Bug 2190344

Hi Chorong, 

This is an adjustable parameter as there may be some reasons a customer would want the old default value, as such this is safe to adjust. 

I would share the following with the customer: 

```
To make the default behavior
desirable for majority of the use cases, set the option ignore_lsp_down
to true by default. This would help saving the control plane cost in
large scale environment, reduce the e2e latency for all flows to be
installed for a VIF, and making the VIF readiness checking more convenient
in test cases and likely in CMS as well. User can still set it to false
in circumstances (if any) when this behavior is not desired.
```

> Is there any way to check the ignore_lsp_down?
Yes, using the follow command: `ovn-nbctl get NB_Global . options`

As you can see from my output the `ignore_lsp_down` value isn't set:
[root@controller-0 /]# ovn-nbctl get NB_Global . options
{mac_prefix="5e:37:e7", max_tunid="16711680", northd_internal_version="21.12.3-20.21.0-61.4", svc_monitor_mac="1a:32:b1:e7:e0:2e"}

The new code that was implemented will now default to true if the value is not explicitly configured[1]:
```
    check_lsp_is_up = !smap_get_bool(&nb->options,
                                     "ignore_lsp_down", true);
```

So to set it to false the customer will need to run the following command in the master ovn-dbs container:

Example:
```
[root@controller-1 ~]# pcs status | grep ovn-dbs-bundle |grep Master
    * ovn-dbs-bundle-1	(ocf::ovn:ovndb-servers):	 Master controller-1
[root@controller-1 /]# podman exec -it ovn-dbs-bundle-podman-1 bash
```

*inside container* 

```
[root@controller-1 /]# ovn-nbctl get NB_Global . options
{mac_prefix="5e:37:e7", max_tunid="16711680", northd_internal_version="21.12.3-20.21.0-61.4", svc_monitor_mac="1a:32:b1:e7:e0:2e"}
[root@controller-1 /]# ovn-nbctl set NB_Global . options:ignore_lsp_down=false
[root@controller-1 /]# ovn-nbctl get NB_Global . options
{ignore_lsp_down="false", mac_prefix="5e:37:e7", max_tunid="16711680", northd_internal_version="21.12.3-20.21.0-61.4", svc_monitor_mac="1a:32:b1:e7:e0:2e"}
```

The only problem I can see is I don't see anywhere to set it in THT or Neutron, so this value may need to be set again in the future.

> Did the default value for the ignore_lsp_down change in RHOSP 16.2.3.?
Yes, RHOSP 16.2.3 is shipped with `ovn-2021-21.12.0-94.el8fdp` which is the first RHOSP version to contain this code as it was added to `21.09`

[1] https://github.com/ovn-org/ovn/blob/8e109f387c85d18ab3763366ff4a81e3ce7b99bf/northd/northd.c#L16621-L16622

Hi Lewis,

Thanks for confirming the ovn package details and share the feedback with us. 
Let me share this with the customer as you mentioned.

Best Regards,
Chorong

This will be fixed in 17.1 tracked by bug 2243885. If operators need this flag to be set, they can run manually the command `ovn-nbctl set nb_global options:ignore_lsp_down=False` that sets it in the Northbound database.