Hello Keigo,

If you want to set those accept_ra sysctls to 0 you can simply do so via https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/17.0/html-single/director_installation_and_usage/index#proc_increase-conntrack-entries_additional-network-configuration 

either globally:

parameter_defaults:
  ExtraSysctlSettings:
    net.ipv6.conf.all.accept_ra_defrtr:
      value: 0
    net.ipv6.conf.default.accept_ra_defrtr:
      value: 0

or per role, using:

parameter_defaults:
  <role>Parameters:
    ExtraSysctlSettings:
...


would that help?

We can't set those sysctls to zero by default (in tht or similar) without risking to break existing installations.

Regards,
Luca

Hi Luca,

Thank you for your comment. Yes. Applying the kernel parameter require the additional caution.

1. During the deployment the node should use default route until BGP routing is received.
2. Once BGP routing is received and the BGP routing should be preferred to default routing, we should apply the kernel parameter and remove the default routing.

Is it possible to provide a new option to enable this behavior?
I'd like to hear your thoughts regarding this.

Best regards,
Keigo Noha

Doing what you propose would require orchestration between initial network setup, frr/bgp configuration and subsequent additional network tweaks to achieve the desired state.
To my knowledge we don't have such orchestrations capabilities in tripleo and it is unlikely we will be able to implement something like this, so I think we could to do something like:

1. set up a temporary default route using FirstBoot or ExtraConfigPre (https://docs.openstack.org/project-deploy-guide/tripleo-docs/latest/features/extra_config.html) 
2. use ExtraConfigPost to remove that route and add the necessary sysctls (if you don't want to add them via ExtraSysctlSettings as suggested previously)


example taken from our lab where we use the same trick. We used ipv4 but it would work with ipv6 as well:

~~~
$ cat extraconfigpre_template.yaml 

heat_template_version: newton

description: >
  Inject stuff before puppet kicks in

parameters:
  server:
    type: string

resources:

  CustomExtraConfigPre:
    type: OS::Heat::SoftwareConfig
    properties:
      group: script
      config: |
        #!/bin/sh
        ip route add 10.0.0.0/8 via 192.168.$(hostname |cut -d. -f1 |cut -d- -f2).1


  CustomExtraDeploymentPre:
    type: OS::Heat::SoftwareDeployment
    properties:
      server: {get_param: server}
      config: {get_resource: CustomExtraConfigPre}
      actions: ['CREATE','UPDATE']

outputs:
  deploy_stdout:
    description: Deployment reference, used to trigger pre-deploy on changes
    value: {get_attr: [CustomExtraDeploymentPre, deploy_stdout]}

~~~


~~~
$ cat extraconfigpost_template.yaml 

heat_template_version: newton

description: >
  Inject stuff at the end of the deployment

parameters:
  servers:
    type: json
  DeployIdentifier:
    type: string
  EndpointMap:
    default: {}
    description: Mapping of service endpoint -> protocol. Typically set
                 via parameter_defaults in the resource registry.
    type: json

resources:
  CustomExtraConfig:
    type: OS::Heat::SoftwareConfig
    properties:
      group: script
      config: |
        #!/bin/sh
        # remove route
        sysctl net.ipv6.conf.all.accept_ra_defrtr=0
        sysctl net.ipv6.conf.default.accept_ra_defrtr=0
        ip r del 10.0.0.0/8        

  CustomExtraDeployments:
    type: OS::Heat::SoftwareDeploymentGroup
    properties:
      config: {get_resource: CustomExtraConfig}
      servers:  {get_param: servers}
      actions: ['CREATE','UPDATE']
      input_values:
        deploy_identifier: {get_param: DeployIdentifier}
~~~


here we used actions: ['CREATE','UPDATE'] but I think it would be more appropriate to use actions: ['CREATE'] so it doesn't run on stack updates, scale ups etc.
Alternatively they could try using setting a route with a weight value such that it would be de-prioritized as soon as the new routes injected via bgp are present. I haven't tested this last option though. 

HTH
Luca