Layer 3 Switch instead of router?

I think you're both right, depending on the circumstances. If you need a traditional WAN connection like a serial or BRI, then you more then likely would be wasting money on a layer 3 switch because you'll still need to have a way to encapsulate your IP network out to the WAN. Cisco routers also use CEF, and some models also employ the VIP cards that also takes the load off the CPU.

Havohej makes some good points here. However as jwj says you're unlikely to find even a BRI ISDN port on a layer-3 switch, no matter how good a router it is, let alone an x.21 or G703 interface. If you need to connect to real-world WAN interfaces then you're going to need a device that lets you do that. I'm also not so certain abot the security aspect. Routers are for routing, so they are extensively tested to make sure they do that as well as possible. When you combine what are essentialy several heavyweight functions in their own right into a single device you might open the door for compromises and oversights. Call it paranoia if you like, but that's the way I see it - kind of like the arguments between music centres and hi-fi separates.
Oh and by the way, I'm not criticising here- just explaining my thinking. As jwj says this one is down to opinion as there isn't really a 'right' answer

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i would just like to add a bit in the discussion .Layer 3 or Layer 4 switches not only can be used to route traffic between VLANs but they can b and are being used to router traffic between Subnets (LANs) .We are using Nortel's product Alteon AD3 and Alteon AD4 (End of life by the way) and they have ASIC chips on each of their ports hence extremely fast switching.
I agree with bishop tht u wont find WAN interfaces on Layer 3 switches hence in the end to connect to real world u'll still b needing a router.

Rgds
Shahzad Bokhari
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