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IEEE 802.1ad[note 1i! an Ethernetnet"orkin# !tandard informally
kno"n a! IEEE 802.1QinQand i! an
amendment toIEEE!tandardIEEE 802.1$%1&&8. 'he technie i!
al!o kno"n a!provider
bridging, Stacked VLANsor !imply QinQor Q-in-Q.
'he ori#inal 802.1$ !pecification allo"! a !in#le*+-header to e
in!erted into an Ethernet frame.
$in$ allo"! mltiple *+- header! to e in!erted into a !in#le
frame, an e!!ential capaility for
implementin# /etro Ethernetnet"ork topolo#ie!. !t a! $in$ etend!
802.1$, $in$ it!elf i!
etended y other /etro Ethernet protocol!. [specify
In a mltiple *+- header contet, ot of conenience the term 3*+-
ta#3 or 4!t 3ta#3 for !hort i!
often !ed in place of 3802.1$ *+- header3. $in$ allo"! mltiple
*+- ta#! in an Ethernet frame5
to#ether the!e ta#! con!titte a ta# !tack. When !ed in the
contet of an Ethernet frame, a $in$
frame i! a frame that ha! 2 *+- 802.1$ header!
(dole%ta##ed).
'here i! a mild conf!ion re#ardin# the namin# eca!e the 802.1ad
!tandard "a! #ro"n ot of
the 802.1QinQprotocol ("hich "a! deeloped a!ed the trademarked
method 802.1Q, "ith capital 3$3
a! a di!tinction in!tead of the 802.1 a! the !tandardi!ed
protocol) "hich ori#inally !ed 0&100 a!
ethernet type in!tead of 088a8. While the net"ork ind!try !ally
mi the namin# the proper,
!tandardi!ed name i! 802.1ad"hich !ometime! #et! appended y the
other alternatie name!
mentioned aoe5 the plain 3802.1$in$3 name !ally refer! to the
old !tandard "hich i! no"
con!idered o!olete.
Contents
[hide]
1 Background
2 Frame ormat
! Tag operations
" #$amples
o ".1 %irtual net&orks
o ".2 Problems &ith previous e$ample
' (ee also
http://en.wikipedia.org/w/index.php?title=802.1ad&redirect=nohttp://en.wikipedia.org/w/index.php?title=802.1ad&redirect=nohttp://en.wikipedia.org/w/index.php?title=802.1ad&redirect=nohttp://en.wikipedia.org/wiki/Wikipedia:Citing_sources#Inline_citationshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sources#Inline_citationshttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edithttp://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edithttp://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edithttp://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sourceshttp://en.wikipedia.org/wiki/Template:Citation_neededhttp://en.wikipedia.org/wiki/Template:Citation_neededhttp://en.wikipedia.org/wiki/Template:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/802.1ad#cite_note-0http://en.wikipedia.org/wiki/802.1ad#cite_note-0http://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/IEEE_802.1Qhttp://en.wikipedia.org/wiki/IEEE_802.1Qhttp://en.wikipedia.org/wiki/VLANhttp://en.wikipedia.org/wiki/VLANhttp://en.wikipedia.org/wiki/VLANhttp://en.wikipedia.org/wiki/Metro_Ethernethttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/802.1adhttp://en.wikipedia.org/wiki/802.1adhttp://en.wikipedia.org/wiki/802.1adhttp://en.wikipedia.org/wiki/802.1ad#Backgroundhttp://en.wikipedia.org/wiki/802.1ad#Frame_formathttp://en.wikipedia.org/wiki/802.1ad#Frame_formathttp://en.wikipedia.org/wiki/802.1ad#Tag_operationshttp://en.wikipedia.org/wiki/802.1ad#Exampleshttp://en.wikipedia.org/wiki/802.1ad#Virtual_networkshttp://en.wikipedia.org/wiki/802.1ad#Problems_with_previous_examplehttp://en.wikipedia.org/wiki/802.1ad#See_alsohttp://en.wikipedia.org/w/index.php?title=802.1ad&redirect=nohttp://en.wikipedia.org/wiki/Wikipedia:Citing_sources#Inline_citationshttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edithttp://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sourceshttp://en.wikipedia.org/wiki/Template:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/802.1ad#cite_note-0http://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/IEEE_802.1Qhttp://en.wikipedia.org/wiki/VLANhttp://en.wikipedia.org/wiki/Metro_Ethernethttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/802.1adhttp://en.wikipedia.org/wiki/802.1ad#Backgroundhttp://en.wikipedia.org/wiki/802.1ad#Frame_formathttp://en.wikipedia.org/wiki/802.1ad#Tag_operationshttp://en.wikipedia.org/wiki/802.1ad#Exampleshttp://en.wikipedia.org/wiki/802.1ad#Virtual_networkshttp://en.wikipedia.org/wiki/802.1ad#Problems_with_previous_examplehttp://en.wikipedia.org/wiki/802.1ad#See_also
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) *eerences
+ #$ternal links
[edit!ackgro"nd
802.1$in$ !pecifie! architectre and rid#e protocol! to proide
!eparate in!tance! of the /6
!erice! to mltiple independent !er! of a 7rid#ed +ocal rea
-et"ork in a manner that doe! not
reire cooperation amon# the !er!, and reire! a minimm of
cooperation et"een the !er! and
the proider of the /6 !erice.
'he idea i! to proide, for eample, the po!!iility for c!tomer!
to rn their o"n *+-! in!ide !erice
proider! proided *+-. 'hi! "ay the !erice proider can 4!t
confi#re one *+- for the c!tomer
and c!tomer can then treat that *+- a! if it "a! a trnk.
IEEE 802.1$in$ "a! created for the follo"in# rea!on!9
1. 802.1$ ha! a 12%it *+- I: field, "hich ha! a theoretical
limit of 212;
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?. It i! ea!ier for net"orkin# eipment maker! to modify their
ei!tin# eipment y creatin#
mltiple 802.1$ header! than to modify their eipment to implement
!ome hypothetical ne"
non%802.1$ etended *+- I: field header.
[edit#ra$e %or$at
In!ertion of 802.1ad :ole'a# in Ethernet%II f rame
'he!e eample! are for an Ethernet II framin#(len#thethertype
field ;G ethertype) frame. 'hi! cold
al!o e applied to 802.B frame! (len#thethertype field ;G
len#th), "ith or "ithot an ++6 (i.e.+o#ical
+ink 6ontrol), ++6HC-D header. 'he top frame i! a !imple
Ethernet II frame. 'he middle frame ha! a
.1$ (!horthand for 802.1q) ta# added to it. 'he ottom frame ha!
yet another .1$ ta# added to it.
.1$ header, "hich i! < yte! lon#, i! added to an nta##ed
Ethernet II frame in the follo"in#
manner9
1. 'he
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B. 'he !econd ta# i! a!!i#ned an ethertype of 088a8 (in!tead of
the .1$ !tandard 08100) y
defalt. ('he old 802.1$in$ [non!tandard protocol !ed
0&100.)
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Cimple $in$ Eample
'hi! !imple eample "ill ill!trate a practical !e of 802.1ad. 'he
dia#ram !ho"! !"itche! a!
hea#on!, and a Cerice Droider (CD) net"ork encompa!!in# all
item! "ithin the dotted oal. 'he
item! on the periphery of the oal are net"ork! elon#in# to CD
c!tomer!. :ifferent phy!ical location!
appear in the !haded rectan#le, and inclde oth c!tomer and CD
net"ork component!.
Cerice Droider (CD) offer! +2 connectiity to c!tomer! in the
citie! of Ceattle and 'acoma. '"o
corporation!, 3cme3 and 3KLM3, hae a camp! located in oth
Ceattle and 'acoma. ll camp!e!
rn Ethernet +-!, and the c!tomer! intend to connect thro#h the
CD! +2 *D- net"ork !o that
their camp!e! are in the !ame +- (+2 net"ork). It i! de!irale
for cme and KLM to hae a !in#le
+- in oth Ceattle and 'acoma, oiatin# the alternatie of hain#
t"o +-! in "hich traffic m!t e
roted et"een the +-!. 'he CD ha! t"o !"itche!, one in Ceattle
(C%C"itch N1), and one in 'acoma
(C%C"itch N2). 'he c!tomer! interface to the CD net"ork in
!"itche! de!i#nated 33 and 373. Each
c!tomer ha! it! o"n pair of and 7 !"itche!. cme !"itch i!
connected to C%C"itch N1 thro#h
link 3135 the re!t of the link! are laelled. C%C"itch N1 and N2
are connected y link C12.
http://en.wikipedia.org/wiki/File:QinQ-example-simple-SP-cloud.JPGhttp://en.wikipedia.org/wiki/File:QinQ-example-simple-SP-cloud.JPG
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cme! +- !e! *+- I:! 10,11,12 in their net"ork. 'he connection! 1
and 2 are Ethernet trnk!
that hae !in#le%ta##ed *+- traffic, the traffic !in# I:!
10,11,12. +ike"i!e KLM !e! I:! 11,12,1B in
their net"ork, !o K1 and K2 are al!o trnk! "ith !in#le ta##ed
traffic of I:! 11,12,1B. 'he CD, hain#
one net"ork and one connection et"een C%C"itch N1 and C%C"itch
N2, m!t !e#re#ate cme! and
KLM! traffic. Cince oth cme and KLM !hare !ome *+- I:!, traffic
cannot e !e#re#ated y
c!tomer *+- I:.
'he !oltion i! for the CD to !e 802.1ad in their net"ork. 'hey
a!!i#n a !in#le, nie oter *+-
ta# I: of 100 for cme, and a nie oter *+- I: of 101 for KLM. ll
traffic !ent from cme to the
CD net"ork (!ent on 1, de!tined for cme 7) "ill hae a ta# of
I:;100 p!hed. 'he inner ta# "ill e
either 10,11,12, the ori#inal cme ta#. 'he traffic "ill e !ent
thro#h C12 in thi! format, and 4!t
efore it eit! C%C"itch N2 ond for cme 7 (link 2), all traffic
"ill nder#o a !in#le pop operation,
remoin# the oter *+- ta# "ith the I: 100. 'hi! pop operation i!
the iner!e of the former p!h
operation, "ith the net re!lt of no chan#e to the traffic. 'he
traffic pa!!e! thro#h the CD net"ork a!
802.1ad frame!, t no 802.1ad frame! are !ent to or receied from
the c!tomer.
[edit*rob(e$s )it+ previo"s e'a$p(e
n eperienced net"ork en#ineer "ill immediately reco#nie the
!hortcomin#! of the aoe eample.
'hi! i! the rea!on "hy 802.1ad i! more of a definition for a
method of addin# mltiple ta#! to a frame
than it i! an end%to%end !elf%contained !oltion. It i! !ed in
con4nction "ith other protocol! and
!tandard!. 'he prolem! "ith the aoe eample are9
1. /any !"itche! rid#e Ethernet traffic a!ed on /6 addre!!e!Anot
on *+- I:!. 'hi! i!
called Chared *+- +earnin# and i! done per 802.1d /6 learnin#/6
a#in#, etc.
2. Chold cme and KLM !e the !ame /6 addre!!e! in their net"ork!,
thi! "ill ca!e
prolem! "ith the /6 learnin#, a! the a!!mption in /6 learnin# i!
that no t"o ho!t! !e
the !ame /6 addre!!. In other "ord!, a /6 !hold only e learned
from a !in#le !"itch!
port.
B. 'he CD net"ork m!t learn all c!tomer /6 addre!!e! in order to
!"itch them. 'hi! doe!
not !cale "ell.
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@o"eer, !"itche! en rote !till hae to learn all in!erted *+-/6
addre!! comination!
(=0 it!).
?. 7roadca!t! from +- to +- i! al"ay! an i!!e to con!ider.
Droider 7rid#e! (802.1ad) and Droider 7ackone 7rid#e! (D77)
addre!! the aoe prolem! y a
frther modified C/6 learnin# method.
[editSee a(so
6onnection%oriented Ethernet
6arrier Ethernet
/etro Ethernet
IEEE 802.1
IEEE 802.1ah%2008Droider 7ackone 7rid#e!
IEEE 802.1aChorte!t Dath 7rid#in#
Droider 7ackone 7rid#e 'raffic En#ineerin#
[edit,e%erences
http://en.wikipedia.org/wiki/802.1adhttp://en.wikipedia.org/wiki/IEEE_802.1ah-2008http://en.wikipedia.org/wiki/IEEE_802.1ah-2008http://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edit§ion=7http://en.wikipedia.org/wiki/Connection-oriented_Ethernethttp://en.wikipedia.org/wiki/Carrier_Ethernethttp://en.wikipedia.org/wiki/Metro_Ethernethttp://en.wikipedia.org/wiki/IEEE_802.1http://en.wikipedia.org/wiki/IEEE_802.1ah-2008http://en.wikipedia.org/wiki/IEEE_802.1aqhttp://en.wikipedia.org/wiki/Provider_Backbone_Bridge_Traffic_Engineeringhttp://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edit§ion=8http://en.wikipedia.org/wiki/802.1adhttp://en.wikipedia.org/wiki/IEEE_802.1ah-2008http://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edit§ion=7http://en.wikipedia.org/wiki/Connection-oriented_Ethernethttp://en.wikipedia.org/wiki/Carrier_Ethernethttp://en.wikipedia.org/wiki/Metro_Ethernethttp://en.wikipedia.org/wiki/IEEE_802.1http://en.wikipedia.org/wiki/IEEE_802.1ah-2008http://en.wikipedia.org/wiki/IEEE_802.1aqhttp://en.wikipedia.org/wiki/Provider_Backbone_Bridge_Traffic_Engineeringhttp://en.wikipedia.org/w/index.php?title=IEEE_802.1ad&action=edit§ion=8
