Remove a neighbour from BGP Route Propergation

[hiltonstroud]

Hi All,

First time poster so hope I have located this in the correct thread etc

I am very new to BGP routing and am in need of help with the following:

BGP has been setup between our Nexus 5k core's ISP router for our private IP network managed by them.  There is 1 BGP router from what I understand and 1 AS number has been used which has 2 nieghbours set on the Nexus 5k.

Is it possible to remove 1 of the neighbours from this without blowing away the config and starting again with BGP? Reason for this is we don't require BGP to send routes to this neighbour anymore.

If more information is required please ask and I will provide.

Many thanks for reading.

[Simon Brooks]

If what I expect you require is correct. You want to keep the bgp config but basically deactivate a neighbor?

Under router bgp xxx
Neighbor x.x.x.x shutdown

That should accomplish what you want I believe.

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[hiltonstroud]

Hi Simon,

Yes, I would like to keep the bgp config that way it is, but remove neighbor x.x.x.x

Will doing a shutdown on the neighbor as you suggested remove this neighbor in question from the bgp config or will it just deactivate it as per normal cisco "shutdown" methods. 

I guess I would like to completely remove this neighbor from it and not just deactivate, but this may not be possible.

[Simon Brooks]

Could you give me the bgp config replacing any public ips with fake ones please and let me exactly which neighbour you want to remove?

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[hiltonstroud]

Hi Simon,

See below as requested.

I have marked the neighbour I would like to remove in "bold" and "italics" -- it is: 172.18.30.14

router bgp xxxx

  log-neighbor-changes

  address-family ipv4 unicast

    network 172.17.x.x/20

    network 172.17.x.x/20

    network 172.17.x.x/20

    network 172.17.x.x/20

    network 172.17.x.x/20

    network 172.17.x.x/20

    network 172.17.x.x/20

    network 172.18.x.x/19

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/24

    network 172.18.x.x/29

    aggregate-address 172.18.x.x/19 summary-only

neighbor 172.18.30.14 remote-as xxxx

    ebgp-multihop 2

    address-family ipv4 unicast

      soft-reconfiguration inbound

  neighbor 172.18.30.22 remote-as xxxx

    ebgp-multihop 2

    address-family ipv4 unicast

      soft-reconfiguration inbound

[Bilal Nawaz · Accepted solution]

Hello, to disable the neighbour as mentioned previously use the shutdown key word.

switch(config)# router bgp xxxx
switch(config-router)# neighbor 172.18.30.14 remote-as xxxx
switch(config-router-neighbor)#
switch(config-router-neighbor)# shutdown

(Optional) Administratively shuts down this BGP neighbor. This command triggers an automatic notification and session reset for the BGP neighbor sessions

This will leave the existing config intact apart from the neighbour being shutdown which is the goal here if I understood correctly.

If you want to remove the configuration for this particular neighbour

switch(config)# router bgp xxxx
switch(config-router)# no neighbor 172.18.30.14 remote-as xxxx

This will remove all commands for this neighbour I believe, but still leave the rest of your BGP configuration intact.

___________________________

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/unicast/5_0_3_N1_1/l3_bgp.html#wp1078063

Hope this helps

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[er.ksnegi]

Hi,

This is good idea to shutdown neighborship instead of removing by above process but still you want to remove neighborship as following -

>enable

>#conf t

)#router bgp xxxx

router)#no neighbor 172.18.30.14 remote-as xxxx

Note it will remove all the configuration regarding this neighbor so take the backup of your configuration if you need it back in future.

[hiltonstroud]

Thanks to all who replied, Bilal & Kunwar answered correctly, however it seems Bilal did so first.

FYI - My original request was to remove this neighbor and not just disable/shutdown, however it is great to have this info as well for future use, I actually did a shutdown first before doing a "no" command for neighbor in question.

Thank you to all for the responses and support provided, this was my first post on Cisco support forums and has been a great experience so far.