Comment 2 for bug 1875852

hi,
I focus this BZ many days, and done a lot of worker.
1) I make new version (21.03.0) for ovn rpm pkgs by [1], and install those rpm pkgs at my environment.
2) Remove the 'reside-on-redirect' option at neutron [2]. Add option redirect-type value is 'bridged' like this [3]:
        if is_gw_port and network.get(pnet.NETWORK_TYPE) == const.TYPE_VLAN:
            options['redirect-type'] = 'bridged'

3) Set local OVSDBs with 'external_ids:ovn-chassis-mac-mappings' for every chassis.
4) Create two vlan tenant networks named net1 and net2 those subnets attach two different routers separately.
4）Set the router gateway by the same external vlan network.
5) Create VM1 at net1, and associated a floating-ip named fp1 (no distributed_floating_ip).
6) Create VM2 at net2
7) VM2 ping fp1, traffic failed.
8) Modify redirect-type value with 'overlay', traffic pass.

I think ovn not completely support centralized floating-ip at now at the scenarios of Vlan backed DVR. This matter also impact sriov.

[1]https://docs.ovn.org/en/latest/intro/install/fedora.html
[2]https://github.com/openstack/neutron/blob/3cbe340846cb00e542afbad238207186cc22a858/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py#L1340
[3]https://github.com/ovn-org/ovn/commit/03493b33c073887a81ba90c84b5e063140712719