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.

 
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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.



 
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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.



 
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UnGuided or also called wireless or wireless communication, transport electromagnetic waves without using a physical conductor. Instead, signals are radiated through the air (or, in a few cases, water) and therefore, are available to anyone with a device capable of accepting them.

The electromagnetic spectrum

 
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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.



 
by Dinesh Thakur

FDDI stands for Fiber Distributed Data Interface. It is a high-speed, high-bandwidth network based on optical transmissions. It is most often used as a network backbone, for connecting high-end computers (mainframes, minicomputers, and peripherals), and for LANs connecting high-performance engineering, graphics, and other workstations that demand a rapid transfer of large amounts of data. It can transport data at a rate of 100 Megabits per second and can support up to 500 stations on a single network. FDDI was designed to run through fiber cables, transmitting light pulses to convey information between stations, but it can also run on copper using electrical signals. It is relatively expensive to implement, although the mixing of fiber-optic with copper cabling can hold down the cost.



 
by Dinesh Thakur

Digital Equipment Corporation (DEC) has given support to network connectivity for networks of its own and networks of other vendors also. DEC has its own architecture known as Digital Network Architecture (DNA) the product that implements the architecture is known as DEC net. The DNA was developed during 1974, to provide communication facility between various DEC systems.

 
by Dinesh Thakur

The Systems Network Architecture (SNA) from IBM uses a 7 layer architecture similar to the OSI model.

 
by Dinesh Thakur

Definition:  General Packet Radio Service is a packet-based wireless communication service. It promises data rate up to 114 kbps. It is a standard technology which extends the Global system. It abbreviated as GPRS. It is designed to replace the current circuit-switched services.

General Packet Radio Service is a non-voice and high-speed technology which is useful for the GSM networks. We make use of GPRS so that we can enable connections which depend on the internet protocol. As we know, IP supports a wide variety of applications. We can send and receive the compressed data and large volume data over the mobile network by using GPRS as the packet switching system used. So, before sending the data, it breaks the whole data into packets and then shifts them through the network. Now the data again assembled at the recipient side.



 
by Dinesh Thakur

Cluster computing or High-Performance computing frameworks is a form of computing in which bunch of computers (often called nodes) that are connected through a LAN (local area network) so that, they behave like a single machine. A computer cluster help to solve complex operations more efficiently with much faster processing speed, better data integrity than a single computer and they only used for mission-critical applications.



 
by Dinesh Thakur

In order to provide computer to computer communication via Internet, we need a global addressing scheme. Such an addressing is provided by Internet Protocol (IP) at the network layer.
It is a 32-bit address This is called an IP address or logical address. Which is made up of the network ID, plus a unique host ID. This address is typically represented with the decimal value of each octet separated by a period (for example, 192.168.7.27).   Every Host and router on the internet has an IP Address. This IP address is unique and no two devices on the Internet can have the same address at the same time.



 
by Dinesh Thakur

ADSL stands for Asymmetric Digital Subscriber Line. ADSL is a type of DSL line and is one of the technologies vying to replace ISDN. It consists of the transmission of digital data supported by the symmetric pair of copper carried by the conventional telephone line or subscriber line, as long as the range does not exceed 5.5 km measured from the Telephone System, or there are no other services on the same cable that may interfere. It is a broadband Internet access technology, which implies a higher rate of data transmission in the data transfer, and supports simultaneous Internet browsing and phone use.

 
by Dinesh Thakur

Dynamic Host Configuration Protocol (DHCP) is a protocol used by networked devices or clients to obtain the parameters necessary for operationin an Internet Protocol network. This protocol reduces system administration workload, allowing devices to be added to the network with little or no manual configurations. Dynamic Host Configuration Protocol is a way to administrator network parameter assignment from a single DHCP server, or a group of DHCP servers arranged in a fault-tolerant manner. Even in small networks,



 
by Dinesh Thakur

Before discussing about Domain Name Server: we are going to explain some factor and simple difference between Domain Name Server and Domain Name System.

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.