Routing protocols are essential for enabling communication and data exchange between different networks. However, they also pose security risks if not properly configured and protected. In this article, you will learn about the security implications of using link state and distance vector protocols in your network, and how to mitigate them.
Link state protocols, such as OSPF and IS-IS, use a database of the network topology and calculate the best paths based on the link costs. They are more efficient and scalable than distance vector protocols, but they also require more resources and bandwidth. Link state protocols are vulnerable to spoofing, flooding, and replay attacks, which can compromise the network integrity and availability. To prevent these attacks, you should use authentication, encryption, and filtering mechanisms to secure the link state updates and the database.
In my experience, link state protocols serve the network best when used in the core where fast convergence is needed. Using a link state protocol in this way combined with a hybrid protocol like BGP for edge routing yields an optimum combination of performance, availability and scalability for large network designs.
Distance vector protocols, such as RIP and EIGRP, use a table of the distances to the destination networks and update it based on the information from the neighboring routers. They are simpler and easier to implement than link state protocols, but they also have limitations and drawbacks. Distance vector protocols are prone to routing loops, count-to-infinity problems, and inconsistent updates, which can affect the network performance and reliability. To avoid these issues, you should use techniques such as split horizon, poison reverse, and route summarization to optimize the routing table and reduce the convergence time.
Hybrid protocols, such as BGP and OLSR, combine the features of both link state and distance vector protocols. They use a hierarchical structure and exchange different types of information depending on the level and the relationship of the routers. They are more flexible and adaptable than pure link state or distance vector protocols, but they also have more complexity and overhead. Hybrid protocols are susceptible to hijacking, misconfiguration, and manipulation attacks, which can disrupt the network connectivity and traffic. To counter these attacks, you should use verification, validation, and monitoring mechanisms to ensure the accuracy and authenticity of the routing information and the router identity.
I agree that the security threat of hijacking exists in using BGP on the Internet. To help mitigate this threat, an out-of-band method of verifying route policy is needed. Routing registries have been the answer to this previously but more recently RPKI using certificate-based validation has been promoted as a more secure solution.
No matter the type of routing protocol you use in your network, you should follow security best practices to bolster your network security and resilience. This includes using strong passwords and keys for authentication and encryption, using access control lists and firewalls to filter out malicious traffic, using secure protocols and channels to communicate with other routers and networks, utilizing logging and auditing tools to track routing activity, and implementing backup and redundancy mechanisms to guarantee network availability.
Despite the security measures and practices implemented in your network, you may still face some security challenges and trade-offs when using routing protocols. These include balancing security and performance, as additional security features may increase complexity, overhead, and latency of the routing process. Adapting to changing network conditions, such as topology, traffic, or policies, may introduce new security risks or vulnerabilities. Additionally, routing protocols may need to interact with different types of networks and routers, which may have different security standards or requirements, leading to conflicts or inconsistencies.
In my experience the best network design is achieved through collaboration of stakeholders in each area of requirements such as performance, availability, security, usability, manageability, scalability, flexibility and affordability. Design standards should be revisited when there are technology changes or the needs of the stakeholders change.