In case of GRE or VXLAN tenants L2 networks the VLAN tags you see in the output of "ovs-vsctl show" and in output of "ovs-ofctl dump-flows br-tun" (mod_vlan_vid) are only locally significant. This VLAN tags are not really L2 tags added to the frames leaving on the physical interface. They are only used by openvswitch to separate traffic on the br-int, so the different tap interfaces corresponding to different neutron subnets do not see each other's traffic. As far as this tags are not 12-bits segments , number 4096 is not important.
**************************
ON CONTROLLER
**************************
[root@juno1 ~(keystone_admin)]# neutron net-list
+--------------------------------------+-----------------+-----------------------------------------------------+
| id | name | subnets |
+--------------------------------------+-----------------+-----------------------------------------------------+
| 90b574e2-f51a-423e-aef9-c201f6f68b76 | kashyap_private | 5fe9e3cc-feee-4f51-bed8-f4891bd8aafe 40.0.0.0/24 |
| 65cbd354-daae-41bb-9d3c-e58b1062be19 | public | 147d5ecd-fe39-489e-8901-3b20a2c50148 192.168.1.0/24 |
| 8b2de478-de3f-448e-8ec1-8f973a762daf | boris_network | 4142d2c6-220c-4b47-8147-cf512f7a753b 15.0.0.0/24 |
| 3fdb2eb7-fff8-4633-824b-1da4c38ccbd5 | kashyap_network | 8bee3a8d-7fac-4d05-84e3-bbe52a601084 70.0.0.0/24 |
| 951715cc-2a19-470e-9987-25b3b7906756 | demo_network | d512bb49-29f0-4fe2-886a-10d880cc83fc 10.0.0.0/24 |
+--------------------------------------+-----------------+-----------------------------------------------------+
[root@juno1 ~(keystone_admin)]# ip netns exec qdhcp-90b574e2-f51a-423e-aef9-c201f6f68b76 ifconfig
lo: flags=73
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10
loop txqueuelen 0 (Local Loopback)
RX packets 1 bytes 576 (576.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1 bytes 576 (576.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
tap5532b72d-8c: flags=4163
inet 40.0.0.11 netmask 255.255.255.0 broadcast 40.0.0.255
inet6 fe80::f816:3eff:fe6e:91a7 prefixlen 64 scopeid 0x20
ether fa:16:3e:6e:91:a7 txqueuelen 0 (Ethernet)
RX packets 27 bytes 2982 (2.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 12 bytes 2112 (2.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@juno1 ~(keystone_admin)]# ovs-vsctl show
f2113bd0-c4ca-4c4b-af16-928ff03e53da
Bridge br-int
fail_mode: secure
Port "tap37cfc1fc-09"
tag: 1
Interface "tap37cfc1fc-09"
type: internal
Port int-br-ex
Interface int-br-ex
type: patch
options: {peer=phy-br-ex}
Port "qr-7ff72517-f3"
tag: 4
Interface "qr-7ff72517-f3"
type: internal
Port patch-tun
Interface patch-tun
type: patch
options: {peer=patch-int}
Port "tap2d26c49a-37"
tag: 5
Interface "tap2d26c49a-37"
type: internal
Port "tap5532b72d-8c"
tag: 4 <==== tag 4 on Controller Node
Interface "tap5532b72d-8c"
type: internal
Port "qr-bd92408c-b4"
tag: 5
Interface "qr-bd92408c-b4"
type: internal
Port "qr-a494fcc8-e5"
tag: 2
Interface "qr-a494fcc8-e5"
type: internal
Port "qr-4162d98e-5c"
tag: 1
Interface "qr-4162d98e-5c"
type: internal
Port br-int
Interface br-int
type: internal
Port "tap305cff35-34"
tag: 2
Interface "tap305cff35-34"
type: internal
Bridge br-ex
Port "qg-88b1ef62-2c"
Interface "qg-88b1ef62-2c"
type: internal
Port phy-br-ex
Interface phy-br-ex
type: patch
options: {peer=int-br-ex}
Port "qg-d3e929c6-ba"
Interface "qg-d3e929c6-ba"
type: internal
Port "enp2s0"
Interface "enp2s0"
Port "qg-5c6dd032-a8"
Interface "qg-5c6dd032-a8"
type: internal
Port br-ex
Interface br-ex
type: internal
Port "qg-7b037650-10"
Interface "qg-7b037650-10"
type: internal
Bridge br-tun
Port "vxlan-c0a80089"
Interface "vxlan-c0a80089"
type: vxlan
options: {df_default="true", in_key=flow, local_ip="192.168.0.127", out_key=flow, remote_ip="192.168.0.137"}
Port br-tun
Interface br-tun
type: internal
Port patch-int
Interface patch-int
type: patch
options: {peer=patch-tun}
ovs_version: "2.1.3"
************************************************************************
So kashyap_private network corresponds tag 4 on Controller
************************************************************************
**********************
ON COMPUTE
**********************
[root@juno2 ~(keystone_kashyap)]# nova list
+--------------------------------------+------------+--------+------------+-------------+------------------------------------------+
| ID | Name | Status | Task State | Power State | Networks |
+--------------------------------------+------------+--------+------------+-------------+------------------------------------------+
| 1359ac92-8092-47bc-b7d6-ee474b641355 | CirrOS321 | ACTIVE | - | Running | kashyap_private=40.0.0.12, 192.168.1.155 |
+--------------------------------------+------------+--------+------------+-------------+------------------------------------------+
VM is running on kashyap_private network (40.0.0.0/24)
[root@juno2 ~(keystone_kashyap)]# nova show 1359ac92-8092-47bc-b7d6-ee474b641355
+--------------------------------------+----------------------------------------------------------+
| Property | Value |
+--------------------------------------+----------------------------------------------------------+
| OS-DCF:diskConfig | AUTO |
| OS-EXT-AZ:availability_zone | nova |
| OS-EXT-STS:power_state | 1 |
| OS-EXT-STS:task_state | - |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2014-11-28T15:21:59.000000 |
| OS-SRV-USG:terminated_at | - |
| accessIPv4 | |
| accessIPv6 | |
| config_drive | |
| created | 2014-11-28T15:21:48Z |
| flavor | m1.tiny (1) |
| hostId | 7339f21099a5d4d918b8e69302c1dab2d5f7af63babf36d02057177d |
| id | 1359ac92-8092-47bc-b7d6-ee474b641355 |
| image | cirros (6f7d1877-9b6b-4530-b868-9fe42a71bca9) |
| kashyap_private network | 40.0.0.12, 192.168.1.155 |
| key_name | oskey37 |
| metadata | {} |
| name | CirrOS321 |
| os-extended-volumes:volumes_attached | [] |
| progress | 0 |
| security_groups | default |
| status | ACTIVE |
| tenant_id | 2a8be6536a864dd0b73782fd0fb2faff |
| updated | 2014-11-28T15:21:59Z |
| user_id | bce3ed8aaa97447b8edfe3cf734b0793 |
+--------------------------------------+----------------------------------------------------------+
****************************
Identifying qvo* port
****************************
[root@juno2 ~(keystone_kashyap)]# brctl show
bridge name bridge id STP enabled interfaces
qbr23b93632-0d 8000.1e955c2e4f2e no qvb23b93632-0d
tap23b93632-0d
qbr37f299e0-de 8000.1a32e0906384 no qvb37f299e0-de
qbra0fa9687-39 8000.f6fd5e4399e7 no qvba0fa9687-39
qbrff853471-05 8000.9ef67b07ba76 no qvbff853471-05
[root@juno2 ~(keystone_admin)]# virsh dumpxml 1359ac92-8092-47bc-b7d6-ee474b641355 | grep 23b93632-0d
<source bridge='qbr23b93632-0d'/>
<target dev='tap23b93632-0d'/>
***********************************************************
Tracking veth-pair ( qvb23b93632-0d, qvo23b93632-0d )
***********************************************************
[root@juno2 ~(keystone_kashyap)]# ovs-vsctl
79e82e7f-9040-4789-b8c8-d7d397ec230b
Bridge br-tun
Port "vxlan-c0a8007f"
Interface "vxlan-c0a8007f"
type: vxlan
options: {df_default="true", in_key=flow, local_ip="192.168.0.137", out_key=flow, remote_ip="192.168.0.127"}
Port br-tun
Interface br-tun
type: internal
Port patch-int
Interface patch-int
type: patch
options: {peer=patch-tun}
Bridge br-ex
Port phy-br-ex
Interface phy-br-ex
type: patch
options: {peer=int-br-ex}
Port br-ex
Interface br-ex
type: internal
Bridge br-int
fail_mode: secure
Port "qvoff853471-05"
tag: 2
Interface "qvoff853471-05"
Port "qvoa0fa9687-39"
tag: 1
Interface "qvoa0fa9687-39"
Port "qvod282b303-3a"
tag: 5
Interface "qvod282b303-3a"
Port int-br-ex
Interface int-br-ex
type: patch
options: {peer=phy-br-ex}
Port "qvo23b93632-0d"
tag: 6 <=== tag 6 on Compute Node
Interface "qvo23b93632-0d"
Port patch-tun
Interface patch-tun
type: patch
options: {peer=patch-int}
Port br-int
Interface br-int
type: internal
Port "qvo37f299e0-de"
tag: 1
Interface "qvo37f299e0-de"
ovs_version: "2.1.3"
****************************************************************************
So kashyap_private network corresponds tag 6 ( Compute Node)
****************************************************************************
