[ntp:questions] OT: GPS18x LVC failure

Uwe Klein uwe_klein_habertwedt at t-online.de
Wed Oct 14 21:49:27 UTC 2009


Rick Jones wrote:
> Uwe Klein <uwe_klein_habertwedt at t-online.de> wrote:
> 
>>then:
>>some pakets are sent as broadcast to all ports.
>>switches store for each port the MAC addresses seen.
>>I have no idea if modern switches do (r)arp queries to
>>find the port a target MAC is sitting on or just broadcast
>>unknown MACs.
> 
> 
> Do you mean "flood?"  Broadcast implies ff:ff:ff:ff:ff:ff destination
> MAC.
Most certainly not.

A switch (usually) forwards packets from one port to _one_ other
port ( the one were the switch has seen the target MAC )
( exempt are broadcast and multicast packets. )

Now if there is no entry for the target MAC the thing to do is
either forward this packet to all ports or start a reverse arp
cycle.

uwe

> 
> 
>>Hail for the times hubs were dumb repeaters with neither memory nor
>>intelligence ;-)
> 
> 
> Indeed :) Of course, then we'd be complaining about variability in
> back-off times and capture effect and whatnot instead :)

Someone sent me a copy of the unix haters handbook today.
Nothing better than having a target for good ol bitching.

uwe




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