BGP Link-State Extensions for BGP-only Networks#

Ketan Talaulikar, Aravind Babu MahendraBabu, Clarence Filsfils, Krishna Swamy (Cisco), Shawn Zandi (LinkedIn), Gaurav Dawra, Muhammad Durrani (Oracle).

• Why: BGP-only fabrics (increasingly the default in AI/ML DCs) lose the topology visibility that link-state IGPs give to FRR and TE computation. This WG document supplies it — and its new use cases tie directly into the two AI-backend drafts above.
• What: BGP-LS extensions (Protocol-ID 7) to advertise topology in BGP-only networks. Since IETF 125 it has added an IPFRR use case (LFA/TI-LFA/ERP in loss-sensitive AI Clos fabrics with strict convergence requirements) and SRv6 scenarios: unified SRv6 domain across DC frontend + WAN eliminating DCI gateway translation, and SR Policy computation for deterministic AI backend paths. Simplified procedures now reference RFC 9857/9514 directly.
• How: Standard BGP-LS address-family advertisement of nodes/links from the BGP-only fabric, consumed by controllers or local PCEs for path computation.
• Where applicable: Any BGP-only DC or WAN. Implemented in SONiC-FRR (merged FRR PR); IANA early allocation for the BGP Route Type TLV is done. Requesting WG review — mature and moving.