Network Switches - Basics

The network switch plays a key role in society and people home networks, but too many confuse what is the purpose of the system and how it differs from a router. I decided to write this blog post to explain the basics of passage - from different species, suppliers to buy from them.

A brief overview of network switches

A network switch is a type of computer network products, network bridge segments. Change sometimes referred to as a packageor simply a switch. The switch is an important component in the most networks (LANs), including medium and large corporate networks that use managed switches connected to each other more.

A switch is much less demanding than a router. While routers and switches are very similar in appearance, they differ significantly in their router internal components.

Types of network switches

Unmanaged Switch: This is usually the least expensive type ofSwitch, most commonly in homes or small offices. They are very easy, takes the plug and play, no specific configuration options

Managed Switches: Managed Switches offer optional configuration options, enabling a wide variety of features. There are several ways to make these options, the use of an instrument at a distance, such as Simple Network Management Protocol (SNMP) access to the switch to a command line interface such as telnet.


IntelligentSwitch: Smart Switches are different from fully managed switches, because they allow only a certain number of changes and functionality. Because users can configure the basic settings, they are often cheaper than the fully-managed breeding. Some basic functions often turn to a switch port Smart are some details on or off, connection speed and duplex settings and the settings for port priority

Enterprise Managed Switches: Enterprise Switches are more configurable andexpensive version of managed switches. They are more common in business networks in a number of other switches. They are more efficient for large enterprises, where the module can access a central administration to save time and money. Some advanced features for business settings switches VLAN, link aggregation and port mirroring.

Switches purchases

There are several switches manufacturer brands that offer differentiated and competitive products, including Cisco,3Com, Alcatel e. While switches are purchased out of the box from online retailers, can a way to save money is to use a switch from a retailer online to find. A business buyer can often save thousands of dollars to buy used Cisco or other networking hardware brand.

If you decide to go the way of an online retailer, you must consider several factors to ensure that skills are a good fit. One factor is a good guarantee as it is always a risk to buy usedEquipment. Another reason is significant discounts (50%) the price of retail. The third aspect which I recommend an online manufacturer of network hardware is a good score. The ability to help people is to talk with your purchase undervalued.

I hope this post "support base switch 'helps those who are confused or looking for a way to buy a switch.

Wireless Basics

How CCNA Wireless Airwaves candidate should understand how RF signals to send data about employees.

Fundamentals CCNA Wireless.

The wireless LAN IEEE has created a work on a specification that defines how to use the same frequency of half-duplex transmit and receive in addition to a. The specification known as 802.11.

To use the frequencies specified by the IEEE 802.11 standard does not require approval by the userprovided that you shall follow the established rules of the IEEE.

Country or region has a regulatory authority (the FCC in North America and Europe ETSI), which governs the frequencies that can be used each can be used together with the amount of power that the wireless device can be operated and transfer of technology types .

(ETSI is a non-profit Journal. ETSI is responsible for levels of performance standards and frequencies in Europe)

In 1986,North America is the FCC allowed the use of a technology called "spread spectrum" in the commercial market in a band called industrial frequency bands scientific and medical (ISM).

Bandwidth and data rate

The world in which we have data is used to refer to past the word "gang" the amount of data measured on a fixed point in bits per second, kilobits, megabits and Gigabit Ethernet. These use the range limit is not technically correct. The correct term would be"Data Rate".

When talking about bandwidth, we refer to the number of vibrations per second. A cycle is in Hertz. A Hertz measures how many cycles per second. Some examples are to be used in FM radio and TV is about 175kHz 4500Khz would.

electromagnetic spectrum

At extremely low frequency (ELF) 3 Hz to 30 Hz
Super Low Frequency (SLF) 30Hz to 300Hz
Ultra Low Frequency (ULF) 300Hz to 3kHz
Very low frequency (VLF) 3KHz to 30kHz
Low frequency (LF) 30 kHz to 300 kHz
Medium Frequency (MF) 300kHz to 3MHz
High frequency (HF) 3 MHz to 30 MHz
High frequency (VHF) 30 MHz to 300 MHz
Ultra High Frequency (UHF) 300MHz to 3GHz
Super high frequency (SHF) 3GHz to 30GHz
Extremely high frequency (EHF) to 30 GHz 300 GHz

Which frequencies can be used depends on the country you are in Europe, allows the use of 2.4 GHz and 5 GHz, these areas as Cipta A, B, C, bands are known.

2.4Ghz

CEPT A =5,15-5.25 GHz
CEPT B = 5.25 5.35Ghz
C = 5.47 CEPT 5.725Ghz

North America uses Unlicensed National Information Infrastructure (UNII) bands.

900Mhz

2.4 GHz ISM

UNII-1 GHz = 5,15-5.25
5,25-5.35 GHz UNII-2 =
Extended GHz UNII-2 = 5.47 to 5725

900Mhz

Range: 900MHz - 928MHz to 902Mhz Start

For phones without core

2.4Ghz

Use of 802.11, 802.11b, 802.11g, 802.11g and 802.11n

The 2.4 GHz channel is divided intoSub-channels. The number of sub-channels used depends on the country:

Northern = 11 channels, each 22MHz wide channel
ETSI (Europe) = 13 channels, each channel is 22MHz wide
Japan = 14 channels, each 22MHz wide channel

Many of the channels overlap and it is recommended that non-overlapping channels, the three non-overlapping channels are used 1, 6 and 11

5GHz

Used by 802.11a and 802.11n.

For the 802.11a data rates from 6 Mbps to 54 Mbps

The802.11

802.11b specification

= 2.4 GHz frequency spectrum
The technology used HF = DSSS (Direct Sequence Spread Spectrum)
Non-overlapping channels = 1, 6 and 11
DBPSK and DQPSK modulation =
Data rate = 1, 2, 5.5 and 11 Mbit / s
= 11 Barker coding and CCK (Complementary Code Keying)

802.11b is an improvement over the simple, that alone could reach 802.11 data rates of 1 or 2 Mbps 802.11b is designed to be compatible with 802.11 Barker11-encoding where it is necessary, and CCK, when not needed, compatible with 802.11.

802.11b allows customers to dynamically transfer data rates, such as the access point and gain speed as they move closer to the transition to the access point.

802.11g Specification

= 2.4 GHz frequency spectrum
The RF technology used = OFDM (Orthogonal Frequency Division Multiplexing) and DSSS nonoverlapping
Channels = 1, 6 and 11
DBPSK and DQPSK modulation =
Data Rates= 1, 2, 5.5 and 11 Mbps DSSS and 6, 9, 12, 18, 24, 36, 48, 54 Mbps OFDM
= 11 Barker coding and CCK (Complementary Code Keying)

The 802.11g specification allows additional 8 data transfer rate up to 54Mbps more like 802.11a.

802.11g is compatible with 802.11b with identical coding and modulation, but it's only 802.11b, 802.11g and return to negotiate prices if access to the medium after it was broadcast 802.11g data rates of early

You should alwaysKeep in mind that still uses the 2.4 GHz and as such are only three non-overlapping channels 1, 6 and 11

802.11a specification

= 5Ghz frequency spectrum

The RF technology used = OFDM (Orthogonal Frequency Division Multiplexing) and DSSS

Non-overlapping channels = 4 non-overlapping channels per band, the middle eight channels with 52 sub-carriers used on each channel

DBPSK and DQPSK modulation =

Data rate = 1, 2, 5.5 and 11 Mbps DSSS and 6, 9, 12,18, 24, 36, 48, 54 Mbps OFDM

UNII-1 is designed for indoor use, for outdoor use with external antenna and UNII UNII-3 is designed for outdoor decks and external antennas designed.

Four non-overlapping channels per frequency band (each band is or UNII-1 = low, 2 = medium-UNII, UNII-3 = high). Consumers generally use the middle and lower bands. With four not on the lapping channels per band. Each channel of each book series has 52 sub-carriers on each channel

Low-and middle-Channels in a total of eight channels each 20Mhz, 20Mhz each of these channels are divided and then divided into 52 sub-carriers of 300kHz.

ETSI allows the use of 19 channels with support for dynamic control of frequency to avoid interfering with radar, which also takes the same bandwidth.

802.11a also encourage the use of Transmit Power Control as not to disturb even the radar.