Stop 02 of 08 · Roaming

Direct connection or roaming hub?

About 6 min · 3 questions ·

Thursday
The situation

The driver's provider has direct OCPI connections to its twelve largest partners.

All other operators, several hundred of them, it reaches through a roaming hub.

The questionWhy connect directly to some and through a hub to others?

Connections grow fast without a hubNumber of links between companies

Computed: peer to peer, n companies need n × (n − 1) ÷ 2 links if everyone connects with everyone; through a hub, each company needs one.

Both are part of OCPI

started as a bilateral protocol for peer-to-peer connections. Soon companies began to use it through hubs as well, and since version 2.2 OCPI supports hubs directly. The specification describes both: platforms that connect only through a hub, and platforms that use a hub and direct connections side by side.

Why many use both

  • Direct for the largest partners: full control over the connection, no hub fees, faster changes.
  • Through a hub for the long tail: one connection reaches hundreds of operators, with one contract and one technical integration.

Hubs such as GIREVE and e-clearing.net are used alongside direct connections. Other platforms run their own protocols, as shown in EV charging fundamentals, stop 03.

Check your understanding

3 questions. Answer all of them to complete this stop. Each answer explains itself.

01Question 1 of 3

How many links do 10 companies need if each connects directly with each?

02Question 2 of 3

Since which version does OCPI support hubs directly?

03Question 3 of 3

Why do many companies combine direct links with a hub?

Further in other paths

  1. EV charging fundamentals · Stop 03What happens after you tap your card?Follow one tap from the card reader to the operator's backend and, for another company's card, across the roaming route and back. OCPP and OCPI in action.
  1. EVRoaming Foundation: OCPI 2.3.0, supported topologies. https://github.com/ocpi/ocpi/blob/2.3.0/release/core/topology.asciidoc. Checked 09 Oct 2026.
  2. EVRoaming Foundation: OCPI 2.3.0, supported topologies. https://github.com/ocpi/ocpi/blob/2.3.0/release/core/topology.asciidoc. Checked 09 Oct 2026.
  3. EVRoaming Foundation: OCPI background: versions, standardisation and adoption. https://evroaming.org/ocpi-background/. Checked 09 Oct 2026.
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