Observer Analyzer : Observer Analyzer : Troubleshooting common issues : “No VLAN” shown while using a Gigabit NIC
“No VLAN” shown while using a Gigabit NIC
Symptoms: “No VLAN” is displayed in VLAN Statistics and/or no 802.1Q tag information is shown in your decode. The network adapter you use to capture traffic is a Gigabit NIC.
Causes: Observer is not seeing the 802.1Q tag on packets being captured. This is sometimes caused by your switch not sending tagged packets to Observer. See VLAN Statistics tool is not working for explanation/resolution before proceeding.
Solutions: If you are using a Gigabit NIC to capture the traffic and you have checked the switch configuration, then try using this solution. For BCM5751M NetXtreme Gigabit chips found in IBM T43, HP laptops, and Dell Latitude laptops; there is a registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet can cause the driver and chip not to strip the 802.1Q headers. To set that key, you must find the correct instance of the driver in Windows registry and change it.
1. Open the Windows registry editor. Start > Run > Command and type regedit.
2. Search for “TxCoalescingTicks” and ensure this is the only instance that you have.
3. Right-click the instance number (e.g., 0008) and add a new string value.
4. Type PreserveVlanInfoInRxPacket and give it the value 1.
5. Restart the computer.
 
The Gigabit NIC no longer strips VLAN tags, so the symptom in Observer is resolved.