BGP Optimization for Medium-Sized ISPs: Technical and Financial Decisions Using Open-Source Tools#

Fernando Tipiani (no affiliation listed in the program)

• Why: A worked, adoptable playbook that connects per-prefix flow data to BGP announcement decisions to the transit bill — the technical-financial bridge the PM's stakeholders constantly ask for, built entirely on open-source tools.
• What: A method for balancing inbound traffic across two (or more) transit providers with different tariffs and percentile-95 commitments: measure per-provider consumption (Observium or LibreNMS SNMP/billing modules), rank traffic per /24 (Akvorado for sFlow/NetFlow/IPFIX — NFSen noted as obsolete), then regroup which prefixes are announced toward which provider to minimize overage. Worked example: a 55 Gbps ISP with 20/10 Gbps commits and $1/$2 per-Mbps tariffs cuts monthly overage from $25,000 to $16,000 — a 36% saving — by shifting traffic groups to the cheaper provider.
• How: Open-source monitoring stack → per-prefix traffic ranking → iterative prefix grouping to hit target consumptions per provider → update BGP announcements and verify. Final recommendations: secure commits without rate-limiting but with burstable capacity; avoid concentrating more than 60% of traffic on a single provider; use IXPs and peering as the primary cost lever.
• Where applicable: Multi-transit ISPs and enterprises on percentile-95 billing. Assumes comparable service quality across providers and stable enough traffic patterns for prefix-level grouping to stick over a billing cycle. Tooling is fully open source and broadly adoptable.