For a long time, I was very happy building Ethernet networks, working with switches
and then moving to 802.11. It took awhile, but eventually I realized that the world of
interconnected networks cannot be reached with Layer 2 alone. In addition, as you
spread your wings from the Layer 2 broadcast domains, you encounter the wonders of
virtual local area networks and trunks. I became an “all over” networking sort of guy.
Like my own progression, this book moves up to the next layers and ideas.
If you read the Packet Guide to Core Network Protocols (O’Reilly), you have a handle
on the type of communication seen on every single network (ARP, ICMP, IP, Ethernet),
regardless of operating system or networking equipment vendor. This book now moves
to the advanced link and internetwork layer protocols that will enable the reader to
expand to internetworks and larger topologies.
Like the first book, each chapter will tear apart a particular protocol or set of ideas,
explaining the structure and operation. The discussion will be supported by ample
packet captures. There is nothing theoretical about the stuff between these covers: the
topologies depicted in each chapter were built in a lab as the chapters took form.
And like the first book, what you see here will be part of every network that you encounter.
So, the practices, ideas and protocols seen here will continue to help you on
your way for many years to come. I’ll also continue to refer to and work with networking
tables including routing (host and router), source address, and ARP tables.
Recently, many in the networking profession experienced, or at least paid attention to,
IPv6 day. But the results were largely unimpressive. Several challenges—such as properly
operating 6to4 tunnels, filters blocking some IPv6 messaging, and a seeming lack
of support for security features—indicate that IPv4 will be with us for some time to
come. That said, many of the chapters touch on IPv6, including some basic configurations
and a comparison to IPv4 operation.
Each chapter contains a collection of review questions to remind the reader about key
ideas. A series of lab experiences ranging from basic to advanced are also included.
These experiences are designed such that the reader can perform them with the help
of the chapter, welding the ideas into place.