The End to End Argument There are some who argue that the routers’ job is moving packets around and nothing else. In this view, the network is inherently unreliable, no matter how it is designed. Therefore, the hosts should accept this fact and do error and flow control themselves. This reasoning is an example of the end-to-end argument.
Routing Algorithms One can think of a router as having two processes inside it. One of them handles each packet as it arrives, looking up the outgoing line to use for it in the routing tables. This process is forwarding.
Congestion Control Summary Unless a network is well designed, it may experience a congestion collapse, in which performance plummets as the offered load increases beyond the capacity. In a virtual-circuit net-work, new connections can be refused if they would cause the network to become congested. This is called admission control. The most direct way to notify a sender of congestion is to tell it directly. In this approach, the router selects a congested packet and sends a Choke Packet back to the source host, giving it the destination found in the packet.
Mobile IP Recap Mobile hosts are distinct from stationary hosts that never move. The basic idea used for mobile routing in the Internet and cellular networks is for the mobile host to tell a host at the home location where it is now. This host, which acts on behalf of the mobile host, is called the home agent