Internet Access Types

---

• Establishing WAN provider link
  • must terminate access provider’s cable to the premises
    • called the demarcation point (demarc) or minimum point of entry (MPOE)
      • marks end of telco responsibility for cabling
  • attach a modem and routing equipment
    • called customer premises equipment (CPE)
  • demarc and CPE should be installed in a secure location
    • need access controls
    • location referred to as entrance facilities in TIA/EIA structure cabling standards

T-Carrier

• enables
  • voice traffic to be digitized for transport around the core of the telecommunications network
  • other types of digital data to be transported and could be provisioned directly to subscribers as a leased line
• based on time division multiplexing (TDM)
  • assigns each circuit (or channel) a time slot
  • Each 64 Kbps channel provides enough bandwidth for a digitized voice call
    • single 64 Kbps channel is known as a DS0 or narrowband link
• For leased line data services
  • foundation level of T-carrier is the DS1 or T1 digital signal circuit
    • comprises 24 channels multiplexed into a single 1.544 Mbps full-duplex digital connection
      • can be used for voice and data
    • can be multiplexed to provide even more bandwidth
    • At the Data Link layer
      • T1 leased lines use either
        • High-Level Data Link Control (HDLC)
        • Point-to-Point Protocol (PPP)

Digital Subscriber Line

Digital subscriber line (DSL) is a technology for transferring data over voice-grade telephone lines.

• referred to as the local loop
• DSL modem is installed as CPE
  • typically as a multifunction “wireless router”
    • RJ11 WAN port connects to the provider’s phone jack
  • can be supplied as
    • separate appliances
    • plug-in cards for routers
  • filter (splitter) must be installed on each phone point
    • prevent noise from affecting either voice calls or the DSL link
• multiple flavors of DSL:
  • Asymmetrical DSL (ADSL)
    • provides a fast downlink but a slow uplink
    • various iterations
      • latest (ADSL2+) offers
        • downlink rates up to about 24 Mbps
        • uplink rates of 1.25 Mbps or 2.5 Mbps
  • Symmetric DSL
    • same uplink and downlink speeds
    • of more use to businesses and for branch office links
      • where more data is transferred upstream than with normal Internet use

Cable Internet

• usually available along with Cable Access TV (CATV)
• networks are sometimes described as hybrid fiber coax (HFC)
  • combine a fiber optic core network with coax links to CPE
• more simply just described as cable broadband
• Installation of a cable modem:
  • same general principles as for a DSL modem
  • Ethernet cable connects the cable modem to the customer’s router
  • short segment of coax connects the WAN port to the provider network
  • coax links all premises in a street with a Cable Modem Termination System (CMTS)
    • routes data traffic via the fiber backbone to the ISP’s point of presence (PoP) then to the Internet
• Data Over Cable Service Interface Specification (DOCSIS)
  • supports downlink speeds of up to
    • 38 Mbps (North America)
    • 50 Mbps (Europe)
  • supports uplinks of up to 27 Mbps
  • DOCSIS version 3 allows the use of multiplexed channels to achieve higher bandwidth