BGP (Border Gateway Protocol) has specific rules for route advertisement between peers.
Step-by-Step Breakdown:
EBGP to IBGP Route Propagation:
BGP peers advertise routes learned from EBGP peers to IBGP peers within the same AS. This ensures that routes learned from external networks are propagated internally within the AS. IBGP to EBGP Route Propagation:
Routes learned from IBGP peers can be advertised to EBGP peers, but when advertising these routes, the router uses its own IP address as the next hop.
IBGP Split Horizon:
By default, IBGP peers do not advertise routes learned from one IBGP peer to another IBGP peer.
This rule (IBGP split horizon) prevents routing loops within an AS.
Juniper
Reference: BGP Advertisement Rules: Junos adheres to BGP standards, where IBGP peers do not propagate routes to other IBGP peers, but EBGP peers receive IBGP routes with the advertising router as the next hop.

The BGP session in the exhibit shows the state as Connect, which indicates that the TCP session between the BGP peers has not been fully established. Step-by-Step Breakdown:
BGP State "Connect":
The Connect state is the second stage in the BGP finite state machine (FSM). At this stage, BGP is trying to establish a TCP session with the peer, but the session has not yet been successfully established.
A successful TCP three-way handshake (SYN, SYN-ACK, ACK) is required before BGP can progress to the OpenSent state, where the peers exchange BGP Open messages.
Possible Causes:
A firewall blocking TCP port 179.
Incorrect IP addresses or network connectivity issues between the BGP peers. Juniper Reference: BGP Troubleshooting: In Junos, if a BGP session is stuck in the Connect state, the issue is likely due to a failure in establishing the underlying TCP connection.