Static routing, OSPF, EIGRP, BGP, redistribution, policy-based routing, ECMP, and first-hop redundancy with HSRP/VRRP — how traffic actually finds its way across, and off, the enterprise network.
Module 5 built the Layer 2 switching fabric traffic rides within a VLAN. This module picks up where that stops working — the moment traffic needs to leave one subnet for another. You will work through when a manually configured static route beats a dynamic protocol, how OSPF's link-state design and area structure actually converges, why EIGRP's DUAL algorithm and Cisco lineage still matter in existing deployments, and how BGP's policy-driven attribute selection differs fundamentally from every interior protocol before it.
The second half covers the parts of routing that get an otherwise well-designed network into trouble in practice: redistribution loops between two protocols that were never designed to talk to each other, policy-based routing and ECMP for steering and load-balancing traffic beyond a simple shortest-path lookup, and the HSRP/VRRP first-hop redundancy that keeps a subnet's default gateway available when its primary router fails.