VLAN Tagging

Detecting and monitoring VLANs can be difficult if the NIC isn뭪 properly configured in Windows. The majority of network cards by default are set up to remove VLAN tag information from the packet header. As a result, you need to verify within Windows that the NIC properties are set to allow VLAN tags to pass through the NIC to Observer or Wireshark for analysis. To check whether VLAN tagging is enabled: 1. From the Windows desktop, go to the Systems Tray. Right-click on theNetwork Connection or NIC icon and select Open Network Connections. 2. Within the Network Connections window, right-click on the appropriate network connection and select Properties. 3. In the Properties Window, verify that the appropriate network card is selected and press Configure. 4. You should be able to select the Advanced tab, which displays all properties and options available for your network adapter. Within this Window, you뭠l want to identify the function that needs to be enabled to allow VLAN tags to pass to Observer. The function name varies based upon the card manufacturer. Intel refers to the feature as QoS Packet Tagging, but it might also be called 802.1p/q, QoS, or ToS Packet Tagging. Select the feature, verify it뭩 enabled, and click Ok. 5. Once you뭭e enabled the NIC, verify that your TAP or SPAN Port is set up correctly to feed Observer or Wireshark the tags. Be sure you have connected to a port that contains VLAN tags. With this completed, you should be able to see VLAN information within Decode or by selecting Statistics and VLAN Statistics.

출처 : http://www.mnex.biz/pageindex.asp?page=vlan