Cómo funciona una conexión en internet. Curso de redes desde 0 | Cap 13 |

Name: Cómo funciona una conexión en internet. Curso de redes desde 0 | Cap 13 |
Uploaded: 2021-01-17T17:00:09.000Z
Duration: 56 min 21 s

Introduction and Overview

In this section, the speaker introduces themselves and the topic of the video, which is about the OSI and TCP/IP models. They mention that they will be discussing protocols within each layer and explain the concept of overhead.

Understanding Protocols and Overhead

A protocol is a set of rules for communication between networks, computers, or devices.

Each layer in the OSI or TCP/IP model has its own set of protocols.

Protocols help standardize communication and ensure understanding between networks.

Overhead refers to the additional data added to each layer when sending information, which increases the cost of transmission.

Protocols in Each Layer

This section focuses on the protocols found within each layer of the OSI or TCP/IP model.

Layer 1 - Physical Layer

The physical layer deals with voltages, intensities, wavelengths, and connectors.

There are no specific protocols at this layer as it primarily involves hardware standards.

Layer 2 - Data Link Layer

The data link layer includes protocols such as Ethernet and Spanning Tree Protocol (STP).

Layer 3 - Network Layer

The network layer includes IP (Internet Protocol), which can be IPv4 or IPv6.

There are additional protocols within this layer for routing purposes.

Layer 4 - Transport Layer

The transport layer mainly consists of two protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

TCP is commonly used for opening ports on routers.

Layer 7 - Application Layer

The application layer has numerous protocols for various applications such as SMTP for email, HTTP/HTTPS for web browsing, FTP for file transfer, etc.

Understanding Headers and Overhead

This section explains the concept of headers and the additional data added at each layer, resulting in overhead.

Each layer adds additional data to the original information being transmitted.

Using an analogy of sending a fragile glass, the speaker explains that to protect it, it needs to be placed inside multiple boxes, which incurs additional costs.

Similarly, in networking, each layer adds extra information for verification and control purposes, leading to overhead.

Conclusion

The speaker concludes by emphasizing the importance of understanding protocols within each layer and the concept of overhead in network communication.

TCP/IP is not a single protocol but rather two separate protocols belonging to different layers.

Overhead occurs due to the additional data added at each layer for proper transmission.

It is crucial to be aware of protocols and their functions within each layer for effective network communication.

Understanding the Cost and Logistics of Shipping Packages

In this section, the speaker explains the cost and logistics involved in shipping packages.

The Cost of Shipping

Shipping a package incurs additional costs at each step of the process.

When a package needs to be sent to Madrid before reaching its final destination in the US, it may be placed inside another larger package or a van with other packages, resulting in additional costs.

Changing Modes of Transportation

As packages move from one transportation mode to another, they undergo changes in name and form.

For example, when a package is shipped by boat, it is placed inside a container and referred to as such. This change in size and name affects the shipping process.

Size Constraints

There are limitations on both very small and very large items that can be shipped.

Very small items may need to be placed in larger boxes for shipment, while very large items may need to be disassembled into smaller packages for easier handling.

Overhead Costs

Sending information electronically also incurs overhead costs due to minimum packet sizes that need to be met.

Similarly, sending extremely large files requires dividing them into smaller packets for transmission.

The Layers of Network Communication: Practical Example

In this section, the speaker provides a practical example of how network communication works using email as an illustration.

Sending an Email

When sending an email, it operates at Layer 7 (Application Layer) using an application like SMTP (Simple Mail Transfer Protocol).

A short email with 100 bytes of data is passed from Layer 7 (Application Layer) to Layer 4 (Transport Layer).

Transport Layer Processing

At Layer 4 (Transport Layer), headers are added to the email packet containing information about its destination.

These headers typically add around 20 bytes to the packet size, resulting in a larger packet of 120 bytes.

Segmenting Packets

In network communication, packets are referred to as segments at the Transport Layer.

The process of segmenting packets allows for efficient transmission and delivery of data.

Conclusion

The transcript provides insights into the cost and logistics involved in shipping packages, as well as a practical example of how network communication works using email. Understanding these concepts is essential for comprehending the complexities of shipping and network protocols.

Packet Transmission Process

This section explains the process of packet transmission and how each layer adds headers to the packet.

Packet Transmission Process

Each layer in the network stack adds its own header to the packet.

The data is divided into packets, which are then passed down to the next layer.

At the network layer (layer 3), the packet is further encapsulated with a new header specific to that layer.

The process continues as each subsequent layer adds its own header.

At the link layer (layer 2), the packet is encapsulated in a larger container with both a header and a trailer.

The size of the packet increases as it moves through each layer, due to additional headers and trailers being added.

Packet Structure at Layer 3

This section discusses the structure of packets at Layer 3 and focuses on IPv4 and IPv6 protocols.

Packet Structure at Layer 3

At Layer 3, packets are still referred to as packets.

The size of the packet may increase due to additional headers added by each layer.

In this example, we have a packet of 140 bytes after passing through all layers.

The primary protocol used at Layer 3 is IP (Internet Protocol).

Encapsulation at Layer 2

This section explains how encapsulation occurs at Layer 2 and introduces concepts like headers and trailers.

Encapsulation at Layer 2

At Layer 2 (link layer), another level of encapsulation takes place.

The packet from Layer 3 is placed inside a larger container, which includes both a header and a trailer.

Additional data is added before and after the original packet, increasing the overall size.

The header may have 14 bytes and the trailer may have 4 bytes, resulting in a total of 158 bytes.

Packet Size at Layer 2

This section discusses how the packet size changes at Layer 2 due to encapsulation.

Packet Size at Layer 2

After passing through Layer 2, the packet size increases to accommodate the added headers and trailers.

In this example, the packet size is now around 150 bytes, which is approximately a 50% increase from the original data size.

The Level 2 layer then passes the packet to Level 1 (physical layer) for further transmission.

Transmission Medium and Reception

This section explains how packets are transmitted through different mediums and received by the destination device.

Transmission Medium and Reception

Packets can be transmitted through various mediums such as Ethernet, LTE, or Wi-Fi.

Regardless of the medium used, packets will eventually reach their destination device.

The physical layer receives the packets and converts them into electrical signals for further processing.

The receiving device's link layer opens up the container and verifies its contents before passing it to higher layers.

Verification at Layer 2

This section focuses on how verification occurs at Layer 2 after receiving a packet.

Verification at Layer 2

At Layer 2 (link layer), the receiving device verifies the integrity of the received packet.

It checks if everything is intact and nothing has been corrupted during transmission.

Once verified, it removes the outer container but retains the original packet with its increased size (140 bytes).

The packet is then passed back to Layer 3 (network layer) for further processing.

Passing through Layers

This section explains the process of passing packets between different layers and protocols.

Passing through Layers

After verification at Layer 2, the packet is passed back to Layer 3 (network layer).

The network layer opens the container, verifies its contents, and retrieves the original packet.

The packet is then passed to higher layers, such as the transport layer (Layer 4), using protocols like TCP or UDP.

This process continues until the packet reaches the application layer (Layer 7).

Headers and Information Exchange

This section discusses how headers contain information for each layer and facilitate communication between layers.

Headers and Information Exchange

Each layer's header contains information about the next layer it needs to reach.

Headers specify which protocol should handle the packet at each level.

They also carry information needed by higher or lower layers for proper communication.

Verification of headers ensures that data is correctly transmitted across different layers.

Protocol Consistency across Layers

This section emphasizes that protocols remain consistent across layers for effective communication.

Protocol Consistency across Layers

Within each layer, both sender and receiver use the same set of protocols.

For example, if TCP is used at Layer 4, both sender and receiver communicate using TCP.

This consistency allows seamless communication between devices at different layers.

Interoperability of Protocols

This section highlights how different programs can still understand standardized protocols despite using different email clients.

Interoperability of Protocols

Different email programs may be used by the sender and receiver.

However, as long as they adhere to standardized protocols like SMTP (Simple Mail Transfer Protocol), they can still understand each other's emails.

The receiving computer opens the email using its email program, regardless of the program used by the sender.

Complex Transmission Scenarios

This section introduces more complex transmission scenarios involving wireless connections and access points.

Complex Transmission Scenarios

In scenarios involving wireless connections and access points, the transmission process becomes more complex.

The packet is passed from Layer 7 to Layer 4, then through various layers until it reaches Layer 1 for physical transmission.

The size of the packet may increase due to encapsulation at each layer.

Despite these complexities, protocols ensure successful communication between devices.

Understanding Data Transmission in a Network

In this section, we will explore how data is transmitted in a network and the various layers involved in the process.

Data Transmission Process

Data transmission occurs at the link layer (layer 2) of the network.

The access point receives data from the computer at the link layer.

The access point then sends the data to the router at the link layer.

The router receives the data and processes it at both the link layer and network layer (layer 3).

The router sends the data to another router or destination through either an ISP or internal network.

Packet Handling and Verification

At each step of transmission, packets are created and verified for integrity.

Each device along the transmission path opens and inspects packets to ensure they are intact.

If any errors are detected, devices may request retransmission of specific parts of the packet.

Complexity and Resource Consumption

As data moves from one device to another, packets need to be opened, inspected, and repackaged.

This process consumes time and resources within each device along the transmission path.

Even small amounts of data require this handling process, which can impact network performance.

Data Transmission Between Devices

In this section, we will discuss how data is transmitted between different devices in a network.

Multiple Devices in a Network

When transferring data between devices connected via switches or access points, each device handles packets individually.

Each device opens packets, verifies their integrity, and repackages them before sending them to subsequent devices.

Error Recovery

If errors occur during transmission, devices may attempt error recovery techniques such as requesting retransmission or repairing corrupted data.

Data Transmission and Network Performance

In this section, we will explore how data transmission and packet handling can impact network performance.

Impact on Network Performance

The process of opening, inspecting, and repackaging packets consumes time and resources.

Even small amounts of data require this handling process, which can affect network performance.

Factors such as packet size and the number of devices involved in transmission can further impact performance.

Considerations for Data Transmission

In this section, we will discuss important considerations for data transmission in a network.

Packet Size

Packets need to have a minimum size to ensure efficient transmission.

Very small packets may not be practical due to the overhead involved in handling them.

Impact on Network Performance

The complexity of the data transmission process can impact overall network performance.

It is essential to consider factors such as packet handling, device resources, and network capacity when designing a network.

Layers 8 and 9 - Introduction

In this section, we introduce layers 8 and 9 of the networking model.

Introduction to Layers 8 and 9

Layers 8 and 9 refer to higher-level layers beyond the traditional OSI model.

These layers are often associated with human interaction with the network or specific applications.

The transcript continues beyond this point but does not provide any relevant information for note-taking purposes.

Using Office 365 for NAS Data Backup

The speaker discusses the benefits of using Office 365 for NAS data backup, specifically for QNAP and Synology devices. Unlike traditional backups that only retain data for a month, Office 365 allows users to recover any data from any backup at any time.

Benefits of Office 365 for NAS Data Backup

With Office 365, users can access and recover data from any backup, regardless of how far back it was created.

This solution eliminates the problem of not having a backup older than a month.

Users can retrieve any necessary data with no time limitations.

Understanding "Layer 8" Errors

The speaker explains the concept of "Layer 8" errors and clarifies that Layer 8 does not actually exist in the TCP/IP model. It is often used humorously to refer to user errors or mistakes.

What are "Layer 8" Errors?

"Layer 8" refers to an error that is attributed to the user or individual behind the computer system.

In reality, there are only seven layers in the TCP/IP model, with Layer 7 being the application layer.

The term "Layer 8" is commonly used when referring to user errors or mistakes made during computer operations.

User Errors and Layer 8

The speaker emphasizes that many errors are caused by users making mistakes while performing tasks on their computers. These mistakes are often referred to as "Layer 8" errors due to their association with user actions.

User Errors and "Layer 8"

When someone mentions an error related to "Layer 8," they are referring to a user error that is not specified within the TCP/IP model.

The term "Layer 8" is often used to indicate that the error lies with the user who made a mistake while performing a task.

Users are considered the "Layer 8" because they are individuals operating behind the computer system.

Humorous Reference to "Layer 9"

The speaker shares a humorous reference to a fictional "Layer 9" above Layer 8, which represents administration or government regulations. This reference serves as an additional joke related to layers in computer systems.

Humorous Reference to "Layer 9"

In addition to the concept of "Layer 8," there is a joke about a non-existent "Layer 9."

This fictional layer humorously represents administration and government regulations that affect various aspects of computer systems.

The mention of "Layer 9" is meant as a lighthearted addition and should not be taken seriously.

Conclusion

The speaker concludes by thanking the audience for watching and encourages them to like the video if they found it helpful or want more information.