IPX may be the abbreviation of the Interplanetary Expeditions corporation on the popular sci-fi TV show Babylon 5, but when it is discussed in tech circles these days we mean the telecommunications interconnection model IP Exchange. In essence, IPX provides interoperability of IP-based services between all service provider types across both mobile and fixed line networks with guaranteed levels of service.
IPX is critical to how ISPs and other operators generate revenues from and add flexibility to their networks, but in most cases end-users will not know whether they are using IPX or not. Nonetheless, the IPX interconnection model allows for wider competition and more choice for all involved, which generally pushes up the service level across all operators.
Why was IPX developed?
Traditionally, networks were created purely for voice (phone) traffic and utilised the international SS7/TDM networks. However, since the development of the internet traffic has largely become data focused and thanks to VoIP (voice over IP) technologies most voice traffic is now also IP-based. Nonetheless, with the combination of packet-switched voice and VoIP currently in use and the conversions needed between the two, it has long been apparent that an IP based network-to-network interface was required – and that is IPX.
Since the turn of the millennium, thousands of GSM operators have been using GPRS Roaming Exchange (GRX) networks for routing IP based roaming traffic, mostly over 2.5G and 3G connections. This exchange demonstrated how multiple different carriers could be connected to each other via peering points, but in this case the limit has been that only GSM operators could be part of the exchange and not all GRXs are technologically capable of meeting the demands of real-time services that we all regularly rely upon.
GRX was, therefore, the starting point for IPX development by the GSM Association, which is made up of more than 750 mobile operators based around the world.
Couldn’t this have been achieved over the internet rather than requiring a private backbone?
The internet is built upon the IP protocol and could certainly handle the volume of connected devices, but whilst the open internet remains a fantastic platform, if you need a guaranteed quality of service, particularly for time-critical and real-time services, then the variation in service providers is a major bottleneck. A private backbone, such as that created by IPX, is one solution to this issue.
How does IPX work
On a technical level, IPX architecture consists of different IPX providers connecting together via an IPX peering point for traffic exchange. The specifications provide for media and signalling traffic to be transported end-to-end, with peering providing a single point where traffic can be exchanged from a mobile to fixed line network or vice-versa.
Moreover, IPX offers both a traditional bilateral interconnection, where two operators write and interconnection contract and set up a connection to each other themselves, and a multilateral connection, where the IPX provider manages the contract and connectivity set-up on behalf of both operators, making the possibility of connections with hundreds of other operators a significantly more efficient process.
Photograph by Geralt