[Bug 2123914] Re: dynamic-routing-port-name option has no effect

[Chris Halse Rogers]

The test plan doesn't seem to cover a basic test of non-dynamic-routing.
I see that ovn is part of the OpenStack update documentation¹ - would
something from there be a good smoke test to ensure that we don't
regress existing uses?

¹: https://documentation.ubuntu.com/sru/en/latest/reference/exception-
OpenStack-Updates/#openstack-qa-process

** Changed in: ovn (Ubuntu Plucky)
       Status: New => Incomplete

** Changed in: ovn (Ubuntu Questing)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/2123914

Title:
  dynamic-routing-port-name option has no effect

Status in ovn package in Ubuntu:
  Fix Released
Status in ovn source package in Plucky:
  Incomplete
Status in ovn source package in Questing:
  Incomplete

Bug description:
  [ Impact ]
  When using the native OVN dynamic routing feature for learning routes, mapping from which interface a route is learned to a specific LRP is required. Failing to do this will create invalid routes in the system.

  The dynamic-routing-port-name option was provided as means to do this,
  however a bug prevents this feature from working as intended.

  Consequently using dynamic routing to learn routes does not work
  without this patch.

  [ Test Plan ]
  The main branch of MicroOVN makes use of this feature [2], and has thorough test suites validating operation.  As a form of verification we will build a version of MicroOVN with the -proposed package and provide test results.

  [ Where problems could occur ]
  OVN 25.03 was the first version with native support for dynamic routing through the use of routing protocol suites such as BIRD or FRR.

  As detailed above the route learning feautre is currently not usable,
  and the fix has been merged to main and backported to 25.09 and 25.03
  branches.

  Due to the feature currently being broken, the regression potential is
  minimal or non-existent.

  [ Other Info ]
  The dynamic-routing-port-name option was added to the Logical_Router_Port table [0] as means of selecting which LRPs should learn routes.  When used together with Open_vSwitch external_ids:dynamic-routing-port-mapping, an LRP can also be mapped to a system interface as found in the system routing tables.

  The description of the option states: "Only learn routes associated
  with the interface locally bound to the LSP or LRP  specified  here".

  However, when an LR has LRPs with this option, learned routes are
  still associated with all LRPs of an LR [1].

  In order for the option to work as documented there would have to be a
  check for whether any LRPs of an LR has this option, and if that is
  the case, only consider those LRPs.

  0: https://manpages.ubuntu.com/manpages/questing/man5/ovn-nb.5.html#logical_router_port%20table
  1: https://github.com/ovn-org/ovn/blob/db748328f36592f76c1ea991f0ea1b1ac79902b5/controller/route.c#L208
  2: https://github.com/canonical/microovn/blob/624123ca227a136343b5e71c68d47f862654d3db/microovn/bgp/redirect.go#L293

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