For ISPs, choosing the right access network protocol can be the difference between a seamless customer experience and constant headaches. Among the options, PPPoE (Point-to-Point Protocol over Ethernet) stands out as a robust and versatile solution for managing last-mile access networks, particularly when compared to alternatives like DHCP. Despite some criticism, particularly from Wireless ISPs (WISPs) using suboptimal hardware, PPPoE offers a host of features and benefits that are hard to ignore.
Understanding PPPoE and Common Complaints
PPPoE combines the benefits of Ethernet and PPP, enabling features like authentication, session management, and bridging. Yet, it often gets a bad rap, especially from WISPs using hardware like MikroTik. The reality? PPPoE on MikroTik, particularly on devices using Tile processors, suffers from performance issues, including higher jitter—a situation akin to a hadeda stepping on a rinkhals. These complaints are more about poor implementation than PPPoE itself.
The solution? Run PPPoE on x86 platforms or purpose-built appliances like the Accel-PPP platform. Modern x86 CPUs handle the computational load far more effectively, offering stable and reliable performance. The primary challenge with most PPPoE implementations is their reliance on CPU processing, limiting the ability to leverage hardware offloading. Using x86-based hardware mitigates this issue, making PPPoE a viable and efficient choice for ISPs.
Why PPPoE Outshines DHCP in ISP Networks
PPPoE brings capabilities that go beyond what DHCP can offer, making it particularly well-suited for ISPs working with Layer 2 Fibre Network Operators (FNOs):
Authentication and Control
PPPoE provides robust authentication via RADIUS, allowing ISPs to control user sessions down to the MAC address. It supports features like:
Locking accounts to specific MAC addresses.
Maximum session limits to prevent account sharing.
Immediate disconnection through RADIUS CoA (Change of Authorization).
Layer 2 Bridging
With PPPoE, ISPs can maintain Layer 2 connectivity over FNO networks. This eliminates the complexity of VLAN configurations or other protocols often required with DHCP setups.
Feature-Rich Management
PPPoE supports advanced features like:
Bridging and L2 circuits.
Framed routes for granular traffic management.
VRFs, MPLS, and static IPs or subnets for enterprise clients.
Usage statistics built into the protocol, providing valuable insights.
Session Monitoring
Using PPP LCP (Link Control Protocol), ISPs can monitor session states, identifying when a line goes down due to connectivity issues. This is far superior to the "ping everyone and guess" approach often associated with DHCP.
Reliability and Scalability
PPPoE on OpenServe, for instance, demonstrates how an open-access network should work. Customers simply input a “username@isp.co.za” without waiting for VLAN changes or other manual configurations. It’s a plug-and-play experience.
Addressing Common PPPoE Challenges
Critics often cite issues like MTU mismatches as reasons to avoid PPPoE. However, these challenges are manageable with proper configurations:
MTU Issues
MTU problems, a frequent complaint, can be resolved using baby jumbo frames. This ensures seamless packet transmission without fragmentation.
Client Isolation
PPPoE inherently supports client isolation, a vital security feature. Yet, some ISPs fail to enable it, exposing networks to vulnerabilities—a problem more about mismanagement than the protocol itself.
FNO CPE Security
A simple Wireshark capture on some FNO customer-premises equipment (CPE) reveals shocking security lapses. Implementing PPPoE ensures better control and reduces reliance on insecure DHCP configurations.
The Power of a PPPoE BRAS
A Broadband Remote Access Server (BRAS) using PPPoE transforms ISP operations by offering unmatched control and flexibility. Here’s what PPPoE-enabled BRAS can do:
Authentication and Session Control
Authenticate users, enforce session limits, and disconnect clients at will.
Traffic Shaping and Rate Limiting
Dynamically control bandwidth and enforce QoS policies.
Advanced Networking Capabilities
Offer VRFs, MPLS, and static IPs, enabling ISPs to cater to both residential and enterprise clients.
Redundancy with Multi-Link PPP
Provide redundancy through Multi-Link PPP, ensuring high availability for critical users.
Usage Analytics
Monitor bandwidth usage and troubleshoot issues with built-in PPPoE statistics.
PPPoE | The Preferred Choice for L2 FNOs
For ISPs leveraging Layer 2 networks from FNOs like OpenServe, PPPoE offers simplicity and efficiency. Unlike Vuma’s unreliable DHCP implementation, PPPoE requires minimal manual intervention and ensures robust client isolation. ISPs can use MAC addresses as circuit IDs, enable DHCP on a private IP range solely for TR-069 provisioning, and even deploy walled gardens for specific use cases.
Wrap | A Case for PPPoE
PPPoE remains a superior protocol for last-mile access networks, offering a suite of features that DHCP and other alternatives cannot match. With the right hardware—preferably x86 or purpose-built appliances like Accel-PPP—it provides reliable, efficient, and secure connectivity.
ISPs should embrace PPPoE for its versatility, control, and ability to scale with the demands of modern networks. While it may require careful configuration and investment in capable hardware, the long-term benefits far outweigh the challenges, ensuring a smoother experience for both ISPs and their customers.
