PRTG - Paessler Router Traffic Grapher

January 5th, 2009

PRTG  Network Monitor / Traffic Grapher is the powerful network monitoring solution from Paessler AG .It enables you to log and monitor data flowing in and out of any SNMP enabled devices.It works with (almost) all SNMP enabled devices, such as managed switches, routers ,ups,and modems.It provides system administrators with live readings and long-term usage trends for their network devices. The most common usage is bandwidth usage monitoring, but you can also monitor many other aspects of your network like memory ,CPU utilizations and many more. It also provides a graphical interface with real-time charts and long term statistical reports covering daily and monthly periods. It also provides an option to generate interactive HTML reports.

Depending upon your requirement , you can choose either  PRTG  Network Monitor or Traffic Grapher

Comparison between     PRTG Network Monitor 7                   PRTG Traffic Grapher 6

  

Monitoring Of

Bandwidth, Usage, Uptime and Availability

Bandwidth

Reporting

Enhanced functionality

Basic functionality

Alerting

Enhanced functionality

Basic functionality

Monitoring Technologies

SNMP, Packet Sniffing, NetFlow, PING, WMI, HTTP, SMTP, and 40 other sensor types

SNMP, Packet Sniffing, NetFlow

User Interface

Modern web-based user interface (Ajax enhanced)

Windows GUI plus web-based read only access to data

Recommended for

Networks of any size with up to 30,000 sensors

Small networks with up to 500 sensors

Download

Freeware or 30 Day Trial

Freeware or 30 Day Trial

 

 

PRTG Network Monitor :

It monitors your network using a whole range of technologies and assures the availability of network components and measures traffic and usage. It saves costs by avoiding outages, optimizing connections, saving time and controlling service level agreements (SLAs).

For more details: http://www.paessler.com/prtg7/

PRTG Traffic Grapher:

PRTG (Paessler Router Traffic Grapher) is an easy to use software that monitors bandwidth usage and many other network parameters via SNMP, Packet Sniffing, or Cisco NetFlow. It allows you to quickly and easily set up and run a monitoring station for networks. With just a few mouse clicks you can log the amount of data flowing through routers and leased lines, monitor CPU utilization, analyze the traffic by type, or check disk space usage.
The most common usage is monitoring the bandwidth usage of leased lines, routers, and firewalls via SNMP, packet sniffing, or NetFlow. But you can also monitor many other aspects of servers, managed switches, printers, and other network components, as long as they are SNMP enabled.
For more details: http://www.paessler.com/prtg6

Installing PRTG

PRTG Network Monitor is optimized for easy installation, configuration and use. It allows you to set up your complete network monitoring scenario within minutes.Simply download the file and double-click it to start installation. The process is simple and consists entirely of answering routine questions, such as the installation path.
What is SNMP?

It stands for Simple Network Management Protocol, and is a set of standards for communication with devices in a TCP/IP network. With the help of an SNMP tool, it is possible to monitor and control network devices such as hosts, routers and switches.

How does Videoconferencing work?

January 5th, 2009

Video conferencing is when two or more parties communicate in real time in separate locations with both video and audio signals.Videoconferencing technology works across IP networks, ISDN (Integrated System Digital Network) phone lines… Through vast networks, videoconferencing has the capabilities for connectivity to worldwide audiences.

A videoconferencing facility consists of many elements.All conferencing systems use CODEC, which stands for coder-decoder. Codec is a device, which converts and compresses an analog audio-video signal into digital data and then sends it over a digital line. The decoder reverses the process at the receiving end.

This compression and decompression allows large amounts of data to be transferred across a network at close to real time (384 kbps with 30 frames of video per second).  All video conferencing systems works in a full duplex mode i.e. encoding and decoding of audio-video in both directions simultaneously.

One can use a choice of networks for conducting video conferencing over wide area networks (WAN) such as ISDN lines or satellite based lease lines. It is perfectly possible to use bandwidth of 128 KBPS for good quality conference. However data rate of 384 kbps may be needed for near TV quality video.

Various components of VC Equipment:

Following are the basic components of a videoconferencing system
• Codec
• Camera
• Control system
• Display equipment
• Audio system

Multipoint Videoconferencing:

Multipoint videoconferencing allows three or more participants to sit in a virtual conference room and communicate as if they were sitting right next to each other. Multipoint Videoconferencing is possible using Multipoint Conference Server.. MCS is the central point of connectivity for endpoints. It enables different networks, different bandwidths and different types of endpoints to communicate effectively.
Multipoint Conference Server acts as a switching device, connecting multiple sites at the same time to become part of same conference. It also provides facility to run multiple conferences with varying data rates, to operate in parallel over one network. The digital video signals from various Codecs are fed to the MCS, which is controlled through a workstation, (commonly a PC) to monitor and control various conferences. Accounting and scheduling related jobs are done through the workstation. For more details , visit www.polycom.com

Advantages of Video Conferencing:
Video conferencing is used by many businesses usually to save both time and money. One of the great advantages of video conferencing is that two or more parties can have a virtual face to face meeting to conduct business, which is seen as more beneficial than just a conference call. Other parties such as educators and health professionals use video conferencing when giving lectures, teaching about topics that require visual cues or visual information. Health professionals can give a diagnosis by conducting an examination via a video conference. There are many advantages to this technology and this has a lot to do with its exponential growth in recent years.

If you are looking for videoconferencing equipments/products ,
visit www.polycom.com or www.tandberg.com

How to Upgrade Flash/Firmware for Comtech Modems

January 5th, 2009

To perform a successful flash update, please follow the instructions:
Download the latest version from the comtech website : http://www.comtechefdata.com/software.asp

You need a cable to connect the PC to the modem. The cable is the same as is used for
normal EIA-232 remote control, and comprises 3-wires between 9 pin ‘D’ type female connectors.

 Serial Cable Detail for Modems:

  DB9  Female at both ends of the cable

  Pin 2  ——-  Pin 2
  Pin 3  ——-  Pin 3
  Pin 5  ——-  Pin 5

  NO OTHER PINS SHOULD BE CONNECTED
1.First,Using the front panel,Check the firmware information on your Modem. The firmware information is usually found in the Main menu. Identify the reflashable product, firmware number, and version to download.

2. The files are available in two formats: *.exe (self extracting) and *.zip (compressed).  For additional help with “zipped” file types, refer to “pkzip” or “winzip”.

3.Download the correct firmware and Extract the same on your PC.

4. Extract the files on your PC.

A minimum of 3 files are extracted:

*.exe - the “uploader” executable program to apply the flash firmware data file

*.hlp - the “help” file used by the “uploader” program

*.ccc, *.cef or *.h86 - the flash firmware data file specific to the product you selected

5. Connect the PC to the device to be reflashed.

Connect the PC to the device to be reflashed using a 9-pin serial cable or USB cable. Consult the product manual to determine which connection type is appropriate.

6. To reflash the device:

From the PC, run the exe program that was extracted in step 4.

Follow the on-screen directions to apply the correct data file (*.ccc) and perform the actual reflash process.

For more information about flash updates, refer to the applicable product manual or Visit Comtech WEbsite for more details!

For Comtech CDM 600 series Modem, Refer the following details!

Product                    Loader to use    File ext

CDM-600 Modem         Flash600            CCC

Step by step Procedure !

1. Click the Loader file (the exe file Flash600.exe).
   Select your Com Port
   The baud rate is dictated by the type of Upload being done.

1-300x250 How to Upgrade Flash/Firmware  for Comtech Modems

2. Click the Software Upload Button ,you will get a Window like the one below!

2-300x250 How to Upgrade Flash/Firmware  for Comtech Modems

3.Click the Choose Button,you will get a window as below.

211-300x250 How to Upgrade Flash/Firmware  for Comtech Modems

 4.Now, Choose the latest firmware file . The extention of the file is *.ccc for CDM 600 Modems. Choose the correct file and click ok.

221-300x250 How to Upgrade Flash/Firmware  for Comtech Modems

5. Now before proceeding further, make sure your Modem is off and no cable is connected to the 25-Pin Data connector(P3B).   Turn off your modem if its on. than click start Upload.

231-300x250 How to Upgrade Flash/Firmware  for Comtech Modems 

6.Now,Switch on the Modem.

24-300x250 How to Upgrade Flash/Firmware  for Comtech Modems
————————————–
3-300x250 How to Upgrade Flash/Firmware  for Comtech Modems

7.Now,The modem will start upgrading the Firmware.

4-300x250 How to Upgrade Flash/Firmware  for Comtech Modems

8.When its done,It will rebbot and query the modem for memory checksums.
51-300x242 How to Upgrade Flash/Firmware  for Comtech Modems

Once its finished, Your modem is with the latest firmware. Now,cycle power the modem and check the main menu for the Firmware version.

Semiconductor

January 5th, 2009

“Semiconductors are solid materials, either non-metallic elements or compounds, which allow electrons to pass through them so that they conduct electricity in much the same way as a metal”.
Semiconductors possess the following characteristics:

1. The resistivity is usually high.
2. The temperature co-efficient of resistance is always negative.
3. The contact between a semiconductor and a metal forms a layer which has a higher resistance in one direction than the other.
4. When some suitable metallic impurity (e.g., Arsenic, Gallium etc.) is added to a semi-conductor, its conducting properties change appreciably.
5. They exhibit a rise in conductivity with the increasing temperature, with the decreasing temperatures their conductivity falls off, and at low temperatures semiconductors become dielectrics.
6. They are usually metallic in appearance but (unlike metals) are generally hard and brittle.

Both the resistivity and the contact effect are as a rule very sensitive to small changes in physical conditions, and the great importance of semiconductors for a wide range of uses apart from rectification depend on the sensitiveness
 
Types of Semiconductor: Semiconductor can be classified into two types:
1. Intrinsic Semiconductors or Pure of semiconductors
2. Extrinsic Semiconductor or Impure of Semiconductors

Instrinsic semiconductors: Two normal (pure) silicon and Germanium are intrinsic semiconductor.They posses  all essential conducting characteristics of a semiconductor. The number of electrons present in the outermost orbit of intrinsic semiconductor is four,hence they are termed as tetra valent . So,intrinsic semiconductor are tetra valent in nature

Extrinsic Semiconductors: The process of adding impurities to an intrinsic semiconductor is known as Doping. With respect to the type of  Impurities  added, extrinsic semiconductor are classified into two types.

1. N-type semiconductors
2. P-type semiconductors

DOPING PROCESS

The pure semiconductor mentioned earlier is basically neutral. It contains no free electrons in its conduction bands. Even with the application of thermal energy, only a few covalent bonds are broken, yielding a relatively small current flow. A much more efficient method of increasing current flow in semiconductors is by adding very small amounts of selected additives to them, generally no more than a few parts per million. These additives are called impurities and the process of adding them to crystals is referred to as DOPING. The purpose of semiconductor doping is to increase the number of free charges that can be moved by an external applied voltage. When an impurity increases the number of free electrons, the doped semiconductor is NEGATIVE or N TYPE, and the impurity that is added is known as an N-type impurity. However, an impurity that reduces the number of free electrons, causing more holes, creates a POSITIVE or P-TYPE semiconductor, and the impurity that was added to it is known as a P-type impurity. Semiconductors which are doped in this manner - either with N- or P-type impurities - are referred to as EXTRINSIC semiconductors.

N-Type Semiconductor :

The N-type impurity loses its extra valence electron easily when added to a semiconductor material, and in so doing, increases the conductivity of the material by contributing a free electron. This type of impurity has 5 valence electrons and is called a PENTAVALENT impurity. Arsenic, antimony, bismuth, and phosphorous are pentavalent impurities. Because these materials give or donate one electron to the doped material, they are also called DONOR impurities.

An N-type semiconductor (N for Negative) is obtained by carrying out a process of doping, that is, by adding an impurity of valence-five elements to a valence-four semiconductor in order to increase the number of free (in this case negative) charge carriers.

P-Type Semiconductor

The second type of impurity, when added to a semiconductor material, tends to compensate for its deficiency of 1 valence electron by acquiring an electron from its neighbor. Impurities of this type have only 3 valence electrons and are called TRIVALENT impurities. Aluminum, indium, gallium, and boron are trivalent impurities. Because these materials accept 1 electron from the doped material, they are also called ACCEPTOR impurities.

A P-type semiconductor (P for Positive) is obtained by carrying out a process of doping, that is adding a certain type of atoms to the semiconductor in order to increase the number of free (in this case positive) charge carriers.

Basic Electronics

January 5th, 2009

What is Electricity ?

Electricity is made up of atom matter.  To understand that you have to understand the basics of atomic structure.
Matter is commonly made up of mass which occupies space.  This mass can become and take into form several different states:
solid   liquid   gas   plasma
Matter

All matter is comprised of molecules. A molecule is the smallest part of matter which can exist by itself. It contains one or more atoms, which are comprised of protons, neutrons and electrons.
The light in your room requires energy to glow. The energy must find a path through the light switch and through the copper wire. This movement is called electron flow.
The word matter includes copper, wood, water, air….everything. If we take a piece of matter such as a drop of water, divide it into two, and keep dividing it by two, finally we will find that it could be divided no more.  We have a molecule of water.
An atom is divisible. The component of interest to us is the electron.   Electrons are the smallest and lightest parts of the atom and are said to be negatively charged. Another part, protons, are about 1800 times the mass of electrons and are positively charged. 

Electrons repel electrons and protons repel protons. Electrons and protons attract one another.

Like forces repel, unlike forces attract.

When an electron and a proton are brought to close proximity, the electron moves because the proton is much heavier. The electron is small, its field is strong negative, and is equal to the positive field of the proton.
When electrons move, the result is an electron flow - electricity. To move an electron,  a negatively charged field will “push it”, a positively charged field will “pull it”. Or there can be combined efforts! 

Ionisation        
                                                                                                     
When an atom loses an electron, it lacks a negative charge. It is then a called a positive ion. In most metals the atoms are constantly losing and gaining free electrons. In this condition the metal is a good conductor. When gas is ionised under certain conditions, this too becomes a good conductor. Examples are lightning, neon lights and fluorescent lights.

Conductors and insulators

Materials with atoms or molecules with many free electrons will allow an easy interchange of their electrons.  

There is another one, but this shouldn’t really concern you right now.  It is called Superconductivity.  Superconductivity is the phenomenon where the electrons move through the material at no opposition at all, no friction, no resistance, no opposition.  But it is hard to make it work under normal everyday human like environments.  -452 F.  So there is still a lot of research that has to be done there and you shouldn’t concern your self with it.

Examples of good conductors are: Silver; Copper; Aluminium; Gold. (Metals) 
If the free electrons are numerous and loosely held the element is a good conductor. 
If there are few free electrons the element is a poor conductor. 
If there are virtually no free electrons, the element is a good insulator.

Examples of good insulators are: Glass; Mica; Rubber, Plastics.

Semiconductors
Semiconductors exhibit conductivity somewhere between that of good conductors and good insulators. Examples are silicon and germanium.  
Electromotive Force      
To produce a drift of electrons or electric current along a wire, there must be a difference in “pressure” or potential between the two ends of the wire. This potential difference can be produced by connecting a source of electrical potential to the ends of the wire.
For example, and simply put, there is an excess of electrons at the negative terminal of a battery and a deficiency of electrons at the positive terminal. This is due to chemical action within the battery.
A potential difference is the result of the difference in the number of electrons between the terminals. The force or pressure due to a potential difference is termed e.m.f. - electromotive force.
An emf also exists between two objects whenever there is a difference in the number of free electrons per unit volume of the object. If the two objects are both negative, and they are connected together, current will flow from the more negatively charged to the less negatively charged . There will also be an electron flow from a less positively charged object to a more positively charged object.
The emf  is expressed in a unit called the volt. A volt can be defined as the pressure required to force a current of one ampere through a resistance of one ohm.
Consider the following example: Consider the water pressure (volts) required to pass water (current) through a copper pipe of a certain small diameter (resistance).
Try to visualise water going through other pipes of varying diameters. The water pressure required will vary and the volume delivered will vary, or both.

This is Ohm’s law, where E = Volts; I = current in amperes and R = resistance in ohms.   

 ohmslaw-300x63 Basic Electronics

Electromotive force can be generated in many different ways. 
Some examples:

Chemical (batteries) e.g. dry cell 1.5V, wet cell storage about 2.1V 
Electromagnetic (generators)
Thermal (heating junctions of dis-similar metals)
Piezoelectric (mechanical vibration of certain crystals)
Photoelectric (light sensitive cells)
 

POWER

Energy is the ability to do work and Power is the rate of doing work. 

It is given by: 

P = W/t
P = Power, W = Work in foot-pounds, t = time

In electronics, we know by now that VOLTAGE is the force and that AMPS is the movement of electricity per second or current. 

One AMPERE = 1 COULOMB per second moving through the wire.

Equation:     P = I x E

Power is measured in WATTS.  Watt is named after James Watt, the inventor of the steam engine.  To convert mechanical power to electrical power this is the equation that we use.

1 HP = 746 watts.   HP stands for HORSEPOWER, and in mechanics this is used to measure the rate of work.

This same above Equation can be written in three different ways.  P = I x E, E = P/I or I = P/E.

Cells                                                                                          

Primary cells 

A common method for producing emf is the chemical action in a cell. Two or more cells form a battery. A flashlight cell is in common use in many small appliances. It’s likely to consists of a zinc can (the negative terminal), a carbon centre rod with a copper cap (positive terminal), and a black, damp, paste-like substance called an electrolyte between them. 

These materials were selected from substances so that electrons are pulled from the outer orbits of the molecules or atoms of the positive carbon terminal chemically by the electrolyte and deposited on the zinc can. The massing of these electrons on the zinc produces a backward pressure of electrons, or an electric strain, equal to the chemical energy in the cell. The cell remains static at 1.5V until it is connected to some load.

Once connected, the electrons flowing through the circuit start to fill up the deficient outer orbits of molecules of the positive rod in a continuous stream. It is important to understand that this motion produces the same current throughout the circuit at the same time. 

Alkaline cells 1.2V, have more energy capacity.  The mercury cell 1.34V is long working. The nickel-cadmium or Nicad 1.25V is rechargeable. 

Secondary cells 

The lead-acid storage battery is in near universal use as a vehicle battery. The cell delivers about 2.1V and is rechargeable. This particular battery is made of coated lead plates immersed in a solution of sulphuric acid and water. The acid content of the dielectric varies with the state of the charge. This may be determined by measuring the specific gravity of the electrolyte. A reading of about 1.27 indicates a full charge while a reading of 1.15 or below indicates the cell needs recharging. 

A 12V battery of these cells may be fast charged PROVIDED that care is taken to let escaping gases free themselves and PROVIDED the electrolyte temperature is below 50oC or 125oF.

The automotive battery was specifically designed for rapid charge and rapid discharge. For example, starting a car can cause currents well in excess of 500 amperes to flow - this is why jumper leads use thick wires. This battery was not designed for continuous use - such as running a radio or headlights in a stationary position for an extended period of time. 

Similar types of cells are ’sealed lead acid’ which may be used for emergency stand-by power.

The connection of cells 

When two or more cells are connected together in series, they form a battery. The voltages add together. Some flashlights or portable radios comprise four cells to make up 6V (4 x 1.5V). A car battery has 6 cells in series - so we get 6 x 2.1V = 12.6V. In  actual practice we get 13.8V for a fully charged vehicle battery.

If we put two batteries or cells in parallel, we get the same voltage, but twice the capacity. Twice the energy is available to us.

Transport Layer

January 5th, 2009

The fourth of seven layers of the ISO/OSI model.The transport layer defines protocols for message structure, and supervises  the validity of the transmission by performing some error checking.Transport Layer never actually transports the data but only prepares for transporting.The Transport Layer is also responsible for fragmentation and reassembly.

The primary function of this layer is to control the communications session between network nodes once a path has been established by the network control layer.

Responsible for the following :
•Segmentation
•End-to-end Communication
•Flow Control
•Error Control
•Multiplexing of Applications

TCP, UDP work at this layer.

Datalink Layer

January 5th, 2009

It is the Layer two, the second lowest layer in the OSI seven-layer model.It controls the transfer of information between nodes over the Physical layer.it splits data into frames for sending on the physical layer.

  • It uniquely identifies each device in the Network.
  • It translates data from Network Layer into bits for the Physical
    layer to transmit.
  • It formats the messages into Data Frames
  • Adds a customized header containing Source and Destination
    hardware address

Devices that works at this layer are
-LAN Card
-Switches
-Bridges etc.

Network Layer

January 5th, 2009

It is the third lowest layer in the OSI seven-layer model,It is the layer which is responsible for routing data across the network.The Network Layer is responsible for end-to-end (source to destination) packet delivery including any routing through intermediate hosts.

In other word, it is responsible for establishing paths for data transfer through the network.

  • The Network Layer resides above the Data Link Layer and below the Transport Layer.
  • It is responsible for communicating Networks.
  • The Network Layer is also responsible for packet sequencing, congestion control, and error handling.
  • It recognizes Networks with the help of Network Addresses
  • Network Address is a logical address like IP Address or IPX Address
  • Path determination or Routing is performed at this layer.
  • Router works at this layer.

Transport Layer

January 5th, 2009

It is the fourth of seven layers of the ISO/OSI model.The transport layer defines protocols for message structure, and supervises  the validity of the transmission by performing some error checking.Transport Layer never actually transports the data but only prepares for transporting.

The Transport Layer is also responsible for fragmentation and reassembly.The primary function of this layer is to control the communications session between network nodes once a path has been established by the network control layer.

Responsible for the following :
• Segmentation
• End-to-end Communication
• Flow Control
• Error Control
• Multiplexing of Applications

TCP, UDP work at this layer.

Session Layer

January 5th, 2009

It is the fifth of seven layers of the ISO/OSI model concerned with network management functions including passwords and network monitoring and reporting.It coordinates communication between systems, and serves to organize their communication by offering three different modes: simplex, half duplex, and full duplex.

In other word, It is a set of rules for establishing and terminating data streams between nodes in a network. The services that this layer can provide include establishing and terminating node connections,
message flow control, dialogue control and end-to-end data control.

  • The Session layer is responsible for setting up, managing, and then tearing down sessions between Presentation layer entities.
  • It coordinates communication between systems, and serves to organize their communication by offering three different modes: simplex, half duplex, and full duplex.
  • The Session layer basically keeps different applications’ data separate from other applications’ data.
  • Examples of Session Layer : RPC, SQL, NFS and NetBIOS .
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