Point-to-Point Protocol over Ethernet (PPPoE)

The Internet is an essential part of our daily lives, so we need a reliable connection. However, getting one can be a challenge, especially when using Ethernet. That's where Point-to-Point over Ethernet (PPPoE) comes in.
Used predominantly in ADSL modem connections, it allows you to connect to the Internet via your Internet service provider. In this article, learn what PPPoE is, how it works, how it's used, and why it's important to modern Internet connectivity.

What is PPPoE?

PPPoE, meaning Point-to-Point Protocol over Ethernet, is a popular networking activity used to establish a point-to-point connection between two devices over Ethernet. It facilitates communication between network endpoints.

PPPoE protocol involves encapsulating PPP frames in Ethernet frames, allowing the PPP packets to transmit over Ethernet networks. The protocol is widely used by Internet service providers (ISPs) to deliver Internet connections to their subscribers. With Point-to-Point Protocol over Ethernet, ISPs are able to manage multiple client systems, provide added security by authentication to establish a connection, and track customer data usage. PPPoE also offers essential networking services such as transmission, data encryption, and compression.

Point-to-Point Protocol over Ethernet is often used in place of the traditional PPP (Point-to-Point) protocol. This older protocol only allowed one-on-one connections. Because multiple clients needed to connect to the same server and access the Internet simultaneously, PPPoE came out.

A Point-to-Point over Ethernet (PPPoE) connection

Essentially, PPPoE is an advanced version of the old dial-up connections. Most DSL Internet providers use PPPoE to offer Internet services to their customers.

What is the purpose of PPPoE?

The sole purpose of PPPoE is to establish a point-to-point connection over Ethernet networks. It ensures secure communication between devices by encapsulating PPP frames within Ethernet frames.

Internet service providers commonly use Point-to-Point Protocol over Ethernet to authenticate and connect subscribers to their network, allowing for more flexible network configurations. It allows ISPs to assign unique IP addresses to every subscriber while they manage their network traffic more efficiently. This enables scalable Internet access as well.

How does PPPoE work?

Point-to-Point Protocol over Ethernet works through two main processes: PPPoE discovery and PPP session. In order to understand these two processes, however, you need to have a grasp on Ethernet and Point-to-Point protocol. Both are vital, but different, networking protocols in Point-to-Point Protocol over Ethernet.

In a PPPoE connection, Ethernet is used as the underlying physical layer protocol to transmit PPP packets in between the devices. PPP, on the other hand, is encapsulated within Ethernet frames and transmitted over the Ethernet network.

PPPoE combines the benefits of both Ethernet and PPP connections to provide a secure method of transmitting data over an Ethernet network.

PPPoE discovery

The first of the two processes in PPPoE is the discovery process. In this process, the client's device sends a PPPoE Active Discovery Initiation (PADI) packet to the local area network, which is received by the PPPoE access concentrator (AC) on the ISP's side. The AC then responds with a PPPoE offer packet containing the service name, maximum transmission unit, and session ID.

Then, the client's device sends a PPPoE Active Discovery Offer (PADO) packet to the AC that includes the service name and a unique session ID. The AC verifies the user's credentials and sends a PPPoE session packet. Finally, this establishes the PPP session between the user's device and the AC.

PPP session

During the PPP session, the user's device can send and receive PPP frames, which are encapsulated within Ethernet frames and sent over the Ethernet network. The AC manages the user's network traffic while it assigns a unique IP address to the user's device, allowing them to access the Internet securely.

When the user ends their session, their device sends a PPPoE termination packet to the AC, which terminates the PPP session and releases the assigned IP address.

The user's computer can now access the Internet once both processes end.

PPPoE architecture

The protocol is made up of several components, including the client, the server, and ADSL modems.

PPPoE client

The client is the device that initiates the Point-to-Point over Ethernet connection. It can be a computer, a router, or any other device capable of establishing a connection. The client sends a connection request to the Point-to-Point Protocol over Ethernet Access Concentrator, which then forwards the request to the server.

PPPoE Access Concentrator (AC)

The Access Concentrator, or AC, is the software that authenticates the user's credentials and assigns an IP address to the computer in use. The NAS establishes a PPPoE session with the computer. The AC also acts as an intermediary between the client and the server, as well as being responsible for maintaining the PPPoE session.

PPPoE server

The Point-to-Point over Ethernet server is the device or software that receives the connection request from the AC and establishes the session with the client. The server is responsible for maintaining the session and ensuring that the communication between the client and the server is secure.

ADSL modem

An ADSL (Asymmetric Digital Subscriber Line) modem can be used for connections; in fact, PPPoE is commonly used in ADSL connections to establish a point-to-point connection between the user's computer and the ISP's network access server line (NAS).

The device acts as a bridge between the user's computer and the ISP's network, connecting them via Ethernet-based networks.

Hosts

Though not strictly a part of the protocol, hosts may be considered a component of PPPoE connections. The term "hosts" refers to the end-user devices that use the protocol to connect to the Internet, like computers or routers.

Without hosts, the PPPoE connections wouldn't be possible, as they are the devices that initiate the PPPoE session. The device provides the necessary credentials for authentication purposes, too.

How is the PPPoE configured?

Some ISPs may supply you with a broadband modem that has the necessary PPPoE support already configured. But in some cases, admins need to set up the PPPoE connections manually.

To configure, you need to know some information like your PPPoE username and password and the maximum transmission unit size. The login credentials are for authentication purposes, and the MTU determines the maximum size of data packets that can travel across the connection.

Other parameters that need to be configured include the service name for identifying the user's service on the NAS and IP address configuration for assigning an IP address to each user.

Fortunately, most major operating systems like Windows and MacOS have native PPPoE support. This makes it relatively easy to set up the connection.

How to set up a Point-to-Point Protocol over Ethernet connection on Windows

If you're using Windows, you can configure a PPPoE connection by following these steps.

  1. Click Start and then click Settings from the menu.
  2. In the Settings window, select Network & Internet.
  3. Click Dial-Up.
  4. Select Set Up a New Connection.
  5. Choose Connect to the Internet and then click Next.
  6. Select Broadband (PPPoE) from the list of methods for connecting to the Internet.
  7. Enter the username and password provided by your ISP. If required, specify the MTU size.
  8. Click Connect when finished entering the information.

After successful authentication, you'll receive an IP address assigned to your computer from the ISP's network access server. Close the window once successfully connected to finish configuring your connection in Windows.

How to set up a Point-to-Point Protocol over Ethernet connection on Mac

Configuring a PPPoE Internet connection in MacOS involves the following steps.

  1. Click on the Apple icon to open up the menu. Click System Preferences.
  2. Then, click on Network in the System Preferences window.
  3. From the menu, select Ethernet.
  4. On the next screen, select Create PPPoE Service from the Configuration drop-down menu.
  5. Enter a name for your PPPoE connection.
  6. In the Account name and Password fields, enter the username and password provided by your ISP. If your ISP requires a specific MTU value, click on the Advanced button, go to the PPP tab, and enter the value in the Maximum Packet Size field.
  7. Click on the Connect button to establish your connection.

How to set up Point-to-Point Protocol over Ethernet on a router

To configure PPPoE on a router, follow these steps.

  1. Access the router's configuration page through a web browser.
  2. Locate the PPPoE settings, which are usually under the wide area network or Internet settings.
  3. Enter the PPPoE credentials provided by the ISP, including the service name and username and password.
  4. Save the configuration and restart the router if necessary.

Point-to-Point over Ethernet advantages

This protocol offers several advantages compared to traditional Internet access methods. These include:

  • A secure connection. PPPoE provides a secure connection by requiring a username and password to authenticate the user.
  • Reduced Internet cost. Unlike PPP, PPPoE allows for the sharing of a single Internet connection among multiple devices. This reduces the cost of Internet access for small businesses and households.
  • Compatibility. The protocol is compatible with a wide range of networking devices. It's easily configured on most routers and modems.
  • Greater control over a network. It allows for more control over network traffic and bandwidth usage, enabling network administrators to manage traffic more easily.
  • Flexible IP address assignment. PPPoE provides both static and dynamic IP address assignment to users.
  • Improved speed. The protocol allows for faster speeds with its compression.

It's also easy for ISPs to provide additional capacity to customers simply by adding new connections at no extra cost.

However, there are also disadvantages to PPPoE. It requires complex configuration, which can make it a challenge for novice users to set up. Additionally, many older computers aren't compatible with the protocol, as it requires a fast Ethernet connection and drivers for proper function. The two layers of the network stack used in PPPoE connections also make troubleshooting connections more difficult.

PPPoE issues can also arise due to the need for authentication at the client level, making it more susceptible to user error than other connectionless protocols.

Comparing PPPoE vs. DHCP

PPPoE is no longer as widely used as before; in many cases, it's being replaced by Dynamic Host Configuration Protocol (DHCP). PPPoE and DHCP are both networking protocols commonly used to provide Internet access. DHCP works to assign IP addresses and other network configuration information to devices on a network. They are prevalent on local area networks to provide automatic IP address assignment to devices.

When comparing DHCP vs. PPPoE, the main difference is their uses. Point-to-Point Protocol over Ethernet connects a device to the Internet, while DHCP servers assign IP addresses to devices on a network. Additionally, PPPoE requires authentication of data, but DHCP doesn't.

Point-to-Point Protocol over Ethernet therefore provides a secure connection between the subscriber's device and the ISP's network, boosting Internet security. DHCP, on the other hand, operates on a trusted network, making security less of a concern.

Frequently asked questions

Do I need PPPoE for my Internet connection?

Not necessarily. The protocol is typically used by DSL providers, but other types of Internet connections (like cable Internet or fiber optic Internet) may use different protocols. Your ISP should provide you with necessary information to set up your Internet connection.

Is Point-to-Point Protocol over Ethernet secure?

If configured correctly, yes. It provides authentication and encryption to protect user data. However, like all technology, it's not immune to vulnerabilities; make sure to keep all security up to date.

How do I troubleshoot PPPoE connection issues?

If you're experiencing issues with your connection, first ensure that you entered the correct credentials. Be sure to configure your device properly. You can also try power cycling your router and modem or contacting your ISP as a last resort.

Can PPPoE cause slow Internet speeds?

Yes, but not always. Sometimes PPPoE can add some overhead to your Internet connection, leading to slightly slower speeds. However, the drop likely isn't noticeable unless you have a very fast Internet connection.