Use the no switchport command to enable Layer 3 processing on an interface of a 3550. To create an SVI interface, use the interface vlan command. Use the following commands to set up routing on your switch: ip routing, router routing_protocol, network network_#, vlan VLAN_#, interface vlan VLAN_#, ip address IP_address subnet_mask, and no shutdown.
A router-on-a-stick routes traffic on a trunk interface on a router. It requires a single interface, but can cause congestion problems and is a single point of failure. When setting up a router-on-a-stick, create a subinterface for each VLAN and place your Layer 3 addressing there. Also, specify the trunking encapsulation type with the encapsulation isl|dot1q command.
CEF uses a FIB and adjacency table to perform MLS. MPLS is an open standard for multilayer switching in an ATM network, whereas CEF is Cisco-proprietary.
With MLS, in the Ethernet frame, the source and destination MAC addresses and the CRC are changed. In the IP packet, the TTL field is decremented and the CRC is changed.
