* Default Behavior of ONUs :
* By default, ONUs (Optical Network Units) connected to the same PON port of a Huawei OLT are isolated at Layer 2 .
* This isolation ensures that ONUs cannot communicate directly with each other, even if they belong to the same service VLAN.
* Why FALSE?
* The statement incorrectly claims that ONUs can communicate with each other at Layer 2 by default. In reality, Layer 2 isolation is a security feature designed to prevent unauthorized communication between ONUs.
* Enabling Communication :
* If Layer 2 communication between ONUs is required, it must be explicitly enabled through configuration (e.g., by disabling Layer 2 isolation).
Thus, the correct answer is B .
References:
* HCIA Huawei ACCESS Official Documentation , Chapter: GPON Security Features.
* OLT Configuration Guide by Huawei.

GPON (Gigabit Passive Optical Network) is a fiber-based access technology that supports downstream bandwidth up to 2.5 Gbps and upstream up to 1.25 Gbps, far exceeding the bandwidth capabilities of DSL technologies. ADSL (up to 8 Mbps), ADSL2+ (up to 24 Mbps), and VDSL (up to 100 Mbps over short distances) are copper-based technologies with significantly lower maximum bandwidth compared to GPON.