q

1. Openstack Neutron Reverse
Engineered
Sridhar K. N. Rao
Thanks to Shreyansh Jain, Manpreet Singh and Nupur Sharma

2. The Flow
• Overall Architecture.
• Description of Components
– Internal Flows.
• System-wide Control and Data Flows
– Communication between the components
• Tips for extensions.
• Documentation structure.

3. Neutron AgentsCompute Node Agent(s)
RPC Mechanism
REST APIs Management
Plugin Neutron DB
Service
Plugins
Mechanism
Driver

4. WSGI

6. WSGI-Server
Requests

7. Collection,
Resources,
{collection_actions,
Member_actions,
Path_prefix
Requirements
Controller}

8. RPC

10. L3

12. ML2

13. ML2
Plugin
Type
Manager
Mechanism
manager
Agents
Extension
Manager
DB
Neutron
Server
(WSGI-
Apps)

14. Initialization
__init__
_register_mechanisms()
This method should only be called once
Register all mechanism drivers via
NamedExtensionManager!!!
initialize
_sync_vlan_allocations()
Initialize
ex: VLAN
__init__
initialize()
for driver in
self.ordered_ext_drivers:
driver.obj.initialize()
initialize each driver
__init__(self):
_register_drivers()
Register all
extension drivers
initialize(self):
driver.obj.initialize()
__init__
_register_types()
_check_tenant_ne
twork_types()

15. Handling of REST calls
Ordered List of Mechanism Drivers
ML2-Plugin
[Create/Update/Delete_Network/Subnet/Port_Pre/PostCommit]
Mechanism-Manager
[Create/Update/Delete_Network/Subnet/Port_Pre/PostCommit]
Mechanism-
Driver-1
Mechanism-
Driver-2
Mechanism-
Driver-N
For each driver in the ordered_list_of_mechanism_Drivers:
Call appropriate function in each driver.

16. Handling of REST calls
ML2-Plugin
DB
Extension Manager Mechanism Manager

17. Handling Rest Calls – Create Port
_notify_l3_agent_new_port
notify_security_groups_member_updated
_bind_port_if_needed***
binding.vif_type !=
VIF_TYPE_UNBOUND or !
binding.host
_notify_port_updated()
if allow_notify and
need_notify:
return context
_bind_port(context)
count >
MAX_BIND_TRIES
_commit_port_binding()
_update_port_dict_binding
Construct a new PortContext
mechanism_manager.bind_port()
Binding:
segment
vif_type
vif_details
vnic_type
host
driver
profile

18. Context!

19. RPC Handling

20. Notifications

21. OVS Mechanism Driver

22. NEUTRON AGENTS
DHCP

23. Initialization

24. Calls from Plugin

25. Enabling DHCP

26. NEUTRON AGENTS
L3

27. Initialization

31. OVS-NEUTRON AGENT

38. Nova-Neutron