Chapter 4:Network Layer Chapter goals: Ounderstand principles behind network layer services: o network layer service models o forwarding versus routing o how a router works o routing (path selection) o dealing with scale o advanced topics:IPv6,mobility instantiation,implementation in the Internet Network Layer 4-2Network Layer 4-2 Chapter 4: Network Layer Chapter goals:  understand principles behind network layer services:  network layer service models  forwarding versus routing  how a router works  routing (path selection)  dealing with scale  advanced topics: IPv6, mobility  instantiation, implementation in the Internet