Chapter 5: Network Layer: Control Plane

Kurose and Keith W. Ross explores the control-plane component of the network layer, which governs the network-wide logic for routing datagrams from source to destination and managing network-layer services. The chapter begins with an in-depth discussion of routing algorithms for computing least-cost paths in a network graph, including link-state and distance-vector approaches. These foundational algorithms lead into the study of real-world Internet routing protocols: OSPF (Open Shortest Path First), used within a single autonomous system, and BGP (Border Gateway Protocol), the inter-domain protocol that effectively acts as the “glue” binding the global Internet together. The authors explain how OSPF leverages link-state advertisements and a hierarchical architecture for scalability, while BGP uses policy-based routing to control how networks exchange reachability information. The chapter then examines Software-Defined Networking (SDN), which separates the control plane from the data plane, centralizing network control in SDN controllers that communicate with forwarding devices via protocols like OpenFlow. Later sections cover essential network management protocols and services, including ICMP for error reporting and diagnostics (e.g., ping, traceroute) and SNMP for device monitoring and configuration. Throughout, the authors combine theoretical underpinnings with practical considerations, showing how the control plane ensures scalability, efficiency, and robustness in modern Internet routing and network management.