HLD-414·Rate Limiting
Expert · 2,000 ptsAnycast L7 WAF, Bot Reputation & Global Token-Bucket Edge
Design Cloudflare / Akamai’s global L7 Web Application Firewall evaluating JA4 TLS fingerprints, dynamic WAF rulesets, and distributed rate limits at 280k+ RPS.
Max p99
≤ 32 ms
Availability
≥ 99.6%
Budget
≤ $11,900
Functional Requirements
- FR-1POST /waf/evaluate — Checks compiled customer WAF ruleset, IP/JA4 reputation, and edge token bucket.
- FR-2POST /waf/rules/{zone_id} — Pushes emergency zero-day mitigation rules across global POPs.
- FR-3PATCH & DELETE /waf/evaluate/{zone_id} — Updates, revokes, or deletes zone_id entries with bounded TTL or explicit cache/index invalidation.
- FR-4Must sustain p99 <= 32ms during volumetric botnet floods and 8x origin analytics brownouts.
Workload Profile
Steady Edge Ingress95,000 WAF Check RPS / 10,000 Reputation/Counter Write RPS
Volumetric L7 Botnet Attack250,000 Check RPS / 32,000 Counter Write RPS
Active Working Set48 GB compiled zone WAF rulesets & hot ASN/JA4 scores
Latency GateUltra-strict inline edge budget p99 <= 32 ms
Consistency Model
Sub-2s eventual rule & reputation gossip across edge POPs; fail-open/cached fallback on origin brownout.
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