CCNP SWITCH/Implementing Inter-VLAN Routing
This article is under development....Inter-VLAN Routing
Because VLANs isolate trafficto a defined broadcast domain and subnet, network devices in different VLANs cannot communicate with each other natively.
Adding an external routing with subinterface routing does not scale beyond 50 VLANs. Cisco IOS routers only support trunking in IP Plus Feature set and above.
Catalyst Multilayer Switches support 3 different routed interface types:
- Routed Port
- A pure Layer 3 interface similar to a routed port on a Cisco IOS router.
- Switched Virtual Interface (SVI)
- A virtual VLAN interface for inter-VLAN routing. In other words, SVIs are the virtual routed VLAN interfaces.
- Bridged Virtual Interfaces (BVI)
- A Layer 3 virtual bridging interface.
All Cisco Layer 3 Switches support routing protocols, but several models requires enhanced software for specific routing protocol features.
To change between routed and switchports use no switchport and switchport interface commands respectively. Catalyst 6500 switches use L3 interfaces by default, so depending on the switching model the swithport and no switchport command might be present in the running-config files.