Lesson 3 Flashcards
Is the geometric representation of the relationship of the links and the linking devices in a network.
Topology
Defines the physical or the Logical Agreement of Links in a Network.
Topology
Linking devices
Nodes
Is the way a network is arranged, including the physical or logical description of how links and nodes are set up to relate to each other.
Network Topology
Categories of Topology
Mesh, Star, Tree, Bus, Ring
Two possible relationships in a network
Peer-to-peer, Primary-Secondary
Devices share the link equally
Peer-to-peer
One devices controls traffic and the others must transmit through it
Primary-secondary
Each device is connected to every other device on the network through a dedicated point-to-point link.
Mesh Topology
Number of links of a mesh topology of n devices
n(n-1)/2
Each device in the network is connected to a central device called hub
Star Topology
There is a main cable and all the devices are connected to this main cable through drop lines.
Bus Topology
Device that connects the drop line to the main cable
Tap
Each device is connected with the two devices on either side of it
Ring Topology
Device that forwards data until the intended device receives it
Repeater
Combination of two or more topology
Hybrid Topology
Is suggestive of how a network is laid out.
Topology of a Network
It refers to the specific configuration and structure of the connections between the Links and the Nodes.
Topology of a Network
What to consider when choosing a Topology
Relative status of the devices to be linked
Advantages of Mesh Topology
- No data traffic issues as there is a dedicated link between two devices which means the link is only available for those two devices
- Mesh topology is reliable and robust as failure of one link doesn’t affect other links and the communication between other devices on the network
- Mesh topology is secure because there is a point to point link thus unauthorized access is not possible
- Fault detection is easy.
Disadvantages of Mesh Topology
- Amount of wires required to connected each system is tedious and headache
- Since each device needs to be connected with other devices, number of I/O ports required must be huge
- Scalability issues because a device cannot be connected with large number of devices with a dedicated point to point link.
Doesn’t allow direct communication between devices, a device must have to communicate through hub
Star topology
If one device wants to send data to other device, it has to first send the data to hub and then the hub transmits that data to the designated device.
Star topology
Advantages of Star Topology
Less expensive , Easier to install, less amount of cables , Robust, Easy fault detection
Disadvantages of Star Topology
- If hub goes down everything goes down, none of the devices can work without hub
- Hub requires more resources and regular maintenance
Connects the drop line to the main cable
Tap
Advantages of Bus Topology
Easy installation, less cable required
Disadvantages of Bus Topology
Difficulty in fault detection, not scalable
If a device wants to send data to another device then it sends the data in one direction, each device in ring topology has a repeater, if the received data is intended for other device then repeater forwards this data until the intended device receives it.
Ring Topology
There are two dedicated point to point links a device has with the devices on the either side of it
Ring topology
Advantages of Ring Topology
Easy to install, managing is easier
Disadvantages of Ring Topology
- A link failure can fail the entire network as the signal will not travel forward due to failure
- Data traffic issues
Advantages of Hybrid Topology
- We can choose the topology based on the requirement for example, scalability is our concern then we can use star topology instead of bus technology.
2.Scalable as we can further connect other computer networks with the existing networks with different topologies.
Disadvantages of Hybrid topology
- Fault detection is difficult.
- Installation is difficult.
- Design is complex so maintenance is high thus expensive.
