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Another term to understand is speed and bandwidth speed is a measure of the data rate of a given link

in the network in bits per second.

As an example my home internet connection is seventy five megabits per second.

This rate is the average number of bits that can be downloaded in one second.

That's seventy five million bits in one second.

Please remember that this is in bits and not in bytes.

A byte is 8 bits.

So be careful in some descriptions we may be talking about one megabyte which is different to one Megat

But now what is cost.

Cost indicates the expense for purchasing network components as well as the cost of installing and maintaining

the network.

Sometimes the cost of installation is very high relative to the cost of the equipment.

What about security.

Security indicates how well a network is protected from both inside and outside threats.

Ettrick security is of great importance especially with the number of attacks taking place on companies

from hackers on the Internet.

What is availability availability is a measure of the probability that a network will be available for

use when it is needed.

It is often represented as a percentage of time that the network is available and is referred to as

up time.

It's not much good having a network if its not available when you need it to calculate the percentage

of up time that a network has experienced.

Divide the number of minutes that a network was available in a year by the total number of minutes in

the year.

So for networks uptime is meant to be 24 hours a day seven days a week 365 days a year.

But availability is calculated by dividing the time that the network is actually available by the total

time in a year and then multiplying by 100 to get a percentage.

So as an example if the network is not available for 15 minutes in a year because of network outages

you can calculate that percentage availability as follows number of minutes in a year minus a downtime

divided by number of minutes any times 100 equals percentage availability.

So in this example weve got five hundred twenty five thousand six hundred minutes and a year minus the

number of minutes downtime in the year which is 15 divided by five twenty five six hundred times 100

gives us an availability percentage of ninety nine point nine nine 7 1 percent for next term to understand

is scalability scale Bovey indicates how easily the network can grow to accommodate more users and greater

transmission requirements.

If you design and optimize the network only for todays requirements it can be very expensive and difficult

to meet new needs as the network grows.

Networks should be designed with growth in mind.

Don't design a network and purchase network devices without considering network scalability and growth.

What is reliability reliability indicates the dependability of the components that make up a network

such as routers switches PCs and servers.

Reliability is often measured as a probability of failure or mean time before failure or so called MTBF.