Networking

							Networking


Chapter 12
Areas of Discussion

•   OSI Model
•   IP Addressing
•   Local Area Networks
•   Wide Area Networks
•   Remote Access
•   Network Management
•   Voice and Data Convergence
•   Additional Resources
OSI Model

•   Application Layer
•   Presentation Layer
•   Session Layer
•   Transport Layer
•   Network Layer
•   Data Link (MAC) Layer
•   Physical Layer
Internet Protocol Suite

• What is a protocol?
  – Set of rules and standards that ease the
    interconnectivity of devices of different platforms and
    from different vendors.
  – TCP/IP: Transmission control protocol/Internet protocol
     •   Application Layer (session, presentation, and application)
     •   Transport Layer (transport)
     •   Inter-network (network)
     •   Link (physical and data link)
IP Addressing

• IP addressing: 32-bit string
  –   4 eight-bit numbers
  –   Each eight-bit number is an octet
  –   Can be value of 0 to 255
  –   Network address and host address
  –   Subnet masks
  –   Class A 1-126
  –   Class B 128-191
  –   Class C 192-223
A Shortage of Addresses

• American Registry for Internet Numbers (ARIN)
  1997 registers and administers IP numbers for
  North America.
• Other global regions are managed by RIPE NCC,
  LACNIC, and APNIC.
• Running out of numbers
• Solutions:
  – Network Address Translation
  – IPv6
• Network Address Translation
  – Translates your internal network addresses into the
    public address assigned to your Internet connection.
  – However, there are agreed upon standards for private
    internal networks:
     • 10.0.0.0 – 10.255.255.255 (1 class – A range)
     • 172.16.0.0. – 172.31.255.255 (16 class – B ranges)
     • 192.168.0.0. – 192.168.255.255 (256 class – C ranges)
• IPv6: IP next generation or IPng
  – IPv4 allows for approximately 4 billion addresses
  – IPv6 allows for 340 undicillion (340 followed by 36
    zeroes) addresses.
  – Changes from a 32-bit address to a 128-bit address
• DNS: Domain Name Server: translates
  alphanumeric names to IP addresses
  – A DNS allows you to name your servers and devices
    and translates those names to IP addresses
  – The DNS environment of the Internet allows you and
    your users to use meaningful names (like browser
    URLs), as opposed to IP addresses.
• DHCP
 – Dynamic Host Configuration Protocol (DHCP):
   automatically assigns IP addresses.
 – Some devices need to have static addresses such as
   printers, which recognize MAC addresses
 – Greatly eases the burden of IP administration
Local Area Networks

• Network that connects the devices in one
  geographic location.
• As a general rule, a LAN’s boundary is
  telecommunication facilities and a router.
• LAN is dependent on needs, plans for future
  growth, and changes of use.
• Ethernet is the de facto standard.
• LAN Design
  – Goals of a good LAN design
     • Maximizing the efficiency of network traffic
     • Reliability
     • Manageability: growth and traffic patterns, bottlenecks, and
       problem areas
     • Flexibility
  – Location of devices
  – Traffic volume
• The Core Network
  – Single device or multiple devices
  – Features of Switches
     • Number and types of connections required
     • Total throughput
     • Redundancies
     • Forwarding methods: store and forward, cut-through
       forward, fragment free
     • Layer 2 and Layer 3
     • Chassis or Stackable
• Wireless LANs
  – WiFi (wireless fidelity) up to 300 feet
  – Eliminates need for running cabling
  – Wireless security
     • Wired equivalent privacy (WEP): the first method developed
       for securing wireless LANs. “Key” (either 40 or 128 bits in
       length). Easy to hack.
     • WiFi protected access (WPA): Temporal Key Integrity
       Protocol (TKIP), developed overcome weakness of WEP.
       Changes the key with each data frame. Built-in
       authentication
– Wireless security
   • Hidden SSID: Service Set Identifier: Environment with
     multiple wireless networks, SSID identifies which network is
     which.
   • MAC Filtering: allow only predetermined devices to connect
     to it by specifying the MAC address of authorized devices.
   • Internet Access only: connects to Internet only. Must use
     other remote access solutions to connect to private internet.
• Bluetooth: shorter range of typically 30 feet
  – Is considered a wireless alternative for USB-type
    connections while WiFi is considered a wireless
    alternative for Ethernet connections.
Wide Area Networks

• Connects the remote locations via
  telecommunication facilities (T-1 lines, ISDN, etc.)
• Span large distances
• Design based upon geography, traffic flow, and
  volumes.
Difference between LANs and WANs


• Majority of LAN costs are up-front capital
  expenditures of cable installation and hardware.
• Majority of WAN costs are recurring operating
  costs of lines.
• Considerations for a WAN
  – Need for high-speed transmissions
  – Need for 24/7 operations
  – User needs: locations, travel
  – Backup/fail-over capabilities and facilities: most critical
    connections need to be most reliable
  – Installation delays: the more sophisticated the line, the
    more time your telecommunications vendor will need to
    install it.
• Routers: key devices for WANs
  – Forwards data to another network
  – Occurs at Layer 3 of OSI model
  – Acts as transfer point between two networks to pass
    data packets between them
  – Routing table is used by the routers to determine the
    best path to use for each data packet
• Key WAN Technologies
  – Connectivity Options
     • Point-to-point circuits: leased, dedicated, and private lines
        – T-1 line: 24 channels of 64 Kbps, for an aggregate
          throughput of 1.544 Mbps
        – T-3 line: (often referred to as DS3) transmission speeds
          of 44,736 Mbps, via 672 circuits, each of 64 Kbps
          transmission
        – Fractional T-1 or fractional T-3. See page 329.
• continued
  – Connectivity Options
     • Dial-up
        – Plain Old Telephone System (POTS) line
        – Based on analog technology
        – 56 Kbps
• continued
     • ISDN: Integrated Services Digital Network
        –   Digital transmission over standard copper telephone wire
        –   Basics Rate Interface (BRI): homes and small businesses
        –   Two 64Kbps B channels and one 16 Kbps D channel
        –   B channel carries the data and D channel carries signaling
        –   Throughput total of 128 Kbps
        –   Primary Rate Interface (PRI) larger sites
        –   23 B channels and one 64 Kbps D channel
        –   Throughput total of 1.4 Mbps
        –   Dial their calls similar to the way POTS lines do
        –   Often used for back up of T1-lines
• continued
     • Broadband (cable modems and DSL)
        – past definition: connection type that can carry more than one signal
          at a time
        – Today: high-speed connection to the Internet
        – Offer faster downstream rate than upstream rate
        – Always on
        – DSL: digital subscriber line. Phone company offering to bring high-
          speed Internet to homes and small businesses over standard copper
          phone lines.
        – Always on
        – High-speed downstream
        – Must be within few miles of telephone company central office
• Continued
    • Broadband (cable modems and DSL)
       – Cable TV companies deliver high-speed Internet access.
       – Speed is often 384 Kbps upstream and 2 Mbps downstream
• Continued
    • Packet switching (ATM and frame relay)
       –   Breaks up data transmission into small packets
       –   Asynchronous Transfer Mode (ATM) and Frame Relay:
       –   Frame relay speeds between 56 Kbps and 45 Mbps
       –   ATM speeds between 25 to 622 Mbps
       –   Used for delay-sensitive applications like voice and video plus data
       –   Frame relay and ATM provided by telecom carriers
       –   ATM : Sustained Information Rate (SIR)
       –   Frame Relay: Committed Information Rate (CIR)
       –   Data below this level will be guaranteed delivery; if dropped, will be
           retransmitted
• Continued
    • High-speed Internet
       –   Connection to the Internet
       –   Point-to-point circuits
       –   Broadband
       –   Fees for line to your office
       –   Fees for Internet access
    • Virtual Private Networks (VPNs): using security and
      tunneling techniques, establish a VPN via the Internet to
      connect sites
       – Split tunneling: remote offices connect to the Internet and establish a
         VPN back to headquarters while local Internet access goes directly
         to Internet
Remote Access

• Companies are now available 24/7
• The Choices
  – Your connection path
     • Internet access
     • Direct access
     • Handheld device
  – What you Connect to
     • Web-based applications
     • Remote control
     • Remote node
     • Handheld device applications
     • Replication (synchronization)
• Questions
  – What are the needs of your customers?
  – Based upon the answer, select your options
• The Connection Path
  – Three options for connection
     • Through the Internet
     • Through a direct connection
     • Through the air waves using a handheld device
• Continued
  – What You Connect To
    • Web-based applications
       – Microsoft’s outlook Web Access (OWA) or iNotes from Lotus Notes
    • Remote control
       – Establish a connection
       – Establish a remote control session
    • Centralized Remote control
       –   Terminal servers
       –   Remote node
       –   Handheld device applications
       –   Replication (Synchronization): use applications and items are saved,
           when connected, can transmit to main headquarters.
• Advantages:
   – reduces time needed for connection
   – Users can work regardless of whether or not they have connectivity
• Disadvantages:
   – Applications must be same for best results: XP vs. Vista
• Continued
  – Security for Remote Access
     • Firewalls
     • VPNs: used for connections that come via the Internet to encrypt
       the data.
         – Point-to-point Tunneling Protocol: losing popularity
         – L2TP: combines two secure communication protocols: Cisco Systems’ Layer
           Two Forwarding (L2F) and Microsoft’s PPTP.
         – IPSec: algorithms and a public key to encrypt the data at Layer 3. Also uses
           Internet Key Exchange (IKE) protocol to authenticate the two end nodes in
           the communication session.
              » Two modes: transport mode, only the data portion of the packet is
                encrypted, but not the header
              » In tunnel mode: both the header and the data are encrypted
• Continued
    • Radius: Remote Authentication Dial-In User Service
      (RADIUS)
       – User attempts to dial in to a remove access device, device
         authenticates, user is routed to network; otherwise; disconnected.
Network Management

• Finding problems
  – Vendors generally offer management functionality that
    allows you to collect data about the network
  – Can purchase management tools
• Management Tools
  – SNMP: Simple Network Management Protocol: works
    by sending messaged, called protocol data units
    (PDUs), to various devices on the network. SNMP-
    compliant devices, called agents, store data about
    themselves in Management Information Bases (MIBs)
    and return this data to the SNMP requesters.
• Management Tools
  – RMON: remote monitoring takes SNMP to the next
    level. While SNMP manages devices, RMON can
    monitor the actual network traffic, collect statistics, and
    record history.
• Quality of Service (QoS) and Bandwidth
  Management
  – QoS allow you to prioritize types of traffic or
    applications
  – Gives priority to time-sensitive applications
  – Built into a variety of hardware and software products
    such as Cisco and Microsoft
• Continued
  – You can
    • Classify different types of traffic (video, audio, data)
    • Prioritize mission-critical and time-sensitive traffic
    • Load balance across multiple resources for redundancy and
      performance.
Voice and Data Convergence

• Voice Over Internet Protocol (VoIP)
• Pros
  –   Administer and manage one infrastructure
  –   Handsets in any location
  –   Not really occurring any additional costs
  –   Telecommunters use laptops for telephone service
  –   Data integration
• Cons
  –   VoIP relatively new technology
  –   Audio-quality problems
  –   Interruption of service with network
  –   Software upgrades for handheld devices
  –   Service in the event of power outage
  –   Latency
  –   Voice people need to learn about network
Summary Slide

•   OSI Model
•   Internet Protocol Suite
•   IP Addressing
•   Local Area Networks
•   Wide Area Networks
•   Remote Access
•   Network Management
•   Voice and Data Convergence