A demarcation point, usually shortened to demarc, is the boundary where a carrier’s responsibility for a circuit ends and the customer’s or building’s responsibility begins. On one side is the carrier’s network, which it installs, monitors and repairs; on the other is the wiring and equipment that you, your landlord or your cabling vendor own and maintain. The demarc is often marked by a carrier device or patch panel in a telecom room, and knowing exactly where it is decides who you call when something breaks.
At a glance
- The demarc is a responsibility boundary, set by the service order, carrier practice and, for some services, regulation.
- It is usually marked by carrier equipment such as a network interface device (NID), optical terminal or small switch, or by a labeled patch panel.
- It may sit at the building’s MPOE, in a shared telecom room, in a meet-me room or inside your suite.
- Cabling from the demarc to your own equipment is often your job, sometimes done as a demarc extension.
- SLA commitments are typically measured up to the demarc, not to your router or desk.
What problem it solves
A circuit passes through many hands on its way to your equipment: the carrier’s outside plant, the building’s entrance and risers, a telecom room, and finally your own cabling and router. When it stops working, each party can reasonably say the fault is somewhere else. The demarc settles that by fixing one point where the carrier’s job ends.
For a buyer, the demarc defines what you are actually buying. The carrier commits to deliver, monitor and repair service up to that point. Anything past it, including the run from a basement telecom room to your suite, is outside the carrier’s responsibility unless you arrange otherwise. Many delays on install day come from a circuit that reached the demarc on time while nobody had planned how to get it from there to the firewall.
How it works
Placement. The carrier sets the demarc when it designs the installation, guided by its own standards, the building’s rules and the service order. In multi-tenant buildings it is commonly at or near the minimum point of entry, where the carrier’s last mile cabling comes in. In single-tenant buildings or premium installs, it may be in the customer’s own equipment room.
Hand-off equipment. For Ethernet and fiber services, the carrier usually installs a device that terminates its network and presents a customer-facing port. This is often called a NID, and it lets the carrier test the circuit remotely up to that point. Some providers treat their managed router as part of the service; in that case, the effective boundary may be the router’s LAN port. The customer premises equipment on your side of the line is yours to supply and support unless the contract says otherwise.
Labeling and documentation. A good install leaves the demarc labeled with the circuit ID and carrier, and records its location on the order. That record is what you will need during an outage or when a second carrier arrives.
Extension. When the demarc is far from your equipment, someone runs cabling to close the gap. That run is a demarc extension, and who does it, who pays for it and who maintains it should be agreed before install day.
Rules. In the US, FCC rules address where the demarc for wireline telephone wiring can be placed, particularly in multi-unit buildings, and give building owners some options. Data services, other countries and individual contracts can follow different practices, so confirm the location for each circuit rather than assuming.
To plan internet circuits for a new or moving office, see our Internet Access solution page.
When it matters for buyers
- Leasing or moving into an office. Ask where carriers typically place their demarc in the building and how circuits get from there to tenant suites.
- Ordering a circuit. Confirm the demarc location on the order, and whether an extension is included, quoted separately or left to you.
- Troubleshooting an outage. Ask the carrier to test to its demarc. If the test is clean, look at the extension, the cabling and your own equipment.
- Adding a second carrier. Knowing where each demarc sits helps you plan separate entrances and avoid sharing a single room or panel.
- Reading an SLA. Availability and repair targets usually apply only to the carrier’s side of the demarc.
Questions to ask vendors
- Where exactly will the demarc be for this circuit, and will that location appear on the order?
- What equipment will you install at the demarc, and does it need power, rack space or a UPS from us?
- Do you offer to extend the demarc to our suite or equipment room, at what cost, and who maintains that run afterwards?
- Can you test the circuit remotely up to the demarc, and will you share the results during a fault?
- If you supply a managed router, where does your support responsibility end?
- How will the demarc and cabling be labeled so our team and the building can identify them?
How it differs from the minimum point of entry (MPOE)
The MPOE is a physical location: where outside carrier cabling enters a building or property, or first becomes accessible. The demarc is a responsibility boundary: where the carrier stops being on the hook. Carriers often put the demarc at the MPOE in multi-tenant buildings, so the terms get used interchangeably, but a demarc can also sit in a tenant’s suite or a meet-me room. When planning a circuit, ask for both locations and for who owns every segment of cabling between them.