Lecture Outline

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Lecture Outline

• LANs VLANs
• Internetworking Devices
• Circuit Switched vs. Packet Switched Services
• Telephony WANs

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Networking Model
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• LANs VLANs

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(No Transcript)
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Switched Ethernet

• The concept behind switched ethernet - and all
  switched media technologies - is simple replace
  the LAN hub with a switch. Each computer now has
  its own dedicated point-to-point circuit.
• Switched ethernet dramatically improves LAN
  performance. However, since much of the network
  traffic is to and from the server, the circuit to
  the server is often the network bottleneck.

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1.       
Types of Ethernet
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Virtual LAN Design

• Switches also have enabled the creation of
  Virtual LANs (VLANs). VLANs are usually faster
  and provide greater opportunities to manage the
  flow of traffic on the LAN.
• VLANs are groups of computers in an intelligent
  switched network.

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Port-Based VLANs
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MAC-Based VLANsLayer-2 VLANs

• MAC-based VLANs use the data link layer addresses
  to form the VLAN groups.
• The advantage is that they are simpler to manage
  when computers are moved.

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IP-Based VLANsLayer-3 VLANs

• IP-based VLANs use the network layer address
  (i.e. TCP/IP address) to form the VLAN groups.
  Layer-3 VLANs reduce the time spent reconfiguring
  the network when a computer is moved as well.
• Some layer-3 VLANs can also use the network layer
  protocol to create VLAN groups. This flexibility
  enables even greater precision in the allocation
  of network capacity.

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Application-Based VLANsLayer-4 VLANs

• Application-based VLANs use the application layer
  protocol in combination with the data link layer
  and network layer addresses to form the VLAN
  groups.
• The advantage is a very precise allocation of
  network capacity.

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• Internetworking Devices

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Repeaters

• A repeater is the simplest type of hardware that
  can be used to connect network segments.
• Receives a signal and regenerates it.
• Operates at the physical layer of OSI model.
• Transparent to data flow.
• Repeaters are used mainly to extend coverage of a
  network by extending the length of any segment.

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Bridges
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Routers
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Gateways
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Comparison of Linkage Alternatives
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Comparison of Linkage Alternatives
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Comparison of Linkage Alternatives
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• Circuit Swithced Packet Switched Services

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Circuit Switched Services
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Packet Switched Services
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Packet Switched Services
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Local loop

• The local loop is the connection from the
  telephone instrument to the switching equipment
  located at the Telecos central office.

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Attenuation

• Attenuation is the reduction of signal strength
  (or voltage) as the signal propagates along the
  circuit.
• This means the voltage level of the signal is
  lowered as the signal moves down the wire.
• To keep the signal at acceptable levels, a
  repeater or amplifier is placed along the circuit
  to amplify the signal.

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Multiplexing
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Frequency division multiplexing

• Frequency division multiplexing (FDM) places
  several signals onto one circuit by placing each
  at a different part of the (analog) frequency
  spectrum.

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Time division multiplexing

• Time division multiplexing (TDM) shares the
  circuits time allocation.
• Simplistically, TDM physically switches from
  originator to originator to share the time
  available, and the receiving unit does the same
  in synchronism.

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Statistical Time Division Multiplexing

• A special form of TDM.
• Most common use has been the terminal-host
  configuration, where the terminals attached to
  the CPU are not always transmitting.

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Synchronous Optical Network (SONET)

• The synchronous optical network (SONET) has
  recently been accepted by the U.S. standards
  agency (ANSI) as a standard for optical (fiber)
  transmission at gigabits per second speed.
• The international telecommunications standards
  agency (ITU-T) also recently standardized a
  version of SONET under the name of synchronous
  digital hierarchy (SDH). The two are very
  similar and can be easily interconnected.

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A PBX Network
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Centrex verses PBX considerations
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Centrex verses PBX considerations
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Narrowband Integrated Services Digital Network

• Narrowband ISDN offers two types of service
• Basic rate interface (BRI, basic access service
  or 2BD) provides two 64 Kbps bearer (B) channels
  and one 16 Kbps control signaling (D) channel.
• One advantage of BRI is it can be installed over
  existing telephones lines. (if less than 3.5
  miles).
• Primary rate interface (PRI, primary access
  service or 23BD) provides 23 64 Kbps B
  channels and one 64 Kbps D channel. (basically
  T-1 service)

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Broadband Integrated Services Digital Network

• The second generation of ISDN is called Broadband
  ISDN (B-ISDN). B-ISDN is a circuit switched
  service and is backwardly compatible with ISDN.
• B-ISDN is currently offered in three services
• Full duplex channel at 155.2 Mbps.
• Full duplex channel at 622.08 Mbps.
• Asymmetrical service with two simplex channels
  (Upstream at 155.2 Mbps, downstream at 622.08
  Mbps).

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T Carrier Circuits

• T Carrier circuits are dedicated digital circuits
  and are the most commonly used form of dedicated
  circuit services in North America today.
• Instead of a modem, a channel service unit (CSU)
  or data service unit (DSU) are used to connect
  the circuit into the network.

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The Mobile Telephone System

• First-Generation Mobile Phones Analog Voice
• Second-Generation Mobile Phones Digital Voice
• Third-Generation Mobile PhonesDigital Voice and
  Data

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Advanced Mobile Phone System
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Global System for Mobile Communications

• GSM uses 124 frequency channels, each of which
  uses an eight-slot TDM system

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Third-Generation Mobile PhonesDigital Voice and
Data

• Basic services an IMT-2000 network should provide
• High-quality voice transmission
• Messaging (replace e-mail, fax, SMS, chat, etc.)
• Multimedia (music, videos, films, TV, etc.)
• Internet access (web surfing, w/multimedia.)

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Packet Switched Services

• A Datagram is a connectionless service which adds
  a destination and sequence number to each packet,
  in addition to information about the data stream
  to which the packet belongs. Packets may follow a
  different route, and are reassembled at the
  destination.
• In a Virtual circuit the packet switched network
  establishes an end-to-end circuit between the
  sender and receiver. All packets for that
  transmission take the same route over the virtual
  circuit that has been set up for that
  transmission.

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X.25

• The oldest packet switched service is X.25, a
  standard developed by ITU-T. X.25 offers
  datagram, switched virtual circuit, and permanent
  virtual circuit services.
• Although widely used in Europe, X.25 is not
  widespread in North America. The primary reason
  is transmission speed, now 2.048 Mbps (up from 64
  Kbps).

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Frame Relay

• Frame relay is a newer packet switching
  technology that transmits data faster than X.25.
  It differs from X.25 and traditional networks in
  three important ways
• 1. Frame relay only operates at the data link
  layer.
• 2. Frame relay networks do not perform error
  control.
• 3. Frame relay defines two connection data rate
  that are negotiated per connection and for each
  virtual circuit as it is established. (Committed
  information rate and Maximum allowable rate).

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Asynchronous Transfer Mode (ATM)

• ATM has three important difference from frame
  relay
• ATM uses fixed packet lengths of 53 bytes (5
  bytes of overhead and 48 bytes of user data),
  which is more suitable for voice transmissions.
• ATM provides extensive quality of service
  information that enables the setting of very
  precise priorities among different types of
  transmissions (i.e. voice, video e-mail).
• ATM is scaleable. It is easy to multiplex basic
  ATM circuits into much faster ATM circuits.

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Commonly Available Services

• Type of Service Approximation Data
  Rates
• Dialed Circuit Services
• Voice-grade 28.8 Kbps to 56 Kbps
• Dedicated Circuit Services
• Voice-grade 28.8 Kbps to 56 Kbps
• T-carrier 65 Kbps to 274 Mbps
• SONET 52 Mbps to 622 Mbps

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Commonly Available Services

• Type of Service Approximation Data
  Rates
• Circuit Switched Services
• Narrowband ISDN 128 Kbps to 1.5 Mbps
• Broadband ISDN 155 Mbps to 622 Mbps
• Packet-Switched services
• X.25 56 Kbps to 2 Mbps
• Frame relay 56 Kbps to 45 Mbps
• ATM 1.5 Mbps to 622 Mbps
• SMDS 56 Kbps to 45 Mbps

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Internode Business Connect

• An alternative to both Internet-based Virtual
  Private Networks, and traditional Frame Relay
  and ISDN Wide Area Networks.
• IBC is a private IP network, with a very high
  data delivery ratio, a very low latency (or
  round trip transit delay), and minimal latency
  variation (or jitter). These parameters combine
  to provide the necessary Quality of Service to
  meet the demanding requirements of internal
  business networks.
• The other significant benefit of the IBC
  private IP network is security. The network has
  multiple levels of security, including physical
  POP security, strict authentication requirements
  and L2TP traffic separation. This security is
  fully managed by Internode staff.

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Internode Business Connect
Sample Network