In the exhibit, on which label value does PE1 expect to receive traffic from CE3 for VPN A?
A.
2002
B.
3001
C.
3002
D.
2001
which label value does PE1 expect to receive traffic from CE3 for VPN A?
Click the Exhibit button.
In the exhibit, on which label value does PE1 expect to receive traffic from CE3 for VPN A?
B is correct.
Agreed. Correct answer is B.
Can either of you explain? I still think A is Correct :
2000+3-1=2002
Now I’m confused totally… Formula is Local Site ID + remote Label Base – Remote offset
Q is what label PE1 is expecting from CE3(PE2).
Then label = 2+3000-1 = 3001
Isn’t it ??
OK . we will fix from A to B
Hi guys! Some of you have already given the exam.. What is the correct anwer ??
I am not sure about answer 3001.. MY logic was driving me towards 3001 but I cant discard 2002 as well.
Can anyone make us clear and set a concrete standpoint ?
la respuesta correcta es 2002 A, tener en cuenta que en L2VPN no se anuncia el label vpn , cada PE debe calcular el label vpn (outgoing label) la cual sera usada para enviar trafico hacia su CE remote. en este caso en particular implicitamente te dice que label debe usar PE2 para enviar trafico hacia CE1 , (PE2 – label outgoing = PE1 label ingoing).
L2VPN label = Label-Base(remote) + Site-Id(Local) – Label-Offset(remote)
When transmitting from PE2 to PE1 formula is as follows:
Remote Base ( 2000 ) + Local Site ( 3 ) – Remote Offset ( 1 ) => 2002
When receiving, formula is Local Base + Remote Site – Local Offset so P2 expects:
Local Base ( 2000 ) – Local Offset ( 1 ) + Remote Site ( in this case PE2 site id = 3 ) => 2002
So I think A -> 2002 is the correct answer
Answer is A ,
The formular to calculate the inner label to receive traffic at CE1 from CE 3 ( asuming the CE3 belongs to VPN-A)
Inner Label value = label-base-local + Remote site ID – Label offet local.
for PE1 , Inner lable = 2000+3-1
= 2002
what happens is when traffic sends from PE2 router 2002 inner label is pushed in to the MPLS packet and pass througt P1 and P2 to PE1. PE 1 finally looked the inner label 2002 and pass the packet to VPN A
Pleae refer JNCIS for this querry ….. just search with label offset you will get scenario explained in details.
Here PE1 is expecting label from PE2, now PE2 outgoing label should be calculated as per formula.
Label = Label base remote – label offset remote + site ID Local
Remember outgoing label is calculated based on advertised route by remote PE which is PE1 here.
Label = 2000-1+3 = 2001 …………. This is one of the exam question.
Sorry above result is 2002 as per calculation.
I also agree answer show be A.
For PE2 to send traffic for CE1 on VPN A. PE2 first look at the received advertisement from PE-1, PE-2 then sends frames destined for CE1 using an inner label of 2002 (Remote base(2000) + local site-id(3) – Remote offset(1)).
So 2000+3-1 = 2002 is the answer.
http://www.juniper.net/techpubs/en_US/junos12.2/topics/example/vpls-label-blocks-configuration.html
RX Label = Label base local + ( site ID remote – label offset local)
TX Label = Label base remote + ( site ID local – label offset remote )
So PE1 expects traffic on RX label = 2000 + ( 3 – 1 ) = 2002 and we got that correct answer is A
PS: rawmaterial & DS are both right
Answer is A
JNCIS study Guide page 658
@dev-null Nice link