e destination where it wants to send the traffic. The two hosts can be either directly connected to each other, or there can be one or more routers in the path between them. Directly connected hosts, such as hosts in same Local Area Network (LAN), may be able to send packets directly between each other. Alternatively, a host can send packets to a router for further delivery. Routers pass packets between different networks and different routers, as described in the previous section. Theoretically, this packet passing can be divided into two different processes: routing and forwarding. Routing involves selecting the route where the packet should be going next. The idea of routing is to find the shortest or fastest route to a des- tination, and then selecting the outgoing interface based on that information. Forwarding, on the other hand, is the process that actually moves the packet through the router to the intended direction. When a packet is forwarded by a router, the router decreases the TTL by one. If the TTL reaches zero, the packet is discarded. Routing decisions are based on routes. Routes define which networks or destinations are reachable through which interface. In addition to routes, the routing decisions can be affected by routing policy. Routing policy is basically a rule that overrides the technical routing calculation. There are various reasons to set a routing policy. For instance one reason is cost - sending a packet through one operator may cheaper than a possibly shorter path through another operator. Routes can be either statically configured, or dynamically calculated. Statically configured routes are usually configured by a network administrator. These routes do not change until the network administrator changes the configuration, regardless of the network status. For dynamic route calculation, routers use dynamic Deploying IPv6 in 3GPP Networks routing protocols to exchange network topology information between each other. The most used routing protocols are Open Shortest Path First (OSPF) [7