satellite communication

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. (more…)

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. (more…)

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. (more…)

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.

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.

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.

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.

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 .

It is the sixth of seven layers in the OSI model concerned with protocols for network security, file transfers, and format functions.It is mainly responsible for how the data is to be presented to the Application Layer.

Points to Remember:

• Tasks like Translation, Encryption, decryption, compression,decompression are associated with this layer.
• Protocols at this layer take care of manipulation tasks that transform data from one representation to another, such as translation, compression and encryption.
• It is used much less often than the other layers , in many types of connections it is not required.
• It receives the data in native format & converts in standard format or receives data in standard format and converts in native format.
• It is mainly responsible for how the data is to be presented to the Application Layer.
• Examples are  MIDI, MPEG, GIFF , PICT, TIFF, JPEGetc.

It is the seventh , or highest, layer in the International Organization for Standardization’s Open Systems Interconnection (ISO/OSI) model  which manages the communication between application processes.This layer handles issues like network transparency, resource allocation, and problem partitioning. It describes how application programs interact with the network operating system, including database management, electronic mail, and terminal emulation programs.

About Application Layer

• This is a point where user or application interfaces with the protocols to gain access to the network.
• This is the top layer of the OSI model.
• This is where communication between two users are established.
• This is where users communicate to the computer.
• The application layer is only concerned with presenting information in human-friendly way.
• The Application Layer receives its information from the ‘Presentation’ layer.
• Examples are WWW, Telnet, FTP, TFTP, E-mail, SNMP,POP3, DNS