In a PIM-SM (Protocol Independent Multicast - Sparse Mode) network setup:
* Before the formation of the rendezvous-point tree, a join message is sent from R1 to R3 (RP):
* R1, being the router connected to the receiver, sends a PIM join message towards the RP (R3) to join the multicast group.
* Before the formation of the rendezvous-point tree, an IGMP is sent from the Receiver to R1:
* The receiver sends an IGMP membership report to its directly connected router (R1), indicating its interest in joining a multicast group.
References:
* The behavior of PIM-SM and the process of join messages and IGMP reports are covered in multicast networking sections of network configuration and design guides.

Type 1 routes are used for per-ES auto-discovery (A-D) to advertise EVPN multi-homing mode. Remote ToR leaf devices in the EVPN network use the EVPN Type 1 route type functionality to learn the EVPN Type 2 MAC routes from other leaf devices. In this route type ESI and the Ethernet Tag ID are considered to be part of the prefix in the NLRI. Upon a link failure between ToR leaf and end server VTEP withdraws Ethernet Auto-Discovery routes (Type 1) per ES. The Juniper EVPN multi-homing Ethernet Tag value is set to the VLAN ID for ES auto-discovery/ES route types. Mass Withdrawal - Used for fast convergence during link failure scenarios between leaf devices to the end server using Type 1 EAD/ES routes.

BGP Path Selection process follows this order
1.Weight (Bigger is better)
2. Local preference (Bigger is better)
3. Self originated (Locally injected is better than iBGP/eBGP learned)
4. AS-Path (Smaller is better)
5. Origin
6. MED (Smaller is better)
7. External (Prefer eBGP over iBGP)
8. IGP cost (Smaller is better)
9. EBGP Peering (Older is better)
10. Router- ID
http://www.next-itsolutions.co.uk/wp-content/uploads/2015/09/CCIE-BGP-Best-Path-Selection1.png
https://www.juniper.net/documentation/us/en/software/junos/vpn-l2/bgp/topics/concept/routing-protocols-address-representation.html