[plug] [OT] Managed switch - Question

[Craig Ringer]

> I understand that, in general terms, switches route data to the intended
> source's port on the switch, whereas a hub broadcasts it to all ports on the
> hub, but I am not completely sure what "managed" means and the difference
> between and unmanaged switch and a hub.

Ignore hubs - if you understand the difference between a hub and switch, 
that's all you need to know there. Both managed and unmanaged switches 
have the same significant difference from a hub (packet switching not 
dumb broadcasting).

A managed switch is a switch that you can manually manage. You can do 
things (depending on the switch) like tell it that a given MAC address 
is on a given port, even if it doesn't think it is. You can create 
things like vLANs. You can sometimes control /how/ it switches 
(store-and-forward or another method). You can also often tell them not 
to "learn" what MAC addrs are behind what ports at all, and take 
complete manual control of that function. They often also provide things 
like the ability to "mirror" all traffic out a single port (handy if 
your switch has gigabit ports).

On the other hand, an unmanaged switch "learns" the network layout and 
makes switching decisions by itsself. Most managed switches can function 
happily as unmanaged switches until you need to take partial or total 
manual control.

I've got a NetGear FSM726S managed switch here and its a perfect example 
of a managed switch that you don't /have/ to manually manage unless you 
need to.

Craig Ringer