Enabling Netflow in Cisco 6509 Switch on physical interface????

I think this may be because your GigE interface is layer 2. Netflow looks at layer 3.

Perhaps this thread from awhile back may help.

Netflow Config On 6509

Netflow only works on a routed interface (layer 3)

You could setup a SPAN port on the switch and use something like nprobe to convert this to flow data. You can SPAN the LAN extension port to another and this is where you connect your nprobe or other traffic analysis system

I believe you can capture bridged traffic with NetFlow. You can specify the list of VLANs here to enable bridged traffic.

ip flow ingress layer2-switched vlan <vlanlist>

ip flow export layer2-switched vlan <vlanlist>

Thanks All. I have checked on the switches and rightly said, does not support later 2 connections.