Overview

Fast forwarding reduces route lookup time and improves packet forwarding efficiency by using a high-speed cache and data-flow-based technology. It identifies a data flow by using the following fields: source IP address, source port number, destination IP address, destination port number, and protocol number. After a flow's first packet is forwarded through the routing table, fast forwarding creates an entry and uses the entry to forward subsequent packets of the flow.

Fast forwarding can process fragmented IP packets, but it does not fragment IP packets.

	NOTE: Fast forwarding can be implementated by software or hardware. Unless otherwise noted, fast forwarding in this chapter refers to software fast forwarding.