Red Hat Bugzilla – Bug 1460687
[RHEL 7.4] - When updating MTU to custom number and after that return to default MTU (1500) the network ifcfg file not updated
Last modified: 2017-07-28 10:10:32 EDT
Created attachment 1287046 [details]
Description of problem:
When updating MTU to custom number and after that return to default MTU (1500) the network ifcfg file not updated on RHEL - 7.4 - 11.el7
by looking on engine side look like the MTU updated
Version-Release number of selected component (if applicable):
RHEL - 7.4 - 11.el7
Kernel Version - 3.10.0 - 663.el7.x86_64
Steps to Reproduce:
1. Create and attach network to host with default MTU (1500)
2. Update the MTU to 9000
3. Update the MTU to 1500
The bridge ifcfg file not updated to 1500
The bridge ifcfg file should be updated to 1500
This bug occur only in RHEL - 7.4
This bug report has Keywords: Regression or TestBlocker.
Since no regressions or test blockers are allowed between releases, it is also being identified as a blocker for this release. Please resolve ASAP.
Unfortunately, I'm unable to read the logs with so many networks defined there.
Please limit the scenario to one or two networks and share the logs again.
BTW: I suspect there is a 7.4 bug here regarding bond defaults.
It relates to the arp_ip_target default content.
Created attachment 1293586 [details]
vdsm and supervdsm logs
Network name mtu_net
Thanks for the logs but I cannot see a problem from the logs.
After the setup is applied, a caps response is issued on 2017-07-02 11:53:55,538 which shows the correct MTU on the bridge.
Only when setting back MTU to 1500 the ifcfg-<bridge-name> is not set to default MTU=1500
The physical interface is set to default MTU=1500 and /var/lib/vdsm/staging/netconf/nets/mtu_net is set to the currect MTU.
Need to fix the bridge ifcfg file to have the correct MTU.
On RLEH 7.4, when the bridge has no ports connected, it falls down to the default MTU.
The code has been adjusted to always write the bridge ifcfg file when the default mtu is set.
Verified on - vdsm-4.19.22-1.el7ev.x86_64 and