# BGP Role model: tracking the adoption of RFC 9234

[Cloudflare](https://yomu.fyi/company/cloudflare) · Bryton Herdes · Aug 18, 2026

**Type:** Problem & solution

## Summary

Border Gateway Protocol route leaks occur when routing announcements propagate beyond their intended customer-provider or peer relationships, causing traffic misdirection and performance degradation. RFC 9234 embeds relationship awareness directly into BGP by establishing negotiated BGP Roles and attaching an Only to Customer (OTC) transitive path attribute to prevent unauthorized route propagation. To assess real-world adoption, Cloudflare monitored OTC attribute transmission across peer networks and discovered that 33.1 percent of IPv4 and 17 percent of IPv6 paths were missing the OTC attribute. Investigation revealed that Tier-1 transit providers AS1299 and AS3257 were stripping the attribute due to legacy defensive BGP error-handling configurations. Following direct engagement, AS1299 updated its configurations to preserve OTC propagation, whereas AS3257 continued stripping it, highlighting the necessity of broader vendor and carrier support across the Internet.

## Context

BGP route leaks occur when Autonomous Systems propagate routing announcements beyond their intended scopes, violating valley-free hierarchy rules and causing traffic misdirection. Historically, preventing these incidents required manual, error-prone prefix filters and routing policies across individual network sessions.

## Approach / What changed

RFC 9234 introduces BGP Roles and the Only to Customer (OTC) path attribute to automate route leak prevention in-protocol. Cloudflare analyzed global adoption by tracking OTC attribute propagation and identified Autonomous Systems dropping the attribute, engaging with major Tier-1 networks like Arelion and GTT to restore OTC preservation.

## Takeaways

- RFC 9234 defines five valid BGP Role pairings between neighbors and automatically terminates sessions with a Role Mismatch notification when local and remote relationship configurations conflict.
- Measurement of missing OTC attributes revealed that two Tier-1 networks, AS1299 (Arelion) and AS3257 (GTT), appeared in over 92% of OTC-absent IPv4 and IPv6 routing paths.
- Applying BGP Roles requires resetting BGP sessions during maintenance windows, with existing protocol support available in Junos OS, RouterOS, BIRD, OpenBGPD, and FRR.

**Tags:** [Architecture](https://yomu.fyi/topic/architecture), [Monitoring](https://yomu.fyi/topic/monitoring), [Reliability](https://yomu.fyi/topic/reliability)

[Read original post](https://blog.cloudflare.com/rfc9234-bgp-role-model)