Basics of Bridge

Summary

This lecture introduces the fundamentals of network bridging, distinguishing it from a repeater by its ability to read MAC addresses, making it a layer two device. It covers two types of bridges: transparent, which requires no node awareness or reconfiguration, and source routing, which involves the source station in routing decisions. The lecture highlights the bridge's role in interconnecting local area networks operating on the same protocol, contrasting it with routers that work across different protocols and handle IP addresses at the layer three level.

Takeaways

• 📚 The lecture introduces the basics of a bridge in computer networking.
• 🔍 A bridge is essentially a repeater with the additional capability to read MAC addresses, making it a layer two device.
• 🌐 Bridges are used to interconnect two local area networks (LANs) that operate on the same protocol.
• 🚪 A bridge typically has two ports, similar to a repeater.
• 🔍 There are two types of bridges: transparent bridges and source routing bridges.
• 👀 Transparent bridges operate without the awareness of the network nodes, eliminating the need for node reconfiguration upon bridge addition or removal.
• 🗺️ Source routing bridges rely on the source station to determine the routing path, with the frame carrying the routing information.
• 🔗 The primary function of a bridge is to extend the range of a LAN and interconnect two networks running the same protocols.
• 🛑 A key distinction between a bridge and a router is that a bridge operates at the data link layer (layer two) and deals with MAC addresses, while a router operates at the network layer (layer three) and handles IP addresses.
• 🔄 Routers can interconnect LANs running different protocols and change the MAC address in a packet, unlike bridges which cannot.
• 📝 The session aims to clarify the types, working, and differences between bridges and routers in networking.

Q & A

What is the primary purpose of a bridge in computer networks?

A bridge is used to interconnect two local area networks (LANs) that operate on the same protocol, extending the range of the network and allowing communication between the two LANs.

How does a bridge differ from a repeater in terms of functionality?

While both a bridge and a repeater are used to extend network signals, a bridge has additional functionality such as reading MAC addresses, making it a more intelligent device compared to a simple signal repeater.

What is a layer two device, and why is a bridge considered one?

A layer two device operates at the data link layer of the OSI model, dealing with MAC addresses. A bridge is considered a layer two device because it processes and filters traffic based on MAC addresses.

What are the two types of bridges mentioned in the script?

The two types of bridges mentioned are transparent bridges and source routing bridges.

How are transparent bridges different from source routing bridges in terms of network configuration?

Transparent bridges do not require any configuration changes in the network nodes, as they are unaware of the bridge's existence. In contrast, source routing bridges rely on the source station to provide routing information for the data frames.

What is the key characteristic of transparent bridges that makes them transparent to network nodes?

Transparent bridges are designed in such a way that network nodes are completely unaware of their existence, eliminating the need for reconfiguration when bridges are added or removed from the network.

In source routing bridges, who is responsible for determining the route of the data frames?

In source routing bridges, the source station or node is responsible for determining the route that the data frames should follow to reach their destination.

How does the working principle of a bridge differ from that of a router?

A bridge operates at the data link layer and interconnects LANs running on the same protocol, focusing on MAC addresses. A router, on the other hand, operates at the network layer and can interconnect LANs running on different protocols, handling IP addresses and changing the data link layer addresses.

What is the main difference between a bridge and a router in terms of the OSI model layers they operate on?

A bridge is a layer two device that operates on the data link layer, while a router is a layer three device that operates on the network layer.

Why is the protocol compatibility important when using a bridge to interconnect two LANs?

Protocol compatibility is crucial because a bridge can only interconnect LANs that are running on the same protocol. If the LANs use different protocols, a router would be required instead.

What is the role of MAC addresses in the operation of a bridge?

MAC addresses play a central role in the operation of a bridge, as the bridge uses these addresses to filter and forward traffic between the interconnected LANs, ensuring efficient communication.

Outlines

00:00

📚 Introduction to Bridges in Computer Networks

In this lecture, we delve into the fundamentals of bridges in computer networks. We begin by outlining the session's objectives, including understanding the basics and types of bridges, their workings, and the differences between bridges and routers. We discuss how a bridge acts as a repeater with additional functionality of reading MAC addresses, making it a layer two device. Bridges are used to interconnect local area networks (LANs) using the same protocol. We then explore the types of bridges: transparent bridges, where nodes are unaware of the bridge's existence and no reconfiguration is needed, and source routing bridges, where the source station determines the routing path.

05:03

🔍 Transparent and Source Routing Bridges

We further explore the two types of bridges: transparent and source routing. Transparent bridges do not require reconfiguration of nodes as they are unaware of the bridge's presence. In contrast, source routing bridges involve the source station specifying the route for the frame to follow. This distinction highlights the different operational methods of the two bridge types within a LAN.

🔧 Functionality and Operation of Bridges

This section covers the practical functioning of bridges. By interconnecting two LANs, a bridge extends the network range and operates on the same protocol. This ensures seamless communication within the same protocol environment. The significance of using the same protocol in bridges is emphasized, differentiating it from routers which can handle different protocols.

🔀 Differences Between Bridges and Routers

Here, we compare bridges and routers. Bridges interconnect LANs using the same protocol and operate as layer two devices, dealing with MAC addresses. Routers, however, connect LANs with different protocols and function as layer three devices, managing IP addresses and altering data link layer addresses. This comparison clarifies the distinct roles and functionalities of bridges and routers in network communication.

✅ Conclusion and Thank You

The session concludes by recapping the key points discussed: the basics of bridges, their types, how they work, and the differences between bridges and routers. The lecture aims to provide a clear understanding of these concepts. The presenter thanks the viewers for their attention and engagement.

Keywords

💡Bridge

A bridge in the context of computer networking is a device that connects two or more LANs (Local Area Networks) and operates at the data link layer (Layer 2) of the OSI model. It is essentially a repeater with additional functionality, such as filtering traffic based on MAC addresses. The script emphasizes the bridge's role in extending the range of a LAN and interconnecting networks running on the same protocol, highlighting its importance in the lecture's theme.

💡Repeater

A repeater is a network device that amplifies and retransmits a signal to extend the range of a network. In the script, it is mentioned that a bridge is essentially a repeater but with enhanced capabilities, such as reading MAC addresses, which differentiates it from a simple repeater in terms of functionality.

💡MAC Address

MAC (Media Access Control) address is a unique identifier assigned to network interfaces for communications on the physical network segment. The script explains that a bridge's additional functionality includes reading MAC addresses, which is crucial for its operation in filtering and forwarding traffic within a LAN.

💡Layer Two Device

A layer two device operates at the data link layer of the OSI model and is responsible for managing the MAC addresses. The script identifies the bridge as a layer two device, emphasizing its role in dealing with MAC addresses and its use in local area networks.

💡Interconnecting LANs

Interconnecting LANs refers to the process of linking two or more local area networks to form a larger network. The script discusses how bridges are used for this purpose, specifically when the LANs operate on the same protocol, which is a key aspect of the lecture's content.

💡Transparent Bridge

A transparent bridge is a type of bridge that operates without the knowledge of the network nodes. The script explains that in a transparent bridge setup, no configuration is needed on the stations, as they are unaware of the bridge's existence, simplifying network management.

💡Source Routing Bridge

A source routing bridge is a type of bridge where the source station is responsible for specifying the route that data must take to reach its destination. The script describes this as a routing operation performed by the source, which is a distinct characteristic of this bridge type.

💡Protocol

In networking, a protocol defines the rules and conventions for data transmission. The script highlights the importance of protocol compatibility when using bridges to interconnect LANs, as they must operate on the same protocol to function correctly.

💡Router

A router is a networking device that operates at the network layer (Layer 3) of the OSI model and is capable of routing data packets between different networks. The script contrasts routers with bridges by explaining that routers can interconnect networks running on different protocols and work with IP addresses, unlike bridges.

💡Layer Three Device

A layer three device operates at the network layer and is involved in routing decisions based on IP addresses. The script uses this term to differentiate routers from bridges, as routers are layer three devices that handle IP addresses and can change the data link layer address in a packet.

Highlights

A bridge is a repeater with additional functionality of reading MAC addresses.

Bridges are layer two devices that operate on MAC addresses.

Bridges interconnect two local area networks using the same protocol.

A repeater has two ports, and so does a bridge.

There are two types of bridges: transparent and source routing bridges.

Transparent bridges operate without the nodes being aware of their existence.

No reconfiguration is needed for nodes when a transparent bridge is added or removed.

Source routing bridges perform routing operations with the source station specifying the route.

Source routing bridges require the source station to have routing information.

Bridges extend the range of local area networks and interconnect them.

Bridges only interconnect networks running on the same protocols.

Routers can interconnect networks running on different protocols unlike bridges.

A bridge is a layer two device that deals with MAC addresses.

A router is a layer three device that deals with IP addresses and changes MAC addresses.

The main difference between a bridge and a router is the layer they operate on and the protocols they handle.

This lecture provides a comprehensive understanding of bridges, their types, working, and differences with routers.

Transcripts

Hello everyone,

welcome to the next lecture in the computer network series.

Today we will see, the basics of bridge.

We will start with the outcomes of today's session.

In today's session, we are going to understand the basics of bridge,

we will know the types of bridges,

and we will understand the working of a bridge,

and finally we will understand

the difference between a router and a bridge.

We will start with the basics of bridge.

A bridge. It is a repeater.

If bridge and repeater are the same,

then why do we need two different terminologies

and two different concepts and two different devices.

A bridge is normally a repeater

but with some additional functionalities

and the additional functionality is that

it has the potential of reading MAC addresses.

So a bridge is normally a repeater

with the additional functionality of reading MAC addresses.

Whenever any device that is dealing something with the MAC address only,

then that device will be a layer two device.

So bridge is also a layer two device.

We will see what is the use of a bridge.

Bridges are also used for interconnecting

two local area networks on the same protocol.

The very important point is -- on the same protocol.

Say we have two local area networks

and these two local area networks are using the same protocol,

then bridges are used to interconnect these two local area network.

Then, it is also a port two device like a repeater.

A repeater has only two ports,

likewise a bridge will also have only two ports.

Let's have a look at the types of bridges.

There are two types of bridges

number one, transparent bridges and number two, source routing bridges.

We will see one by one briefly.

Transparent bridges. These are the bridge in which stations

or nodes are completely unaware of the bridge's existence.

It means in a local area network, if there exist a bridge

the stations or nodes are unaware of the existence of the bridge.

It means, we need not do any configuration in the stations.

In a router, we used to give the IP address of the interface

as the default gateway for all the stations or PCs.

Whereas in a bridge, we need not do that

because the stations are completely unaware of the bridge's existence.

So, reconfiguration of stations is unnecessary

even if the bridge is added or removed from the network.

Suppose if we add a bridge or remove a bridge

we need not do any configuration or reconfiguration in the stations.

That's about the transparent bridges.

Let's now have a look at the second type of bridge

which is the source routing bridges.

In source routing bridges,

the routing operation is performed by the source station

and the frame specifies which route to follow.

For example in a local area network,

there is a source station or a source node,

if that node is going to send some data to other node,

then this node, that is the source station

will have the routing information

how this frame has to reach the destination.

So that information is processed by the source routing bridges.

So there are two types of bridges

number one, transparent bridges and number two, source routing bridges.

Let's have a look at the working of the bridge now.

Suppose if we have a local area network

and we have another local area network,

to connect these two local area networks we bring in a bridge

and this bridge extends the range of the local area network

and interconnects these two networks.

That's the working of a bridge.

And the very important point to note about bridge is that

this bridge interconnects two network that are running on the same protocols.

So same protocol is a very important point to note here.

If this is a router, router can interconnect

two different local area networks,

that need not be the same protocols,

they can run two different protocols.

Now you may have a question in your mind.

If bridge can interconnect two local area networks,

router can also interconnect two local area networks,

then what is the difference between a bridge and a router?

Let's see the difference between a bridge and a router now.

The difference between a bridge and a router is that

a bridge interconnects local area networks

that are running on the same protocol

and the bridge is a layer two device.

That is, it processes or it deals with the MAC addresses.

Whereas if it is a router, then this router interconnects

two different local area networks that are running

with two different protocols and router is a layer three device.

So at the basic level, bridges interconnects local area networks

that are running in the same protocol

and it is a layer two device, it deals with the MAC addresses only.

Whereas a router, it interconnects two different local area network

that has two different protocols and router is a layer three device.

It deals with the IP addresses

and a router changes the data link layer address

that is the physical address or MAC address in a packet.

And that's the difference between a bridge and a router.

I hope now we understood the basic of bridge,

we know the types of bridges that is

transparent bridges and source routing bridges.

We understood the working of a bridge

and we also understood the difference between a router and a bridge.

I hope the session is informative

and thank you guys for watching.