Understanding PPPoE ATM-over-ADSL and ATM-over-SHDSL Interfaces

When an ATM network is configured with a point-to-point connection, Point-to-Point Protocol over Ethernet (PPPoE) can use ATM Adaptation Layer 5 (AAL5) for framing PPPoE-encapsulated packets. The AAL5 protocol provides a virtual connection between the client and the server within the same network. The device encapsulates each PPPoE frame in an ATM frame and transports each frame over an asymmetric digital subscriber line (ADSL) or symmetric high-speed DSL (SHDSL) loop and a digital subscriber line access multiplexer (DSLAM). For example, Figure 35 shows a typical PPPoE over ATM session between a device and an access concentrator on an ADSL loop.

For PPPoE on an ATM-over-ADSL or ATM-over-SHDSL interface, you must configure encapsulation on both the physical and logical interfaces. To configure encapsulation on an ATM-over-ADSL or ATM-over-SHDSL physical interface, use Ethernet over ATM encapsulation. To configure encapsulation on an ATM-over-ADSL or ATM-over-SHDSL logical interface, use PPPoE over AAL5 logical link control (LLC) encapsulation. LLC encapsulation allows a single ATM virtual connection to transport multiple protocols.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices
• Understanding Point-to-Point Protocol over Ethernet
• Example: Configuring PPPoE Encapsulation on an ATM-over-ADSL Interface