Routing protocols (for example, static, dynamic)

What is the difference between static and dynamic routing on AWS, and in which scenarios would you use each?

Static routing in AWS involves manually configuring routes in your route table to direct network traffic to specific destinations. It’s simple, provides stable and predictable routing paths, but lacks scalability and adaptability to network changes. Dynamic routing involves protocols like BGP that automatically adjust routes based on network topology changes. In AWS, dynamic routing is used with VPN connections and Direct Connect. You use static routing when you have a small, simple network or when you want total control over the routing paths. Dynamic routing is suitable for larger, more complex networks or when you need more adaptability and automation.

Can you explain the significance of BGP in AWS, especially in the context of AWS Direct Connect?

BGP, or Border Gateway Protocol, is integral to AWS Direct Connect as it manages the exchange of routing information between your on-premises network and your AWS VPC. BGP facilitates dynamic routing, which ensures that the path traffic takes is the most efficient and available at all times, optimizing connectivity and minimizing downtime. When using AWS Direct Connect, BGP is used to advertise your public and private prefixes to AWS and to receive AWS prefixes, enabling seamless integration of your environments.

What are some of the limitations of static routing within the context of AWS networking?

The primary limitations of static routing in AWS include the lack of automatic rerouting around network failures or changes, which can lead to increased downtime. It is not suitable for large or complex networks due to its lack of scalability and the administrative overhead associated with maintaining the routing tables. Furthermore, human error in configuring static routes can lead to routing mistakes and potential security issues.

Describe two dynamic routing protocols and discuss their practicality in hybrid cloud deployments that involve AWS services.

The two common dynamic routing protocols are OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol). In a hybrid cloud context, BGP is more relevant as it handles routing between different autonomous systems, such as between an on-premises network and AWS infrastructure. OSPF, being an Interior Gateway Protocol (IGP), is typically used within a single autonomous system and would be less applicable in hybrid deployments directly. BGP is preferred in hybrid scenarios for its ability to provide a resilient, self-healing network topology that adapts to network changes.

In AWS, what is the purpose of route propagation, and how does it work in conjunction with dynamic routing protocols?

In AWS, route propagation is used to automatically add network routes to a route table in a Virtual Private Cloud (VPC) for connections that use dynamic routing, such as a VPN connection or AWS Direct Connect with BGP. When you enable route propagation on a route table, it allows routes learned through BGP to be automatically added to the table, simplifying the management of routing and ensuring the VPC’s route table has the most up-to-date network routes for the connections.

How does AWS support the use of dynamic routing protocols for on-premises connections?

AWS supports dynamic routing protocols specifically through BGP for on-premises connections when utilizing VPN or AWS Direct Connect services. With a VPN, you can establish a BGP session over the Internet to advertise your on-premises network routes and receive AWS VPC routes. With AWS Direct Connect, the BGP session is established over a dedicated network connection, providing more consistent performance and bandwidth compared to VPN connections over the Internet.

What factors should be considered when deciding between static and dynamic routing for a network involving AWS components?

When deciding between static and dynamic routing in an AWS environment, consider factors such as the size and complexity of the network, the administrative overhead of managing routes, the need for automatic rerouting and network resilience, the frequency of network changes, and the need for integrations with on-premises environments. Additionally, weigh the benefits of predictable routing paths with static routing against the scalability and flexibility benefits of dynamic routing with BGP.