83 lines
3.8 KiB
Plaintext
83 lines
3.8 KiB
Plaintext
The Modular Layer 2 (ml2) plugin is a framework allowing OpenStack
|
|
Networking to simultaneously utilize the variety of layer 2 networking
|
|
technologies found in complex real-world data centers. It currently
|
|
works with the existing openvswitch, linuxbridge, and hyperv L2
|
|
agents, and is intended to replace and deprecate the monolithic
|
|
plugins associated with those L2 agents. The ml2 framework is also
|
|
intended to greatly simplify adding support for new L2 networking
|
|
technologies, requiring much less initial and ongoing effort than
|
|
would be required to add a new monolithic core plugin.
|
|
|
|
Drivers within ml2 implement separately extensible sets of network
|
|
types and of mechanisms for accessing networks of those types. Unlike
|
|
with the metaplugin, multiple mechanisms can be used simultaneously to
|
|
access different ports of the same virtual network. Mechanisms can
|
|
utilize L2 agents via RPC and/or use mechanism drivers to interact
|
|
with external devices or controllers. Virtual networks can be composed
|
|
of multiple segments of the same or different types. Type and
|
|
mechanism drivers are loaded as python entrypoints using the stevedore
|
|
library.
|
|
|
|
Each available network type is managed by an ml2
|
|
TypeDriver. TypeDrivers maintain any needed type-specific network
|
|
state, and perform provider network validation and tenant network
|
|
allocation. The initial ml2 version includes drivers for the local,
|
|
flat, and vlan network types. Additional TypeDrivers for gre and vxlan
|
|
network types are expected before the havana release.
|
|
|
|
RPC callback and notification interfaces support interaction with L2,
|
|
DHCP, and L3 agents. This version has been tested with the existing
|
|
openvswitch and linuxbridge plugins' L2 agents, and should also work
|
|
with the hyperv L2 agent. A modular agent may be developed as a
|
|
follow-on effort.
|
|
|
|
Support for mechanism drivers is currently skeletal. The
|
|
MechanismDriver interface is currently a stub, with details to be
|
|
defined in future versions. MechanismDrivers will be called both
|
|
inside and following DB transactions for network and port
|
|
create/update/delete operations. They will also be called to establish
|
|
a port binding, determining the VIF type and network segment to be
|
|
used.
|
|
|
|
The database schema and driver APIs support multi-segment networks,
|
|
but the client API for multi-segment networks is not yet implemented.
|
|
|
|
A devstack patch supporting use of the ml2 plugin with either the
|
|
openvswitch or linuxbridge L2 agent for the local, flat and vlan
|
|
network types is under review at
|
|
https://review.openstack.org/#/c/27576/. Note that the gre network
|
|
type and the tunnel-related RPCs are not yet implemented, so use the
|
|
vlan network type for multi-node testing. Also note that ml2 does not
|
|
yet work with nova's GenericVIFDriver, so it is necessary to configure
|
|
nova to use a specific driver compatible with the L2 agent deployed on
|
|
each compute node.
|
|
|
|
Note that the ml2 plugin is new and should be conidered experimental
|
|
at this point. It is undergoing rapid development, so driver APIs and
|
|
other details are likely to change during the havana development
|
|
cycle.
|
|
|
|
Follow-on tasks required for full ml2 support in havana, including
|
|
parity with the existing monolithic openvswitch, linuxbridge, and
|
|
hyperv plugins:
|
|
|
|
- Additional unit tests
|
|
|
|
- Implement MechanismDriver port binding so that a useful
|
|
binding:vif_type value is returned for nova's GenericVIFDriver based
|
|
on the binding:host_id value and information from the agents_db
|
|
|
|
- Implement TypeDriver for GRE networks
|
|
|
|
- Implement GRE tunnel endpoint management RPCs
|
|
|
|
|
|
Additional follow-on tasks expected for the havana release:
|
|
|
|
- Extend MechanismDriver API to support integration with external
|
|
devices such as SDN controllers and top-of-rack switches
|
|
|
|
- Implement TypeDriver for VXLAN networks
|
|
|
|
- Extend providernet extension API to support multi-segment networks
|