Table of contents
The difference between forwarding and routing
Processing of packets received on the wire
router structure
divided into two parts
1. Routing part: also called the control part, the core component is the routing processor
The routing processor constructs a routing table according to the selected routing protocol, and exchanges information with neighboring routers frequently or periodically.
Routing tables are constantly updated and maintained with information
2. Packet forwarding part
It consists of switching structure, input port, and output port. The switching structure processes packets according to the forwarding table, and the port is the hardware interface.
The difference between forwarding and routing
Forwarding means that the router forwards the user's IP datagram from the appropriate port according to the forwarding table
Routing is based on a distributed algorithm, according to the changes in the network topology sorting obtained from each adjacent router, dynamically
Change the chosen route
The routing table is derived from the routing algorithm, and the forwarding table is derived from the routing table
When discussing the principle of routing, often do not distinguish between forwarding table and routing table
Processing of packets received on the wire
Input port processing
Handling of output ports
There are three commonly used methods to achieve exchange:
via memory, via bus, via crossbar fabric
