Domains
How Prelude TE separates IGP scopes into domains, how to switch between them in the UI, and how to view several at once.
A domain in Prelude TE is one IGP scope — typically an ISIS area, an OSPF area, or a routing realm you keep separate. Each domain has its own in-memory graph and its own NATS topic. You browse them through the Topology page in the web UI.
How domains are identified
Prelude TE keys each domain on the BGP-LS Instance Identifier advertised in the Node NLRI. Every BGP-LS speaker that exports a given IGP carries an instance ID alongside the data; routers configured for the same IGP advertise the same value, so Prelude TE groups their reports into a single domain.
Use the same BGP-LS instance ID on every peer for a given IGP
If two peers export the same IGP scope with different instance IDs, Prelude TE treats them as two separate domains and consolidation does not happen. Configure the same instance ID on every router or route reflector that exports the same IGP. See BGP Peers / Peer redundancy for the broader consolidation picture.
Switching domain in the UI
The Topology page has a domain selector at the top. It lists every domain Prelude TE has heard about since it started, plus an All domains entry.
- Pick a specific domain to scope the graph view to that IGP.
- Pick All domains to merge every domain into a single rendering. This is what you want when your network spans several connected IGPs (multi-area ISIS, inter-area OSPF, multi-IGP cores) and you want to see them as one network.
Empty domains and licensing
Domains appear in the selector as soon as Prelude TE receives the first NLRI tagged with their instance ID. If you are on a tier with a limited domain count and you exceed it, additional domains are skipped: the engine logs a warning and the affected NLRIs are not processed. The domain selector shows only the licensed domains in that case.
See Getting Started / Licensing for the per-tier domain caps.