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VLAN Trunking question

"In inter-VLAN routing, the router interfaces are connected to switch trunk ports. The router interfaces or sub interfaces must be running a trunking protocol either ISL or 802.1Q." Is this always a must? It makes sense if we use one physical interface with many sub-interfaces on a router for each VLAN. If we use multiple dedicated physical interfaces connected to each VLAN, Do we still need to connect those ports to trunk ports on switches? In that case, will different VLAN act like different networks that are connected to a router (just like there is nothing about VLAN)? Does it work the same in both configurations: with/without trunking port protocol enabled? Is there any performance drop if VLAN trunking is used? Which way is recommended?


Re: VLAN Trunking question

You have a pretty good grasp of things .You only need to trunk if you have one router port and you want multiple vlans on a attached switch and they need to talk to each other. If you have multiple ports on the router and you just want to run individual links to the switch that will also work and just look like another subnet . Of course the performance will better if you have individual links because you are not trying to shove all the trunked vlans traffic down a single link . On the same subnet it will make no difference . There is no set way depends on what you are trying to do . If you just want 2 or 3 vlans on a switch and they must talk to each other doesn't really make sense to run multiple links to a single switch .

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