Liste des cours Se connecter

Informations

Auteur(s) Olivier Bonaventure
Date limite Pas de date limite
Limite de soumission Pas de limite

Se connecter

Se connecter

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.

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 ?