The five places multicloud networking costs hide
Inter availability zone traffic. Traffic between zones inside one region is charged per gigabyte on the major hyperscalers. A microservice mesh that ignores zone topology can generate surprising volume for no functional benefit.
Inter region replication. Copying data between regions for resilience or latency is metered and recurring. It is often justified, but it should be a decision, not an accident.
Internet egress. Data leaving a provider to the public internet is the classic budget eater. OCI is materially cheaper here than AWS, Azure, or GCP and applies a generous monthly allowance, which is one reason data heavy workloads sometimes land there.
NAT gateway processing. NAT charges an hourly rate plus a per gigabyte processing fee. Routine service calls routed through NAT can cost more to move than to compute.
Cross cloud transit. Moving data between two providers pays egress on the way out and sometimes ingress handling on the way in, plus the cost of the interconnect itself. This is the line multicloud adds that a single cloud does not.
An indicative cost ranking
The figures below are indicative and depend on region, volume, and contract; verify against each provider's current pricing before relying on them.
| Path | Relative cost | How to reduce it |
|---|---|---|
| Inter availability zone | Low | Make services zone aware; keep chatty pairs together |
| NAT gateway processing | Low to medium | Use VPC endpoints or equivalent to bypass NAT for service calls |
| Inter region | Medium | Replicate only what resilience genuinely requires |
| Internet egress | Medium to high | Cache at the edge; place egress heavy workloads where rates are lowest |
| Cross cloud transit | High | Minimize data that crosses providers; colocate data and compute |
What to do this week
Pull the data transfer lines out of your bill and put one owner on them. Map which workloads cross zones, regions, and providers, then ask whether each crossing earns its keep. Move egress heavy workloads toward the cheapest viable provider for that traffic, and bypass NAT for service calls. These are no regret moves that lower the rate without touching the application.
For the wider picture, read the cross cloud cost optimization guide. For neighbouring detail, see egress fees across the four clouds and data gravity and its cost consequences.
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