Lesson 42: Static vs. Dynamic Routing

Routing tables can be populated in two primary ways: manually (static) or automatically (dynamic).

1. Static Routing

Static routes are manually configured by the network administrator. The administrator specifies the exact path a packet must take to reach a destination network.

Pros:

• Security: Very secure as routes are not advertised.
• Low Overhead: Requires no processor power to calculate routes.
• Simplicity: Easy to set up in small, simple networks.

Cons:

• Scalability: Not viable for large, changing networks (if a link fails, the administrator must manually change the route).
• Maintenance: Labor-intensive.

2. Dynamic Routing

Dynamic routes are learned and maintained automatically by the routers using specialized Routing Protocols.

How Dynamic Routing Works:

Routers running the same routing protocol exchange route updates and automatically recalculate the best path when network conditions change (e.g., a link goes down).

Key Dynamic Routing Protocols:

• RIP (Routing Information Protocol): Older, distance-vector protocol.
• OSPF (Open Shortest Path First): Modern, interior gateway protocol for large enterprises.
• EIGRP (Enhanced Interior Gateway Routing Protocol): Cisco-proprietary, high-performance protocol.
• BGP (Border Gateway Protocol): The protocol that runs the global internet, used between ISPs.

Real-World Use: Small networks often use static routes for simplicity. Large enterprise and ISP networks must use dynamic routing for resilience and scalability.