Network Support in the Philippines

Building a simple Computer Network

A simple computer network may be constructed from two computers by adding a network adapter (Network Interface Controller (NIC)) to each computer and then connecting them together with a special cable called a crossover cable. This type of network is useful for transferring information between two computers that are not normally connected to each other by a permanent network connection or for basic home networking applications. Alternatively, a network between two computers can be established without dedicated extra hardware by using a standard connection such as the RS-232 serial port on both computers, connecting them to each other via a special crosslinked null modem cable.

Practical networks generally consist of more than two interconnected computers and generally require special devices in addition to the Network Interface Controller that each computer needs to be equipped with. Examples of some of these special devices are hubs, switches and routers.

Network Support by connection method

Computer networks may be classified according to the hardware technology that is used to connect the individual devices in the network such as Ethernet, Wireless LAN, HomePNA, or Power line communication. Ethernets use physical wiring to connect devices. Often, they employ the use of hubs, switches, bridges, and routers. Wireless LAN technology is built to connect devices without wiring. These devices use a radio frequency to connect.

Network Support by Providing Electrical Power

Individual network components may have surge protectors - an appliance designed to protect electrical devices from voltage spikes. Surge protectors attempt to regulate the voltage supplied to an electric device by either blocking or shorting to ground voltage above a safe threshold. Beyond the surge protector, network elements may have uninterruptible power supplies (UPS), which can be anywhere from a line-charged battery to take the element through a brief power dropout, to an extensive network of generators and large battery banks that can protect the network for hours or days of commercial power outages.

When networks are critical the general rule is that they should have no single point of failure. The broad factors that can bring down networks, according to the Software Engineering Institute at Carnegie-Mellon University:

1. Attacks: these include software attacks by various miscreants (e.g., malicious hackers, computer criminals) as well as physical destruction of facilities.
    
2. Failures: these are in no way deliberate, but range from human error in entering commands, bugs in network element executable code, failures of electronic components, and other things that involve deliberate human action or system design.
    
3. Accidents: Ranging from spilling coffee into a network element to a natural disaster or war that destroys a data center, these are largely unpredictable events. Survivability from severe accidents will require physically diverse, redundant facilities. Among the extreme protections against both accidents and attacks are airborne command posts and communications relays, which either are continuously in the air, or take off on warning. In like manner, systems of communications satellites may have standby spares in space, which can be activated and brought into the constellation.

Network Support by Dealing with Power Failures

One obvious form of failure is the loss of electrical power. Depending on the criticality and budget of the network, protection from power failures can range from simple filters against excessive voltage spikes, to consumer-grade Uninterruptible Power Supplies (UPS) that can protect against loss of commercial power for a few minutes, to independent generators with large battery banks. Critical installations may switch from commercial to internal power in the event of a brownout, where the voltage level is below the normal minimum level specified for the system. Systems supplied with three-phase electric power also suffer brownouts if one or more phases are absent, at reduced voltage, or incorrectly phased.

To help standardize approaches to power failures, the Advanced Configuration and Power Interface (ACPI) specification is an open industry standard first released in December 1996 developed by HP, Intel, Microsoft, Phoenix and Toshiba that defines common interfaces for hardware recognition, motherboard and device configuration and power management.

Source: http://www.wikipedia.org