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VLANs and Trunking

Okay, I know this is not strictly a Cisco question as the switches in question are HP ProCurve 2524's, but hopefully I'll be granted a pardon for that. I'm trying to create a network with two VLANs who don't speak to each other but can each access the internet on their own through a Cisco 1721 router. I know I need to set up two different VLANs on the network and that I'll set up access-lists and subinterfaces on the one fast ethernert interface on the router. But here's the real question: the network I need to keep separate is all on switch 3. So obviously, I put every port on that switch on VLAN 2. Now, switch 3 goes to port 0/24 on switch 2. So I put interface 0/24 on switch 2 into VLAN 2 as well, and make switch 2's uplink, port 0/25 a trunking port. Here's the problem though: switch 2 is connected to switch 1, which is connected to the router. Obviously I can't make that incoming port on switch 1 part of VLAN 2, since some traffic from VLAN 1 will be coming through it! Do I simply set up switch 1's uplink port to do trunking and leave it at that, or is there some sort of strangeness I need to do in order to get switch 1 to pass along traffic from both VLAN 1 and VLAN 2 to the router?

1 REPLY
Purple

Re: VLANs and Trunking

I think you've got the right idea there. Configure the interface between the router and switch1 as a trunk interface. Then, create ethernet sub-interfaces on the 1721 for both of the VLANs. If you don't want inter-vlan traffic between the VLANs, create appropriate ACLs on these two sub-interfaces.

That should do it.

Hope that helps - pls rate the post if it does.

Paresh

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