Moving IP technology to the base station is next major challenge


Orange’s core network was ‘quite a different looking beast’ today to that of the early 1990s, the company’s Principal Design Consultant, Andy Sutton, told delegates at Transport Networks for Mobile Operators.

In 1993 it had been a ‘single, off-the-shelf, GSM-only network’, he said. ‘We held it together with lots and lots of E1s.’ Today, however, it had ‘base station sites with 2G and 3G, lots of IP and Ethernet and a common CS and PS core.’ Subscriptions had expanded exponentially during the mid-late 1990s, which meant that the organisation had to establish an optical network – a second, parallel, core network. ‘It’s a high capacity optical infrastructure with 3,000km of optical fibre. It was really designed to be a high capacity network, with 10G packets. There are no E1s on the network.’

The network was built to be a convergence MPLS network, he said. ‘If we were building this network again you’d probably see a closer integration between packet and optics.’ The Orange network now had a higher capacity throughout on SGSNs as a result of the use of GE interfaces. ‘The goal was migration from ATM to full IP TNL.’ The network had a one GTP-U tunnel feature, he continued, that facilitated the separation of control plane and user plane as well as removed most of the UP traffic from the SGSN, enhancing scalability.

Most if not all operators had now implemented IP/MPLS as the core transport network of choice, he said. Mobile flows were complex, owing to the location of policy/control points such as GGSNs and SGSNs, while the location of policy elements like BNG also had a large impact, while the mobile core network had evolved significantly since. The company has realised significant cost reduction since implementing the optical express links that by-pass P routers to connect HSI (High-Speed Internet) directly to the Internet peering sites the introduction of GSM, and a similar evolution had been seen within the core transport network. The next major challenge, however, would be ‘moving IP technology to the edge, to the base station’. ‘I’m sure we’ll be hearing a lot more about that,’ he told delegates.

Orange had used ‘a fair amount’ of Ethernet in the core network, but there was work still to be done, he stressed. ‘The challenge is as much organisational as technological. Quite a small team of guys run core networks. As soon as you start to move beyond the core network edge it involves a much larger team, who are not necessarily as IP aware. You have to take them on that journey with you.’

 

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