Computer Networking (Appendix C)
Objectives
• Understand networking fundamentals
• Understand network services and transmission
media
• Understand network software and hardware
Networking Fundamentals
• Network consists of:
– Servers – provides services
– Clients – requests services
– Peers – both requests and provides services
• Types of networks
– Server-centric networks
– Peer-to-peer networks
Networking Fundamentals
• Network Services
–
–
–
–
File services
Print services
Message services
Applications services
Networking Fundamentals
• Network Operating System (NOS)
– Two parts:
• System software that runs on the server
• Client software on each workstation
– Examples
•
•
•
•
Banyan Vines
Novell NetWare
Microsoft LAN Manager
LANtastic
Networking Fundamentals
• Transmission Media
– The pathway to send data and information
between two or more entities on a network
– Bandwidth: transmission capacity
– Attenuation: weakening of a signal over distance
– EMI: electromagnetic interference
Networking Fundamentals
• Cable Media
– Twisted pair cable
– Coaxial cable (“coax”)
– Fiber-optic cable
Networking Fundamentals
• Wireless Media
– Infrared line of sight
– High-frequency radio
• Pager – one way wireless
• Cellular phone – two way wireless
• Wireless LANs
– Microwave
• Terrestrial
• Satellite
Network Software and Hardware
• Media access control
– Rules that govern how a workstation gains
access to the network
• Distributed access control
– Token passing
• Random access control
– “Listens” for network traffic
Network Software and
Hardware
• Network topologies
– Star network
– Ring network
– Bus network
A star network topology
• Use: This topology is useful for applications where
processing must be centralized and some can be
performed locally.
• Advantages:
– Easy to lay out and modify.
– It is easy to diagnose problems at individual
workstations.
• Problems:
– Costly, it requires the largest amount if cabling.
– Since all communication pass through the central
computer, the communications in the network will
stop if the host/hub computer stops functioning.
A ring network topology
• Use: This topology is useful in LANs.
• Advantages:
– It does not rely on central host.
– The connecting wire, cable, or optical fiber forms a closed
loop. Data are passed along the ring from one computer to
another and always flow in one direction. The message is
regenerated and passed to the next computer if it is not for
the previous computer. This regeneration process enables
ring networks to cover much larger distances than star or
bus networks.
• Disadvantages:
– A failure of any node on the ring network can cause
complete network failure.
– It is difficult to modify and reconfigure the network.
A bus network topology
• Use: This topology is useful in LANs.
• Advantages:
– It does not rely on central host.
– This network can still function if one of the
computers malfunctions.
– Other advantages: easy to wire, quick response,
less expensive.
• Disadvantages:
• The main disadvantage is bad connection to the cable
can bring down the entire network. Another problem:
collision occurs when 2 nodes send messages
simultaneously.
Network Software and Hardware
• Protocols: Set of rules ( format of
transmitting data, error checking
method, data compression technique)
– OSI model – open systems interconnection
– Ethernet
– TCP/IP
OSI RM
OSI RM
Network Software and Hardware
•
Connectivity hardware
1.
Transmission Media Connectors: T-connector for coax cable and
RJ-45 connectors for twisted pair
2. Network interface card (NIC)
3. Modems
4. Repeaters
5. Hubs
6. Bridges
7. Multiplexers
8. Routers
9. Brouters
10. Channel service units (CSU): buffer between a LAN and a WAN
11. Gateway