neutron/releasenotes/notes/advertise_mtu_by_default-d8b0b056a74517b8.yaml
Sean M. Collins 7e7d5dc861 Make Neutron attempt to advertise MTUs by default
It seems like a useful option, and it could be a more sane default,
rather than pushing the responsibility to enable this onto deployers and
provisioning tools[1]. In fact, it may be worth doing some more work to
take away some of the hassle of configuring all these things correctly,
and see if it can be automatically determined.

[1]: https://specs.openstack.org/openstack/fuel-specs/specs/7.0/jumbo-frames-between-instances.html

Related-Bug: #1527675
Change-Id: I5cbbc4660f8c4e15e59f8f5ce0419501bdd27348
2016-01-18 13:34:16 +01:00

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YAML

---
features:
- By default, the DHCP agent provides a network MTU value to instances using
the corresponding DHCP option if core plugin calculates the value. For ML2
plugin, calculation mechanism is enabled by setting [ml2] path_mtu option
to a value greater than zero.
upgrade:
- To disable, use [DEFAULT] advertise_mtu = False.
other:
- For overlay networks managed by ML2 core plugin, the calculation algorithm
subtracts the overlay protocol overhead from the value of [ml2] path_mtu.
The DHCP agent provides the resulting (smaller) MTU to instances using
overlay networks.
- The [DEFAULT] advertise_mtu option must contain a consistent value on all
hosts running the DHCP agent.
- Typical networks can use [ml2] path_mtu = 1500.