The first step in LAN switching is receiving the frame or packet, depending on the capabilities of the switch, from the transmitting device or host. Switches making forwarding decisions only at Layer 2 of the OSI model refer to data as frames, while switches making forwarding decisions at Layer 3 and above refer to data as packets. This chapter's examination of switching begins from a Layer 2 point of view. Depending on the model, varying amounts of each frame are stored and examined before being switched.
Three types of switching modes have been supported on Catalyst switches:
Store and forward
These three switching modes differ in how much of the frame is received and examined by the switch ...