Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 1753128

Summary: Cannot set MTU lower than 1280
Product: Red Hat Enterprise Linux 8 Reporter: Gris Ge <fge>
Component: NetworkManagerAssignee: Beniamino Galvani <bgalvani>
Status: CLOSED ERRATA QA Contact: Desktop QE <desktop-qa-list>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 8.1CC: atragler, bgalvani, edwardh, fgiudici, lrintel, pasik, rkhan, sukulkar, thaller, toneata, vbenes
Target Milestone: rcKeywords: ZStream
Target Release: 8.2Flags: pm-rhel: mirror+
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: NetworkManager-1.22.0-0.1.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1775136 (view as bug list) Environment:
Last Closed: 2020-04-28 16:53:06 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1775136    
Attachments:
Description Flags
System logs with NM trace enabled none

Description Gris Ge 2019-09-18 07:50:56 UTC
Created attachment 1616113 [details]
System logs with NM trace enabled

Description of problem:

Cannot set `802-3-ethernet.mtu` lower than 1280, the network manager
will still activate the profile with 1280 MTU.

Version-Release number of selected component (if applicable):
NetworkManager-1.20.0-3.el8.x86_64

How reproducible:
100%

Steps to Reproduce:

#!/bin/bash
nmcli c del veth1
ip link del veth1
nmcli c del veth1

ip link add veth1 type veth peer name veth1.ep
ip link set veth1 up
ip link set veth1.ep up
nmcli device set veth1 managed yes

nmcli c add  type ethernet ifname veth1 \
    connection.id veth1 \
    ipv4.method disabled \
    802-3-ethernet.mtu 1200 \
    ipv6.method disabled
nmcli c up veth1
ip link show veth1

Actual results:

The MTU of veth1 show as 1280.

Expected results:

The MTU of veth1 show as 1200.

Additional info:

Comment 1 Beniamino Galvani 2019-09-18 09:05:38 UTC
Added a couple of commits to fix this to merge request

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/merge_requests/273

Comment 3 Gris Ge 2019-10-15 12:02:26 UTC
This problem does not exists in NetworkManager-1.12.6-5.fc29.x86_64 of Fedora 29.

Regression it is.

Comment 5 Edward Haas 2019-11-18 14:11:42 UTC
RHV customers have the capability to set the MTU lower than 1280, so it is a regression if we do not fix it for RHEL 8.1.z
Could you please backport it?

Comment 8 sushil kulkarni 2019-11-18 16:09:03 UTC
Per comment c#5, requesting a z stream update for this. Will be required for RHV to pick up this change for their 4.4 release.

Anita, Can you please provide z stream+?

Thanks!
Sushil

Comment 12 errata-xmlrpc 2020-04-28 16:53:06 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:1847