Which two things are correct about QinQ technology? (Choose two.)

Question

Options

• AThe Outer.1Q tag represents customer VLAN ID and inner.1Q tag represents Service Provider VLAN
• BIt is an effective way to achieve VLAN transparency between Provider and enterprise customer by tunneling
• CThe Outer.1Q tag represents Service Provider VLAN (PVLAN) and inner.1Q tag represents customer VLAN
• DQinQ is a way to hide native VLAN which can conflict with Provider native VLAN

• A
  5% (3)
• B
  84% (46)
• D
  11% (6)

Explanation

IEEE 802.1ad[note 1] is an Ethernet networking standard informally known as IEEE 802.1QinQ[by whom?] and is an amendment to IEEE standard IEEE 802.1Q-1998. The technique is also known as provider bridging, Stacked VLANs, or simply QinQ or Q-in-Q. "Q-in-Q" can for supported devices apply to C-tag stacking on Ctag (Ethernet Type = 0x8100) but this has limited application in the modern methodology of network routing. The original 802.1Q specification allows a single Virtual Local Area Network (VLAN) header to be inserted into an Ethernet frame. QinQ allows multiple VLAN headers to be inserted into a single frame, an essential capability for implementing Metro Ethernet network topologies. Just as QinQ extends 802.1Q, QinQ itself is extended by other Metro Ethernet protocols.[specify] In a multiple VLAN header context, out of convenience the term "VLAN tag" or just "tag" for short is often used in place of "802.1Q VLAN header". QinQ allows multiple VLAN tags in an Ethernet frame; together these tags constitute a tag stack. When used in the context of an Ethernet frame, a QinQ frame is a frame that has 2 VLAN 802.1Q headers (double-tagged). There is a mild confusion regarding the naming because the 802.1ad standard was grown out of the 802.1QinQ[citation needed] protocol (which was developed based the trademarked method 802.1Q, with capital "Q" as a distinction instead of the 802.1q as the standardised protocol) which originally used 0x8100 as ethernet type instead of 0x88a8. While the network industry usually mix the naming, the proper, standardized name is 802.1ad which sometimes gets appended by the other alternative names mentioned above; the plain "802.1QinQ"[citation needed] name usually refers to the old standard which is now[when?] considered obsolete.

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