The Control Plane: Static & Dynamic Routing
Explore the role of the control plane in maintaining routing tables, understand static versus dynamic routing methods, and examine routing algorithms such as distance vector and link-state. Gain insight into how networks model routing paths as graphs and how routing protocols adapt to network changes to ensure efficient data transmission.
The main purpose of the control plane is to maintain and build routing tables. This is done via a number of algorithms and protocols which we will discuss here.
Note: Routing Algorithms vs. Routing Protocols. The software/hardware implementation of routing algorithms are known as routing protocols!
Modeling the Network as a Graph
A network can be modeled as a directed weighted graph. Each router is a node, and the links between routers are the edges in the graph. A positive weight is associated with each directed edge. Routers use the shortest path to reach each destination. In practice, different types of weights can be associated with each directed edge:
- Unit weight. If all links have a unit weight, shortest path routing prefers the paths with the least number of intermediate routers.
- Weight proportional to the propagation delay. If all link weights are configured this way, shortest path routing algorithms will prefer the paths with the smallest propagation delay.
- Weight proportional to the available bandwidth.