[c-nsp] Determining which ports have another switch attached?

[Phil Mayers]

On 07/21/2011 11:42 PM, Martin T wrote:
> Phil, Gabriel,
> one situation where this MAC counting does not work is when there is a
> virtual machine hypervisor connected to a switch port and virtual
> machines have NIC's configured to bridge mode.

Well, you've got a database containing all of your kit and their MAC 
addresses, right, so you can just exclude ports with VMs?

;o)

>
> IMHO counting MAC addresses in combination of checking incoming BPDU
> frames on particular interface is probably the best option if CDP is
> not enabled..

What if the downstream switch doesn't have STP enabled?

Hell, what if the downstream switch doesn't have any other hosts on it 
at the moment? There will only be 1 (or maybe 0) MACs on the port.

There's no perfect way to magically find unmanaged switches (managed 
ones are not a problem, because they're managed!).

One approach that hasn't been mentioned is: just enable BPDU guard and 
see what breaks. That's essentially how we handled it.

The switches are unmanaged, so presumably shouldn't be connected to the 
network anyway, or should be managed, or you're dealing with a customer 
handoff point, in which case liase with the customer contact address.