CDN Capacity & Failure Planner
How will a CDN behave when traffic, cache reuse, or a delivery path changes?
A content delivery network serves reusable responses from edge locations near users. Its value comes from shortening the hit path and preventing cache misses from overwhelming the origin.
Step 1
Model
Edit traffic, payload size, cache hit rate, edge and origin capacity, regional footprint, shield behavior, stale coverage, and unit costs. Every number is an illustrative assumption that you can replace.
Step 2
Observe
Trace requests through the edge, optional shield, and origin. Compare origin offload, p95 and p99 latency, availability, egress, saturation, and monthly run-rate.
Step 3
Challenge
Start with normal delivery, then inject a global purge, low-hit workload, regional loss, or origin outage. Adjust the plan until both the request path and capacity envelope recover.
Trace every request from edge to origin
Change demand, cache behavior, routing, capacity, and unit costs. The figures are illustrative assumptions, not vendor quotes or performance claims.
Challenge the healthy path
Plan is operating under pressure
Tail latency or capacity headroom is outside the recommended planning range.
Scenario: Normal delivery
93.0%
1,837 of 26.4K req/s reach origin
259ms
Fast path unless more than 5% of requests miss
313ms
Tail follows the miss or failure path
100.00%
0 req/s cannot be served
12.3PB
857.3TB leaves the origin
$533,033
Selected conditions projected for 30 days
Live request map
Where the peak load is served
26.4K incoming req/s · 88% effective hit rate
26.4K req/s
2.2x peak demand
23.2K hits
80% capacity used
1,331 reused
42% of edge misses
1,837 req/s
57% capacity used
Request disposition
88.0% of incoming demand
Misses absorbed before origin
1,837 req/s consume origin capacity
0 req/s are not served
Capacity envelope
The marker indicates 100% physical capacity. Plan below 75% to preserve recovery headroom.
3 active × 11K req/s per region
1,837 demand / 3,200 req/s capacity
Editable cost model
What creates the monthly run-rate
These inputs are illustrative planning assumptions. Replace them with your own contract, region, and workload values.
$431,101
12.3PB × $0.04/GB
$64,296
857.3TB × $0.08/GB
$37,636
68.4KM × $0.55
Planning consequence
The modeled path serves 100.00% of peak demand with 93.0% origin offload. Preserve the remaining headroom for deploys, retries, and regional failover.