Junos Cup 2014
Junos Cup 2014

Tournament 3: France Challenge & Solution: Seamless MPLS

[ Edited ]
‎06-26-2014 07:12 AM

Country Flag: France


Author: Krzysztof Szarkowicz


Title: Seamless MPLS


Type: Service Provider


Difficulty: High (2 points).


Technical Description: Achieve MPLS end-to-end connectivity between PE1 and PE2, using five set commands in total.






Challenge Instructions:

Your colleague configured a simple seamless MPLS network whereby:

-       OSPF area 1 is a totally stubby area: ABR injects default route

-       OSPF area 0 is the backbone area: no routes are leaked from area 1 to area 0

-       PE loopbacks are exchanged via BGP-LU between areas, with ABR acting as a BGP route reflector

-        LDP is configured as a transport MPLS protocol inside each area


Unfortunately, something is still missing, as the MPLS pings do not work as shown here:

From PE1:

juniper@PE1> ping mpls bgp                 

 Requested FEC not found, exiting.


Now, from PE2:

juniper@PE2> ping mpls bgp   

 Requested FEC not found, exiting


To solve this challenge you must change the configuration so that:


-       MPLS (BGP) ping from PE1 to the loopback of PE2 works

-       MPLS (BGP) ping from PE2 to the loopback of PE1 works


Here are the requirements for the configuration changes:

  • You are not allowed to add IP addresses to the interfaces.
  • You are not allowed to configure static routes.
  • You are not allowed to change (explicitly configured or default) OSPF advertisement policies.
  •  The commands edit, configure, commit are needed but are not counted towards the five-command solution.
  • Before committing the configuration, execute show | compare. No line should start with a minus (-) sign.
  • The number of set commands is counted according to the display set output. For example, the following set command actually counts as three set commands, instead of one:


user@router# set interfaces ge-0/0/3 mtu 1500 unit 1 vlan-id 1 family inet                      



user@router# show interfaces ge-0/0/3 | display set

set interfaces ge-0/0/3 mtu 1500

set interfaces ge-0/0/3 unit 1 vlan-id 1

set interfaces ge-0/0/3 unit 1 family inet


To solve this challenge submit the five set commands issued, specifying which router each of the commands is applied to.


NOTE: If you have issues connecting to the Junosphere topology please check Junosphere Technical documentation, or request assistance in the Junosphere forum 

Send an email with your proposed solution to junos-cup@juniper.net:

  •  The subject should be “<country-name-of-the-challenge> -  <your-full-name>”. For example: “Brazil – Wolfgang Amadeus Mozart”.
  • In the email body, please include your proposed solution, along with your first and last name and complete mailing address including zip/postal code and your shirt size (S, M, L, XL, XXL, XXXL) (Only if you haven’t already submitted your address/shirt size on a previous submission)


Deadline to Respond: Tuesday, 1st of July 23:59:59 Pacific Daylight Time (PDT) 

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Some additional notes:

  • You can try to solve and submit answers for as many active challenges as you wish
  • The answers will be read by the organization right after the deadline
  • The challenge instructions are final, and no additional information or tips will be provided before the publication of the solution and the winner list. Please don’t expect a reply from junos-cup@juniper.net.
  • If you feel that your initial solution is wrong or incomplete, you can send up to three messages for the same challenge, but please note that only your last message (received before the deadline) will be read.
  • If you think there is an error in the definition of the challenges, please send us an email with subject (“<country-name> ERROR”); if there is no reply, then it’s likely an intentional condition of the challenge, rather than an error.




At ABR, configure:


set protocols bgp group IBGP advertise-inactive

set protocols ldp egress-policy SEND-LO

set protocols ldp transport-address

set policy-options policy-statement SEND-LO from interface lo0.0

set policy-options policy-statement SEND-LO then accept


Julie Wider
Advocacy Manager
Twitter: @JNetCommunity & @jawider