IXP is a layer 2 network where multiple network entities meet, for the purposes of interconnection and exchanging traffic with one another. Internet Exchange Points start with a single Layer 2 switch at one location. Networks, peer with each other in this facility. When the number of participants grows, more switches are added at that location and more locations are added to the IXP itself.
For example, AMS-IX in Netherlands has many places inside many data centers and for each data center, they have more than one switch for Settlement Free Interconnection.
Disclaimer: This post is written based on information presented in Orhan Ergun’s Service Provider Network Design and Architecture book.
- IXP is often referred to as an Internet Exchange (IX), or “Public Peering”
- Today most Exchange Points are Ethernet based LANs, where all members are sharing a common broadcast domain, and each member is given a single IP per router out of a common IP block (such as a /24) owners provide racks for the peering fabric for free.
- IXP’s are typically done at the carrier neutral data centers and in many cases; Datacenter
Figure – London Internet Exchange Point Building
IXP Best Practices
- The IXP provides a layer 2 shared switch fabric for peering networks to interconnect.
- There must be at least 3 networks (ASNs) connected for a facility to be considered as an IXP.
- The IXP should have neutral ownership and or management.
- The IXP should be at a secure location.
- The IXP should have a website with basic information’s such as: Contact Information, Peering member’s information, Peering statistics, Membership & Joining and Peering and technical policy.
- The IXP design is a Layer 2 fabric with most possible reliability, security and stability features (Many IXP’s are considering to move their Layer 2 fabric to VPLS).
- Access to the IXP by members and fiber providers should be easy
- IXP location should be closer to the participant as much as possible.
IXPs are not generally involved in the peering agreements between connected ISPs, though some IXPs encourage their users to sell or buy Transit and involve peering negotiations.
IXPs do not provide services that compete with their members such as Commercial Hosting Services and Transit Services.
Why Networks Peer at the IXP?
An Exchange Point acts as a common gathering point, where networks who want to peer can find each other. A network new to peering will typically go to an exchange point as their first step, to also be able to connect to many other like-minded networks interested in peering with them. The more members an exchange point has, the more attractive it becomes to new members that are looking to interconnect with the most other networks. This is called as “critical mass”.
Where are the Internet Exchange Points?
Most of the IXPs in the World are in Europe. There are many IXP’s in North America as well. IXPs in Europe mainly work based on Membership model, while IXPs in U.S work based on Commercial model. There are exceptions in each case though. Most European IXPs grew from non-commercial ventures, such as research organizations. Most African IXPs were established by ISP Associations and Universities.