TRADUCTION OF THE BLOG

The Frame Relay

Frame Relay   (or   Frame-mode Bearer Service ) is a communication technique through frame relay for virtual circuit networks, introduced by the   ITU-T  from recommendation I.122 of 1988. It consists of a simplified form of technology   packet switching   that transmits a variety of frame sizes or frames ("frames ") for data, perfect for transmitting large amounts of data.

The technique   Frame Relay   it is used for a high-speed voice and data transmission service that allows the interconnection of geographically separated local area networks at a lower cost.

Types

PVC:   PERMANENT VIRTUAL CIRCUIT.

Virtual circuit that is established permanently. PVCs save bandwidth associated with the establishment and cutting of circuits, if certain virtual circuits must exist at all times. The PVC, permanent virtual circuits, are pre-configured by the communications company and once configured it only works in the DATA TRANSFER and IDLE modes

SVC : VIRTUAL SWITCHED CIRCUIT

Switched virtual circuit. Virtual circuit that is established dynamically on request and that is interrupted when the transmission is complete. SVCs are used when data transmission is sporadic.
The SVC, switched virtual circuits, are defined dynamically by sending signaling messages (CALL SETUP, DATA TRANSFER, IDLE, CALL TERMINATION).

Computer rack or closet

A rack is a metal rack whose main purpose is to house electronic, computer and communications equipment where the width measurements are standardized so that they are compatible with the equipment of any brand or manufacturer. The specifications of a standard rack are under the equivalent standards DIN 41494 part 1 and 7, UNE-20539 part 1 and part 2 and IEC 297 part 1 and 2, EIA 310-D and have to comply with RoHS environmental regulations .

The measurements of a rack Rack

All rack and wall cabinets in   www.dns-system.es   have their measurements expressed in the form High (U) x Width (mm) x Depth (mm), (example : 27U 600 x 800) where the "U" describe the useful mounting height (space available inside the cabinet for installation of the hardware), the next figure is the outer width and the last one is the outer bottom of the cabinet.

Height

A rack unit or simply "U" is a unit of measure used to describe the height of equipment prepared to be mounted in a 19-inch-wide rack, for example:

• 4U rack case
• 2U Sai for rack

Each "U" is equal to 1.75 inches (44.45 mm) high and given that as we said above, is a measure of the interior useful space, to know the total height of the cabinet is necessary to add to the "U" of the height about 10-15 cm that correspond to the sum of the base and the roof. If you have, you should add the height of the wheels or support socket, another 10 cm approximately. Thus, a 42U cabinet has a useful internal mounting height of about 186 cm and a total external height of approximately 210 cm.

 

 

Width

It is the outer width of the cabinet, usually 600 mm. Remember that the 19 "standard refers to the width distance between the interior profiles of the cabinet,   not to the total outside width of the rack . In fact, cabinets with a width of 800 mm are manufactured which allows greater ease of use to the installers because, maintaining the standard of 19 "between the profiles they contribute an extra space of 100 mm from the profile on each side, which it facilitates the installation and maintenance besides allowing more space to add accessories that can help us achieve a more efficient and orderly installation.

Background

It is the outer bottom of the rack cabinet in millimeters. Enclosures with funds of 600, 800, 900, 1000 and up to 1200 mm are manufactured to house hardware of great depth.The bottom of the cabinet should be at least 15 cm larger than the hardware with the greater depth that we are going to install to allow enough space for the connection of all the elements without having to force curvatures that could cause damage to the wiring. It is also important that there is sufficient space between the hardware and the walls of the cabinet for air to circulate inside, maintaining the ventilation circuit and thus eliminating possible hot spots that may compromise the operation of the installation.

Differences between a Router and a Switch

Both a   Router   as a   Switch , are connection devices used in networks.

A   Router is used to choose the smallest route for a package to reach its destination . A   Switch stores the received packet, processes it to determine its destination address and forwards it   to a specific destination.

The basic difference between a router and a switch is that a   router connects different networks to each other , while a   switch connects multiple devices to each other   to create a network.

WAN network

A   wide area network , or   WAN   ( Wide Area Network   in English), is a   Computer network   that unites several local networks, although its members are not all in the same physical location. Many WANs are built by organizations or companies for private use, others are installed by Internet providers ( ISP ) to provide connection to their customers.

Types

There are several types of WAN network, and three of them are grouped under the network classification   switched   (in physics, commutation consists of changing the destiny of a   signal   or of an electric current):

By circuits

They are dial-up networks, such as the basic telephone network (RTB) and ISDN. During the time the call lasts, the bandwidth is dedicated.

By message

Their switches are usually   computers   that fulfill the task of accepting the traffic of each terminal that is connected to them. These computers evaluate the address found in the message header and can store it for later use. It should be mentioned that it is also possible to delete, redirect and respond to messages automatically.

For packages

Every message sent by the   users   and they are transformed into a number of small parts called packages, which are put together once they arrive at the destination equipment, to reconstruct the initial data. These packages move through the network independently, and this has a positive effect on traffic, in addition to facilitating the correction of errors, since in case of failures only the affected parties must be forwarded. The bandwidth is shared among all the users that use the network.

Network diagrams

Also know as   Network Graph, Network Map, Node-Link Diagram .

This type of visualization shows how things are interconnected through the use of nodes / vertices and link lines to represent their connections and help illuminate the type of relationships between a group of entities.

Normally, the nodes are drawn as small dots or circles, but icons can also be used. The links are usually shown as simple lines connected between the nodes. However, in some network diagrams, not all nodes and links are created equally: additional variables can be displayed, for example, by having the size of the node or the proportion of the link weight of the link have an assigned value.

By assigning the connected systems, the network diagrams can be used to interpret the structure of a network through the search of any grouping of the nodes, the connection density of the nodes or by how the diagram is organized.