Retro networking / WAN communities

[Paul Koning]

> On Apr 12, 2022, at 11:40 AM, Todd Goodman <tsg at bonedaddy.net> wrote:
> 
> 
> On 4/12/2022 10:50 AM, Paul Koning wrote:
>> 
>>> ...
>> 
>> Learning has always been part of what bridges do.  It's a core part of the DEC bridge spec, and a core part of the DECbridge-100 functionality.  It is the reason why Tony Lauck and George Varghese invented the "timer wheels" scheme for keeping 8000 timers in constant time.
>> 
>> A device that doesn't do address learning and floods unicast frames is not a bridge but rather a non-standard piece hardware.  I don't actually know if anyone ever implemented such a device.  Certainly I've never seen one or built one myself, even though what I built was called "bridge".
>> 
>> 	paul
> 
> 
> I'm not talking about pre-standard DEC devices.
> 
> I can show you a standard commodity bridge from multiple vendors right now that will allow you to monitor unicast traffic destined for other ports just by plugging in to one of the other ports on the bridge.
> 
> I don't have my 802.1d spec I implemented a bridge from in the 90s

I do have 802.1d, but it's a box.

I know for a fact that learning is part of it, just as it was in the DEC spec, for the obvious reason that they are basically the same architecture.  So any compliant bridge forwards unicast traffic to the port on which that address is known to be, flooding only to unknown addresses.

	paul