Bug 1329012

Description of problem:

The original design goal behind using OVS as the bonding mechanism in TripleO was simplicity: since OVS was being used for bridging, adding bonding support directly to the OVS bridge made sense.

Unfortunately, in a few large-scale deployments with high traffic, packet loss has been observed in OVS bonds using LACP.

To counteract this behavior, support was added to TripleO to support Linux kernel-mode bonds, which are not susceptible to packet loss at scale.

When using OVS bonds, an OVS bridge is required. This necessitated the use of a bridge even on the storage nodes, where this wouldn't be required if using kernel bonds.

Now that we have the option of using kernel-mode bonds, we recommend this in most cases, unless an OVS-specific bonding mode is required (although different packet loss issues have occurred when using balance-slb mode bonds, see https://bugzilla.redhat.com/show_bug.cgi?id=1289962).

Actual results:
The sample bonding templates included with OSP 8 are configured for OVS bonds.

Expected results:
The proper use of Linux bonds should be properly documented, and we should provide equivalent sample templates that show the optimum use of Linux bonds.

Additional info:
The following applies when using Linux bonds instead of OVS bonds:

  * Bond interfaces use "linux_bond" instead of "ovs_bond" for the type:
  * Templates use "bonding_options" instead of "ovs_options" for the bond options
  * Linux kernel bonding options have a different form, such as "mode=802.3ad" to indicate LACP bonding.  For more info, see https://www.kernel.org/doc/Documentation/networking/bonding.txt
  * Bridges must still be used for interfaces used for Neutron tenant or provider VLANs, or for SNAT/Floating IPs, whether or not bonding is used on a particular interface. These bridges can be OVS bridges or Linux bridges, but OVS bridges provide more features.