port mirror destination port thru traffic

[Eric Shartle]

We have a port mirror in place - with a sniffer on the destination port.  We cannot access the sni via IP "through" the destination port - is that by design?   

[Seb Rupik]

Hi there,

A SPAN port does not behave like a trunk or access mode port. Only mirrored traffic is transmitted. As such you will not be able to make a DHCP request via it. You traffic monitoring device should ideally have two interfaces, one for management (with routable IP) and the other interface in promiscuous mode to capture the SPAN traffic.

cheers,

Seb.