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Testing a VLAN from a PC with SmartBits

Mar 15, 20042 mins

* Dr. Internet columnist Steve Blass offers advice on how to test a VLAN from a PC with SmartBits

I am testing in a lab where my SmartBits ( has a public address while my two routers and two PCs are on a private address on two subnets. I can see how the virtual LAN across my two routers handle Differentiated-Service code points and how the routers will apply my access control lists.

Can I connect the SmartBits directly to one of my PCs to generate traffic? I have two ports on the SmartBits – can I then connect the two ports to my two PCs to get bidirectional traffic?

You can generate bidirectional traffic across the routers to test the VLAN performance by hanging one PC off each router to be the destination for SmartBits-generated traffic and connecting the two SmartBits ports to the opposite routers and driving traffic both ways through the configuration.

You can connect the SmartBits ports directly to a PC using a null-modem (crossover) Ethernet cable, but you probably want to connect the SmartBits to the routers and configure the virtual transmit engines to send traffic to the PCs across the VLAN routers.

To push traffic through the PCs first and then to the VLAN you will need to enable packet forwarding on the PCs and be extremely careful with the route table entries to test the intended traffic paths.