Additional info:

In this output, port 68e5740d-81e1-4355-bb48-867305f706bc is the port formerly associated with the gateway_ip for the respective tenant subnet. The details of which are:

root@controller01-utility-container-8ad9622f:~# neutron port-show 68e5740d-81e1-4355-bb48-867305f706bc
+-----------------------+-----------------------------------------------------------------------------------+
| Field                 | Value                                                                             |
+-----------------------+-----------------------------------------------------------------------------------+
| admin_state_up        | True                                                                              |
| allowed_address_pairs |                                                                                   |
| binding:host_id       |                                                                                   |
| binding:profile       | {}                                                                                |
| binding:vif_details   | {}                                                                                |
| binding:vif_type      | distributed                                                                       |
| binding:vnic_type     | normal                                                                            |
| created_at            | 2017-09-25T19:28:18Z                                                              |
| description           |                                                                                   |
| device_id             | eee05405-f4c7-4a7a-9100-fc09bbfc9d82                                              |
| device_owner          | network:router_interface_distributed                                              |
| extra_dhcp_opts       |                                                                                   |
| fixed_ips             | {"subnet_id": "099a6d6e-1353-4b7a-aab3-ede9d592328d", "ip_address": "10.10.1.10"} |
| id                    | 68e5740d-81e1-4355-bb48-867305f706bc                                              |
| mac_address           | fa:16:3e:2e:33:cc                                                                 |
| name                  |                                                                                   |
| network_id            | 06b4c4da-9de0-447b-8892-ccc45f3393ba                                              |
| port_security_enabled | False                                                                             |
| project_id            | 340c72665c664f52bba3ac61a81fd501                                                  |
| qos_policy_id         |                                                                                   |
| revision_number       | 207200                                                                            |
| security_groups       |                                                                                   |
| status                | ACTIVE                                                                            |
| tenant_id             | 340c72665c664f52bba3ac61a81fd501                                                  |
| updated_at            | 2017-10-26T21:22:41Z                                                              |
+-----------------------+-----------------------------------------------------------------------------------+
root@controller01-utility-container-8ad9622f:~# neutron subnet-show 099a6d6e-1353-4b7a-aab3-ede9d592328d
+-------------------+-----------------------------------------------+
| Field             | Value                                         |
+-------------------+-----------------------------------------------+
| allocation_pools  | {"start": "10.10.2.70", "end": "10.10.2.220"} |
| cidr              | 10.10.0.0/16                                  |
| created_at        | 2017-09-25T19:17:47Z                          |
| description       |                                               |
| dns_nameservers   | x.x.x.x                                       |
|                   | y.y.y.y                                       |
| enable_dhcp       | True                                          |
| gateway_ip        | None                                          |
| host_routes       |                                               |
| id                | 099a6d6e-1353-4b7a-aab3-ede9d592328d          |
| ip_version        | 4                                             |
| ipv6_address_mode |                                               |
| ipv6_ra_mode      |                                               |
| name              | floating-ipv4                                 |
| network_id        | 06b4c4da-9de0-447b-8892-ccc45f3393ba          |
| project_id        | 340c72665c664f52bba3ac61a81fd501              |
| revision_number   | 5                                             |
| service_types     |                                               |
| subnetpool_id     |                                               |
| tenant_id         | 340c72665c664f52bba3ac61a81fd501              |
| updated_at        | 2017-10-26T21:12:05Z                          |
+-------------------+-----------------------------------------------+