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Webcast-Catalyst9k
New Member

multiple networks on a switch

Is it possible to have a layer 2 switch with multiple networks? The networks do not need to talk to each other.

If the above situation is possible, could I hook up a 2600 series router and use vlans to get the networks to communicate?

4 REPLIES
New Member

Re: multiple networks on a switch

Yes, its called router on a stick. as long as the

2600 has an fastethernet interface you can sub interface it by vlan.

New Member

Re: multiple networks on a switch

Thanks,

What happens if I have a firewall device between my router and the switch? Might help if I gave you some background information. My setup is going to have a router, firewall device, and a switch. Between the switch and firewall will be two links (two networks). Between the firewall and router will be one link. If I manage the switch so that it is 2 VLANs, one for each network, will that be difficult to implement? The switch is 3com, so would I just implement 802.1q and make the link from firewall to router a trunk link? Any advice would be appreciated!

New Member

Re: multiple networks on a switch

you may be able to do this if your FW supports 802.1q VLAN tagging. The Cisco router (need FE ports) will be able to support 802.1q or ISL tagging. Make sure you have up to date IOS and specify dot1q tagging not isl. There are probably implications with setting up your FW rules per VLAN but that is all dependant on your FW.

New Member

Re: multiple networks on a switch

Unless I have the wrong picture in my head, I don't think you need the router. The firewall should route between the two vlans without having to worry about ISL or 802.1q trunks. Plug one interface of the firewall into a switch port assigned to one of the vlans. Plug another firewall interface into a switch port assigned to the other vlan. Setup your firewall rules to permit/deny appropriate traffic between the two networks.

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