Provisional reality: Each BGP speaker is dropping the ingress BGP messages from the other BGP speaker.

Configuration:


user1@R2> show configuration protocols bgp group internPeers
type internal;
traceoptions {
    file bgpDebugWassim;
}
peer-as 22;
neighbor 4.4.4.4;

user1@R2>

Observed reality:

user1@R2> show log bgpDebugWassim
Jul  2 07:54:16 trace_on: Tracing to "/var/log//bgpDebugWassim" started
Jul  2 07:54:28.866558 advertising graceful restart receiving-speaker-only capability to neighbor 4.4.4.4 (Internal AS 22)
Jul  2 07:54:28.866776 advertising LLGR receiving-speaker-only capability to neighbor 4.4.4.4 (Internal AS 22)
Jul  2 07:54:28.871406 bgp_handle_notify:5119: NOTIFICATION received from 4.4.4.4 (Internal AS 22): code 6 (Cease) subcode 5 (Connection Rejected)
Jul  2 07:56:56.882622 advertising graceful restart receiving-speaker-only capability to neighbor 4.4.4.4 (Internal AS 22)
Jul  2 07:56:56.882686 advertising LLGR receiving-speaker-only capability to neighbor 4.4.4.4 (Internal AS 22)
Jul  2 07:56:56.889349 bgp_handle_notify:5119: NOTIFICATION received from 4.4.4.4 (Internal AS 22): code 6 (Cease) subcode 5 (Connection Rejected)

user1@R2>

Adjusted provisional reality: the BGP speakers do not recognize the source address of the received BGP messages. Action: set source addresses of BGP messages on both routers.

Implementation:

root@R4>

root@R4> show configuration protocols bgp
group ebgp-peerz {
    type external;
    export [ R4-loopback LAN-segments ];
    peer-as 17;
    neighbor 10.10.10.9;
}
group internPeers {
    type internal;
    traceoptions {
        file BGPdebugWassim;
    }
    local-address 4.4.4.4;
    peer-as 22;
    neighbor 2.2.2.2;
}
user1@R2> show configuration protocols bgp
group extern-p-17 {
    type external;
    export LAN-segments;
    peer-as 17;
    neighbor 10.10.10.1;
}
group internPeers {
    type internal;
    traceoptions {
        file bgpDebugWassim;
    }
    local-address 2.2.2.2;
    peer-as 22;
    neighbor 4.4.4.4;
}

user1@R2>

Observed reality: BGP peering is established.

root@R4>

root@R4> show bgp neighbor 2.2.2.2
Peer: 2.2.2.2+49881 AS 22      Local: 4.4.4.4+179 AS 22
  Group: internPeers           Routing-Instance: master
  Forwarding routing-instance: master
  Type: Internal    State: Established    Flags: <Sync>
  Last State: OpenConfirm   Last Event: RecvKeepAlive
  Last Error: None
  Options: <LocalAddress PeerAS Refresh>
  Options: <GracefulShutdownRcv>
  Local Address: 4.4.4.4 Holdtime: 90 Preference: 170
  Graceful Shutdown Receiver local-preference: 0
  Number of flaps: 1
  Last flap event: RecvNotify
  Receive eBGP Origin Validation community: Accept
  Error: 'Cease' Sent: 0 Recv: 1
  Peer ID: 2.2.2.2         Local ID: 4.4.4.4           Active Holdtime: 90
  Keepalive Interval: 30         Group index: 1    Peer index: 0    SNMP index: 1
  I/O Session Thread: bgpio-0 State: Enabled
  BFD: disabled, down
  NLRI for restart configured on peer: inet-unicast
  NLRI advertised by peer: inet-unicast
  NLRI for this session: inet-unicast
  Peer supports Refresh capability (2)
  Stale routes from peer are kept for: 300
  Peer does not support Restarter functionality
  Restart flag received from the peer: Notification
  NLRI that restart is negotiated for: inet-unicast
  NLRI of received end-of-rib markers: inet-unicast
  NLRI of all end-of-rib markers sent: inet-unicast
  Peer does not support LLGR Restarter functionality
  Peer supports 4 byte AS extension (peer-as 22)
  Peer does not support Addpath
  NLRI(s) enabled for color nexthop resolution: inet-unicast
  Table inet.0 Bit: 20001
    RIB State: BGP restart is complete
    Send state: in sync
    Active prefixes:              0
    Received prefixes:            2
    Accepted prefixes:            2
    Suppressed due to damping:    0
    Advertised prefixes:          2
  Last traffic (seconds): Received 4    Sent 11   Checked 380
  Input messages:  Total 18     Updates 2       Refreshes 0     Octets 442
  Output messages: Total 17     Updates 1       Refreshes 0     Octets 379
  Output Queue[1]: 0            (inet.0, inet-unicast)
  Trace options:  none
  Trace file: /var/log//BGPdebugWassim size 131072 files 10

root@R4>
user1@R2> show bgp neighbor 4.4.4.4
Peer: 4.4.4.4+179 AS 22        Local: 2.2.2.2+49881 AS 22
  Group: internPeers           Routing-Instance: master
  Forwarding routing-instance: master
  Type: Internal    State: Established    Flags: <Sync>
  Last State: OpenConfirm   Last Event: RecvKeepAlive
  Last Error: None
  Options: <LocalAddress PeerAS Refresh>
  Options: <GracefulShutdownRcv>
  Local Address: 2.2.2.2 Holdtime: 90 Preference: 170
  Graceful Shutdown Receiver local-preference: 0
  Number of flaps: 0
  Receive eBGP Origin Validation community: Accept
  Peer ID: 4.4.4.4         Local ID: 2.2.2.2           Active Holdtime: 90
  Keepalive Interval: 30         Group index: 1    Peer index: 0    SNMP index: 1
  I/O Session Thread: bgpio-0 State: Enabled
  BFD: disabled, down
  NLRI for restart configured on peer: inet-unicast
  NLRI advertised by peer: inet-unicast
  NLRI for this session: inet-unicast
  Peer supports Refresh capability (2)
  Stale routes from peer are kept for: 300
  Peer does not support Restarter functionality
  Restart flag received from the peer: Notification
  NLRI that restart is negotiated for: inet-unicast
  NLRI of received end-of-rib markers: inet-unicast
  NLRI of all end-of-rib markers sent: inet-unicast
  Peer does not support LLGR Restarter functionality
  Peer supports 4 byte AS extension (peer-as 22)
  Peer does not support Addpath
  NLRI(s) enabled for color nexthop resolution: inet-unicast
  Table inet.0 Bit: 20001
    RIB State: BGP restart is complete
    Send state: in sync
    Active prefixes:              0
    Received prefixes:            2
    Accepted prefixes:            2
    Suppressed due to damping:    0
    Advertised prefixes:          2
  Last traffic (seconds): Received 13   Sent 1    Checked 353
  Input messages:  Total 17     Updates 2       Refreshes 0     Octets 423
  Output messages: Total 15     Updates 1       Refreshes 0     Octets 341
  Output Queue[1]: 0            (inet.0, inet-unicast)
  Trace options:  none
  Trace file: /var/log//bgpDebugWassim size 131072 files 10

user1@R2>

#LessonLearned always specify the local-address option in the BGP config.