A young woman boards a commuter train in a small town in Quebec, changes trains a couple of times, and, a day later, arrives in New York City. She walks up the stairs from the platform into Grand Central Terminal, looks up above her head, and, for the first time, sees the constellations, hundreds of feet above on the ceiling.
A high school student in New Zealand downloads maps of Sri Lanka from a local (Sri Lankan) web site. The maps show the natural features, the political boundaries, the flora and fauna, rainfall, ancient kingdoms, languages, and religions. The download takes thousands of IP packets that find their way from Sri Lanka to the student’s PC in New Zealand.
Just as our Canadian friend changed trains at several stations along the way, the IP packets from the Sri Lankan web site may have bounced through dozens of routers before arriving at the student’s machine.
The routing of IP packets in an IP network is the set of tasks required to move an IP packet from router to router to its destination, as specified in the IP header field. This book is about the set of tasks that accomplish IP routing.
There are similarities in routing concepts between IP networks, transportation systems, and mail delivery operations. Throughout this text, we will often illustrate IP routing concepts by comparison with these other systems.
Get IP Routing now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
