200-155 · Question #149
Which description of a VNTag is true?
The correct answer is A. A VNTag is inserted between the source MAC address and the 802.1Q field. A VNTag (Virtual Network Tag) is a proprietary Cisco encapsulation inserted into an Ethernet frame to carry additional virtual networking information.
Question
Which description of a VNTag is true?
Options
- AA VNTag is inserted between the source MAC address and the 802.1Q field.
- BThe VNTag is used to identify the service level that is granted to a frame.
- CA VNTag is based on the destination MAC address and the 802.1Q field.
- DA VNTag requires a Cisco Nexus 1000v Series Switch.
How the community answered
(26 responses)- A92% (24)
- C4% (1)
- D4% (1)
Why each option
A VNTag (Virtual Network Tag) is a proprietary Cisco encapsulation inserted into an Ethernet frame to carry additional virtual networking information.
The VNTag is inserted into the Ethernet frame after the source MAC address and typically before the 802.1Q VLAN tag field, if one is present. This placement allows the tag to carry information about the virtual interface or source FEX without altering the fundamental Ethernet or VLAN structure from a packet forwarding perspective.
The VNTag is used to identify the source virtual port or FEX, not primarily to identify the service level granted to a frame, which is typically handled by QoS markings.
The VNTag is a distinct header that identifies virtual network information, not something that is 'based on' the destination MAC address or the 802.1Q field itself.
While VNTag is used with the Cisco Nexus 1000v Series Switch for virtualized environments, it is also a fundamental component of the Cisco Nexus FEX architecture for bare-metal servers, so it does not exclusively require a Nexus 1000v.
Concept tested: VNTag frame format and placement
Source: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-2000-series-fabric-extenders/white_paper_c11-585141.html
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