Now I'm getting to understand the vlan concept a little better. However there are still a number of pieces that don't fit in my head! Firstly when it comes to addressing the hosts on the different VLAN's (ie different subnets) what does each VLAN's clients default gateway become. Is it the address of the layer3 switch?
Previously the DG for all my hosts has been the Cisco router on my perimeter which connects to our other office LAN's. This is fine when the network is all on one subnet (10.20.x.x /16) When the machines on different VLAN's (subnets) need to get out what does their DG become?
answering both questions, it depends on some factors.
you can either configure de DG of pcs within your lan as the multilayer swith or the router, it is dessicion of the network admin.
But I recommend you to put the multilayer switch, why??
for better performance all the routing desicions, and layer 2 mac header rewrite is done in hardware in the multilayer switch, if it is enabled with CISOC CEF, the same procee so diferent with the router, when it does the same thing but in software.
and for the second question, how the switch gets to the remote or destionation network, maybe crossing a wan?? if you have static routing, the switch must point to the remote oficess adress to the wan router.
If you have dynamic routing, liek for example eigrp, dont worry, if it is correctly configured, it does it alone.
ok, thanks, so basically each vlans clients will have a dg of the layer3 switch, and then I setup static routes to my other offices on the switch so that traffic destined for remote offices/subnets is routed correctly to my WAN router.