The IXP Architecture


The vast majority of European IXs have adopted a layer 2 switched Ethernet architecture. There are examples of other architectures such as ATM and FDDI, however, these are not common. ATM is often disfavoured by ISPs since it is a technology that is significantly different to that with which they are experienced, and requires skills to manage that are not always available to them. FDDI does not have these particular issues. It can interconnected with Ethernet based networks, but the speed limitation of 100Mbps, the limited support for FDDI on current layer 2 switch equipment and the probable lack of any further development suggests that it would not be an appropriate technology for a new IX to adopt for its core infrastructure.
At least one of the earliest European IXs began in the mid 1990s with a very simple non-switched 10Mbps Ethernet architecture, which consisted of a length of Ethernet cable connected to the participant's routers. (The use of the term 'architecture' for this solution is perhaps over stating the case). However it worked and proved the usefulness of the IX. This IX soon moved to a switched Ethernet technology, and most IXs since then have started with switched Ethernet technology as their core architecture.