158.235 Networks, Security and the Internet
LAN – Local Area Network – room, building, group of PC’s that share a
BN – Backbone Network – less than a few kms, high speed backbone
linking together organizational LANs.
MAN – Metropolitan Area Network – more than a few kms, connects
LANs and BNs, size of a city.
WAN – Wide Area Network – Global scale, far greater than 10 kms.
Intranet vs. Extranet
LAN that uses the internet technologies within an organization. Only
available to those in the organization.
Eg. The Warehouse intranet for staff members.
LAN that uses the internet technologies across an organization, open to
those invited users outside the organization.
Eg. The Warehouse website for customers to browse products.
Multi-Layer Network Models
Open System Interconnection Model (OSI Model): Historic
Created by International Standards Organisation(ISO) in 1984.
1. Physical 5. Session
2. Data Link 6. Presentation
3. Network 7. Application
“Please Do Not Touch Steve’s Pet Alligators”
Internet Model: Popular
Created by DARPA in 1970’s
Developed to solve the problem of internetworking
1. Physical 4. Transport
2. Data Link 5. Application also covers session and
3. Network presentation layers
“Please Do Not Touch Alligators” Protocols
Used by the network model layers
Sets of standardi