ITNW 1333 -- Microsoft Networking Essentials
Course Syllabus
 
 
 

Chapter 11

Enterprise and Distributed Networks

 
 

Modems in Network Communication

  • MOdulator/DEModulator = modem
  • Hayes compatible
    • early 1980 Smartmodem was built
  • Serial RS232 computer port
  • RJ-11 phone plug
 
 

Modem Speed

Standard

Bps

Year Introduced

V.22bis

2400

1984

V.32

9600

1984

V.32bis

14,400

1991

V.32ter

19,200

1993

V.FastClass (V.FC)

28,800

1993

V.34

28,800

1994

V.42bis

57,600

1995

V.90

115,200

1998
Note: The term baud (oscillation of a sound wave that carries one bit of data) no longer represents bits per second. New compression technologies have increased the number of bits per second beyond the number of oscillations per second
 

Asynchronous Modems

 

Synchronous Modems

 
 

Carriers

  • Which modem & connection to choose
  • Modem communication considerations
    • Throughput
    • Distance
    • Cost
  • Options through PSTN
    • Public Switched Telephone Network
  • Dial-up
  • ISDN
  • Dedicated lease lines
 

Dial-Up

  • Use existing telephone lines
  • Temporary connection to network
  • Line quality varies greatly
  • Generally limited to 28,800 bps
  • Experimental to 115Kbps
 

ISDN

  • Integrated Services Digital Network
  • Basic Rate Interface (BRI)
    • Two 64 Kbps B, one 16 Kbps D channels
  • Primary Rate Interface (PRI)
    • Twenty three B & one D channels
  • B for voice/data & D for signal control
 

Dedicated Lease Lines

  • Continuous connection
  • Between two sites
  • Higher speed
  • 56 Kbps to 45 Mbps
  • Higher cost
 
 

Remote Access Networking

 

Remote Access Server

  • Installed with NT server
  • RAS
  • Allows up to 256 remote clients
  • Windows 95 client Dial Up Networking
  • DUN
 

RAS and DUN Protocols

  • Serial Line Internet Protocol (SLIP)
    • Supports only TCP/IP
    • Has no error correction
  • Point To Point Protocol (PPP)
    • Dynamic link where modem becomes NIC
    • Multiple protocols IP, IPX, NetBEUI
 
 

Creating Larger Networks

  • Physically expand the network
  • Segment network to filter traffic
  • Extend network to connect separate LANs
  • Connect two separate computer environments
 

Devices to Expand the Network

  • Repeaters
  • Bridges
  • Routers
  • Brouters
  • Gateways
  • Switches
 

Repeaters

 

Bridges

  • Connect two segments
  • Limit traffic, remove bottlenecks
  • Connect different architectures
    • Ethernet & Token-Ring
  • Forward packets between architectures
  • Work at the data link layer of OSI model
  • Read network addresses at the MAC
  • Media Access Control sublayer
  • Decide which segment address is on
  • Decide whether or not to forward packet
  • Two methods to determine segment:
    • Transparent bridging a.k.a. learning bridges
      • Ethernet networks
      • Bridging table
    • Source routing
      • Token-Ring networks
      • Packet source provides address
 

Advantage of a Bridge

Disadvantage of a Bridge

Easily extend network distances

Slower than repeaters

Filter traffic to ease congestion

Pass broadcast packets

Connect networks with different media

More expensive than repeaters

Translation bridges can connect different network architectures

 
 

Routers

 

Routable Protocols

  • TCP/IP
  • IPX/SPX
  • DECNet
  • OSI
  • DDP (AppleTalk)
  • XNS
 

Nonroutable Protocols

  • NetBEUI
    • Microsoft
  • DLC
    • HP printers, IBM mainframes
  • LAT
    • Local Area Transport, DEC network
 

Advantages of routers

Disadvantage of routers

Connect networks of different physical media and network architectures

More expensive and more complex than bridges or repeaters

Choose the best path for a packet through an internetwork

Only work with routable protocols

Reduce network traffic by not forwarding broadcasts or corrupt packets

Dynamic routing updates create network traffic

 

Slower than bridges because they must perform more intricate calculations on the packet
 

Brouters

  • Choose mode by type of packet received
  • Maintain bridging & routing tables
  • More efficient use of the network
  • Helpful in hybrid networks
  • Use may outnumber bridges and routers
 

Gateways

 

Advantages of gateways

Disadvantages of gateways

Connect completely different systems

More expensive than other devices

Dedicated to one task and perform that task well

More difficult to install and configure

 

Greater processing requirements means less speed than other devices
 

Switches

  • A high speed multiport bridge
  • Replacing repeaters & routers in UTP
  • Intelligent hub maintains a bridging table
  • Dedicated bandwidth to each port
  • Each port can use full 10Mbps