Is it Time to Say Farewell to GPON?

Gigabit passive optical network (GPON, if you're scoring at home) is a great technology. It is the predominant technology in place that is delivering fiber last mile broadband. GPON quickly became popular because it allowed the provisioning of a gigabit service to customers. A GPON link delivers 2.4 GB downstream and 1.2 GB upstream to serve up to 64 customers, although most networks I’ve seen don’t deliver to more than 32 customers. The biggest long-term advantage of GPON is that the technology serves more customers than active Ethernet, and most of the R&D for last-mile fiber over the past decade has gone to PON (passive optical network) technology. There are a few interesting benefits of GPON versus active Ethernet. One of the most important is the ability to serve multiple customers on a single feeder fiber. PON has one laser at a hub talking to 32 or more customers. This means a lot less fiber is needed in the network. The other advantage of PON that providers like is that there are no active electronics in the network – electronics are only at hubs and at the customer. That’s a lot fewer components to go bad and fewer repairs to make in the field. We’re now seeing most new fiber designs using XGS-PON. This technology increases bandwidth and delivers a symmetrical 10-GB path to a neighborhood. The technology can serve up to 256 customers on a fiber, although most providers will serve fewer than that. The biggest advantage of XGS-PON is that the electronics vendors have all gotten smarter, and XGS-PON is being designed as an overlay onto GPON networks. A provider can slip an XGS-PON card into an existing GPON chassis and instantly provision customers with faster broadband. The faster speeds just require an upgraded ONT (optical network terminal) – the electronics at the customer location. I’m sure GPON will be around for years to come. But as happens with all technology upgrades, there will probably come a day when the vendors stop supporting old GPON cards and ONTs.