What is IX?
Internet Exchange (IXP, Internet Exchange Point)
An IX (Internet Exchange, or IXP) is a shared network where many networks connect routers to exchange traffic directly, without a transit provider.
At its core an IX is a large layer-2 switching fabric, often spread across several data centres in a city. Each member connects a router port and gets an address on the IX's peering LAN, then runs eBGP sessions with other members over that shared network. Traffic exchanged this way is called peering: usually settlement-free, so neither side pays the other, and only the members' own routes and their customers' routes are exchanged, not the whole internet. Members can peer bilaterally, with a session to each network they agree terms with, or multilaterally through the IX's route servers. A route server collects routes from every connected member and passes them on to the others, so one or two sessions reach most of the exchange. It does not insert its own ASN into the AS path or change the next hop, so traffic still flows directly between members' routers.
For an edge router, an IX connection is a second kind of neighbour beside transit: you announce only your own prefixes and accept only routes for the members' networks, never a default route. Route servers commonly filter what members announce using IRR data and RPKI, so a missing route object or ROA can mean your prefix is quietly dropped. The classic mistake is a route leak: re-announcing routes learnt at the IX to your transit provider, offering to carry traffic for networks that aren't yours. IX details such as peering LAN addresses and route server ASNs are published in PeeringDB. The Setting up VyOS with basic BGP lesson connects an edge router to both a transit provider and an IX route server.
Lessons that use IX
- Setting up VyOS with basic BGPTeaches this term · Intermediate · 50 min
Build a VyOS edge router from scratch: one upstream transit provider, one Internet Exchange route server, and the import and export policy that keeps both safe. Every command and output comes from a real VyOS lab.
- Edge and core: building out a VyOS networkIntermediate · 60 min
Split one BGP router into edge routers that face the outside world and a core that carries traffic inside: loopbacks, OSPF for infrastructure, iBGP between loopbacks, next-hop-self, and what happens when a link fails. Built and broken on three real VyOS routers.
- IPv4 over an IPv6-only core (RFC 8950)Intermediate · 40 min
Carry IPv4 routes over IPv6 BGP sessions with IPv6 next hops, so core routers need no IPv4 addresses at all. Built on VyOS: the missing router ID, what breaks without the extended next hop capability, native IPv4 on the wire, and why traceroute shows 192.0.0.8.
- BGP on loopbacks vs interface addressesIntermediate · 45 min
Why BGP sessions between loopbacks survive link failures and use parallel links, and what they need to work: an IGP or static routes, update-source, the eBGP connected check, and BFD. Every failure is reproduced on two real VyOS routers.
- OSPF on VyOS: costs and OSPFv3Intermediate · 30 min
OSPF the VyOS way: interface-based configuration, reading the interface and database output, steering traffic with costs (and the asymmetric routing that follows), and OSPFv3 for IPv6 over link-local addresses. Captured on the three-router edge/core lab.
- IRR, RPSL and AS-SETsIntermediate · 60 min
How networks publish what they announce and how their neighbours turn it into filters: Internet Routing Registries, whois queries, RPSL objects and attributes, AS-SET expansion, bgpq4, and the pitfalls of unsigned routing data.