I just don't seem to understand the concept of inter Vlan routing in L3 Switches. I am already 1 year into networking, and planning to take my switching CCNP paper in a month, i Just feel embarresed when i realise that i am not clear with Inter Vlan routing at this stage, i am comfartable with eveything else though.I would be thankful if someone could explain.
I have a Cisco 6509 multilayer switch, with about 20 Vlans. and the vlan interface IP in this switch is the gateway for each VLan. There are no routing protocols being used in the switch, all i have is a Default route to my Firewall.
I always read that "IP routing" is the command that enables InterVlan routing. But there isn't any other command other that the default route to my firewall that talks about routing in the switch.
Now i need to know the following
1. How am i able to communcicate with all other vlans when there is no "Ip routing" command
2. How do i limit Access to particular vlans, i.e. i need only some Vlans to be able to access My server VLAN.
3.Everything else i need to know about inter Vlan routing on L3 switches.
Thanks in advance.
1) ip routing is a global command that enables the multilayer switching on C6509. Without it the C6509 becomes a L2 LAN device and you need an external router to perform inter-vlan routing.
You don't see ip routing because it is probably enabled by default on Cat6509 and IOS config doesn't show default commands (it is so also on my Cat6509), however if you do sh ip route you see a static to 0.0.0.0/0 via the firewall and not a default-gateway.
Inter-vlans : you don't need any routing protocol to route traffic between connected interfaces on a single node.
The firewall in its turn has one or more static routes that describes your 20 Vlan subnets for the return path
2) you can use ACLs to limit access . You can apply them under interface Vlan X
3) inter vlan routing is one thing, multilayer switching is hardware based and use TCAM table to define what action to perform to a packet with a given destination.
modern switches populate the TCAM table using CEF so I would go to study it.
Hope to help