway. Each of these boxes also connects to the
   building-wide backbone Ethernet at its location, thus bridging the locations
   together at the link level. Within each location almost all of our Ethernets
   are bridged with DEC LanBridge 100s, with the fiber version interconnecting
   multiple buildings at a location. At last count, the routing tables on the
   Translans showed something like 600 active hosts.

Question: How well would all this work if you decided that you need
redundant routes or if you decided that you do not want a start topology
but have an arbitrary topology? Can you have a configuration like the
following:

        ---------------Ethernet-----------------
               | |
               | |
             Bridge Bridge
               | |
               | |
        ---------------Ethernet-----------------
               | |
               | |
             Bridge Bridge
               | |
               | |
        ---------------Ethernet-----------------

We currently have about 40-50 Ethernets connected with about 20 IP
gateway boxes. The gateways are connected via Ethernet, Broadband, 56Kb
land lines, 9.6Kb land lines, and soon T1 and 64Kb satelite links.
The gateways we use (cisco Systems) are both fast (we have measured
them at 1000 large packets per second between Ethernets) as well as
have reasonable routing algorithms (though they will speak RIP they
talk amongst themselves with IGRP). We have not seen any problems with
the routing (or anything else related to the gateways).

You are right---it is unfair to compare standalone level 2 bridges with
general purpose systems (especially when they are runing RIP).

-Norm Kincl
 HP Labs



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