5. Demarcs and Perimeter Networks

Part 0⁣5 of Computer Networking Fundamentals: Demarcs and Perimeter Networks

Demarcation and Perimeter Networks

At the end of this episode, I will be able to:

1. Describe the characteristics and importance of demarcation points and perimeter networks.

Learner Objective: Describe the characteristics and importance of demarcation points and perimeter networks.

Description: In this episode, the learner will explore what demarcation points and perimeter networks are as well as what the importance of these technologies are in networking.

• Introduction to Network Infrastructure
  • Demarcation point - The physical point that a carrier's network connection ends and a private network starts (think network boundaries). The term demarcation is often abbreviated demarc.
    • Types of demarcation points
      • Residential - These are utilized in homes, either at the first socket (typically the kitchen) or a junction box on the exterior of the house
      • Business - These demarcation points are either installed on the exterior of the building, or the carrier will install a specialized device within the interior of the building at a main distribution frame (think server closet/datacenter)
    • Demarcation wiring runs either overhead or underground
    • A demarc is important to understand in networks today as this marks the point of responsibility for networked components and service. The carrier's network up to the demarc is the responsibility of the carrier, however the demarc point that connect on the residential or business side is the responsibility of the subscriber.
    • Demarc connections can be fiber, coaxial or PSTN lines
  • Perimeter Network (Screened Subnets) - A logical boundary between a privately owned network and the Internet. There are other names for perimeter networks such as demilitarized zone (DMZ), screened subnet and edge network.
    • Purpose
      • Security - A companies internal network must remain secure and not allow public access. Most organizations will install security devices in the perimeter network to control the flow of inbound and outbound traffic such as firewalls, intrusion detection systems (IDSs), intrusion prevention systems, honeypots or devices called unified threat management systems (UTM) which combine all the previous devices' functionality into one centralized device.