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by Dinesh Thakur

The MAN network (Metropolitan Area Network) is a high-speed network (broadband) that covers larger geographic area such as city (tens of kilometers) or districts than local area network (LAN) but smaller than wide area network (WAN) and providing the ability to integrate multiple services through the transmission of data, voice, and video, on transmission media such as copper, fiber optics, and microwaves.

The term is applied to the single network such as a cable television network, or it can be a way of connecting a certain number of LANs in a more extensive network so that resources can share from LAN to LAN and from device to device. For example, a company can use a MAN to connect the LANs of all its offices scattered around the city. Local libraries and government agencies often use a MAN to connect to citizens and private industries. It may also connect MANs within a larger area than LAN. The geographical limit of a MAN may span a city.

 
by Dinesh Thakur

WAN is the acronym for, Wide Area Network and refers to a network used to connect different equipments from remote areas. This technology connects sites that are in diverse locations. Wide Area Networks (WANs) connect larger geographic area, such as New York, Canada, or the world. The geographical limit of WAN is unlimited. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of network. Hence, a WAN may be defined as a data communications network that covers a relatively broad geographic area to connect LANs together between different cities with the help of transmission facilities provided by common carriers, such as telephone companies. WAN technologies function at the lower three layers.            

 
by Dinesh Thakur

what is lan: It is a privately-owned network and stands for local area network. A network is a group of computers and other devices connected so they can pass information back and forth. The local area network (LAN) is a network which is designed to operate over a small physical area such as an office, factory or a group of buildings up to a few kilometers in size. LANs very widely used in a variety of computers to share resources (e.g., printers) and exchange information.



 
by Dinesh Thakur

A Distributed computing is a model of computation that is firmly related to Distributed Systems, refers to as multiple computer systems located at different places linked together over a network and use to solve higher level computation without having to use an expensive supercomputer. Distributed system is called, When collection of various computers seems a single coherent system to its client, then it is called distributed system.



 
by Dinesh Thakur

In general, a computer network composed of one or more servers, workstations, network interface cards, active and passive hub, routers, bridges, gateways, modem, software components like network operating systems, and other application software. The following components widely used for the construction of networks.



 
by Dinesh Thakur

Protocol Definition: It is a digital language through which we communicate with others on the Internet. protocol meaning is that it a set of mutually accepted and implemented rules at both ends of the communications channel for the proper exchange of information. By adopting these rules, two devices can communicate with each other and can interchange information. We can't even think of using the Internet without Protocols. Each protocol is defined in different terms and different use with unique name. Message travel from sender to reciever via a medium (The medium is the physical path over which a message travels) using a protocol.



 
by Dinesh Thakur

Transmission is the method by which computer networks send electrical signals. Data communication is concerned with the process of exchanging data electronically between two communication devices. In a local area network, all communication functions performed through direct cables. Computers located far away are connected through a particular form of the data communication link. The existing telephone or telegraphic network may also use for connecting computers located at remote locations.



 
by Dinesh Thakur

A network is a set of computers connected through a transmission medium, to transmit and receive information from other computers in the network. You can also define a network as a set of devices (often called nodes) connected by links from a physical medium. A node can be a computer, a printer, or any other device capable of sending and receiving data generated by other nodes of the network. The links connected to the devices, often referred to as communication channels.



 
by Dinesh Thakur

We are talking of Wireless LAN (WLAN) that is to say, "Wireless LAN", not to be confused with WAN course. Also referred Radio LAN (WLAN) if the communication medium is the radio (not light infrared for example).The stations of the wireless network can communicate directly with each other, we called Ad Hoc network type, or via relay terminals called APs (Access Points, PA) then it is an infrastructure network. the second type is by far the most common in business.

 
by Dinesh Thakur

Fast Ethernet is based on twisted pair and fiber-optic media systems, and provide high-speed network channels for use in the backbone systems. Fast Ethernet standard uses a particular protocol called auto-negotiation protocol that allows multi-speed Ethernet interfaces to be built. This section deals with 100BaseT.
To speed up the original Ethernet system to 100 Mbps, keeping the original CSMA/CD medium access control mechanism as it is. This approach is called 100Base-T Fast Ethernet. 100BaseT is the IEEE specification for the 100Mbps Ethernet implementation over Unshielded Twisted-Pair (UTP) and Shielded Twisted-Pair (STP) cabling.



 
by Dinesh Thakur

This uses traditional thick baseband coaxial cable in bus topology to connect multiple computers as shown. This single transmission line is called a segment. A coaxial cable 10 mm in diameter, known as a thick coaxial cable is used as a transmission line. A terminator is connected at each end of the cable. Note that proper data communication cannot be assured even if one of these terminators is missing or not properly connected.

 
by Dinesh Thakur

Data link layer is the second layer in OSI reference model and lies above the physical layer. The physical layer provides only a raw bitstream service between computers. The data link layer provides data reliability and provides tools to establish, maintain, and release data link connections among the network nodes.

 
by Dinesh Thakur

The function of the network layer is to provide an end-to-end communication capability to the transport layer, which lies above it as shown in Figure. The OSI reference model specifies that the transport layer need not know the method by which the network layer performs communications.

 
by Dinesh Thakur

A computer network can be classified into different categories. Different criteria are used to classify computer networks. Following are the criteria widely used.



 
by Dinesh Thakur

The access point (abbreviated AP or WAP (for wireless access point)), is a networking hardware device, such as a wireless router, that transmits and receives data (sometimes referred to as a transceiver) and also can serve as the bridge between the WAP device and a wired LAN (Local Area Network), which facilitates connectivity between nearby wireless clients. A WAP (also known as a hotspot) acts as a central transmitter and receiver of wireless radio signals.

 
by Dinesh Thakur

Definition: Ethernet (pronounced "eether net") is a computer network technology which is used in different area networks like LAN, MAN, WAN. Ethernet connecting computers together with cable so the computers can share information. Within each main branch of the network, "Ethernet" can connect up to 1,024 personal computers and workstations.



 
by Dinesh Thakur

What is Hub: Another name of Hub is Ethernet Hub, Repeater Hub, Active Hub and Network Hub. Basically, it is a similar to switch but are not as "smart", 

Hub Definition and Meaning

hub in computer network is used for connecting multiple computers or segments of a LAN. Normally, it is used for Peer to Peer small Home Network. LAN Hub receive data packets (frames) through one port and broadcasts them through all other ports, so that all other computers or other network devices can see all packets.



 
by Dinesh Thakur

Guided means are those that provide a conductor from one device to the other and include twisted-pair cables, coaxial cables, and fiber optic cables. A signal traveling by any of these means is directed and contained by the physical limits of the medium. Twisted pair and coaxial cable use metallic (copper) conductors that accept and carry electrical current signals. Fiber optic is a glass or plastic cable that accepts and transports signals in the form of light.

 
by Dinesh Thakur

Server: A server is a computer program or device in the network that provides resources, data, services, or programs to the client computer such as login requests processing, files access and storage, internet access, printing access and many other types of services. This architecture is called the client-server model. Servers are often referred to as dedicated.



 
by Dinesh Thakur

Definition: Storage area network is abbreviated as SAN. SAN is a network which is designed to attach computer storage devices such as disk array controllers and tape libraries to servers. SAN network can be accessed by multiple computers. It is a secure and high-speed data network. It is also known as SAN storage, SAN network, etc.
We assemble the storage area network by using three principal components:
•    Cabling
•    Host bus adapters
•    Switches
We attach the switches to storage arrays and servers. Generally, all storage arrays were hard disk drives but nowadays flash solid-state drives are used.

A storage area network is most commonly used for:
• For improving the availability of applications
• For enhancing the performance of applications like off-loading storage functions.
• For increasing the utilization of storage and its effectiveness which include consolidating storage resources, tiered storage, etc.
• For improving security and data protection
• For organizing Business Continuity Management activities.

Storage area network

Types of SAN (Storage area network)

The most commonly used SAN protocols are as follows:
Fibre Channel Protocol (FCP): it is the most widely used SAN protocol. It makes use of Fibre Channel transport protocol which is embedded with the SCSI commands. This protocol is deployed in 70 to 80% of the total SAN market.
Internet Small Computer System Interface: It is the another most common type of SAN protocol which is used in the SAN market. It is deployed in 10 to 15% of the total SAN market. This protocol encapsulates with the SCSI command inside an Ethernet frame. It also makes use of an IP Ethernet network for transport purpose.
Fibre Channel over Ethernet (FCoE): it is deployed in less than 5% of the SAN market. It is somewhere similar to iSCSI as it also encapsulated with SCSI command inside an Ethernet frame.
Similarly, it also makes use of IP Ethernet network for transport.
Non-Volatile Memory Express over Fibre Channel (FC-NVMe): it is an interface protocol. We make use of this protocol for accessing the flash storage. We can access this flash storage via PCI Express (PCIe) bus. It supports tens of thousands of parallel queues. Each queue can help tens of thousands of concurrent commands.

SAN Use Cases

We deploy the storage area network in support of business-critical, performance-sensitive applications which are illustrated as below:
Oracle databases: Oracle databases are business-critical. It requires high performance and availability.
Large virtualization deployments using VMware, KVM, or Microsoft Hyper-V: This kind of environments extend to thousands of virtual machines. These machines run a broad range of operating system and applications. It has different performance requirements. The large virtual environments may concentrate on many forms.
SAP or other massive ERP or CRM environments: San architectures are ideal for customer resource management workloads and enterprise resource planning.
Microsoft SQL server databases: MS SQL Server database similar to Oracle database stores the most valuable data of the enterprises. So, they also require high performance and availability.
Large virtual desktop infrastructures (VDIs): it serves virtual desktops to large numbers. By doing the centralization of virtual desktops, the data protection and data security can be easily managed by the organizations.

Advantages of SAN

Storage virtualization: In this, the capacity of the server is not linked to the single storage devices. Now we can make use of large and consolidated storage pools for software applications.
High-speed disk technologies: we can consider FC (Fiber Channel) as an example for this. FC is a network that offers speed for retrieval of data is more than 5 Gbps. In this, we can directly transfer the data from the source device to the target device such that there is either decidedly less or no intervention of servers. Also, storage-to-storage data transfer is also available.
Centralized backup: it contains advanced backup features which includes block level and incremental backups, streamline IT system administrator responsibilities, etc., In this, the backup of data is stored on local disks instead of multiple disks.
Dynamic Failover Protection: it provides continuous network operation. Suppose if our system fails in between, or some other maintenance problem occurs due to which it enables built-in redundancy and automatic rerouting of traffic, even then our operation will work.



 

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Dinesh Thakur is a Technology Columinist and founder of Computer Notes and Technology Motivation. Turn Mobile View Off