In order to monitor traffic on an entire VLAN:
- Connect your laptop to the central switch and to one of the ports.
- Configure the port mirror from the monitored VLAN to the port you are connected to. For example, if you connect your laptop to SW1 port 4 and you want to monitor traffic from VLAN10, the commands will be (in Cisco):
- Switch(config)#monitor session 1 source vlan 10
- Switch(config)#monitor session 1 destination interface fastethernet0/4
This will show you traffic from VLAN10 that is forwarded through the central switch, SW1.
For further information on how to configure port mirroring on various vendor websites, search for SPAN (in Cisco), port mirror, or mirroring (HP, Dell, Juniper, and others). While monitoring traffic in a blade center, usually you can only monitor traffic on a physical port; however, there are applications that enable you to monitor traffic on a specific server on a blade (for example, Cisco Nexus 1000V).