Lecture on Routing Protocols

Static vs. Dynamic Routing

Static Routing
- Requires manual configuration of every route on each router.
- Feasible with a small number of routers (e.g., 3-4).
- Becomes cumbersome with many routers.
Dynamic Routing
- Automates the process of route configuration.
- Routers automatically discover and update routes.
- Reduces the need for manual configuration.
- Updates occur in real-time without user intervention.
- Requires initial configuration of a dynamic routing protocol.
- Needs monitoring due to CPU and memory overhead.

Scenario: Communication across a network with multiple routers.
- Sam communicates to Jack or Tilk.
- Three routers involved; focus on Router 1.
Routing Updates
- Router 2 sends an EIGRP update to Router 1.
  - Adds route to 10.10.20.0/24 via 10.10.40.2.
- Router 3 sends an EIGRP update to Router 1.
  - Adds route to 10.10.30.0/24 via 10.10.50.2.
- Updates are real-time and automatic.

EIGRP (Cisco-Centric)
- Generally used in Cisco environments.
- Simple setup and configuration on Cisco routers.
- Converges quickly and prevents routing loops.
- Efficient in bandwidth usage.
OSPF (Open Shortest Path First)
- Available across many manufacturers.
- Suitable for an autonomous system (AS).
- Determines routes based on link state and cost.
- Enables load balancing across equal-cost links.
BGP (Border Gateway Protocol)
- Used for routing between autonomous systems on the internet.
- Known as the 'Three Napkins Protocol'.
- Essential for dynamic internet routing.

Decision criteria include:
- Link state (up or down).
- Number of hops or speed.
- Type of routers in use (manufacturer compatibility).
- Speed of convergence.
EIGRP
- Efficient within Cisco-dominated networks.
OSPF
- Standardized for use across multiple devices.
BGP
- Critical for internet connections, supports dynamic updates.