Technical resources for Open Access Fiber Networks?

Thu Jun 10 19:58:07 UTC 2021

On 6/9/21 8:16 PM, Mark Leonard wrote:
> 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?

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.
--
Brandon Martin