Configure PPPoE on the core switch

To configure PPPoE on a core switch, you need to set up VLANs, create IP pools, configure authentication, and bind virtual templates to interfaces.

Step 1: Understand PPPoE Basics

PPPoE encapsulates PPP frames inside Ethernet frames, allowing point-to-point connections over a Layer 2 network. It uses a client/server model where the PPPoE client initiates a session and the server authenticates and provides IP addresses. PPPoE sessions are uniquely identified by a SESSION_ID and the client's MAC address, and MTU should be set to 1492 to avoid fragmentation issues .

Step 2: Create VLANs

• Define VLANs to segment user traffic and server connections.
• Assign interfaces connected to users as hybrid or access ports and add them to the appropriate VLAN.
• Example: VLAN 10 for users, VLAN 20 for the RADIUS server .

Step 3: Configure IP Address Pools

• Create a local IP address pool to allocate IP addresses dynamically to PPPoE clients.
• Assign IP addresses to VLAN interfaces (VLANIF) to ensure routing between clients, the switch, and internal servers .

Step 4: Set Up Authentication

• Configure a RADIUS server template and AAA scheme on the switch.
• Define an authentication domain so the RADIUS server can authenticate PPPoE users.
• PPPoE supports username/password authentication and can enforce per-user access control .

Step 5: Configure Virtual Templates

• Create a virtual template to define PPP negotiation parameters:
  • Authentication method (PAP/CHAP)
  • Retransmission times for handshake packets
  • Negotiation timeout interval
  • Maximum Receive Unit (MRU)
• Bind the virtual template to the physical interfaces connected to users .

Step 6: Enable PPPoE Server

• Activate the PPPoE server on the switch.
• Ensure interfaces are correctly bound to VLANs and virtual templates.
• Monitor session establishment: clients broadcast PADI packets, the server responds with PADO, and a session is established after negotiation .

Step 7: Security and Management

• Use PPPoE relay if multiple clients share a single session to enhance security and manageability.
• The relay can add vendor-specific tags to identify client location and control access .
• Avoid using static IP or DHCP on the same interfaces as PPPoE to prevent conflicts . By following these steps, your core switch will function as a PPPoE server, providing authenticated, point-to-point connectivity for users while maintaining network segmentation and security.