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