+ 0 Votes What does that acl NetMan1958 4 years ago look like? I usually restrict vlans on a trunk with the "switchport trunk allowed vlan" configuration command. + 0 Votes My apologies - Core Switch is acting as router kidica 4 years ago It's a Cisco 3750 with routing capabilities. We're doing inter-vlan routing. but no routing protocols. + 0 Votes By default VLANs don't pass traffic to other VLANs CG IT Updated - 4 years ago unless you route traffic between them using a layer 3 device. So in reality what your ACL is doing is allowing VLANs to talk to each other through routing. Has nothing to do with "regular" swtiche capabilities. If you hook up 2 "regular" switches and create different VLANs, the different VLans won't talk to each other until you configure a routing device to route traffic between them. Even on trunk ports. Trunk ports just allow hosts in same VLANs located on seperate physical switches to pass traffic. Not route between different VLANs.