Chapter 8 - IP Routing Overview

Chapter 8 - IP Routing Overview

1. Routing Basics

   • Routing refers to taking a packet from one device and sending it through the network to another device on a different network
   • Routers dont care about hosts
     • they only care about networks
       • and the best path to each one of them
   • The logical network address of the destination host is key to get packets through a routed network
     • BUT
       • The hardware address of the host is used to deliver the packet from a router and ensure it arrives at the correct destination
   • 5 minimum factors a ROUTER must know to be able to affectively route packets
     • Destination address
       • Neighbour routers from which it can learn about remote networks
         • Possible routes to all remote networks
           • The best route to each remote network
             • How to maintain and verify routing information
   • ROUTING TABLE
     • is basically a map of the internetwork, and it describes how to find remote networks
       • If a network is directly connected to the router then the router already knows how to get to it
         • BUT
           • If a network is not directly connected to the router, the router must use one of two ways to learn how to get to the remote network
             • STATIC ROUTING
               • requires someone to hand-type all network locations into the routing table
                 • If static routing is used, the administrator is responsible for updating all changes by hand onto all routers.
             • DYNAMIC ROUTING
               • a protocol on one router communicates with the same protocol running on neighbouring routers
                 • the routers then update each other about all the networks they know about
                   • and place this info into the routing table
                     • If a change occurs in the network, the dynamic routing protocols automatically inform all routers about the event.
     • Routers learn about remote networks from neighbouring routers or from an administrator

2. IP Routing Process

3. Static Routing

4. Default Routing

5. Dynamic Routing