[openstack-dev] [neutron] 'routed' network type, DHCP agent + devstack support - review requested

Neil Jerram Neil.Jerram at metaswitch.com
Sun Jul 19 10:46:30 UTC 2015

Hi Neutron folk!

I'd like to give an update on and encourage wide review of my work on
a type of network that connects VMs through IP routing instead of
through bridging and tunneling at L2.  I believe the core Neutron
pieces of this are now complete and ready for detailed review and
potential merging.

The change at [1] creates and describes a new 'routed' value for
provider:network_type.  It means that a compute host handles data
to/from the relevant TAP interfaces by routing it, and specifically
that those TAP interfaces are not bridged.  It is the job of a
particular mechanism driver and agent implementation to set up the
required routing rules, and my team's Calico project [2] is one
example of that, although not the only possible example.

The DHCP agent needs enhancement to provide DHCP service to routed TAP
interfaces, and the change for that is at [3].

A devstack plugin is included in the Calico repository at [4]. Using
this it is possible to see 'routed' networking in action, using the
Calico mechanism driver and agent, simply by running devstack with the
following in local.conf:

   enable_plugin calico https://github.com/Metaswitch/calico routed

Demonstration steps once stack.sh completes are suggested at [5].

[1] https://review.openstack.org/#/c/198439/
[2] http://projectcalico.org/
[3] https://review.openstack.org/#/c/197578/
[4] https://github.com/Metaswitch/calico/tree/routed
[5] https://github.com/Metaswitch/calico/blob/routed/devstack/README.rst

FYI I also plan to propose a networking-calico project (or continue
proposing, given [6]), to contain the Calico mechanism driver and
devstack plugin pieces that are currently in [4], so that all of
Calico's OpenStack-specific code is under the Neutron big tent.  But I
believe that can be decoupled from review of the core Neutron changes
proposed above.

[6] https://review.openstack.org/#/c/194709/

Please do let me know if you have thoughts or comments on this.

Many thanks,

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