Broadband networks; Internetworking; The Internet


  1. Announcements

  3. Review:
    1. Build me a FDDI network
    2. When would I use FDDI over ethernet or token ring?
    3. List the basic building blocks (hardware technologies) required for any local area network


  4. Baseband vs. Broadband
    1. To Modulate or Not to Modulate, That is the Question.
      1. 3 Camps:
        1. voice people
        2. Data people
        3. Community access television people (CATV)
      2. Motivations:
    2. Problems with Putting Everything on the LAN
    3. Alternative Integration Solutions:
      1. PBX
      2. Baseband Cable Systems
        1. Arguments in Support of Baseband:
  1. Broadband Cable Systems
    1. Definitions
      1. Any wide area communications channel >=56 Kbps. Although analog facilitieis can technically be broadband, they are rarely described that way. T1 services and below are typically categorized as narrowband, and T3 and up are typically categorized as wideband.
      2. Any of a specific set of service offerings from common carriers (e.g., SMDS. T1, T3, ATM, frame relay, SONET, etc.)
      3. The specific technique of using coax cable to carry multiple channels over LAN distances. Broadband signaling on coax cable for a LAN is unique.
  2. Broadband LAN architecture
    1. Broadband LANs are based on the same underlying technology as cable television.
    2. Broadband is inherently analog.
    3. Broadband modems
    4. What can Broadband cable systems actually support?
    5. Downsides of Broadband Cable Plants
  3. Broadband Services
    1. Why we're looking to broadband
    2. Some Terms
      1. Connection oriented=>connection is established for the duration of the session
      2. Connectionless=>connection is only present during data transmission or receipt
      3. Mesh Network=>network of leased-line connections (see pg 456)
      4. Cloud=>In network diagrams, the place where internetworking connections take place. Presented as a cloud because this is where the Public Data Network takes over.
      5. Logical/Virtual Connection/Path=>not quite real. Bandwidth is shared among multiple users for maximum efficiency. Old-style party line is a good example.
      6. Permanent Virtual Circuit=>one path or circuit is established and used for the duration of the session. Only available in connection-oriented services like frame relay and ATM.
      7. Switched Virtual Circuit=>path or circuit is established each time a transmission flows through. Available in SMDS, which is not a connection-oriented service.
      8. Latency=>delay in delivery or transmission due to bandwidth inavailability or network device bottlenecks.
    3. Characteristics of Broadband Services
      1. Fast=>
      2. Packet=>
      3. Services=>
  4. ADSL and HDSL
    1. ADSL: Asynchronous Digital Subscriber Lines
      1. Offered by LECs
      2. 1.544 Mbps downstream connection
      3. 64Kbps upstream channel
      4. See Ameritech Q&A page at:
    2. High bit-rate Digital Subscriber Lines
      1. Eliminates repeaters in the T1 local loop for up to 12000 feet
      2. 2 pair of 784Kbps UTP, for a 1.544 Mbps connection
      3. T1 service over standard UTP
  5. Switched Multimegabit Data Service (SMDS)
    1. About
      1. D=>high-speed connectionless public, packet-switching service. Packets are cells. Generally delivered over SONET ring, with maximum effective radius of about 30 miles. Optimized as a medium-access control standard for use with dual, counter-flowing unidirectional bus subnetworks (subnets of MANs)
    2. SMDS Advantages
    3. SDMS Disadvantages
  6. Frame Relay
    1. About
      1. D=>network interface, or access standard, residing at OSI layers 1 and 2. Similar to supercharged X.25.
    2. Frame Relay Advantages
    3. Frame Relay Disadvantages
    4. Applications
  7. ISDN
    1. About
      1. Integrated Services Digital Network
      2. D=>networking service based on telephony networks that provides end-to-end digital connectivity to support a wide range of services, including voice, and non-voice services.
      3. Why do we need ISDN?
    2. ISDN Architecture
      1. Basic Rate Interface
      2. Primary Rate Interface
    3. Bearer Services
    4. Clear Channel Capability
    5. Applications
    1. Synchronous Optical Network/Synchronous Digital Network=>set of international standards for broadband communications over single-mode fiber, allowing manufacturers to build equipment to support full interconnectivity and interoperability.
    2. Topology
    3. SONET Pipe:
      1. Virtual Paths or Virtual Containers=>end-to-end communication paths or routes or circuits that carry traffic from one point to another. Path is not fixed or dedicated. VP consists of many virtual tributaries.
      2. Virtual Tributaries=>carry one form of signals, such as DS-1, DS-2, or Ds-3, within a byte-interleaved frame. VTs can be channelized or unchannelized.
      3. Virtual Channels=>exist within VTs. If VT is carrying a T1 frame, there will be 24 Virtual Channels set up to handle each channel of the channelized T1.
    4. Advantages of SONET
  9. ATM
    1. About
      1. D=>fast packet, connection-oriented, cell switchin technology for broadband signals. Supports voice, video, data, fax, and images. Access rates defined from DS3/OC1 (51.84 MBps) to OC96 (4.976 Gbps).
    2. Access
    3. Transmission facilities
    4. Quality of Service
    5. ATM Advantages
    6. Disadvantages
  10. Internet
    1. What is the Internet and who "owns" it?
      1. Network of networks
      2. Developed by Department of Defense
      3. Frame Relay and SONET backbones
      4. NSF=>MCI
    2. Connectivity from a LAN
      1. Router/Gateway required
      2. Physical connection points
        1. csu/dsu
      3. Physical connectivity
        1. ISDN
        2. Fractional T1
        3. T1 or greater
    3. Gaining Internet Connectivty
      1. Public Access Providers
        1. NetIllinois
        2. QalCom
      2. Internet Service Providers
        1. MCS
        2. InterAccess
        3. Tezcat
        4. AOL
    4. Firewalls
      1. Servers that block incoming and outgoing traffic by IP address