What is SLIP (Serial Line Internet Protocol)? | How Does It Work?

SLIP (Serial Line Internet Protocol) is a type of connection that works with speeds between 1200 bits per second (bps) and 19.2 thousand bits per second (Kbps). It takes IP packets along serial lines and manages the flow of data.

What is the SLIP Protocol in Networking?

The SLIP protocol doesn’t do things like address, figure out what type of package it is, compress, or fix mistakes along the transmission line. But, using it is simple and easy.

As the Internet grew, PCs became a part of the global networks. So, to make communication easier, they developed two main modem protocols: SLIP and PPP.

History of SLIP Protocol

In the past, before the Internet became widespread, it played a perfect role in enabling contact between PCs. But, because it’s an old tech, it has been replaced by more advanced protocols today.

It is an old Internet protocol. Its history first dates back to 1984. At that time, Berkeley and Sun Microsystems used this protocol on their Unix systems.

They started using TCP/IP in the following years because PCs improved. At the same time, the use of the SLIP protocol increased on PCs.

They started using a modem to connect the two places, which changes digital data into sound signals. They make this link using phone lines with something called frequency modulation.

Thanks to the SLIP connection, it became easier for PCs to communicate with IP addresses. So they no longer need to be connected to the Internet or a central system.

In short, they improved this protocol. Now, they directly make Internet services to PCs.

In terms of its history and development, it improved in two critical ways:

1. The Spread of Modems

In the 1980s, thanks to the widely used modem, PCs communicated over serial connections. Because of this, advancing technology brought newer solutions along with it.

2. The Birth and Development of the Internet

During these times, the first versions of the Internet emerged. Thus, there was still a need for a newer protocol for data transfer.

Features of SLIP Protocol

Although it is an old type of communication, there are some pros and cons.

1. Packaging Structure

It transforms info into the correct format before sending it properly. But it uses ASCII codes during communication. That’s why it adds start and end markers to the packet structure to separate it correctly.

2. Simple Marking

It uses a simple marking method to determine when the transfer begins and ends. In this case, the packet structure starts with “/START/” and ends with “/END/.”

3. Data Transmission Capability

It offers a flexible way to carry data. Using ASCII characters to represent data enables the transmission of various data types. So, its packets can easily take text, numbers, or other info types.

4. Connection Based

Working with serial connections requires a physical link between two devices. This process means they use modems or serial ports. In short, they are more preferred for point-to-point setups.

5. Less Resource Usage

It’s suitable for more straightforward, lighter devices that don’t need many resources. Primarily, it is for older PCs or modems with older tech.

6. Lack of Multipoint Communication

It only works between two devices and doesn’t do more than that. However, newer technologies support communication between multiple points.

7. Lack of Security and Error Checking

Data transmission could be more robust because it lacks security and error control. But modern types have these features.

How Does SLIP Work?

You can look at the steps below to understand how SLIP works using serial connections.

Establishing a Physical Connection

First, establish a device connection through a serial port or modem to enable communication. However, when PCs communicate, they do it smoothly over phone lines.

Data Packaging

The second step uses ASCII to mark the start and end of the packets it will send. So, it uses “/START/” and “/END/” signs.

Sending Data

After getting the packet ready, it sends it to the destination through the serial connection. However, SLIP sends the data in the correct order.

Data Retrieval

When the target device accepts the packet, it looks at the start and end markers. Then, it securely delivers it back to the source PC.

Response and Transmission

This step also sends info, responding to packets bidirectionally. It receives information from the sender’s serial port and then packages it to the target.

Termination of Connection

In the final step, the session closes once the PCs complete the info transfer.

Advantages and Disadvantages of SLIP

Serial Line Internet Protocol (SLIP) used to be quite popular. But it’s not widely used in today’s technology. Still, let’s discuss its pros and cons:

Pros

1. Simplicity and Lightness

This protocol works effectively on simple and low-resource devices, and it doesn’t need a lot of hardware.

2. Compatibility with Serial Connections

It works with older devices, making it useful for more aging tech networks.

Cons

1. No Multipoint Communication Support

It only supports up to two devices because it only works between two. So, it’s not suitable for modern networks.

2. Lack of Security and Error Checking

It could be more robust in terms of security when transferring data. Meaning it doesn’t do error checking and control during transfer.

3. Has Limited Abilities

It doesn’t offer the high data transfers that modern networks do. So, it only meets basic requirements.

4. More Advanced Protocols Available

For example, newer techs like PPP or Ethernet provide more security and speed. That’s why they use these instead of the SLIP protocol.

5. Developmental Mismatch

People nowadays use newer and better methods instead of SLIP, an old tech. So, because it doesn’t work well with modern systems, people no longer use this protocol.

Differences Between SLIP and PPP

The Serial Line Internet Protocol integrates old communication methods into the TCP/IP package. So, it doesn’t have any other job. In short, it’s a simple technology that doesn’t provide addresses or fix errors. As a result, it’s an older protocol compared to PPP.

An advanced protocol, PPP surpasses SLIP in extra info transfer on the Web. Thus, it supports various network technologies.

When delivering info packets, PPP does error checking. But it doesn’t provide any control. Also, it compresses and encrypts traffic, while SLIP doesn’t do this.

Overall, PPP has the same functions as SLIP but is a newer and more robust protocol.

A summary table:

Conclusion

To wrap up, SLIP played a significant role in making the Internet what it is today. Even though it’s old, it set the stage for modern protocols. People liked this protocol because it was simple and worked with lots of stuff. But nowadays, its limits mean it’s not as helpful.

Still, it’s essential in the history of Internet communication. However, we still hear the term in today’s technology.