Explain static routing. What are some pros and cons of static routing? Explain dynamic routing. What are some pros and cons of dynamic routing? Why do you think we see both existing on our network?

Answer 1

Static Routing

Definition:
Static routing is a routing technique that involves manually configuring routes in a network. Each route in a static routing table is defined by the network administrator, specifying the next hop or the exit interface for data packets destined for various subnets.

Pros of Static Routing:

1. Simplicity: Easier to configure for small networks with few routes, as there’s no need for complex protocols.
2. Predictability: Routing paths are predetermined, reducing the chances of route flapping or network instability.
3. Lower Overhead: No need for routing protocol overhead or resource consumption since routes are not dynamically updated.
4. Security: More control over the routing paths, potentially leading to better security as only specified routes are allowed.

Cons of Static Routing:

1. Scalability Issues: As the network grows, managing a large set of static routes can become cumbersome and error-prone.
2. Manual Configuration: Requires manual intervention to update routes when network changes happen, which can lead to longer downtime during changes.
3. No Fault Tolerance: If a link goes down, the static route will not automatically adjust; manual updates are required to reroute traffic.
4. Limited Flexibility: Does not adapt well to changing network conditions, which can lead to suboptimal routing.

Dynamic Routing

Definition:
Dynamic routing uses protocols such as RIP, OSPF, EIGRP, or BGP to automatically adjust routing tables based on current network conditions. Routers communicate with one another to share information about the network topology and route availability.

Pros of Dynamic Routing:

1. Adaptability: Automatically adjusts to changes in network topology, such as link failures or congestion, ensuring optimal routing.
2. Reduced Administrative Overhead: Easier to manage large networks as routes are automatically discovered and maintained.
3. Scalability: Better suited for large and complex networks, as new routers can easily be integrated, and dynamic updates happen automatically.
4. Load Balancing: Some dynamic protocols support load balancing across multiple paths.

Cons of Dynamic Routing:

1. Complexity: Configuration and troubleshooting are often more complex than static routing, requiring a deeper understanding of routing protocols.
2. Resources: Uses more CPU and memory resources on routers due to the need for route calculations and protocol communications.
3. Routing Loops: Improper configurations can lead to routing loops or other network issues.
4. Security: Dynamic routing can be more vulnerable to certain attacks, as routes are shared between routers and can be spoofed.

Coexistence of Static and Dynamic Routing

The reason both static and dynamic routing coexist in networks stems from their complementary advantages. Here are some reasons why both types might be used:

1. Network Design: Certain parts of a network may require stable and predictable routing (static) while other areas may benefit from adaptability and flexibility (dynamic).
2. Performance: Static routes may be used for specific high-performance needs while dynamic routing handles less critical paths.
3. Backup Routes: Static routes can serve as backup options for dynamic routes, providing a fallback in case of protocol failure.
4. Security Policies: Some organizations may impose security policies that require certain routes to be static to control and limit routing paths.
5. Ease of Management: Static routing can simplify routing for small branches or remote sites, while dynamic routing simplifies management for larger, more complex core networks.

In summary, static and dynamic routing each offer unique benefits and drawbacks, and their combined use allows networks to be both efficient and robust, capable of adapting to changes while maintaining stability where necessary.