Networking Concepts - Introduction to Network Security - Lecture Slides, Slides of Network security

Download Networking Concepts - Introduction to Network Security - Lecture Slides and more Slides Network security in PDF only on Docsity!

Networking Concepts

LAN

• Concepts
  • Attenuation, Noise
• Hardware
  • Repeater, Amplifier
  • Bridge, Router, Gateway, Switch, Hub
  • Twisted pair, Coaxial cable, Fiber optics
  • Server, Workstation
  • Wireless access point
• Topology
  • Bus, Tree, Star, Ring

Communications Hardware

• Repeater
  • Extends distance limitation on networks (both voice and data)
  • Filters noise
  • Regenerates signals
  • For twisted pair wire, repeaters are placed every 100 meters
• Amplifier
  • Extends distance limitation on networks (both voice and data)
  • Amplifies both signal and noise

Communications Hardware

• Bridge

• Connects two LANs using same protocol
• Single path between LANs
• Minimal sophistication

• Router

• Connects multiple LANs using same protocol
• Choice of paths between LANs
• Mainstay of internetworking

Communications Hardware

• Switch

• Connects multiple LAN segments using the

same protocol

• Connections may use twisted pair, coaxial

cable, or fiber optics wiring

• Faster than bridges
• Enables simultaneous communication between

multiple network segments

Ethernet

• Ethernet was developed jointly by Xerox, Intel,

and DEC in 1980

• DEC (Digital Equipment Corporation) a computer

company that specialized in mini-computers in the

1970s. It was acquired by Compaq and Compaq

merged with HP.

• This was the first commercial LAN system
• Ethernet is a simple protocol to implement
• Ethernet addresses the layers 1 and 2 functionality

for the OSI model

• Ethernet standard is very close to IEEE 802.

standard, but has some minor differences

Ethernet frame format

6-bytes 6-bytes 2-bytes Variable length 4-bytes

Destination address

Source address

length (^) User data CRC-

Ethernet diagram

PC

PC

PC Segment 1

Repeater

PC-B

PC-A

PC-C Segment 2

Bus topology diagram

PC1 PC2 PC3 PC

Tap for a new node

Tree topology

• Tree topology is a variation on bus topology

• A special node is designated as root

• The primary reason for this topology is to

segment nodes so that not all nodes need to

listen to packets broadcast on a segment

• This adds a layer of security in the form of

unwanted nodes not listening to the network

traffic

• Speeds up data transfer since there will be

fewer nodes on each segment

Star topology

• This is another variation on bus topology
• This has a central hub, a passive device
• Star is a logical bus and a physical ring
• Hub has ports in multiples of 8. Multiple hubs can be connected in a daisy chain format
• Easy to add nodes to the network and remove nodes from the network
• Central node does switching between nodes
• Multiple nodes can communicate simultaneously without collision
• Potential problem is the single point of failure for the network when the central node fails

Star topology diagram

Ring topology diagram

• PC 1 Hub PC - PC - PC - PC 2 PC
  • PC 8 PC
    • PC
      • PC
        • PC
  • PC
• PC
• PC

OSI 7-layer model

Source Destination

Application

Presentation

Session

Transport

Network

Data link

Physical

Application

Presentation

Session

Transport

Network

Data link

Physical