Computers require a physical network infrastructure to communicate over. This infrastructure allows and controls communication between computers. Understanding these components and how they work is essential to understanding how data moves through a computer network and to troubleshooting network communication.
Question: Which of these devices is present in your network?
Twisted-pair cabling is the most common type of cabling used on internal corporate networks. A single cable consists of four pairs of wire that are twisted around eachother. Maximum length when used for Ethernet is 100m. Fiber optic cabling carries light pulses rather than electrical signals. This type of cabling is less susceptible to signal deterioration and can be used for longer distances. Multimode fiber uses a plastic core to carry the light pulses, while single-mode fiber uses a glass core. Multimode fiber supports distances up to 2 km for 100 Mbps Ethernet while single-mode fiber supports distances up to 40 km for 10 Gbps Ethernet. Wireless networking is used in corporate networks to support users that roam within a building or within a campus. The primary advantage of wireless networking is lack of cabling requirements. However, wireless access points must be place carefully to ensure that signal strength is strong enough in all areas. Question: What type of media would you implement between two buildings 1 km apart?
Computers on an internal network are connected to a switch that controls network communication. A switch is a layer 2 device that has multiple ports and a computer or another network device can be connected to each port.The switch tracks the location ofeach computer or network device and delivers packets only to the appropriate network port. Question: If a single port in a switch fails, how will network communication be affected?
A router is a layer 3 device that is used to move packets between networks.A routeruses a routing table to keep a list of available networks. A router does not track the location of individual computers. This makes a router more scalable and suitable for tasks such as moving packet on the Internet. Question: If a port on a router fails, how will network communication be affected?
A firewall is a layer 4 device that is used to protect corporate networks. A typical firewall acts as a router between two networks and filters out packets that do not meet the specified criteria. Packets may be filtered based on the source and destination addresses or the application generating the packets.Question: Why is it important to have a firewall between corporate networks and the Internet?
The physical network infrastructure is used to organize computer networks into a logical network organization. The logical organization of computers and network devices makes it easier to understand how the physical network infrastructure is used.
A local area network (LAN) is a network with a single physical location. This location could be a single building or a campus with multiple buildings in close proximity. Question: What controls do you think should be in place to control LAN traffic?
A wide area network (WAN) is used between physical locations, such as a head office and branch office. In general, a WAN has much slower connectivity than within a LAN. For example, a T1 connection between WAN locations operates at 1.5 Mbps versus LAN speeds of 100 Mbps and up. Question: What are some examples of WAN connectivity?
A branch office is a remote location that is connected by WAN links to the head office. Question: What are some examples of branch offices?
Answer the questions in a classroom discussion.
A perimeter network is used to isolate externally accessible resources from the LAN and from the Internet. A perimeter network is formed by using two firewalls. One firewall is located between the Internet and the perimeter network. The second firewall is located between the perimeter network and the LAN. Question: Why would using a single firewall to create a perimeter network be considered less secure than using two firewalls?
Remote access is the process used to give users access to LAN resources from outside the office. This type of connectivity is increasingly important as more users become mobile and work from home and other locations outside the office Question: Why do users need access to data and applications remotely?
Active Directory provides a single repository of information that is used for network management. A workgroup is a peer-to-peer network without a centralized security database.
A domain is a logical grouping of objects such as: • User accounts. These are required for users to log on and access network resources. Information such as e-mail addresses and mailing addresses can be stored as part of a user account. • Computer accounts. These are required for a computer to participate in the domain and become part of the security infrastructure. To log onwith a domain user account, you must use a computer that has a computer account in the domain. • Groups. These are used to organize users and computers into sets for assigning permissions to resources. Using groups make is easier to manage access to resources such as files.
Lesson 4: Network Infrastucture
Discussion: Network Components Common Types of Media What is a switch? What is a router? What is a firewall?
Is a LAN communicate device Tracks the location of computers
Moves packets between networks Tracks networks not computers Is required between physical locations Is sometimes referred to as a gateway
Is a router with rules Controls inbound and outbound communication Protects hosts behind the firewall
What is a LAN? What is a WAN? What is a Branch office Discussion: branch office challenges What is a perimeter network? What is remote access?
Is a single physical location Has fast network connectivity Has typically minimal control
Is used between physical locations Has slower connection speed than a LAN Is more expensive than LAN connectivity Uses connectivity typically provided by another company
A branch office is remote location that is connected by WAN links to the head office with A generally small number of users Limited local support resources Limited local computing resources
What are the challenges of branch office communication?