Data Transfer Billing
What it is
Data Transfer is a pay-per-gigabyte meter with an optional prepaid package on top. You buy a monthly package in gigabytes (or terabytes), every outbound byte counts against that package, and if you exceed it you pay an overage rate per GB. The meter runs per EIP — one EIP, one package, one overage line.
It is the right choice when throughput is bursty and total monthly volume is predictable. You are not paying for a wide pipe; you are paying for the bytes you actually move.
How the package works
When you create an EIP with Data Transfer billing, you supply two things:
Bandwidth — the maximum Mbps the EIP is allowed to push. This is not the meter; it is the upper bound of the pipe. If you do nothing it defaults to
10 Gbps(see Bandwidth Cap).Flow package size — the prepaid volume in TB (the console exposes 0, 0.5, 1, 5, 10, or Custom TB/month).
A package of 0 TB is legal: you pay for every gigabyte at the overage rate with no prepaid bucket. A package of 5 TB means the first 5 TB of the month are paid for up front, and anything beyond that is billed as overage.
What counts, what doesn't
Data Transfer bills outbound public-network traffic. Inbound traffic is not metered on this plan. Traffic that never leaves Zenlayer's network — VPC-to-VPC, same-region private IP, Cross-Region Network default mesh — is outside the scope of public network billing entirely and is not counted here regardless of the billing method.
Combining Data Transfer with a bandwidth cap
Because Data Transfer prices bytes, nothing in the meter itself protects you from a runaway workload that saturates the line for a full day. The bandwidth cap is how you put a ceiling on that: you keep the pay-per-GB economics but clamp the worst case. The cap has no effect on the per-GB price; it just prevents the meter from running any faster than the cap allows.
See Bandwidth Cap for the two cap behaviors (loose vs. tight) and the 10 Gbps default.
When this is the right choice
Predictable monthly volume. You have a good estimate of the total gigabytes your workload moves per month and want the package discount.
Bursty throughput. Your peak Mbps is high for short windows but the time-averaged throughput is low. Flat Rate would force you to pay for the peak; 95th-based plans would bill you on that peak; Data Transfer doesn't care about the shape.
One EIP, one workload. The meter is per-EIP, so it does not help when you want to amortize cost across a fleet.
When to reach for something else
Steady, heavy throughput. If you sit near your peak 24/7, the per-GB price dominates and a Flat Rate commitment is usually cheaper.
Many EIPs with uncorrelated peaks. The aggregation discount of Aggregated Burstable 95th will beat per-EIP packages.
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