The Device That Built The Internet
We take our technological world so much for granted, and we seem to forget all of the things that make it work. The protocols that scaled the Internet have been ARP, IP, TCP, and UDP, along with the application layer protocols (HTTP, FTP, TELNET and so on). But the device that has really built the Internet is the humble router.
The idea behind the router was created by Sandra Lerner and Leonard Bosack, and who were working in the computer department at Stanford. After the university effectively dismissed it for commercialisation, in 1984, they went ahead and founded Cisco Systems Inc. Their first router product went live in 1986, and within a year they had sales of around $250,000 per month. The company have never looked back since then.
So, what is a router? Well, it does what it says on the tin … it routes data packets. Basically, it has a routing table and a number of interfaces. When a packet arrives on one of the interfaces, the router examines it, and then looks into its routing table, and decides whether it needs to forward the data packet to another of its interfaces. In this way, routers pass packets from one device to another. If we route for IP addresses, we define this as Layer 3 routing. We can also route data frames within a switch, and which is known as Layer 2 switching.
