Country Flag: Belgium
Author: Victor Rodriguez
Title: BGP Multicast VPN
Type: Service Provider
Difficulty: Medium (1 point)
Technical Description: Using just one configuration set command, fix the scenario in such a way that the multicast flow reaches the receiver.

Challenge Instructions:
For this challenge, you need to start the topology called: “BELGIUM – BGP Multicast VPN”.
This challenge shows a VPN named vpn1. CE2 is the source for the multicast group 239.22.22.22, while CE1 is a receiver for that multicast group.
You need to launch a ping in CE2 to generate the multicast traffic. Execute on a session connected to CE2:
juniper@CE2> ping 239.22.22.22 interface ge-0/0/1 bypass-routing ttl 20
You won’t get a response. Let the ping run while you are troubleshooting this challenge. Once you have succeeded you will get a response to the above ping.
You need to fix the problem with just one set command on a single router similar to the following:
configure
set <command>
commit and-quit
To solve this challenge submit a brief explanation of the problem and the single-command fix.
NOTE: If you have issues connecting to the Junosphere topology please check Junosphere Technical documentation, or request assistance in the Junosphere forum
OFFICIAL SOLUTION:
PE2 receives the (10.22.22.22, 239.22.22.22) flow, but it doesn’t advertise it via BGP because PE2 is not the DR at the access network ge-0/0/1:
juniper@PE2> show pim interfaces instance vpn1 ge-0/0/1
Stat = Status, V = Version, NbrCnt = Neighbor Count,
S = Sparse, D = Dense, B = Bidirectional,
DR = Designated Router, P2P = Point-to-point link,
Active = Bidirectional is active, NotCap = Not Bidirectional Capable
Name Stat Mode IP V State NbrCnt JoinCnt(sg/*g) DR address
ge-0/0/1.0 Up S 4 2 NotDR,NotCap 1 0/0 10.22.22.22
We fix if by forcing PE2 to become the DR on the access segment:
juniper@PE2# set routing-instances vpn1 protocols pim interface ge-0/0/1.0 priority 100
juniper@PE2> show pim interfaces instance vpn1 ge-0/0/1
Stat = Status, V = Version, NbrCnt = Neighbor Count,
S = Sparse, D = Dense, B = Bidirectional,
DR = Designated Router, P2P = Point-to-point link,
Active = Bidirectional is active, NotCap = Not Bidirectional Capable
Name Stat Mode IP V State NbrCnt JoinCnt(sg/*g) DR address
ge-0/0/1.0 Up S 4 2 DR,NotCap 1 0/0 10.22.22.2
As a result, PE2 advertises a “Source Active” BGP route:
juniper@PE2> show route advertising-protocol bgp 172.16.255.1 table vpn1.mvpn
vpn1.mvpn.0: 4 destinations, 5 routes (4 active, 0 holddown, 0 hidden)
Prefix Nexthop MED Lclpref AS path
1:100:1:172.16.255.2/240
* Self 100 I
5:100:1:32:10.22.22.22:32:239.22.22.22/240
* Self 100 I
And the ping command at CE2 starts getting replies.
Julie Wider
Advocacy Manager
Twitter: @JNetCommunity & @jawider