Technical resources for Open Access Fiber Networks?


Not so long ago I learned about Open Access Fiber Networks. I’m quite curious about how these are actually implemented. I’m able to find boatloads of marketing material and management-targeted boilerplate, but I’ve not yet been able to find any technical resources.

My first thoughts were:

  • Are these just massive VPLS networks?
  • Are they just giant L2 networks?

I can’t imagine that either of the above would scale particularly well.

I’m looking for any books / papers / config guides / magic tomes / etc on the subject.

Can anyone point me in the right direction?


In New Zealand we have a nationwide government sponsored FTTH open access network based on GPON and XGSPON. There are local access companies (LFC or Local Fibre Company) that handover double tagged layer2 that the various service providers (RSP or Retail Service Provider) can either pick up themselves in each region or pay a third party to backhaul to where they need to get to. This has resulted in a very competitive market to the retail consumer (very low margin to the retail service provider, this has resulted in broadband often being a “loss leader” used to bundle other phone/power/entertainment services). Technically each end user has an ONT provided by the LFC and the RSP leases a layer2 service on a per-port basis that is delivered double tagged at the service provider handover point. This means each 1gig or 10gig port on the ONT can be used to present a different RSP service to the end user if desired. The handover point (10G/100G with or without LAG) can provide 4096x4096 possible layer2 services to end user ports.

The end result of this is almost ubiquitous high quality 100/20, 1000/500 up to 4000/4000 being available to the end user. Retail for an unlimited 1000/500 service to the end user is about 70USD/month with 4000/4000 (XGSPON) being about $130USD/month. Here’s a speedtest from my primary home workstation -

I work for a company that provides backhaul from the various regions around the country to the various retail service providers. We take the double tagged LFC handovers and transport them over MPLS to where the various service providers want them delivered to. Normally we will hand them over triple tagged with the third tag added to represent each handover point and the first two tags being preserved from the LFC handover. This works pretty well overall.

I think part of why you're not finding a lot of technical information is that things built under the name "open access network" come in all shapes, colors, and sizes.

Things I've seen:

* Fully open glass: Point-to-point fiber from central location(s) to each individual service point. Providers co-lo at the central location(s) and bring their own backhaul to them (which the open network operator may offer turnkey separately) and buy usage of the fiber from the open network operator. They can run whatever they want on it. CPE is provided by the service provider. Multiple strands can enable multiple service providers simultaneously at the same customer prem, but the number of fibers grows reeeally fast.

* Central split open PON: Each service point has one or two fibers to central split cabinets in the field, and service providers buy customer glass to the splitter cabinet, space in the splitter cabinet for passives, and backhaul glass to each cabinet in areas they want to serve. They run whatever they want on it via co-location in central PoPs which need not be active for everyone in the facility (could be another layer of a hierarchical split), but the cost/availability of the baukhaul glass generally implies a PON architecture (but it could be e.g. WDM-PON since you can put whatever you want at the field split locations). CPE is provided by the service provider. Multiple strands between the field split and customer prem, if available, enables the customer to buy service from multiple providers with each provider having their own glass path and CPE.

* Open L2 access: Could be active-E, xPON, or some mix. The open network operator hands off customer services on either a VLAN/VLL-per-customer basis or just adds customers to your VLAN/VPLS(s) on demand. Service providers establish either a central NNI (open network operator handles regional backhaul) or co-locates with their own backhaul as above. This architecture favors customers being able to buy service from multiple provides at once via a multi-port CPE ONT handled by the open network operator, but sometimes that responsibility gets delegated out to the service provider. The open network operator is responsible for bandwidth management, etc.

* Private label of central services: There's fundamentally just one network (per type of service, e.g. IP, linear video, voice, etc.), and service providers just private label it. They may or may not even get separate blocks of number resources. The open network operator is really responsible for everything except maybe end-user billing.

Most people seem to be focusing on open L2 type systems as it provides the most rapid deployment of service with lots of "providers", but it requires you have a competent administrator of the open-access network which is often not the case. I've also seen open glass (of both forms) especially with geographically larger deployments. I've had munis and HOAs inquire about all types. I'm not sure I've ever seen anyone actually deploy the private label only variety since it doesn't actually provide much beyond just directly selling the whole-stack service yourself, but it's been talked about.

A lot of DSL got deployed back in the day on a similar basis with service providers either co-locating in COs and buying dry pairs or re-selling someone else's DSL product (could be the ILEC or someone who already co-lo'd DSLAMs) with backhaul over ATM on a VPI-per-customer basis to a central NNI.

Linear video has proven to be problematic on them since it's difficult/expensive to get retrans rights for small geographic areas which can make it tough to get providers willing to come in and offer it without some exclusivity arrangements. Thankfully, demand for linear video is rapidly dropping as people abandon it entirely or switch to over-the-top alternatives.

My general "favorite" where someone does want to do open access is the central split open PON model with ample excess fiber on both the backhaul and customer legs, but it is situational of course.