(Thanks to Practical Networking for their informative YouTube channel, available here).
This follows my previous post.
In a network, data crossing a wire connecting two hosts decays as it travels, up to invalidating the sharing of data if the distance is significant.
A repeater is a device which regenerates a signal: when inserted between two hosts, the signal entering one end of the repeater is regenerated on the other side. This allows data to travel greater distances.
Definition: A repeater in networking is a device that amplifies and re-transmits signals, extending the reach of a network by regenerating and boosting the strength of the transmitted data, allowing it to travel over longer distances.
If you have more complex networks with more than two hosts, a device called hub is needed.
The hub connects multiple hosts in a network, allowing them to communicate by forwarding data to all connected devices. Hubs do not make intelligent decisions about where to send data; instead, they broadcast incoming data to all connected devices, regardless of the intended recipient. This can lead to network congestion and inefficiency. Hubs are largely obsolete in modern networks, with switches being more commonly used for better performance and efficiency*.
*(I will write more about this further down).
Hub’s purposes:
A repeater is a device which regenerates a signal: when inserted between two hosts, the signal entering one end of the repeater is regenerated on the other side. This allows data to travel greater distances.
Definition: A repeater in networking is a device that amplifies and re-transmits signals, extending the reach of a network by regenerating and boosting the strength of the transmitted data, allowing it to travel over longer distances.
If you have more complex networks with more than two hosts, a device called hub is needed.
The hub connects multiple hosts in a network, allowing them to communicate by forwarding data to all connected devices. Hubs do not make intelligent decisions about where to send data; instead, they broadcast incoming data to all connected devices, regardless of the intended recipient. This can lead to network congestion and inefficiency. Hubs are largely obsolete in modern networks, with switches being more commonly used for better performance and efficiency*.
*(I will write more about this further down).
Hub’s purposes:
- Connecting hosts directly to each other doesn’t scale; therefore, a central device to handle funnelling communications is needed.
- We want an easy setup if we connect another host to the existing network: thanks to the hub, this new host will have connectivity to the other hosts in the network.
Hub is a multi-port repeater: it takes a packet from a single host and duplicates it to multiple hosts.
To avoid this, two hubs can be created (each one connected to a specific and closed network of hosts) and linked together through a bridge.
Bridges have two ports only, one for each hub (each hub represents a contained network). Bridges know how to contain communications inside one relative network without sending unwanted communications from one hub to the other one. However, bridges learn what hosts are on each side and therefore, if required, they can allow communications between the two relative networks.
This solution can put two networks in communication, however, what is pushed through the bridge is pushed to all the hosts in the network on the other side. And this is not ideal.
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If you combine hubs and bridges, you have a switch, which is a central device that facilitates communication within a network without pushing unwanted packets to all the hosts in the network (a switch learns which hosts are on each port).
Networks share the same IP address space. So, if 192.168.1.X is the hypothetical IP space of a network made of various hosts, each host of that network will be identified by a specific number replacing X (e.g., the IP can be 192.168.1.1 for one host, 192.168.1.2 for another host of the same network etc.). Imagine this to be the home Wi-Fi where your computer, phone, printer etc. are connected (after all, these are all hosts identified by an IP).
A switch can only facilitate communications within the same network so if there are two separate networks inside the same organisation and each one of them has a switch, these cannot communicate. To solve this, we need a router.
A router “sits” between networks and facilitates communications between them. A router provides a traffic control point (a logical location) to implement security measures, redirect and filter traffic. It can also connect networks with the internet. Switches cannot provide such filtering (actually, modern switches can but since they sit inside the network and not on its “edge” like a router, filtering is typically not required).
A router learns which networks they are attached to; this knowledge is known as “route”, and it is stored in routing tables.
A router has an IP for each network it is attached to. So, each of its IPs (can be multiple) is part of the IP spaces of the networks attached to it.
If a host in network A wants to communicate with another host in network B, and a router is involved, the router’s IP address which is in the IP space for network A serves as Gateway for the hosts in network A. In other words, it is a host’s way out of their local network.
In an organisation with different departments and locations, it is likely that every department and location has a router and that these routers are connected to the internet (which represents a bunch of different routers itself!).
A switch can only facilitate communications within the same network so if there are two separate networks inside the same organisation and each one of them has a switch, these cannot communicate. To solve this, we need a router.
A router “sits” between networks and facilitates communications between them. A router provides a traffic control point (a logical location) to implement security measures, redirect and filter traffic. It can also connect networks with the internet. Switches cannot provide such filtering (actually, modern switches can but since they sit inside the network and not on its “edge” like a router, filtering is typically not required).
A router learns which networks they are attached to; this knowledge is known as “route”, and it is stored in routing tables.
A router has an IP for each network it is attached to. So, each of its IPs (can be multiple) is part of the IP spaces of the networks attached to it.
If a host in network A wants to communicate with another host in network B, and a router is involved, the router’s IP address which is in the IP space for network A serves as Gateway for the hosts in network A. In other words, it is a host’s way out of their local network.
In an organisation with different departments and locations, it is likely that every department and location has a router and that these routers are connected to the internet (which represents a bunch of different routers itself!).
Routing is the process of moving data between networks; switching instead happens within networks. There are many different devices working with networks (e.g., load balancer), but each one of them performs routing and/or switching.
