TABLE OF CONTENTS The primary difference between an ordinary host and a router is that the router is configured to accept packets intended for another destination and to forward those packets to what the router determines is the best next hop. The router usually also supports at least one routing protocol through which it can acquire current information about network routes. In this chapter, after an overview of IP routing in general, we ll introduce the changes necessary to support IPv6 routing.
The simplest of routers are those serving a single network with two interfaces: one for the local network and the other for sending all other traffic. These routers function as gateways for the local network. Local hosts recognize two types of destinations: those hosts that are on the local logical IP subnet ( LIS) and that can be reached directly over the local link and those hosts that are not local (everywhere else). Hosts on this network are configured to deliver local packets directly, on their own, over the link layer, and all other packets are sent to the IP gateway system (the local router), which forwards them along its other interface.
The typical small office/home office (SOHO) network uses a simple gateway like this, as do almost all networks connected to the Internet via broadband services. The local router (or gateway) will typically be configured to accept inbound packets destined for the local network and to forward any packets it receives...
