Quiz Entry - updated: 2026.09.17
Which federation topologies exist, and are they mutually exclusive?
RP-centred, IdP-centred, full mesh and hub-and-spoke; mixed forms are possible and common.
* The four pure federation layouts side by side. *
The four pure layouts differ in how many IdPs and RPs there are and whether they talk directly:
| Topology | Shape | Typical example |
|---|---|---|
| RP-centred | One RP, several IdPs | A website offering login with Google, Apple or Facebook |
| IdP-centred | One IdP, several RPs | A university's student login, or Google as IdP for many apps |
| Full mesh (cross-domain) | Several organisations, each with IdP and RPs, federating with each other | Switch-AAI, eduroam |
| Hub-and-spoke | IdPs and RPs connected through a central broker | A national or sector-wide identity hub |
In practice an organisation sits in several of these at once: its own IdP serves internal RPs (IdP-centred), it accepts partner IdPs for a collaboration portal (RP-centred), and it takes part in an academic federation (full mesh).
Go deeper:
NIST SP 800-63C-4 Federation and Assertions — the reference for how IdPs, RPs and assertions interact, including brokered federation.