The middle mile: Glossary of broadband technology terms |

The middle mile: Glossary of broadband technology terms

Access point

The physical point for transmission by fixed wireless broadband access.


The link between cell towers and the POP where they tie into the provider's core network.

Cable head end

The cable provider's main facility from which to broadcasts television channels through a distribution network of coaxial cable.

Recommended Stories For You

Carrier-neutral location (CNL)

A POP, colocation center or other physical location owned by a neutral third party that allows ISPs to connect and exchange traffic.

Central office (CO)

The location that houses the telecommunication company's telephone exchange and other equipment. The point-to-point DSL connection from a home or business heads to the CO.

Core network

The backbone of a telecommunications network that connects primary nodes.

Dark fiber

Optical fiber that is not lit or not activated for use.

Digital subscriber line (DSL)

A type of broadband service offered over twisted pair copper phone lines. It allows a constant connection by utilizing a wide band so as not to interrupt phone service.

Digital subscriber line access multiplexer (DSLAM)

Located in the CO, a DSLAM connects multiple customer DSL lines to the wider network.


Access to a source of connectivity when one of the provider's main sources fails or is interrupted. It allows for traffic to be diverted around cut lines or interference.


Optical fiber is a thin, flexible medium that conducts pulses of light with each pulse representing a bit. It is immune to electromagnetic interference.

Indefeasible right of use (IRU)

An agreement between operators of fiber or other communications cable. The bandwidth acquired can be used unconditionally for the time of the agreement, and the purchaser assumes all costs. The agreement is an exclusive, irrevocable right.

Internet service provider (ISP)

A company that provides access to the Internet.

Last mile

The network segment from the middle mile provider to the residence or business. The local ISPs that supply customers are last mile providers. In Steamboat, this includes CenturyLink, Comcast, Zirkel Wireless and Resort Broadband. CenturyLink acts as both a middle mile and a last mile provider in Steamboat. A last mile network can be fiber, copper, both or a mix of the two plus wireless.

Middle mile

The network segment between the core network and last mile providers. It can range in length from tens of miles to thousands of miles.

Network tiers

Networks operated by ISPs are separated into tiers loosely defined by what other networks each communicates with. Tier 1 networks are the largest and peer with other Tier 1 networks in addition to supplying access to smaller networks. Tier 2 networks contract for access to Tier 1 networks and peer with other Tier 2 networks. Tier 3 networks are smaller still and contract access from Tier 2 networks.

Open access transport

Provisions of the Broadband Technology Opportunities Program require grantees allow private telecommunications and broadband service providers access to use of the network.

Peering site

The POP where networks peer.


The settlement-free (without payment) exchange of traffic between networks of equal tiers communicating at a POP. Networks may peer at multiple POPs.

Point of presence (POP)

A point where routers from ISPs can provide access to their networks and connect to other ISPs.


A structure to receive and transmit cellular signals or radio waves for fixed wireless access.

Source: "Computer Networking: A Top-Down Approach," fifth edition, James F. Kurose and Keith W. Ross, 2010, Addison Wesley

Go back to article