Packet handling by MPLS router

Consider the R7 MPLS router shown in the figure below.

https://inginious.info.ucl.ac.be/course/lingi2142-QCM/mpls-router/mpls-router.png

This router uses per-node label space and has the following LFIB

Label	Outgoing intf	Operation
L3	North-E	SWAP( L0)
L4	East	POP
L6	Local	POP
L5	South-E	PUSH (L1)
L9	South-East	SWAP (L8); PUSH (L4)

For this exercice, the MPLS stack of a packet is represented as as sequence of labels separated by a colon. For example, LX:LY:LZ is an MPLS stack containing three labels. LZ is the top label, LY the second one and LX the bottom one.

Paste this command into your terminal:

The password to connect is

Question 1: Packet observed

We observe a packet with the L2:L0 label stack on the link to R1. What is the packet that router R7 has received ?

Question 2: Packet observed

We observe a packet with the L8:L4 label stack on the link to R3. What is the packet that router R7 has received ?

Question 3: Packet observed

We observe a packet with the L0 label stack on the link to R1. What is the packet that router R7 has received ?

Question 4: Packet observed

We observe a packet with the L0:L5:L1 label stack on the link to R3. What is the packet that router R7 has received ?

Question 5: Packet observed

We observe a packet with the L5 label stack on the link to R2. What is the packet that router R7 has received ?

Author(s)	Olivier Bonaventure
Deadline	No deadline
Submission limit	No limitation

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