5 Networking Fundamentals Flashcards
Six types of networks:
Local area network (LAN)
Wide area network (WAN)
Personal area network (PAN)
Metropolitan area network (MAN)
Storage area network (SAN)
Wireless local area network (WLAN)
What is LAN ?
LANs (local area network) simply link computers in order to share resources within a closed environment.
What is (WAN) ?
A wide area network (WAN) . Whereas LANs are limited to single buildings, WANs can span buildings, states, countries, and even continental boundaries. It’s safe to think of a WAN as multiple dispersed LANs connected
together.
What is PAN ?
Personal Area Networks (PANs) used in reference to Bluetooth networks.
wireless personal area network (WPAN)
Whenever two Bluetooth devices get close enough to each other, they can communicate directly with each other—no central communication point is required. This dynamically created network is called a
piconet. A Bluetooth-enabled device can communicate with up to seven other devices in one piconet. Two or more piconets can be linked together in a scatternet. In a scatternet, one or more devices would serve as a bridge between the piconets.
What is a MAN ?
Metropolitan Area Networks (MAN). For those networks that are larger than a LAN but confined to a relatively small
geographical area, there is the term metropolitan area network (MAN). A MAN is generally defined as a network that spans a city or a large campus. For example, if a city decides to install wireless hotspots in various places, that network could be considered a MAN. The difference between MAN and WAN is who has responsibility for managing the connectivity.
In a MAN, a central IT organization, such as the campus or city IT staff, is responsible. In a WAN, it’s implied that you will be using publicly available communication lines, and there will be a phone company or other service provider involved.
What is a SAN ?
A storage area network (SAN) is designed to do exactly what it says, which is to store
information. This network won’t have client computers or other types of servers on it.
It’s for storage only.
Denefits to SAN:
Dedicated SANs relieve network loads. With a SAN, all storage traffic, which may
include huge data files or videos, is sent to a specific network or network segment,
relieving traffic on other network segments.
SANs offer fast data access. Most SANs use high-speed Fibre Channel connections,
which allow for very fast access even for huge files.
SANs are easily expandable. In most cases, it’s a matter of connecting a new storage
unit, which might even be hot-swappable
(removed and replaced without powering
down the system), and a few clicks to configure it. Then it’s ready to go.
Block-level storage is more efficient. Most
SANs are configured to store and retrieve data in a system called block storage. This
contrasts with the file-based access systems you’re probably used to, such as the ones in Windows and macOS.
Block storage allows a file to be broken into more manageable chunks rather than
being stored as one entity. This allows the operating system to modify one portion of
a file without needing to open the entire file. In addition, since data reads and writes
are always of the same block size, data transfers are more efficient and therefore faster. Latency with block storage is lower than with other types of storage.
What is WLAN ?
A wireless local area network (WLAN) is simply a LAN, but one in which clients connect wirelessly rather than through
network cables.
Wireless clients on a network typically access the network through a wireless access point
(WAP). The WAP may connect wirelessly to another connectivity device, such as a wireless router, but more likely uses a wired connection to a router or switch.
Primary Network Components:
Servers
Clients or workstations
Resources
Every network requires two more items to tie these three components together: a network operating system (NOS) and some kind of shared medium (wired or wireless connectivity).
What are Servers ?
They provide a link to the resources necessary to perform any task. The link that the server provides could be to a resource existing on the server itself or to a resource on a client computer.
Servers offer networks the capability of centralizing the control of resources and security, thereby reducing administrative difficulties. They can be used to distribute processes for balancing the load on computers and can thus increase speed and performance. They can also compartmentalize files for improved reliability. That way, if one server goes down, not all of the files are lost. Servers can perform several different critical roles on a network. For example, a server that provides files to the users on the network is called a file server. Likewise, one that hosts printing services for users is called a print server. Servers can be used for other tasks as well, such as authentication, remote access services, administration, email, and so on.
Networks can include multipurpose and single-purpose servers. A multipurpose server can be, for example, both a file server and a print server at the same time. If the server is a single-purpose server, it is a file server only or a print server only.
What is a dedicated server ?
A dedicated server is assigned to provide specific applications or services for the network and nothing else. Because a dedicated server specializes in only
a few tasks, it requires fewer resources than a nondedicated server might require from
the computer that is hosting it. This savings may translate to efficiency and can thus be
considered as having a beneficial impact on network performance. A web server is an
example of a dedicated server; it is dedicated to the task of serving up web pages and
nothing else.
What is a non-dedicated server ?
Nondedicated servers are assigned to provide one or more network services and local access. Nondedicated servers can be used to direct network traffic and perform administrative actions, but they also are often used to serve as a frontend for the administrator to work with other applications or services or to perform services for more than one network. For example, a dedicated web server
might serve out one or more websites, whereas a nondedicated web server serves out websites but might also function as a print server on the local network or as the administrator’s workstation.
What are workstations ?
Workstations are the computers on which the network users do their work, performing
activities such as word processing, database design, graphic design, email, and other office or personal tasks. A workstation is basically an everyday computer, except for the fact that it is connected to a network that offers additional resources. In network terms, workstations are also known as client computers. As clients, they are allowed to communicate with the servers in the network to use the network’s resources.
What are network resources ?
Printers and other peripherals
Disk storage and file access
Applications
What are Network Operating Systems ?
Network Operating Systems PCs use a disk operating system that controls the filesystem and how the applications communicate
with the hard disk. Networks use a network operating system (NOS) to control the communication with resources and the flow of data across the network. The NOS runs
on the server. Some of the more popular NOSs are Linux, Microsoft’s Windows Server series (Server 2022, Server 2019, and so on), and macOS Server.
Two resource access models:
peer-to-peer
client-server
Peer to Peer:
In a peer-to-peer network (referred to as workgroups), the computers act as both service providers and service requestors.
The peer-to-peer model is great for small, simple, inexpensive networks. This model can be set up almost instantly, with little extra hardware required. Generally speaking, there is no centralized administration or control in the peer-to-peer
resource model. Every workstation has unique control over the resources that the computer owns, and each workstation must be administered separately. However, this lack of centralized control can make administering the network difficult; for the same reason, the network isn’t very secure. Each user needs to manage separate passwords for each computer on which they wish to access resources, as well as set up and manage the shared resources on
their own computer. It may not be easy to locate resources. The person who is in charge of a file may have moved it without anyone’s knowledge. Also, the users who work under this arrangement need more training because they are not only users but also administrators.
Client-Server:
Client-Server Resource Model (also known as server-based model) is better than the peer to-peer model for large networks (more than 10 computers) that need a more secure environment and centralized control. Server-based networks use one or more dedicated, centralized servers. All administrative functions and resource sharing are performed from this point. This makes it easier to share resources, perform backups, and support an almost unlimited number of users. This model also offers better security than the peer-to-peer model. However, the server needs more hardware. In addition, it requires specialized software (the NOS) to manage the server’s role in the environment. With the addition of a server and the NOS, server-based networks can easily cost more than peer-to-peer resource models. However, for large networks, it’s the only
choice.
5 Network Topologies:
Bus
Cheap. Easy to install.
Difficult to reconfigure. A break in the bus disables the entire network.
Star
Cheap. Very easy to install and reconfigure.
More resilient to a single cable failure.
More expensive than bus.
Ring
Efficient. Easy to install.
Reconfiguration is difficult. Very expensive.
Mesh
Best fault tolerance.
Reconfiguration is extremely difficult,
extremely expensive, and very complex.
Hybrid
Gives a combination of the best features
of each topology used.
Complex (less so than mesh, however).
Bus Topology:
A bus topology is the simplest. It consists of a single cable that runs to every workstation. This topology uses the least amount of cabling. Each computer shares the same data and address path. With a bus topology, messages pass through the trunk, and
each workstation checks to see if a message is addressed to it. If the address of the message matches the workstation’s address, the network adapter retrieves it. If not, the message is ignored.
Star Topology:
A star topology (also called a hub-and-
spoke topology) branches each network device off a central device called a hub or a switch, making it easy to add a new workstation. If a workstation goes down, it does not affect the entire network; if the central device goes down, the entire network goes with it. Because of this, the hub (or switch) is called a single point of failure.
Star topologies are very easy to install. A cable is run from each workstation to the
switch. The switch is placed in a central location. Star topologies are more expensive to install than bus networks because several more cables need to be installed, plus the switches. But the ease of reconfiguration and fault tolerance (one cable failing does not bring down the entire network) far outweigh the drawbacks. This is by far the most commonly installed network topology in use today.
Ring Topology:
In a ring topology, each computer connects to two other computers, joining them in a circle and creating a unidirectional path where messages move from workstation to workstation. Each entity participating in the ring reads a message and then regenerates it and hands it to its neighbor on a different network cable.
The ring makes it difficult to add new computers. Unlike a star topology network, a
ring topology network will go down if one entity is removed from the ring. Physical ring
topology systems rarely exist anymore, mainly because the hardware involved was fairly expensive and the fault tolerance was very low.
Mesh Topology:
The mesh topology is the most complex in terms of physical design. In this topology, each device is connected to every other device. This topology is rarely found in wired LANs, mainly because of the complexity of the cabling.
Because of its design, the physical mesh topology is expensive to install and maintain.
Cables must be run from each device to every other device. The advantage you gain is high fault tolerance. With a mesh topology, there will always be a way to get the data from source to destination. The data may not be able to take the direct route, but it can take an alternate, indirect route. For this reason, the mesh topology is often used to connect multiple sites across WAN links. It uses devices called routers to search multiple routes through the mesh and determine the best path. However, the mesh topology does become inefficient with five
or more entities because of the number of connections that need to be maintained.
Hybrid Topology:
The hybrid topology is simply a mix of the other topologies. Most networks today are not only hybrid but heterogeneous. (They include a mix of components of different types and brands.) The hybrid network may be more expensive than some types of network topologies, but it takes the best features of all the other topologies and exploits them.
