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ot able to ping the router of the external net configured in neutron ext-net

Hi,

I am trying to make a icehouse setup on opensuse 13.1. with repository http://download.opensuse.org/repositories/Cloud:/OpenStack:/Icehouse/openSUSE_13.1/

But I am stuck on the neutron configuration. I think I have set it up according to http://docs.openstack.org/icehouse/install-guide/install/zypper/content/ch_networking.html


However I am not able to ping the router of the external net configured in neutron ext-net.
Here is what happens
external net: 172.16.0.0/24
physical router 172.16.0.1
the neutron router of the ext-net: 172.16.0.110

ping from 172.16.0.21 to 172.16.0.110

On physical nic
tcpdump -ieno1
07:58:22.540247 ARP, Request who-has 172.16.0.110 tell 172.16.0.21, length 46
07:58:22.964585 ARP, Request who-has 172.16.4.35 tell 172.16.4.1, length 46
07:58:23.032330 ARP, Request who-has 172.16.0.96 tell 172.16.0.99, length 46

on bridge
tcpdump -ibr-ex
07:57:32.535197 ARP, Request who-has 172.16.0.110 tell 172.16.0.21, length 46
07:57:32.616321 ARP, Request who-has 172.16.0.98 tell 172.16.0.99, length 46
07:57:33.032401 ARP, Request who-has 172.16.0.96 tell 172.16.0.99, length 46

on router
ip netns exec qrouter-24ab9088-6283-4053-a78f-61feb56d4e63 tcpdump -iany
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
<empty/nothing>


I am confused here, The only thing I find strange is the router port is connected to the br-int and not the br-ex, (see output of vs-vsctl show below)

Any help would be helpfull.

mfg,
Jeroen


ovs-dpctl dump-flows
skb_priority(0),in_port(4),eth(src=78:24:af:2c:09:5e,dst=ff:ff:ff:ff:ff:ff),eth_type(0x0806),arp(sip=172.16.0.21/255.255.255.255,tip=172.16.0.110/255.255.255.255,op=1/0xff,sha=78:24:af:2c:09:5e/00:00:00:00:00:00,tha=00:00:00:00:00:00/00:00:00:00:00:00), packets:23, bytes:1380, used:0.239s, actions:3

phoenix:~ # ovs-ofctl dump-flows br-ex                                                                              
NXST_FLOW reply (xid=0x4):                                                                                          
 cookie=0x0, duration=44511.022s, table=0, n_packets=196728, n_bytes=18082154, idle_age=0, priority=0 actions=NORMAL

phoenix:~ # ovs-dpctl show
system@ovs-system:
        lookups: hit:184051 missed:62864 lost:0
        flows: 8
        port 0: ovs-system (internal)
        port 1: br-int (internal)
        port 2: br-tun (internal)
        port 3: br-ex (internal)
        port 4: eno1
        port 5: qg-cf14cdbc-ec (internal)
        port 6: qr-d44098bf-8f (internal)


phoenix:~ # ip netns
qrouter-24ab9088-6283-4053-a78f-61feb56d4e63
phoenix:~ # ip netns exec qrouter-24ab9088-6283-4053-a78f-61feb56d4e63 ifconfig -a
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:1538 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1538 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:172222 (168.1 Kb)  TX bytes:172222 (168.1 Kb)

qg-cf14cd Link encap:Ethernet  HWaddr FA:16:3E:F4:48:36
          inet addr:172.16.0.110  Bcast:172.16.0.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:fef4:4836/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:1124 (1.0 Kb)

qr-d44098 Link encap:Ethernet  HWaddr FA:16:3E:41:D0:59
          inet addr:192.168.4.1  Bcast:192.168.4.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:fe41:d059/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1500  Metric:1
          RX packets:2468 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:249768 (243.9 Kb)  TX bytes:998 (998.0 b)

phoenix:~ # ovs-vsctl show
ddd79663-5439-4a5e-befb-272f8ca3f756
    Bridge br-ex
        Port br-ex
            Interface br-ex
                type: internal
        Port "eno1"
            Interface "eno1"
    Bridge br-int
        fail_mode: secure
        Port "qr-d44098bf-8f"
            tag: 1
            Interface "qr-d44098bf-8f"
                type: internal
        Port "qg-cf14cdbc-ec"
            tag: 2
            Interface "qg-cf14cdbc-ec"
                type: internal
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port br-int
            Interface br-int
                type: internal
    Bridge br-tun
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
        Port br-tun
            Interface br-tun
                type: internal
    ovs_version: "2.0.0"



phoenix:~ # neutron net-list
+--------------------------------------+----------+-----------------------------------------------------                                                +
| id                                   | name     | subnets                                                                                             |
+--------------------------------------+----------+-----------------------------------------------------+
| ca6b6d12-f5f9-471f-bf51-9fbc598709fc | ext-net  | be31f1f6-023b-4082-93e7-e89709b46710 172.16.0.0/24  |
| d0edb986-fcd2-43b2-9049-f7a7f6a68b4f | demo-net | 0263d67c-8f18-4c5c-8e3d-68cd887cace7 192.168.4.0/24 |
+--------------------------------------+----------+-----------------------------------------------------+

phoenix:~ # neutron net-show ca6b6d12-f5f9-471f-bf51-9fbc598709fc
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | True                                 |
| id                        | ca6b6d12-f5f9-471f-bf51-9fbc598709fc |
| name                      | ext-net                              |
| provider:network_type     | gre                                  |
| provider:physical_network |                                      |
| provider:segmentation_id  | 1                                    |
| router:external           | True                                 |
| shared                    | True                                 |
| status                    | ACTIVE                               |
| subnets                   | be31f1f6-023b-4082-93e7-e89709b46710 |
| tenant_id                 | 03110aa32a35426bbc7d861dcb61ad94     |
+---------------------------+--------------------------------------+



phoenix:~ # neutron subnet-list
+--------------------------------------+------------+----------------+--------------------------------------------------+
| id                                   | name       | cidr           | allocation_pools                                 |
+--------------------------------------+------------+----------------+--------------------------------------------------+
| be31f1f6-023b-4082-93e7-e89709b46710 | ext-subnet | 172.16.0.0/24  | {"start": "172.16.0.110", "end": "172.16.0.150"} |
| 0263d67c-8f18-4c5c-8e3d-68cd887cace7 | ext-subnet | 192.168.4.0/24 | {"start": "192.168.4.2", "end": "192.168.4.254"} |
+--------------------------------------+------------+----------------+--------------------------------------------------+

phoenix:~ # neutron subnet-show be31f1f6-023b-4082-93e7-e89709b46710
+------------------+--------------------------------------------------+
| Field            | Value                                            |
+------------------+--------------------------------------------------+
| allocation_pools | {"start": "172.16.0.110", "end": "172.16.0.150"} |
| cidr             | 172.16.0.0/24                                    |
| dns_nameservers  | 8.8.8.8                                          |
| enable_dhcp      | False                                            |
| gateway_ip       | 172.16.0.1                                       |
| host_routes      |                                                  |
| id               | be31f1f6-023b-4082-93e7-e89709b46710             |
| ip_version       | 4                                                |
| name             | ext-subnet                                       |
| network_id       | ca6b6d12-f5f9-471f-bf51-9fbc598709fc             |
| tenant_id        | 03110aa32a35426bbc7d861dcb61ad94                 |
+------------------+--------------------------------------------------+


phoenix:~ # neutron router-list
+--------------------------------------+-------------+-----------------------------------------------------------------------------+
| id                                   | name        | external_gateway_info                                                       |
+--------------------------------------+-------------+-----------------------------------------------------------------------------+
| 24ab9088-6283-4053-a78f-61feb56d4e63 | demo-router | {"network_id": "ca6b6d12-f5f9-471f-bf51-9fbc598709fc", "enable_snat": true} |
+--------------------------------------+-------------+-----------------------------------------------------------------------------+

phoenix:~ # neutron router-show 24ab9088-6283-4053-a78f-61feb56d4e63
+-----------------------+-----------------------------------------------------------------------------+
| Field                 | Value                                                                       |
+-----------------------+-----------------------------------------------------------------------------+
| admin_state_up        | True                                                                        |
| external_gateway_info | {"network_id": "ca6b6d12-f5f9-471f-bf51-9fbc598709fc", "enable_snat": true} |
| id                    | 24ab9088-6283-4053-a78f-61feb56d4e63                                        |
| name                  | demo-router                                                                 |
| routes                |                                                                             |
| status                | ACTIVE                                                                      |
| tenant_id             | 0c7c025a9519414992a40ab9af9a18e0                                            |
+-----------------------+-----------------------------------------------------------------------------+


phoenix:~ # neutron port-list
+--------------------------------------+------+-------------------+-------------------------------------------------------------------------------------+
| id                                   | name | mac_address       | fixed_ips                                                                           |
+--------------------------------------+------+-------------------+-------------------------------------------------------------------------------------+
| cf14cdbc-ecb8-4557-a850-1a931da6e99a |      | fa:16:3e:f4:48:36 | {"subnet_id": "be31f1f6-023b-4082-93e7-e89709b46710", "ip_address": "172.16.0.110"} |
| d44098bf-8f82-4942-86ce-e5185d736394 |      | fa:16:3e:41:d0:59 | {"subnet_id": "0263d67c-8f18-4c5c-8e3d-68cd887cace7", "ip_address": "192.168.4.1"}  |
+--------------------------------------+------+-------------------+-------------------------------------------------------------------------------------+

phoenix:~ # neutron port-show cf14cdbc-ecb8-4557-a850-1a931da6e99a
+-----------------------+-------------------------------------------------------------------------------------+
| Field                 | Value                                                                               |
+-----------------------+-------------------------------------------------------------------------------------+
| admin_state_up        | True                                                                                |
| allowed_address_pairs |                                                                                     |
| binding:host_id       | phoenix                                                                             |
| binding:profile       | {}                                                                                  |
| binding:vif_details   | {"port_filter": true, "ovs_hybrid_plug": true}                                      |
| binding:vif_type      | ovs                                                                                 |
| binding:vnic_type     | normal                                                                              |
| device_id             | 24ab9088-6283-4053-a78f-61feb56d4e63                                                |
| device_owner          | network:router_gateway                                                              |
| extra_dhcp_opts       |                                                                                     |
| fixed_ips             | {"subnet_id": "be31f1f6-023b-4082-93e7-e89709b46710", "ip_address": "172.16.0.110"} |
| id                    | cf14cdbc-ecb8-4557-a850-1a931da6e99a                                                |
| mac_address           | fa:16:3e:f4:48:36                                                                   |
| name                  |                                                                                     |
| network_id            | ca6b6d12-f5f9-471f-bf51-9fbc598709fc                                                |
| security_groups       |                                                                                     |
| status                | ACTIVE                                                                              |
| tenant_id             |                                                                                     |
+-----------------------+-------------------------------------------------------------------------------------+
click to hide/show revision 2
No.2 Revision

ot able to ping the router of the external net configured in neutron ext-net

Hi,

I am trying to make a icehouse setup on opensuse 13.1. with repository http://download.opensuse.org/repositories/Cloud:/OpenStack:/Icehouse/openSUSE_13.1/

But I am stuck on the neutron configuration. I think I have set it up according to http://docs.openstack.org/icehouse/install-guide/install/zypper/content/ch_networking.html


However I am not able to ping the router of the external net configured in neutron ext-net.
Here is what happens
external net: 172.16.0.0/24
physical router 172.16.0.1
the neutron router of the ext-net: 172.16.0.110

ping from 172.16.0.21 to 172.16.0.110

On physical nic
tcpdump -ieno1
07:58:22.540247 ARP, Request who-has 172.16.0.110 tell 172.16.0.21, length 46
07:58:22.964585 ARP, Request who-has 172.16.4.35 tell 172.16.4.1, length 46
07:58:23.032330 ARP, Request who-has 172.16.0.96 tell 172.16.0.99, length 46

on bridge
tcpdump -ibr-ex
07:57:32.535197 ARP, Request who-has 172.16.0.110 tell 172.16.0.21, length 46
07:57:32.616321 ARP, Request who-has 172.16.0.98 tell 172.16.0.99, length 46
07:57:33.032401 ARP, Request who-has 172.16.0.96 tell 172.16.0.99, length 46

on router
ip netns exec qrouter-24ab9088-6283-4053-a78f-61feb56d4e63 tcpdump -iany
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked), capture size 65535 bytes
<empty/nothing>


I am confused here, The only thing I find strange is the router port is connected to the br-int and not the br-ex, (see output of vs-vsctl show below)

Any help would be helpfull.

mfg,
Jeroen


ovs-dpctl dump-flows
skb_priority(0),in_port(4),eth(src=78:24:af:2c:09:5e,dst=ff:ff:ff:ff:ff:ff),eth_type(0x0806),arp(sip=172.16.0.21/255.255.255.255,tip=172.16.0.110/255.255.255.255,op=1/0xff,sha=78:24:af:2c:09:5e/00:00:00:00:00:00,tha=00:00:00:00:00:00/00:00:00:00:00:00), packets:23, bytes:1380, used:0.239s, actions:3

phoenix:~ # ovs-ofctl dump-flows br-ex                                                                              
NXST_FLOW reply (xid=0x4):                                                                                          
 cookie=0x0, duration=44511.022s, table=0, n_packets=196728, n_bytes=18082154, idle_age=0, priority=0 actions=NORMAL

phoenix:~ # ovs-dpctl show
system@ovs-system:
        lookups: hit:184051 missed:62864 lost:0
        flows: 8
        port 0: ovs-system (internal)
        port 1: br-int (internal)
        port 2: br-tun (internal)
        port 3: br-ex (internal)
        port 4: eno1
        port 5: qg-cf14cdbc-ec (internal)
        port 6: qr-d44098bf-8f (internal)


phoenix:~ # ip netns
qrouter-24ab9088-6283-4053-a78f-61feb56d4e63
phoenix:~ # ip netns exec qrouter-24ab9088-6283-4053-a78f-61feb56d4e63 ifconfig -a
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:1538 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1538 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:172222 (168.1 Kb)  TX bytes:172222 (168.1 Kb)

qg-cf14cd Link encap:Ethernet  HWaddr FA:16:3E:F4:48:36
          inet addr:172.16.0.110  Bcast:172.16.0.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:fef4:4836/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:1124 (1.0 Kb)

qr-d44098 Link encap:Ethernet  HWaddr FA:16:3E:41:D0:59
          inet addr:192.168.4.1  Bcast:192.168.4.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:fe41:d059/64 Scope:Link
          UP BROADCAST RUNNING  MTU:1500  Metric:1
          RX packets:2468 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:249768 (243.9 Kb)  TX bytes:998 (998.0 b)

phoenix:~ # ovs-vsctl show
ddd79663-5439-4a5e-befb-272f8ca3f756
    Bridge br-ex
        Port br-ex
            Interface br-ex
                type: internal
        Port "eno1"
            Interface "eno1"
    Bridge br-int
        fail_mode: secure
        Port "qr-d44098bf-8f"
            tag: 1
            Interface "qr-d44098bf-8f"
                type: internal
        Port "qg-cf14cdbc-ec"
            tag: 2
            Interface "qg-cf14cdbc-ec"
                type: internal
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port br-int
            Interface br-int
                type: internal
    Bridge br-tun
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
        Port br-tun
            Interface br-tun
                type: internal
    ovs_version: "2.0.0"



phoenix:~ # neutron net-list
+--------------------------------------+----------+-----------------------------------------------------                                                +
| id                                   | name     | subnets                                                                                             |
+--------------------------------------+----------+-----------------------------------------------------+
| ca6b6d12-f5f9-471f-bf51-9fbc598709fc | ext-net  | be31f1f6-023b-4082-93e7-e89709b46710 172.16.0.0/24  |
| d0edb986-fcd2-43b2-9049-f7a7f6a68b4f | demo-net | 0263d67c-8f18-4c5c-8e3d-68cd887cace7 192.168.4.0/24 |
+--------------------------------------+----------+-----------------------------------------------------+

phoenix:~ # neutron net-show ca6b6d12-f5f9-471f-bf51-9fbc598709fc
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | True                                 |
| id                        | ca6b6d12-f5f9-471f-bf51-9fbc598709fc |
| name                      | ext-net                              |
| provider:network_type     | gre                                  |
| provider:physical_network |                                      |
| provider:segmentation_id  | 1                                    |
| router:external           | True                                 |
| shared                    | True                                 |
| status                    | ACTIVE                               |
| subnets                   | be31f1f6-023b-4082-93e7-e89709b46710 |
| tenant_id                 | 03110aa32a35426bbc7d861dcb61ad94     |
+---------------------------+--------------------------------------+



phoenix:~ # neutron subnet-list
+--------------------------------------+------------+----------------+--------------------------------------------------+
| id                                   | name       | cidr           | allocation_pools                                 |
+--------------------------------------+------------+----------------+--------------------------------------------------+
| be31f1f6-023b-4082-93e7-e89709b46710 | ext-subnet | 172.16.0.0/24  | {"start": "172.16.0.110", "end": "172.16.0.150"} |
| 0263d67c-8f18-4c5c-8e3d-68cd887cace7 | ext-subnet | 192.168.4.0/24 | {"start": "192.168.4.2", "end": "192.168.4.254"} |
+--------------------------------------+------------+----------------+--------------------------------------------------+

phoenix:~ # neutron subnet-show be31f1f6-023b-4082-93e7-e89709b46710
+------------------+--------------------------------------------------+
| Field            | Value                                            |
+------------------+--------------------------------------------------+
| allocation_pools | {"start": "172.16.0.110", "end": "172.16.0.150"} |
| cidr             | 172.16.0.0/24                                    |
| dns_nameservers  | 8.8.8.8                                          |
| enable_dhcp      | False                                            |
| gateway_ip       | 172.16.0.1                                       |
| host_routes      |                                                  |
| id               | be31f1f6-023b-4082-93e7-e89709b46710             |
| ip_version       | 4                                                |
| name             | ext-subnet                                       |
| network_id       | ca6b6d12-f5f9-471f-bf51-9fbc598709fc             |
| tenant_id        | 03110aa32a35426bbc7d861dcb61ad94                 |
+------------------+--------------------------------------------------+


phoenix:~ # neutron router-list
+--------------------------------------+-------------+-----------------------------------------------------------------------------+
| id                                   | name        | external_gateway_info                                                       |
+--------------------------------------+-------------+-----------------------------------------------------------------------------+
| 24ab9088-6283-4053-a78f-61feb56d4e63 | demo-router | {"network_id": "ca6b6d12-f5f9-471f-bf51-9fbc598709fc", "enable_snat": true} |
+--------------------------------------+-------------+-----------------------------------------------------------------------------+

phoenix:~ # neutron router-show 24ab9088-6283-4053-a78f-61feb56d4e63
+-----------------------+-----------------------------------------------------------------------------+
| Field                 | Value                                                                       |
+-----------------------+-----------------------------------------------------------------------------+
| admin_state_up        | True                                                                        |
| external_gateway_info | {"network_id": "ca6b6d12-f5f9-471f-bf51-9fbc598709fc", "enable_snat": true} |
| id                    | 24ab9088-6283-4053-a78f-61feb56d4e63                                        |
| name                  | demo-router                                                                 |
| routes                |                                                                             |
| status                | ACTIVE                                                                      |
| tenant_id             | 0c7c025a9519414992a40ab9af9a18e0                                            |
+-----------------------+-----------------------------------------------------------------------------+


phoenix:~ # neutron port-list
+--------------------------------------+------+-------------------+-------------------------------------------------------------------------------------+
| id                                   | name | mac_address       | fixed_ips                                                                           |
+--------------------------------------+------+-------------------+-------------------------------------------------------------------------------------+
| cf14cdbc-ecb8-4557-a850-1a931da6e99a |      | fa:16:3e:f4:48:36 | {"subnet_id": "be31f1f6-023b-4082-93e7-e89709b46710", "ip_address": "172.16.0.110"} |
| d44098bf-8f82-4942-86ce-e5185d736394 |      | fa:16:3e:41:d0:59 | {"subnet_id": "0263d67c-8f18-4c5c-8e3d-68cd887cace7", "ip_address": "192.168.4.1"}  |
+--------------------------------------+------+-------------------+-------------------------------------------------------------------------------------+

phoenix:~ # neutron port-show cf14cdbc-ecb8-4557-a850-1a931da6e99a
+-----------------------+-------------------------------------------------------------------------------------+
| Field                 | Value                                                                               |
+-----------------------+-------------------------------------------------------------------------------------+
| admin_state_up        | True                                                                                |
| allowed_address_pairs |                                                                                     |
| binding:host_id       | phoenix                                                                             |
| binding:profile       | {}                                                                                  |
| binding:vif_details   | {"port_filter": true, "ovs_hybrid_plug": true}                                      |
| binding:vif_type      | ovs                                                                                 |
| binding:vnic_type     | normal                                                                              |
| device_id             | 24ab9088-6283-4053-a78f-61feb56d4e63                                                |
| device_owner          | network:router_gateway                                                              |
| extra_dhcp_opts       |                                                                                     |
| fixed_ips             | {"subnet_id": "be31f1f6-023b-4082-93e7-e89709b46710", "ip_address": "172.16.0.110"} |
| id                    | cf14cdbc-ecb8-4557-a850-1a931da6e99a                                                |
| mac_address           | fa:16:3e:f4:48:36                                                                   |
| name                  |                                                                                     |
| network_id            | ca6b6d12-f5f9-471f-bf51-9fbc598709fc                                                |
| security_groups       |                                                                                     |
| status                | ACTIVE                                                                              |
| tenant_id             |                                                                                     |
+-----------------------+-------------------------------------------------------------------------------------+

UPDATE

Thank you for your input, I tried recreating the network through the neutron commands several time. However the router was always bridged on br-int.

BUT, the openstack docs were recently updated on how to configure JUNO. at http://docs.openstack.org/juno/install-guide/install/zypper/content/ch_networking.html

Although I have Icehouse installed, I configured neutron like it is described for Juno. And now it works! The router is bridged at br-ex and the router of the ext-net can be pinged.

ovs-vsctl show
ddd79663-5439-4a5e-befb-272f8ca3f756
    Bridge br-ex
        Port br-ex
            Interface br-ex
                type: internal
        Port "eno1"
            Interface "eno1"
        Port "qg-1efd575e-ad"
            Interface "qg-1efd575e-ad"
                type: internal