To administratively shutdown a BGP neighbor in a Cisco router, issue a neighbor <BGP PEER IP> shutdown command under the BGP routing process. This will stop the BGP route exchange with the BGP neighbor/peer and it's often useful when performing a maintenance such as policy change with the peer/upstream ISP.
R1#show run | sec router bgp
router bgp 64001
bgp router-id 62.19.10.15
bgp log-neighbor-changes
no bgp default ipv4-unicast
neighbor 62.19.10.16 remote-as 700
neighbor 62.19.10.16 description ISP
neighbor 62.19.10.16 password cisco123
neighbor 62.19.10.16 update-source GigabitEthernet0/0
neighbor 62.19.10.16 version 4
<OUTPUT TRUNCATED>
R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R1(config-router)#neighbor 62.19.10.16 ?
ao TCP-AO authentication
bmp-activate Activate the BMP monitoring for a BGP peer
cluster-id Configure Route-Reflector Cluster-id (peers may reset)
description Neighbor specific description
disable-connected-check one-hop away EBGP peer using loopback address
dont-capability-negotiate Send Capability parameters in Open
ebgp-multihop Allow EBGP neighbors not on directly connected networks
fall-over session fall on peer route lost
ha-mode high availability mode
inherit Inherit a template
local-as Specify a local-as number
log-neighbor-changes Log neighbor up/down and reset reason
password Set a password
path-attribute BGP optional attribute filtering
peer-group Member of the peer-group
remote-as Specify a BGP neighbor
shutdown Administratively shut down this neighbor
timers BGP per neighbor timers
transport Transport options
ttl-security BGP ttl security check
update Modify update processing
update-source Source of routing updates
version Set the BGP version to match a neighbor
R1(config-router)#neighbor 62.19.10.16 shutdown
R1(config-router)#end
R1#show run | sec router bgp
router bgp 64001
bgp router-id 62.19.10.15
bgp log-neighbor-changes
no bgp default ipv4-unicast
neighbor 62.19.10.16 remote-as 700
neighbor 62.19.10.16 description ISP
neighbor 62.19.10.16 shutdown
neighbor 62.19.10.16 password cisco123
neighbor 62.19.10.16 update-source GigabitEthernet0/0
neighbor 62.19.10.16 version 4
<OUTPUT TRUNCATED>
R1#show ip bgp summary
BGP router identifier 62.19.10.15, local AS number 64001
BGP table version is 394500023, main routing table version 394500023
860025 network entries using 213286200 bytes of memory
1720036 path entries using 233924896 bytes of memory
431848/148584 BGP path/bestpath attribute entries using 120917440 bytes of memory
240343 BGP AS-PATH entries using 11369538 bytes of memory
25898 BGP community entries using 3703042 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 583201116 total bytes of memory
BGP activity 19138181/18274056 prefixes, 156266333/154546297 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
62.19.10.16 4 700 0 0 1 0 0 00:00:28 Idle (Admin)
R1#show ip bgp neighbor 62.19.10.16
BGP neighbor is 62.19.10.16, remote AS 700, external link
Description: ISP
Administratively shut down
BGP version 4, remote router ID 0.0.0.0
BGP state = Idle, down for 00:00:43
Neighbor sessions:
0 active, is not multisession capable (disabled)
Stateful switchover support enabled: NO
Do log neighbor state changes (via global configuration)
Default minimum time between advertisement runs is 30 seconds
<OUTPUT TRUNCATED>
To re-enable the BGP neighbor, just use the 'no' form of the said command.
R1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 64001
R1(config-router)#no neighbor 62.19.10.16 shutdown
R1(config-router)#end
R1#show run | sec router bgp
router bgp 64001
bgp router-id 62.19.10.15
bgp log-neighbor-changes
no bgp default ipv4-unicast
neighbor 62.19.10.16 remote-as 700
neighbor 62.19.10.16 description ISP
neighbor 62.19.10.16 password cisco123
neighbor 62.19.10.16 update-source GigabitEthernet0/0
neighbor 62.19.10.16 version 4
<OUTPUT TRUNCATED>
