Two industry insiders debate the benefits of passive optical networking vs. Active Ethernet.
World Wide Packets’ Dave Curry believes Active Ethernet is a better option for curing last-mile bandwidth bottlenecks.
Optical technology is the clear cure for last-mile bandwidth bottlenecks, but Active Ethernet, not passive optical networking, will be the technology of choice. Deploying PON today might provide more bandwidth than DSL or cable modems, but it also introduces limitations that severely restrict the potential of an optical infrastructure.
Notably, PON architecture imposes bandwidth limits – hardly ideal for easing a bottleneck or gaining revenue by offering more services. Bandwidth is shared among subscriber terminals. The total amount and range of bandwidth available depends on the specific type of PON technology and the split ratio deployed. Speed upgrades can come in one of two ways: reduce the number of subscribers and bear the increase in cost per subscriber, or completely overhaul the technology.
The other side by John Griffin
Debate the issue with Griffin and Curry.
In contrast, Active Ethernet supports a minimum of 100M bit/sec symmetrical connection to each subscriber, far in excess of PON. More importantly, Active Ethernet scales seamlessly to 1G bit/sec, 10G bit/sec and beyond, fully supporting any combination of subscriber access speeds and application requirements.
A large portion of the first cost of a PON deployment is the central terminal, which requires a unique and expensive optical transceiver. When PON vendors highlight low cost per subscriber figures, they imply that each central terminal is fully utilized. However, the cost per subscriber increases dramatically when the number of subscribers is less than approximately 70% of the maximum number of supported subscribers.
Every aspect of an Active Ethernet solution, including the optical transceivers, uses standard off-the-shelf components. Because optical transceivers are only added when subscribers are added, Active Ethernet exhibits very linear costs from the first few subscribers to many thousands of subscribers.
PON vendors say passive components result in significantly lower operational expense. The truth is that even in a passive network, all the central units and subscriber terminals will incur an ongoing operational expense and require the same support as in an Active Ethernet network.
Anyone concerned about the security of the information they send over a public network should be wary of PON. Because of the shared nature of PON, information intended for one subscriber is sent to all subscribers connected to the same passive splitter. The receiving terminals are expected to discard traffic not intended for the subscriber on that terminal. Services delivered over an Active Ethernet infrastructure are contained within virtual LANs that only send the information to the specific destination for which it is intended.
In a day and age when success is based on who can most rapidly meet customer demands at the lowest cost, PON is a fading technology. Only by embracing Active Ethernet can service providers make the most of the vast potential of their optical network investments.
Curry is president and CEO of World Wide Packets, an Ethernet access networking vendor. He can be reached at dave.curry@wwp.com.
