RFC 9234: Simplifying BGP Routing and Preventing Route Leaks

The Border Gateway Protocol (BGP), a cornerstone of internet routing since its inception over three decades ago, has been plagued by accidental route leaks and hijacks. These issues arise from its original design limitations, which overlooked the roles of Autonomous Systems (AS) in managing routing policies. However, a groundbreaking solution has emerged in the form of RFC 9234, a specification designed to address these challenges effectively. Initially introduced three years ago, major players like Quagga/FRR and HPE Juniper Networking have already implemented support for RFC 9234, simplifying routing configurations while mitigating errors.

Understanding RFC 9234 and Its Role in BGP Policies

At its core, RFC 9234 introduces a concept rooted in the typical relationships between Autonomous Systems: Provider-Customer and Peer-Peer connections. These connections define how data is routed between networks based on predefined roles. Historically, network engineers implemented complex routing policies to distinguish these roles and ensure proper data flow. Such configurations were prone to human error, particularly during urgent manual changes. Mistakes often resulted in route leaks, where rogue routes unintentionally disrupted network traffic.

This new RFC simplifies these configurations by enabling the use of an Only-To-Customer (OTC) attribute, which defines the local role of an AS in relation to its neighbors directly in BGP configurations. By doing so, networks can enforce these relationships without relying on extensive manual policies, reducing the chance of misconfigurations. For example, the AS roles — whether Customer, Peer, or Provider — can be set directly through the BGP interface, eliminating the need for complicated policies and oversight.

Practical Benefits and Implementation of RFC 9234

The operational impact of RFC 9234 is immense. Consider a real-life scenario: a single wrong community or omitted export policy could lead to widespread disruptions. With OTC attributes, however, AS configurations are streamlined, ensuring only the intended routes are advertised based on predefined roles. For example, HPE Juniper Networking’s Junos OS 25.2R1 now supports this feature, allowing engineers to configure roles at the global, group, or neighbor level with commands as simple as set protocols bgp otc-local-role provider.

The inclusion of a strict mode even allows safer interactions with neighbors that do not yet support the OTC capability. This mode ensures that if a neighbor’s capabilities are misaligned or missing, the device will handle the situation safely, often by terminating the connection to prevent unintended consequences.

RFC 9234: A Step Forward, But Not a Cure-All

While RFC 9234 offers a powerful tool for addressing route leaks and misconfigurations, it is not a replacement for well-architected routing policies. Adopting this feature is akin to installing a circuit breaker in a home—it provides an added layer of security, but it does not absolve homeowners from proper wiring practices. Similarly, network operators must continue adhering to best practices, such as MANRS and RFC 8212, for overall BGP policy implementation.

For networks with complex requirements, such as mobile and enterprise systems where peers may require specific route exceptions, RFC 9234 provides flexibility. Administrators can override roles for individual routes using Junos’ policy tools, granting granular control over routing configurations without compromising the consistency provided by OTC attributes. This makes RFC 9234 versatile enough for specialized routing needs while maintaining its integrity in standard use cases.

Conclusion

RFC 9234 represents a critical evolution in internet routing, transforming how Autonomous Systems manage their roles and relationships in BGP. By introducing a mechanism that simplifies configuration and reduces errors, this specification enhances network resilience and stability. As adoption grows across vendors and AS operators, RFC 9234 is poised to reshape the landscape of routing policy implementation, offering a streamlined, efficient, and secure approach to internet traffic management.