Routing Activities

Getting packets to their next hop requires a router to perform two basic activities: path determination and packet switching. These activities are very basic, but you need to have a thorough understanding of how they are accomplished.

Path determination involves reviewing all available paths to a destination network and choosing the optimal route on which to send a packet. Network topology information used to determine optimal routes is collected and stored in routing tables, which contain information such as the destination network, the next hop, and an associated metric (the cost of sending packets to that next hop).

Packet switching involves changing a packet's physical destination address to that of the next hop. However, the packet's destination logical address remains constant during the packet-switching process.