Technical Tip: BGP Neighbors Created via CLI Without Remote-AS may Remain in Admin-Down State on FortiGate

Unlike the GUI, the FortiGate CLI allows BGP neighbor creation without specifying a remote-as.

FGT # config router bgp
FGT (bgp) # config neighbor
FGT (neighbor) # edit 192.168.1.1
new entry '192.168.1.1' added
FGT (192.168.1.1) # end
FGT (bgp) # end

Neighbors created this way remain in the Admin-down state when the remote-as is added later, even if shutdown is disabled:

FGT # config router bgp
FGT (bgp) # config neighbor
FGT (neighbor) # edit 192.168.1.1
FGT (192.168.1.1) # set remote-as 65000 <----- Configure remote-as.
FGT (192.168.1.1) # get | grep shut
shutdown : disable <----- Though shutdown is disabled, BGP neighborship remains in Admin down state.
FGT (192.168.1.1) # end
FGT (bgp) # end

FGT # get router info bgp summ

VRF 0 BGP router identifier 3.3.3.3, local AS number 65002
BGP table version is 1
1 BGP AS-PATH entries
0 BGP community entries

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.168.1.1 4 65000 0 0 0 0 0 never Idle (Admin) <----- Shows as admin down.

Starting with v7.6.3, configuring a BGP neighbor via CLI requires specifying the remote-as:

FGT (bgp) # config neighbor
FGT (neighbor) # edit 192.168.1.1
FGT (192.168.1.1) # end
remote-as must be set.
object set operator error, -89 discard the setting
Command fail. Return code -89

Workaround:
Toggle the neighborship status using the commands below:

FGT # config router bgp
FGT (bgp) # config neighbor
FGT (neighbor) # edit 192.168.1.1
FGT (192.168.1.1) # set shutdown enable <----- Enable shutdown.
FGT (192.168.1.1) # end
FGT (bgp) # end

FGT # config router bgp
FGT (bgp) # config neighbor
FGT (neighbor) # edit 192.168.1.1
FGT (192.168.1.1) # set shutdown disable <----- Disable shutdown.
FGT (192.168.1.1) # end
FGT (bgp) # end

FGT # get router info bgp summary
VRF 0 BGP router identifier 3.3.3.3, local AS number 65002
BGP table version is 1
1 BGP AS-PATH entries
0 BGP community entries

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.168.1.1 4 65000 2 2 0 0 0 00:00:07 0 <----- Neighbor UP.