OpenStack Networking (Neutron)
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neutron/doc/source/devref/layer3.rst

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Layer 3 Networking in Neutron - via Layer 3 agent & OpenVSwitch
===============================================================
This page discusses the usage of Neutron with Layer 3 functionality enabled.
Neutron logical network setup
-----------------------------
::
vagrant@precise64:~/devstack$ neutron net-list
+--------------------------------------+---------+--------------------------------------------------+
| id | name | subnets |
+--------------------------------------+---------+--------------------------------------------------+
| 84b6b0cc-503d-448a-962f-43def05e85be | public | 3a56da7c-2f6e-41af-890a-b324d7bc374d |
| a4b4518c-800d-4357-9193-57dbb42ac5ee | private | 1a2d26fb-b733-4ab3-992e-88554a87afa6 10.0.0.0/24 |
+--------------------------------------+---------+--------------------------------------------------+
vagrant@precise64:~/devstack$ neutron subnet-list
+--------------------------------------+------+-------------+--------------------------------------------+
| id | name | cidr | allocation_pools |
+--------------------------------------+------+-------------+--------------------------------------------+
| 1a2d26fb-b733-4ab3-992e-88554a87afa6 | | 10.0.0.0/24 | {"start": "10.0.0.2", "end": "10.0.0.254"} |
+--------------------------------------+------+-------------+--------------------------------------------+
vagrant@precise64:~/devstack$ neutron port-list
+--------------------------------------+------+-------------------+---------------------------------------------------------------------------------+
| id | name | mac_address | fixed_ips |
+--------------------------------------+------+-------------------+---------------------------------------------------------------------------------+
| 0ba8700e-da06-4318-8fe9-00676dd994b8 | | fa:16:3e:78:43:5b | {"subnet_id": "1a2d26fb-b733-4ab3-992e-88554a87afa6", "ip_address": "10.0.0.1"} |
| b2044570-ad52-4f31-a2c3-5d767dc9a8a7 | | fa:16:3e:5b:cf:4c | {"subnet_id": "1a2d26fb-b733-4ab3-992e-88554a87afa6", "ip_address": "10.0.0.3"} |
| bb60d1bb-0cab-41cb-9678-30d2b2fdb169 | | fa:16:3e:af:a9:bd | {"subnet_id": "1a2d26fb-b733-4ab3-992e-88554a87afa6", "ip_address": "10.0.0.2"} |
+--------------------------------------+------+-------------------+---------------------------------------------------------------------------------+
vagrant@precise64:~/devstack$ neutron subnet-show 1a2d26fb-b733-4ab3-992e-88554a87afa6
+------------------+--------------------------------------------+
| Field | Value |
+------------------+--------------------------------------------+
| allocation_pools | {"start": "10.0.0.2", "end": "10.0.0.254"} |
| cidr | 10.0.0.0/24 |
| dns_nameservers | |
| enable_dhcp | True |
| gateway_ip | 10.0.0.1 |
| host_routes | |
| id | 1a2d26fb-b733-4ab3-992e-88554a87afa6 |
| ip_version | 4 |
| name | |
| network_id | a4b4518c-800d-4357-9193-57dbb42ac5ee |
| tenant_id | 3368290ab10f417390acbb754160dbb2 |
+------------------+--------------------------------------------+
Neutron logical router setup
----------------------------
* http://docs.openstack.org/admin-guide-cloud/content/ch_networking.html#under_the_hood_openvswitch_scenario1_network
::
vagrant@precise64:~/devstack$ neutron router-list
+--------------------------------------+---------+--------------------------------------------------------+
| id | name | external_gateway_info |
+--------------------------------------+---------+--------------------------------------------------------+
| 569469c7-a2a5-4d32-9cdd-f0b18a13f45e | router1 | {"network_id": "84b6b0cc-503d-448a-962f-43def05e85be"} |
+--------------------------------------+---------+--------------------------------------------------------+
vagrant@precise64:~/devstack$ neutron router-show router1
+-----------------------+--------------------------------------------------------+
| Field | Value |
+-----------------------+--------------------------------------------------------+
| admin_state_up | True |
| external_gateway_info | {"network_id": "84b6b0cc-503d-448a-962f-43def05e85be"} |
| id | 569469c7-a2a5-4d32-9cdd-f0b18a13f45e |
| name | router1 |
| routes | |
| status | ACTIVE |
| tenant_id | 3368290ab10f417390acbb754160dbb2 |
+-----------------------+--------------------------------------------------------+
vagrant@precise64:~/devstack$ neutron router-port-list router1
+--------------------------------------+------+-------------------+---------------------------------------------------------------------------------+
| id | name | mac_address | fixed_ips |
+--------------------------------------+------+-------------------+---------------------------------------------------------------------------------+
| 0ba8700e-da06-4318-8fe9-00676dd994b8 | | fa:16:3e:78:43:5b | {"subnet_id": "1a2d26fb-b733-4ab3-992e-88554a87afa6", "ip_address": "10.0.0.1"} |
+--------------------------------------+------+-------------------+---------------------------------------------------------------------------------+
Neutron Routers are realized in OpenVSwitch
-------------------------------------------
.. image:: http://docs.openstack.org/admin-guide-cloud/content/figures/10/a/common/figures/under-the-hood-scenario-1-ovs-network.png
"router1" in the Neutron logical network is realized through a port ("qr-0ba8700e-da") in OpenVSwitch - attached to "br-int"::
vagrant@precise64:~/devstack$ sudo ovs-vsctl show
b9b27fc3-5057-47e7-ba64-0b6afe70a398
Bridge br-int
Port "qr-0ba8700e-da"
tag: 1
Interface "qr-0ba8700e-da"
type: internal
Port br-int
Interface br-int
type: internal
Port int-br-ex
Interface int-br-ex
Port "tapbb60d1bb-0c"
tag: 1
Interface "tapbb60d1bb-0c"
type: internal
Port "qvob2044570-ad"
tag: 1
Interface "qvob2044570-ad"
Port "int-br-eth1"
Interface "int-br-eth1"
Bridge "br-eth1"
Port "phy-br-eth1"
Interface "phy-br-eth1"
Port "br-eth1"
Interface "br-eth1"
type: internal
Bridge br-ex
Port phy-br-ex
Interface phy-br-ex
Port "qg-0143bce1-08"
Interface "qg-0143bce1-08"
type: internal
Port br-ex
Interface br-ex
type: internal
ovs_version: "1.4.0+build0"
vagrant@precise64:~/devstack$ brctl show
bridge name bridge id STP enabled interfaces
br-eth1 0000.e2e7fc5ccb4d no
br-ex 0000.82ee46beaf4d no phy-br-ex
qg-39efb3f9-f0
qg-77e0666b-cd
br-int 0000.5e46cb509849 no int-br-ex
qr-54c9cd83-43
qvo199abeb2-63
qvo1abbbb60-b8
tap74b45335-cc
qbr199abeb2-63 8000.ba06e5f8675c no qvb199abeb2-63
tap199abeb2-63
qbr1abbbb60-b8 8000.46a87ed4fb66 no qvb1abbbb60-b8
tap1abbbb60-b8
virbr0 8000.000000000000 yes
Finding the router in ip/ipconfig
---------------------------------
* http://docs.openstack.org/admin-guide-cloud/content/ch_networking.html
The neutron-l3-agent uses the Linux IP stack and iptables to perform L3 forwarding and NAT.
In order to support multiple routers with potentially overlapping IP addresses, neutron-l3-agent
defaults to using Linux network namespaces to provide isolated forwarding contexts. As a result,
the IP addresses of routers will not be visible simply by running "ip addr list" or "ifconfig" on
the node. Similarly, you will not be able to directly ping fixed IPs.
To do either of these things, you must run the command within a particular router's network
namespace. The namespace will have the name "qrouter-<UUID of the router>.
.. image:: http://docs.openstack.org/admin-guide-cloud/content/figures/10/a/common/figures/under-the-hood-scenario-1-ovs-netns.png
For example::
vagrant@precise64:~$ neutron router-list
+--------------------------------------+---------+--------------------------------------------------------+
| id | name | external_gateway_info |
+--------------------------------------+---------+--------------------------------------------------------+
| ad948c6e-afb6-422a-9a7b-0fc44cbb3910 | router1 | {"network_id": "e6634fef-03fa-482a-9fa7-e0304ce5c995"} |
+--------------------------------------+---------+--------------------------------------------------------+
vagrant@precise64:~/devstack$ sudo ip netns exec qrouter-ad948c6e-afb6-422a-9a7b-0fc44cbb3910 ip addr list
18: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
19: qr-54c9cd83-43: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
link/ether fa:16:3e:dd:c1:8f brd ff:ff:ff:ff:ff:ff
inet 10.0.0.1/24 brd 10.0.0.255 scope global qr-54c9cd83-43
inet6 fe80::f816:3eff:fedd:c18f/64 scope link
valid_lft forever preferred_lft forever
20: qg-77e0666b-cd: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
link/ether fa:16:3e:1f:d3:ec brd ff:ff:ff:ff:ff:ff
inet 192.168.27.130/28 brd 192.168.27.143 scope global qg-77e0666b-cd
inet6 fe80::f816:3eff:fe1f:d3ec/64 scope link
valid_lft forever preferred_lft forever
Provider Networking
-------------------
Neutron can also be configured to create `provider networks <http://docs.openstack.org/admin-guide-cloud/content/ch_networking.html#provider_terminology>`_
Further Reading
---------------
* `Packet Pushers - Neutron Network Implementation on Linux <http://packetpushers.net/openstack-neutron-network-implementation-in-linux/>`_
* `OpenStack Cloud Administrator Guide <http://docs.openstack.org/admin-guide-cloud/content/ch_networking.html>`_
* `Neutron - Layer 3 API extension usage guide <http://docs.openstack.org/api/openstack-network/2.0/content/router_ext.html>`_
* `Darragh O'Reilly - The Quantum L3 router and floating IPs <http://techbackground.blogspot.com/2013/05/the-quantum-l3-router-and-floating-ips.html>`_