Routing
Routing is the backbone of the Internet. Without it there would be no Internet. Routing is the means by which logically addressed packets are forwarded from their local subnetwork toward their ultimate destination. In large networks packets may be passed to many intermediary destinations before reaching its destination.
Knowing where to send packets requires a knowledge of the structure of the network. In small networks, routing can be very simple, and is often configured by hand. In large networks the topology of the network is complex, and constantly changing, making the problem of constructing the routing tables very complex.
Routing protocols are used to exchange routing information between networks, allowing routing tables to be built dynamically. Routing protocols come in two varieties:
- telling the world who your neighbors are: distance-vector routing protocols such as RIP
- telling your neighbors what the world looks like: link-state routing protocols such as OSPF
Although this dynamic routing is very complex, it makes the Internet very flexible, and has allowed it to grow in size by more than eight orders of magnitude over the last thirty years.
- Router (includes a list of manufacturers)
- Routing Protocols
- NAT (Network Address Translation)