Which two things are correct about QinQ technology? (Choose two.)
A.
The Outer.1Q tag represents customer VLAN ID and inner.1Q tag represents Service Provider
VLAN (PVLAN)
B.
It is an effective way to achieve VLAN transparency between Provider and enterprise customer
by tunneling one ser of VLAN tags inside a second VLAN tag
C.
The Outer.1Q tag represents Service Provider VLAN (PVLAN) and inner.1Q tag represents
customer VLAN
D.
QinQ is a way to hide native VLAN which can conflict with Provider native VLAN
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.