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TE-A-CH

# What is topology?

## Topology — structure of the network.

The topology of a network indicates how the individual network participants (usually computers) are connected to one another — both logically and physically.

The logical topology describes the most effective path that the data will take.

The physical topology is the structure of the cabling of the individual hosts and systems, i.e., the physical form of the network.

When planning a network, there are many different ways in which the devices and lines are arranged to exchange data with one another.

Security, flexibility, performance and administration play a major role here in a successful and effective topology.

# Line topology

All network participants are connected in series. A line is laid from host to host. So linear topologies have a start and an end. So, if you remove a host, the chain is broken and the network fails.

• Little wiring, low installation costs
• No active network components required

• Interruption of the transmission medium (cable) or the failure of individual hosts leads to the failure of the network
• Relatively slow

# Bus-Topology

With this topology, all hosts are connected to one another by a transmission medium — the bus. All hosts can therefore access the bus and thus also access to the data to be transmitted that are sent via the bus. However, they share this transmission medium (physical connection), which is why only one communication can take place at a time.

There is no central network component that regulates the processes and communication between the individual hosts. There are special procedures for this, the rules of which must be adhered to by all network participants.

• Little wiring, low installation costs
• No active network components required
• Failure of individual hosts does not lead to network failure

• Interruption of the transmission medium (cable) leads to the failure of the network
• No secure transmission
• Only 1 end device can send data at the same time, the others are blocked during this time

# Ring topology

The ring topology has a similar structure to the line topology, with the difference that the beginning and end are connected to one another. So the ring is closed. Each network participant therefore has a predecessor and a successor. When data is sent, it is passed on by Host-to-Host. Each host now checks whether the data is intended for it or not (intermediate storage). If this is the case, the data is processed, if it is, it is forwarded to the next host.

• Additional devices can be connected without any problems
• No collisions

• Interruption of the transmission medium (cable) or the failure of individual hosts leads to the failure of the network
• The intermediate storage of the data can lead to delays
• Data are not secure against eavesdropping

# Star topology

With the star topology, each network participant is connected to a central point. Similar to the tree topology, the central element is usually a hub or switch. The individual network participants are thus connected to the central network component in a star shape.

• The failure of individual hosts does not lead to the failure of the network
• Additional devices can be connected without any problems
• Data is relatively secure against eavesdropping, as there is only one connection between two participants during communication
• Fast data transfer

• If the central device fails, the network also fails

# Tree topology

Network participants are arranged hierarchically here. So there is a root element from which one or more branches (edges) start.

A higher-level network element, for example a router, often forms the root element. When data is sent, it is first sent to the root element. From there, the data is finally forwarded to the respective hosts.

• The failure of individual hosts does not lead to the failure of the network, unless it is a root element
• Well suited for sorting and search algorithms

• Active and passive network components are required
• Data are not secure against eavesdropping
• Additional devices can be appended or removed, but not inserted in between

# Meshed topology

In mesh networks, each host is connected to one or more other hosts. If a line is interrupted, an alternative route is sought. With fully meshed networks, each network participant is connected to all the others.

• Data is relatively secure against eavesdropping

• Complicated implementation
• A lot of wiring, high installation costs
• Active network components are required