Introduction to Integrated Fiber in the Loop (IFITL/FITL)

Author: Lawrence Baldwin
Created: 15-Nov-2001
Updated: 17-Feb-2002

What is Fiber-to-the-Curb (FTTC)?

This is "start-of-the-art" technology...pushing fiber optic termination closer and closer to the home itself. Fiber optic cables extend all the way to a pedestal that serves a small number of homes (e.g. 4-8). From the pedestal Voice, Video, and Data is delivered to the home using twisted pair cabling (voice/data) and coax (video).

What is IFITL?

IFITL = Integrated Fiber in the Loop

IFITL is an implementation of FTTC by Marconi Communications which delivers integrated voice, Digital TV, and high-speed data (PCDATA).

PCDATA which is simply 10Mbps Ethernet delivered to your doorstep. You can't buy "PCDATA" itself because there are no tarrifs for that class of service. Instead Bellsouth sells a throttled version (1.5Mbps down/ 256Kbps up) of PCDATA as "Fast Access". Some call this "DSL over Fiber", but this is a misnomer as there is no DSL signalling involved at all...it's Ethernet, period.

IFITL is deployed to thousands of homes in Atlanta and South Florida, but represents a very small proportion of total phone lines.

What is FITL?

FITL = IFITL without the video and data services (e.g. no PCDATA).

If you are in the unfortunate circumstance of being located in a sub-division serviced by FITL, you are ironically, at a major disadvantage. Remember, DSL requires copper cabling, a DSL modem in your home AND a DSL modem on the other end of the copper (a DSLAM). Since FITL pushes fiber to the curb, the only copper that exists is between your home and the pedestal....and their ain't no DSLAMS in the pedestals.

Marconi (the maker if IFITL gear) is working on DSL line cards for the pedestals:

Marconi MX

The good news is that if/when MX is deployed, you will get FANTASTIC DSL service. The shorter the DSL copper loop, the higher the sync rates. With IFITL, the loop length is the distance from your home to the ONU (usually < 500ft). The bad news, is that converting an existing FITL installation to support MX is very expensive...probably too expensive to justify.

Happen to snap the above pictures during construction in a Forsyth County, GA subdivision (Three Chimney's Farm). Note: Optical Network Unit (ONU) only has OIU-41, thus Voice only.

Covered
Main Cover Removed
Internal Chassis

Note: Upper left-hand interface card determines the type of IFITL features that are available:

OIU-41 - Voice Telephony ONLY (FITL)
OIU-43 - Voice Telephony + ONE Digital T1 circuit
OIU-45 - Voice Telephony, Digital TV, and 4 ports of PCDATA (10Mbps Ethernet) (IFITL)
OIU-48 - Voice Telephony, Digital TV, and 8 ports of PCDATA (10Mbps Ethernet) (IFITL)

17-Feb-2002: UPDATE

I have recently learned about about the existence of the OIU-43 interface card for the pedestal.
This card adds the ability to provision traditional T1 (1.5Mbps) data service to any FITL customer (I had previously assumed that no such service was available).
At first glance this may not seem exciting as T1 service is generally cost-prohibitive for consumer users (e.g. $750 - 1500/month). However I'm aware of offerings from two providers which could make use of this FITL capability:
CBeyond Communications - Atlanta, Dallas, Denver Only
Covad TeleXtend Service - Nationwide

Though the Cbeyond service is currently only available in three markets, the value proposition is pretty staggering: Full T1 service, static IP, 5 POTS phone lines (via Voice-over-IP), 2000 minutes of long distance, conference calling, calling card for $550/month (1 yr. contract). I currently have this service on order, so I should have some hands on feedback shortly. In my case, the long-distance savings and the ability to drop two of my existing phone lines means that my net cost for full T1 service will be less than $350/month.

Covad's Telextend service is also delivered over a T1 local loop. In the central office it terminates into one of Covad's existing DSLAMS (DSL access multiplexors). Internet access is then acheived through Covad's ATM network (the same network they use to provide DSL service). So although this is a T1 local loop, actual throughput will be subject to the Quality of Service options used to provision the connection across their ATM network. I could not get details from Covad on what kind of ATM PVC (Permanent Virtual Circuit) would be used. If it a CBR (constant bit rate) with a high value (e.g. 1.5Mbps), then this service should provide equivalent T1 throughput. However, if they use UBR (unspecified bit rate), then I'd be very wary as you'd be competing for shared bandwidth with their existing DSL users. The Covad service also doesn't have any of the voice features that Cbeyond has, but when compared to traditional T1 services they cost about 50% less.

Disclaimer: I hold an equity position on Covad Communications (COVD). If you are considering using either of these services, please do you own due diligence!