What is PPPoE? (Point-to-Point Protocol over Ethernet)

🔍 In broadband networking—especially for DSL and fiber connections—PPPoE (Point-to-Point Protocol over Ethernet) is a widely used protocol that allows ISPs (Internet Service Providers) to manage user authentication, session control, and IP allocation over Ethernet networks. It’s commonly used in home and small business internet setups, including on devices like MikroTik routers and DSL modems.

💡 PPPoE Explained

Definition:

PPPoE is a protocol that encapsulates PPP (Point-to-Point Protocol) frames inside Ethernet frames. It combines the functionality of PPP—like authentication, encryption, and compression—with Ethernet, allowing multiple users to connect to a single Ethernet line and be individually authenticated by the ISP.

⚙️ Function of PPPoE

PPPoE is used to:

1. Authenticate Users – Users must enter a username and password, which the ISP verifies.
2. Assign IP Addresses – Once authenticated, the ISP dynamically assigns an IP address (private or public).
3. Track Usage/Billing – The ISP can manage and monitor usage per user session.
4. Support Multiple Users – It allows multiple clients on the same link to be handled separately.

🔁 How PPPoE Works: Step-by-Step

1. Discovery Phase
   • The router or PC sends out a PPPoE discovery packet (PADI) looking for an Access Concentrator (ISP device).
2. Session Initialization
   • The ISP replies, and a session is established (PADR, PADS).
3. Authentication Phase
   • The user provides credentials (username/password).
   • ISP uses PAP or CHAP to authenticate.
4. Session Established
   • Once authenticated, the ISP assigns an IP address to the client.
   • A virtual tunnel is formed between the user’s router and the ISP.
5. Data Transfer
   • Internet access begins over this authenticated tunnel.
6. Session Termination
   • The session can be terminated by the user, router, or ISP.

🔍 Comparison: PPPoE Account vs Public IP Address

PPPoE provides a secure, manageable way for ISPs to authenticate and assign IP addresses to users over Ethernet networks. It plays a crucial role in environments where user-level session management is needed. While a PPPoE account focuses on authenticated access to the internet service, a public IP address defines how a device is reachable on the internet. Understanding both is vital for network administrators, especially when setting up routers like MikroTik or Cisco. Visit the diagram of the PPPoE process or example configurations for MikroTik or Cisco routers.