US-based Infinera has made another step forward with its prototype XR Optics technology, flagging what it claimed was a successful trial with the UK's Virgin Media. According to official feedback from the pilot, transfer rates of up to 400 Gbit/s were achieved in a single fiber. The results were impressive enough for Virgin Media to conclude that XR Optics "could" deliver 400Gbit/s symmetrical services over existing PON network deployments. This is a reference to capacity rather than end-user speeds, however, since 400G is shared among users in a point-to-multipoint PON. Green light: Infinera's XR Optics trial with Virgin Media has gone well.