What is a Network Topology | Types of network topology

Network Topology

What is a Network Topology | Types of network topology

Hello, I’m Sourav Khanna and welcome to the session on network topologies. Today we’re going to discuss what a topology is. Then we’re going to discuss peer to peer and client-server networking. And then we’re going to talk about some common network topologies. And with that, let’s go ahead and begin this session.

What is a Network Topology

What is a topology? 

Well, a topology is basically a map that can be used to describe how a network is laid out or how a network functions. A network topology can be described as either being logical or physical. a logical topology describes the theoretical signal path, while a physical topology describes the physical layout of the network.

And you should know that a logical and physical topology doesn’t need to match. And with that, let’s move on to peer to peer versus the client-server networks.

So are these really topologies? No, not really. They don’t describe the signal path or the physical layout of the network. But yes, they are topologies because they do describe how the network function. So that’s why they’re here in this discussion.

Now in a peer to peer topology, the nodes control and grant access to resources on the network. No one node or group of nodes controls access to a single specific type of resource. There’s no real server present. Each node is responsible for the resource, it’s willing to share. No client-server topology differs.

Network resource access is controlled by a central server or servers. A server determines what resources get shared, and who is allowed to use those resources. And even when those resources can be used.

Now, in the small office home office, it’s common to find a hybrid topology. That’s where a combination of peer to peer and client-server networking is, you know, let’s move on to some common network topology models. The first one we’re going to discuss is the bus.

The original Ethernet standard established a bus topology for the network, both logically and physically. And what I mean by a bus topology is the signal travelled along a predetermined path from end to end, it went from one direction to the other direction, and then it could come back.

Now as time went on, the bus developed some mechanical problems that led to the development of different physical topologies. But the logical topology remained the same in order to maintain backward compatibility. So when we discuss Ethernet networks, the logical topology is always a bus topology, while the physical topology can be different.

So let’s talk about the bus. Again, the signal traverses from one end of the network to the other, no break in the line breaks the network and the ends of the bus line needed to be terminated in order to prevent signal bounce.

And what that means is that if there was a break or the ends of the line were not terminated, when the signal got to the end, it would bounce back through and create a storm. In a bus topology, the network cable is the central point.

Now kind of related to the bus is the ring, it’s a bus line with the endpoint connected together, a break in the ring breaks the ring. In a ring topology, it’s common to use two rings or multiple rings that can rotate the safeguards against a break in one ring bringing down the whole network.

Now ring topologies are not very common anymore in the land. But they’re still used in the wide-area network, especially when SONET or SDH is used.

Moving on from the ring we have the star, the nodes radiate out from a central point. Now when a star topology is implemented with a hub, a break in a segment brings down the whole bus, because the hub retransmits out all ports. Now when it’s implemented with a switch of braking, the segment only brings down that segment, it is the most common implementation in the modern LAN. Then there’s the mesh.

A true mesh topology is when all nodes are connected to all other nodes, that’s a full mesh. Now, those aren’t very common because they are expensive and difficult to maintain. But it’s common to find partial meshes. That’s where there are multiple paths between nodes. Now everyone knows at least one partial mesh network and that would be the internet.

Now let’s move on to the point to point topology. That’s where two nodes or systems are connected directly together. Now if you’re talking about two PCs, that’s when they use a crossover cable to create a point to point topology. There’s no central device to manage the connection.

Now, this is still a common topology when implemented across a LAN connection utilizing a T-one line. We also need to discuss point to multipoint. In a point, multipoint topology, a central device controls the paths to all other devices. This differs from the star in that the central device is intelligent.

Now wireless networks often implement point to multipoint topologies. When the wireless access point sends all devices on the network receive the data. But when a device sends its messages only passed along to the destination. It’s also a common topology when implementing a win across a packet switch network.

Now let’s discuss MPLS, MPLS is multiprotocol Label Switching and it is a topology that’s used to replace both frame-relay switching in ATM switching. It’s a topology because it specifies a signal path in layout. MPLS is used to improve the quality of service and flow of network traffic.

It uses label edge routers, le RS which are MPLS labels to incoming packets if they don’t already have them know the Le RS and the labels and pass the packets along to the LSRS Label Switching router, these forward packets based on their MPLS labels.

That’s what makes this a topology.
Now that concludes this session on network topologies. We discussed what a topology is. Then we discussed the differences between peer to peer and client-server networking. And then I brought up some common network topology models that you should know.

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