There are two types of routing: direct and indirect.
direct When a machine can send an IP packet to another machine without going through a third machine, the route the packet will travel is said to be a ``direct route'' and the selection of that route is called ``direct routing''. In Figure 5-1, ``Example internetwork'', the machine columbia can trace a direct route to any of the machines on the 132.147.118 network (that is, seine , thames , and volga ). The machine columbia cannot reach london or paris directly.
Figure 5-1 Example internetwork
indirect When a machine wishing to send an IP packet to a second machine must send that packet through a third machine, the route the packet will travel is said to be an ``indirect route'' and the selection of the intermediary machine is called ``indirect routing''. The intermediary machine, a router, has connections to more than one network and is said to provide a gateway between the networks. Therefore, a router may also be called a ``network gateway''. In Figure 5-1, ``Example internetwork'', the machine volga is a network gateway between the 132.147.118 network and the 132.147.246 network. If the machine seine needs to send an IP packet to paris , it must send the packet to volga , which forwards the packet to paris .