neutron/releasenotes/notes/path-mtu-back-to-zero-e4f9e8bdd8317ad4.yaml
Ihar Hrachyshka 38531ca59c Revert "ML2: Configure path_mtu to default to 1500 bytes"
This reverts commit 7a4633a9ca.

Revert to using 0 as the default value for path_mtu.

In most situations, underlying MTU does not differ for tunnel backed and
vlan/flat tenant networks, in which case the only configuration expected
from operators is setting global_physnet_mtu to the appropriate MTU
value as reflecting all data paths that tenant traffic may take between
nodes.

But with the non-zero value set for path_mtu, if an operator would like
to raise the global underlying MTU used by neutron to support Jumbo
frames, both global_physnet_mtu and path_mtu need a bump, which is not
ideal.

So switch back to using a zero value for path_mtu, effectively making it
not participating in MTU calculation, unless explicitly overridden.

Left the original release note intact since it reflects the state for
Mitaka.

Added a release note for the change.

Conflicts:
	neutron/plugins/ml2/config.py
	releasenotes/notes/1500-default-mtu-b0d6e4ab193b62a4.yaml

Change-Id: I97c4aa647efc85d7b6b45359e43e2a2ae2514a69
2016-04-21 15:50:34 +02:00

10 lines
397 B
YAML

---
upgrade:
- In case you rely on the default ML2 path_mtu value of 1500 to cap MTU used
for new network resources, please set it explicitly in your ml2_conf.ini
file.
fixes:
- The default value for ML2 path_mtu option is changed from 1500 to 0,
effectively disabling its participation in network MTU calculation unless
it's overridden in the ml2_conf.ini configuration file.