> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/welcome/elastic-compute/networking/01-overview-1/03-region-links.md).

# Cross-Region Bandwidth

Every VPC ships with a free default bandwidth between regions, but it is **intentionally very small** — enough to verify reachability (a `ping` between regions, a quick latency check) and not much more. Any real workload — even a lightly used production service — needs the rate raised. Setting the right number for each region pair is what this page is about.

You do this by raising the **Cross-Region Bandwidth** for the region pair. This is the only knob the console exposes for cross-region capacity. There is no "Region Link" object to create, no peering to accept, no route to add — you pick a region pair, pick a committed rate, and pay for it.

The rate is flexible: you can set it anywhere from **a few Mbps up to 10 Gbps and beyond**, and you can adjust it up or down at any time without dropping existing connections.

![Cross-Region Bandwidth](/files/sYrwmBxUZwRDLEtHfARY)

## When to Raise Bandwidth

Effectively, **whenever real application traffic has to cross regions.** The free baseline is there to prove the path exists and to measure latency — it is not sized to carry a production workload. A few concrete signals that you need to raise it:

* **You're deploying anything beyond a connectivity test.** Even a small replication stream, a message bus, or a cross-region health check will outgrow the free baseline.
* **Large scheduled transfers.** Replication, data-warehouse sync, video transcoding pipelines, backups — size to the window, not the 24-hour average.
* **A critical path needs a committed floor.** Production-critical region pairs should not ride on the free baseline; raise the bandwidth to the rate you can plan against.

## When You Don't Need To

**You're only verifying the path.** If all you need is a `ping` between regions or a one-time latency sample, the free default is sized for exactly that.

**Cross-VPC reachability.** Cross-Region Bandwidth applies to traffic inside a VPC. It does not create a path between two separate VPCs — no amount of bandwidth will connect VPCs that aren't connected.

**Reaching a regulated region (e.g., China).** Regulated regions are not solved by raising bandwidth. Their connectivity is arranged under the applicable regulatory constraints — that's a separate conversation with [support](mailto:support@zenlayer.com).

## How It's Purchased

In the console, navigate to [**Cross-Region Bandwidth**](https://console.zenlayer.com/zec/bandwidth) (under the VPC section), then:

1. Choose the VPC.
2. Choose the **source region** and **destination region** — the pair you want to accelerate.
3. Pick a committed bandwidth in Mbps.
4. Confirm. The rate applies within a short provisioning window.

You can adjust the bandwidth of an active pair at any time. The change takes effect within a short provisioning window and does not drop existing connections.

Bandwidth you purchase applies to the chosen pair in both directions.

## Billing

Cross-Region Bandwidth bills on the **configured rate**, not actual usage. A 1 Gbps purchase costs the same whether the path runs at 50% or 0.5%. This makes the cost predictable but also means under-utilized purchases are wasted spend — review them periodically.

The free default mesh continues to exist alongside any paid bandwidth. If you cancel a purchase, the pair falls back to the best-effort baseline rather than going dark.

## Sizing

A few guidelines:

* **Replication and backup workloads** — size to the peak rate you want to sustain, not the average. If a nightly sync needs to move 1 TB in four hours, that's roughly 560 Mbps, not the 24-hour average of 93 Mbps.
* **Interactive traffic** — latency is usually the constraint, not bandwidth. Raising bandwidth rarely helps a chatty RPC workload.
* **Leave headroom** — sustained traffic above the configured rate is shaped, which causes loss at TCP's congestion point. Size 20–30% above the peak you expect.

## Common Patterns

**Replication pipe between primary and replica.** Primary database in one region, replica in another, both in the same VPC. The free mesh handles everyday chatter, but you purchase Cross-Region Bandwidth sized for the replication stream to give it a committed floor.

**Scheduled bulk transfer.** A nightly job moves warehouse extracts between regions. You size the purchase to the job's window so the transfer finishes on time.

**Burst-prone interactive service.** A service that's usually quiet but occasionally surges. Buy enough bandwidth to cover the surge, not the average. The shaping behavior at the ceiling is what determines user experience at peak.

## Things to Watch

* **Bandwidth is a hard ceiling.** The committed rate is also the max rate. Traffic beyond it is shaped, not bursted. Size accordingly.
* **Purchases are per region pair.** Raising bandwidth between Hong Kong and Frankfurt does nothing for Hong Kong ↔ Singapore. Each pair is priced independently.
* **Default baseline stays.** You don't need to buy bandwidth for pairs that are happy on the free mesh. Only pay for the pairs that actually need more.