Sachin,
   Verified with nodec43 (openstack + openvswitch)

The behavior is different in two ways: 
1) In std openstack, it doesnt let me create a port for router from another tenant unless the user had admin role on that project

2) router-port-list does show the port from the shared VN in the current project. 

root@nodec43:~# neutron net-show net_1_1
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | True                                 |
| id                        | 02b7d689-ea66-4d7b-9373-658f10ad1012 |
| name                      | net_1_1                              |
| provider:network_type     | gre                                  |
| provider:physical_network |                                      |
| provider:segmentation_id  | 3                                    |
| router:external           | False                                |
| shared                    | True                                 |
| status                    | ACTIVE                               |
| subnets                   | 6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5 |
| tenant_id                 | 3136f090ef9c493e9c70184ce678482c     |
+---------------------------+--------------------------------------+
root@nodec43:~#

root@nodec43:~# source openrc 
root@nodec43:~# export OS_TENANT_NAME=project2
root@nodec43:~# neutron router-create router2
Created a new router:
+-----------------------+--------------------------------------+
| Field                 | Value                                |
+-----------------------+--------------------------------------+
| admin_state_up        | True                                 |
| external_gateway_info |                                      |
| id                    | f48f38d8-7f9d-426c-976d-156c95a8b914 |
| name                  | router2                              |
| status                | ACTIVE                               |
| tenant_id             | 5ca0a1c56d47409c90befe31521c7eac     |
+-----------------------+--------------------------------------+
root@nodec43:~#


root@nodec43:~# neutron router-interface-add f48f38d8-7f9d-426c-976d-156c95a8b914 6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5
{"NeutronError": {"message": "User does not have admin privileges: Cannot create resource for another tenant", "type": "AdminRequired", "detail": ""}}
root@nodec43:~# 

I then made 'admin' user to be of role "admin" in project1

root@nodec43:~# set |grep OS_
OS_AUTH_URL=http://10.204.217.83:5000/v2.0
OS_PASSWORD=password
OS_TENANT_NAME=project2
OS_USERNAME=admin
root@nodec43:~# 

root@nodec43:~# neutron router-interface-add f48f38d8-7f9d-426c-976d-156c95a8b914 6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5
Added interface 9f28d338-7b4b-48c8-a75d-7b344c88bdfb to router f48f38d8-7f9d-426c-976d-156c95a8b914.
root@nodec43:~# 

root@nodec43:~# neutron router-list
+--------------------------------------+-----------+-----------------------+
| id                                   | name      | external_gateway_info |
+--------------------------------------+-----------+-----------------------+
| 4d3ad899-1b46-4628-820e-d6bb673a1284 | vedu1_rtr | null                  |
| 6da97f23-9217-4795-a3f4-0f1a8fe047c1 | rtr1      | null                  |
| ad4f8868-fbfe-4134-b9b7-d1ab52ae3e62 | router1   | null                  |
| f48f38d8-7f9d-426c-976d-156c95a8b914 | router2   | null                  |
+--------------------------------------+-----------+-----------------------+
root@nodec43:~# neutron router-port-list router2
+--------------------------------------+------+-------------------+--------------------------------------------------------------------------------+
| id                                   | name | mac_address       | fixed_ips                                                                      |
+--------------------------------------+------+-------------------+--------------------------------------------------------------------------------+
| 9f28d338-7b4b-48c8-a75d-7b344c88bdfb |      | fa:16:3e:a9:f8:89 | {"subnet_id": "6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5", "ip_address": "1.1.1.1"} |
+--------------------------------------+------+-------------------+--------------------------------------------------------------------------------+
root@nodec43:~#

root@nodec43:~# source openrc 
root@nodec43:~# export OS_TENANT_NAME=project2
root@nodec43:~# neutron subnet-show 6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5
+------------------+------------------------------------------+
| Field            | Value                                    |
+------------------+------------------------------------------+
| allocation_pools | {"start": "1.1.1.2", "end": "1.1.1.254"} |
| cidr             | 1.1.1.0/24                               |
| dns_nameservers  |                                          |
| enable_dhcp      | True                                     |
| gateway_ip       | 1.1.1.1                                  |
| host_routes      |                                          |
| id               | 6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5     |
| ip_version       | 4                                        |
| name             |                                          |
| network_id       | 02b7d689-ea66-4d7b-9373-658f10ad1012     |
| tenant_id        | 3136f090ef9c493e9c70184ce678482c         |
+------------------+------------------------------------------+
root@nodec43:~# keystone tenant-list |grep 3136
| 3136f090ef9c493e9c70184ce678482c |  project1 |   True  |
root@nodec43:~# 

root@nodec43:~# neutron port-show 9f28d338-7b4b-48c8-a75d-7b344c88bdfb
+-----------------------+--------------------------------------------------------------------------------+
| Field                 | Value                                                                          |
+-----------------------+--------------------------------------------------------------------------------+
| admin_state_up        | True                                                                           |
| allowed_address_pairs |                                                                                |
| binding:capabilities  | {"port_filter": true}                                                          |
| binding:host_id       | nodec43                                                                        |
| binding:vif_type      | ovs                                                                            |
| device_id             | f48f38d8-7f9d-426c-976d-156c95a8b914                                           |
| device_owner          | network:router_interface                                                       |
| extra_dhcp_opts       |                                                                                |
| fixed_ips             | {"subnet_id": "6f63e3e3-0bc0-4bfd-bf08-dbe562ac5fe5", "ip_address": "1.1.1.1"} |
| id                    | 9f28d338-7b4b-48c8-a75d-7b344c88bdfb                                           |
| mac_address           | fa:16:3e:a9:f8:89                                                              |
| name                  |                                                                                |
| network_id            | 02b7d689-ea66-4d7b-9373-658f10ad1012                                           |
| security_groups       |                                                                                |
| status                | DOWN                                                                           |
| tenant_id             | 3136f090ef9c493e9c70184ce678482c                                               |
+-----------------------+--------------------------------------------------------------------------------+
root@nodec43:~#  

root@nodec43:~#  cat openrc 
export OS_AUTH_URL=http://10.204.217.83:5000/v2.0
export OS_TENANT_NAME=admin
export OS_USERNAME=admin
export OS_PASSWORD=password
root@nodec43:~# cat vedurc 
export OS_AUTH_URL=http://10.204.217.83:5000/v2.0
export OS_TENANT_NAME=project1
export OS_USERNAME=vedu
export OS_PASSWORD=vedu
root@nodec43:~#