L2VPN stays down after intra-domain link failure despite alternate path availability

[gretelliz]

-----------------New description

An L2VPN is provisioned between Tenet01 and Tenet02 using an intra-domain link.

When the direct intra-domain link between Tenet01 and Tenet02 is set to down, the SDX topology is correctly updated.
However, even though an alternate path exists in the exported topology (from SAX), the SDX Controller does not verify connectivity nor re-route the service.

As a result, the L2VPN transitions to down instead of remaining up.

Expected:
If an alternate path exists, SDX should keep the L2VPN up and ensure connectivity.

Actual:
L2VPN status becomes down even though a valid alternate path is available.

See test_011_intra_domain_link_down_path_found

-----------------Old description

After setting a link down and finding an alternate path, connectivity between hosts is not checked (see test_011_update_intra_domain_link_down_path_found)

[YufengXin]

@gretelliz Could you pls elaborate? How is it different from the link failure handling test in Main that succeeded?

[gretelliz]

See comment in issue #456

[italovalcy]

so, looking into the end-to-end testing code, the situation with this test will also require integration with monitoring and BAPM. Basically, the test is simulating link failure on Tenet01 - Tenet02. In this case, there is no alternative path that can be provisioned by the OXP. In this case the expected behavior would be: OXP will identify that a L2VPN was affected by the link failure and it cannot recovery; OXP's BAPM/Monitoring component will send a notification to SDX to change the status of the L2VPN; SDX-Controller will try to find another path possible using other OXP's entry point.

Anyway, for this issue we should also put it into on-hold until we have the bapm/monitoring.