Software Secure Firewall Threat Defense
Platform Secure Firewall Threat Defense Virtual
Activity Onboard

Advanced Network Analysis and Preprocessing Transport and Network Layer Preprocessors Advanced Transport/Network Preprocessor Settings Ignored VLAN Headers

Last updated: Jul 29, 2025

Ignored VLAN Headers

Different VLAN tags in traffic traveling in different directions for the same connection can affect traffic reassembly and rule processing. For example, in the following graphic traffic for the same connection could be transmitted over VLAN A and received over VLAN B.

Diagram showing
			 traffic for a single connection that could be transmitted over two VLANs

You can configure the system to ignore the VLAN header so packets can be correctly processed for your deployment.