intervlan routing with L3 switches vs router

[curtis03_2]

I have several LANs each configured with 2821 gateways and Cat4506 L3 switches.

Default Vlan 1 used in each site.

I am considering segnemting each LAN with VLANs due to expansion and clearly identifiable business functions.

I am in two minds: -

1) use sub-interfaces on router LAN interface to route the VLANs or

2) use interVLAN routing with the L3 capable 4506s.

Can anyone please explain the advantages of utilising the L3 switches.

Would the router still need to advertise the VLAN addresses?

Would this negate the need for the router?

thanks in advance

[glen.grant]

The L3 switches have been optimized for these functions will always be faster than than say a 2821 . Also if you use subinterfaces everything will be coming down the same pipe to be routed as opposed to being routed in the 4506.

[dcrown]

The advantage to L3 switching over routing is that your L3 switch can route data at its wire speed vs. the uplink speed on the router.

Now your router doesnt advertise VLAN's at all. thats a function of VTP, or VLAN Trunking Protocol. It listens for frames encoded with a 802.1Q Tag (thats what the encapsulation statement does in each sub int). What you would have to is shut down the on the 2821's.

And I'm assuming the 2821 provide connectivity to your wan, so i would keep the 2821 handling that side of life.

[curtis03_2]

thanks

can you please explain what you mean in the last sentence of second paragraph?