Communications

  1. INTRODUCTION (p. 381)
    1. OSI Reference Model
      In an effort to standardize telecommunication the OSI (Open Systems Interconnect) model was developed. The seven layer model has the physical connection the lower layer and applications protocols at the upper layers. This model is widely accepted as a basis for the understanding of how a network protocol stack should operate. It also serves as a reference for comparing network stack implementations.

      Application

      Network applications such as terminal emulation and file transfer.

      Presentation

      Formatting of data and encryption

      Session

      Establishment and maintenance of sessions

      Transport

      Provision of reliable and unreliable end-to-end delivery
      TCP CRC

      Network

      Packet delivery, including routing
      Routers

      Data Link

      Framing of units of information and error checking
      Switches

      Physical

      Transmission of bits on the physical hardware
      Repeaters and NICS.


    2. Basic Principles of Networks (381).
      Three components of ALL networks.
      1. A network interface, such as a network card or software for a dial-up modem, in each computer to act as a doorway for information to flow in and out. 
        C:\ACCWeb\BCIS>ipconfig /all

Windows IP Configuration

        Host Name . . . . . . . . . . . . : ask
        Primary Dns Suffix  . . . . . . . :
        Node Type . . . . . . . . . . . . : Hybrid
        IP Routing Enabled. . . . . . . . : No
        WINS Proxy Enabled. . . . . . . . : No
        DNS Suffix Search List. . . . . . : austin.rr.com

Ethernet adapter Wireless Network Connection:

        Media State . . . . . . . . . . . : Media disconnected
        Description . . . . . . . . . . . : LAN-Express AS IEEE 802.11g miniPCI
Adapter
        Physical Address. . . . . . . . . : 00-0E-9B-4E-C5-FF

Ethernet adapter Local Area Connection:

        Connection-specific DNS Suffix  . : austin.rr.com
        Description . . . . . . . . . . . : Realtek RTL8139/810x Family Fast Ethernet NIC
        Physical Address. . . . . . . . . : 08-00-46-EE-2B-81
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . . . . : Yes
        IP Address. . . . . . . . . . . . : 192.168.1.101
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.1.1
        DHCP Server . . . . . . . . . . . : 192.168.1.1
        DNS Servers . . . . . . . . . . . : 24.93.41.125
                                            24.93.41.126
        Lease Obtained. . . . . . . . . . : Wednesday, July 12, 2006 10:05:29 AM

        Lease Expires . . . . . . . . . . : Tuesday, July 18, 2006 10:05:29 AM
      2. A connecting device is needed to physically connect the computers together 
        C:\ACCWeb\BCIS>netstat -r

Route Table
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 0e 9b 4e c5 ff ...... LAN-Express AS IEEE 802.11g miniPCI Adapter - Packet Scheduler Miniport
0x10004 ...08 00 46 ee 2b 81 ...... Realtek RTL8139/810x Family Fast Ethernet NIC - Packet Scheduler Miniport
===========================================================================
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0      192.168.1.1   192.168.1.101       20
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
      192.168.1.0    255.255.255.0    192.168.1.101   192.168.1.101       20
    192.168.1.101  255.255.255.255        127.0.0.1       127.0.0.1       20
    192.168.1.255  255.255.255.255    192.168.1.101   192.168.1.101       20
        224.0.0.0        240.0.0.0    192.168.1.101   192.168.1.101       20
  255.255.255.255  255.255.255.255    192.168.1.101   192.168.1.101       1
  255.255.255.255  255.255.255.255    192.168.1.101               2       1
Default Gateway:       192.168.1.1
===========================================================================
Persistent Routes:
  None
      3. Some sort of communications medium, either wired or wireless, that carries information back and forth is necessary.

  2. PEER-TO-PEER HOME NETWORK (p. 382)
    1. Home Network Components
      1. An Ethernet network card in every computer.
      2. A home router as a connecting device.
      3. Cat 5 cables to connect the network devices together.
      4. Windows or Linux, which will serve as the network operating system.
    2. Wireless Access to Your Home Network
      1. WiFi is the usual means of connecting computers wirelessly.
      2. Types 802.11a is five times faster than 802.11b, but doesn't work as well as a and g
      3. Types 802.11b and 802.11g are compatible, but 802.11g is faster - as fast as 802.11b
      4. Bluetooth is used mostly for connecting devices wirelessly, rather than for a whole network.

  3. INTERNET ACCESS (p. 385)
    1. Connecting
      1. Telephone or Dial-Up Connection
      2. Digital Subscriber Line (DSL)
      3. Cable Modem
      4. Internet over Satellite
      5. Wireless Internet Connection
    2. Connected
      1. DNS Name translation 
        C:\ACCWeb\BCIS>nslookup codered.austincc.edu
Server:  dns-cac-lb-01.texas.rr.com
Address:  24.93.41.125

Non-authoritative answer:
Name:    m20677144061.austincc.edu
Address:  206.77.144.61
Aliases:  codered.austincc.edu
      2. Is a host connected? 
        C:\ACCWeb\BCIS>ping mit.edu

Pinging mit.edu [18.7.22.69] with 32 bytes of data:

Reply from 18.7.22.69: bytes=32 time=70ms TTL=239
Reply from 18.7.22.69: bytes=32 time=70ms TTL=239
Reply from 18.7.22.69: bytes=32 time=68ms TTL=239
Reply from 18.7.22.69: bytes=32 time=81ms TTL=239

Ping statistics for 18.7.22.69:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 68ms, Maximum = 81ms, Average = 72ms
      3. How is traffic directed? 
        C:\ACCWeb\BCIS>tracert mit.edu

Tracing route to mit.edu [18.7.22.69]
over a maximum of 30 hops:

  1     8 ms     7 ms    10 ms  10.64.160.1
  2     8 ms     8 ms     7 ms  gig2-4.austtxa-rtr2.austin.rr.com [24.27.12.89]
  3     7 ms     7 ms    17 ms  srp0-0.austtxrdcsc-rtr2.austin.rr.com [24.27.12.50]
  4    10 ms     9 ms    10 ms  . [24.93.33.150]
  5    17 ms    16 ms    17 ms  son0-1-0.hstqtxl3-rtr1.texas.rr.com [24.93.37.22]
  6    17 ms    16 ms    20 ms  tenge-2-4.car1.Houston1.Level3.net [4.79.88.25]
  7    16 ms    17 ms    16 ms  ae-11-11.car2.Houston1.Level3.net [4.69.132.234]
  8    64 ms    54 ms     *     ae-5-5.ebr1.Atlanta2.Level3.net [4.69.132.238]
  9     *        *        *     Request timed out.
 10    75 ms     *       72 ms  ae-3.ebr1.NewYork1.Level3.net [4.69.132.90]
 11    66 ms   149 ms    66 ms  ae-1-51.bbr1.NewYork1.Level3.net [4.68.97.1]
 12    71 ms    69 ms    70 ms  so-3-0-0.mp1.Boston1.Level3.net [209.247.9.125]
 13    69 ms    73 ms    70 ms  ae-12-55.car2.Boston1.Level3.net [4.68.100.131]
 14    74 ms    79 ms    69 ms  4.79.2.2
 15    69 ms    70 ms    71 ms  W92-RTR-1-BACKBONE.MIT.EDU [18.168.0.25]
 16    80 ms    71 ms    69 ms  WEB.MIT.EDU [18.7.22.69]

Trace complete.

    3. LANs, MANs, WANs, WLANs, AND COMMUNICATIONS MEDIA (p. 397)
      1. Classification of Networks by Geographic Distance
        Lans - token ring, ethernet
      2. Telecommunications Media: The Paths That Carry Information
      3. Bandwidth
      4. Wired Communications Media
      5. Wireless Communications Media
      6. Infrared and Omnidirectional Microwave for Short Distances
      7. Directional Microwave for Medium Distances
      8. Satellites for Long Distances

    4. COMMUNICATIONS SERVICE PRIVIDERS (p. 401)
      1. Key Considerations for Communications Media