Demarc Extension Services

The circuit is installed. The carrier says it is live and tested. And nothing at your rack is connected to it, because the handoff sits in a locked room in the basement three floors down and the provider’s obligation stopped at that wall. Closing that gap is a demarc extension.

The boundary this page sits on

A demarc extension is a single path carrying a single carrier circuit, from the point where the provider’s responsibility ends to the equipment that will use the service. That is a much narrower scope than a building’s general-purpose cabling system, which is structured cabling installation, and narrower than the horizontal runs serving the building’s own devices, covered on Ethernet and data cabling. What makes this work its own service is ownership. On one side of the demarcation point a fault is the carrier’s problem; on the other side it is yours, and an extension that is not documented turns every outage into an argument about which side the fault is on.

Find the actual handoff first

Before anything is pulled, the handoff has to be identified rather than assumed. That means the minimum point of entry, the network interface device or smart jack the carrier terminated on, and the physical interface presented there. A T1 handed off on an RJ-48C is a different extension from a fiber handoff on an SFP with LC connectors, and both are different from an Ethernet electrical handoff. The circuit ID matters as much as the connector, because it is the string you will read back to the carrier at two in the morning.

Carrier rooms rarely look like the records. Tenants come and go, cable is abandoned in place rather than removed, and the labeling in a shared entrance facility reflects whoever was last in the room. Identifying the correct pair or strand out of that, and tagging it at both ends before it is disturbed, is where the risk in this job concentrates.

The route is a property question before it is a cabling question

The path from the entrance facility to your suite usually crosses space you do not control. In older buildings in New York and Boston especially, the riser is landlord-controlled, congested with decades of cable nobody removed, and reachable only with a building engineer escorting the work during an approved window. Permission, escort and access hours often set the schedule more than the cable pull does. Anywhere the extension penetrates a rated floor or wall, the penetration is restored with a listed firestop system, and in a shared riser that is a condition of being allowed back.

Copper, coax or fiber

Distance decides this more than anything else. A balanced twisted-pair extension has to live inside the same 100-meter channel limit as any other Ethernet run, which a basement-to-upper-floor path in a large building can exceed on its own. Beyond that reach, the extension is run in fiber with media conversion at one or both ends. Fiber is also the right answer where the two ends sit on separate electrical services or in separate buildings, since it avoids carrying a difference in ground potential between them, and it leaves headroom if the circuit speed is upgraded later without another pull.

Turn-up, and who owns the ticket afterward

An extension is not finished when the cable is terminated. It is finished when the service has been proven end to end and the record says who owns what:

• The circuit ID labeled identically at the carrier end and at the customer equipment
• Certification results for the extension itself, so its performance is established independently of the carrier’s own test
• A loopback or provider test coordinated with the carrier while a technician is still on site
• Photographs of both ends, and a named contact for escalation on each side of the demarcation point

The point of that last item is simple. When the circuit drops six months from now, whoever picks up the phone should be able to say in one sentence where the carrier’s responsibility ends and where the extension begins.

Scope an extension

Have the carrier order, the circuit ID, the demarc location and the equipment location ready. Call (888) 360-0035 or reach TekRoute at 6201 Fairview Rd, 2nd Floor, Charlotte, NC 28210.