18-06-2014, 02:35 PM
Industrial Data Networks
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. Define networks?
A network is a set of devices (referred to as nodes) connected by media links. A node can be a computer, printer, or any other device capable of sending or/receiving data generated by other nodded on the network. The links connecting the devices are called as communication channels.
2. Give some applications of networks?
a)Marketing and sales, b)Financial services, c)Manufacturing, d)Electronic messaging, e)Directory services, f)Information services, g)Electronic data interchange, h)Teleconferencing, i)Cellular telephone, j)Cable television.
3. Define line configuration?
Line configuration refers to the way two or more communication devices attach to a link. A Link is the physical communication pathway that transfers data from one device to another.
4. Define point-to-point line configuration?
A point-to-point line configuration provides a dedicated link between two devices. The entire capacity of the channel is reserved for transmission between those two devices.
5. Define multipoint line configuration?
A multipoint line configuration also called multidrop line configuration is one in which more than two specific devices share a single link.
6. Define topology? What are the different types of topology?
Topology refers to the way a network is laid out, either physically or logically. Two or more devices connect to a link; two or more links forms a topology. The different types of topology are, a)Mesh, b)Star, c)Tree, d)Bus e)Ring
7. Define peer-to-peer and primary-secondary transmissions?
Peer-to-peer is one where the devices share the link equally Primary-secondary is one where one device controls traffic and the others must transmit through it.
8. What is meant by Mesh topology?
In a mesh topology every device has a dedicated point-to-point link to every other device. A fully connected mesh n/w therefore has n(n-1)/2 physical channels to link n devices.
9. What is meant by star topology?
In a star topology, each device has a dedicated point-to-point link only to a central controller, usually called a hub. The devices are not directly linked to each other.
10. What is meant by tree topology?
A tree topology is a variation of a star. As in a star, nodes in a tree are linked to a central hub that controls the traffic to the n/w. Every devices do not connect directly to the hub. The majority of devise connect to a secondary hub that in turn is connected to the central hub.
11. What is the difference between active hub and passive hub?
Active hub:-The central hub in the tree is an active hub. An active hub contains a repeater, which is hardware device that regenerates the received bit patterns before sending them out. Passive hub:-A passive hub provides a simple physical connection between the attached devices.
12. What is meant by bus topology?
A bus topology is a multipoint configuration. One long cable acts as the backbone to link all devices in the network. Nodes are connected to the bus cable by drop lines and taps.
13. What is meant by Ring topology?
In a ring topology each device has a dedicated point-to-point line configuration only with the two devices on either side of it.
14. Define transmission modes? What are the types of transmission modes?
Transmission mode is used to define the direction of flow between two linked devices. There are three types of transmission modes;
a) Simplex: - The communication is unidirectional, as on a one-way street. Only one of the two stations on link can transmit; the other can only receive.
b) Half-duplex:- each station can transmit and receive but not at the same time. When one device is sending the other can only receive, and vice versa.
. What is the function of repeaters?
A repeater or regenerators is an electronic device that operates on only physical layer of the OSI model. A repeater installed on a link receives the signal before it becomes too weak or corrupted. Regenerates the original bit pattern and puts the refreshed copy back onto link.
2. What is the function of bridges?
It operate on the physical layer and data link layers of the OSI model. Bridges can divide a large network into the small segments. They can also relay frames between two originally separate LANs. Bridges contain logic that filters traffic, thus making them useful for controlling congestion and isolating problem links.
3. What is the function of routers?
These have access to network layer address and contain software that enables them to determine which of several possible paths between those addresses in the best for a particular transmission. Routers operate in the physical , data link and network layers of the OSI model.