dnsmasq.conf misconfigs mgmt MTU to 1500 even if it is configered to 9216

Bug #1811404 reported by Yang Liu on 2019-01-11
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
StarlingX
Medium
Teresa Ho

Bug Description

Brief Description
-----------------
/etc/dnsmasq.conf is setting a default of 1500 for the mgmt interface even when system is configured with 9216 mgmt MTU

Severity
--------
Major

Steps to Reproduce
------------------
1. Install and configure a system with large mgmt MTU
2. check /etc/dnsmasq.conf on a compute host
3. grep MTU /var/log/kern.log on a compute host

Expected Behavior
------------------
1. mgmt MTU is 9216 in system host-if-list <host>
2/3. mgmt MTU should not be set to 1500

Actual Behavior
----------------
1. as expected
2. mgmt mtu is set to 1500 in dnsmasq.conf
3. mgmt MTU on compute was set to 9216 by ifcfg, it is then got reset to 1500 after DHCPDISCOVER
compute-1:/home/wrsroot# grep MTU /var/log/kern.log
    2019-01-08T20:15:05.820 compute-1 kernel: info [ 120.136433] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216
    2019-01-08T20:15:13.249 compute-1 kernel: info [ 127.565644] ixgbe 0000:83:00.1 ens801f1: changing MTU from 9216 to 1500
    2019-01-09T16:46:57.116 compute-1 kernel: info [ 38.450255] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216
    2019-01-09T16:47:04.038 compute-1 kernel: info [ 45.372024] ixgbe 0000:83:00.1 ens801f1: changing MTU from 9216 to 1500
    2019-01-10T19:32:28.146 compute-1 kernel: info [ 38.470733] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216
    2019-01-10T19:32:38.194 compute-1 kernel: info [ 48.517861] ixgbe 0000:83:00.1 ens801f1: changing MTU from 9216 to 1500
    2019-01-10T21:36:43.011 compute-1 kernel: info [ 38.362522] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216

Reproducibility
---------------
Reproducible

System Configuration
--------------------
Dedicated storage (probably also Multi-node system)

Branch/Pull Time/Commit
-----------------------
master as of 2019-01-06_20-18-00

Timestamp/Logs
--------------
compute-1:/home/wrsroot# grep MTU /var/log/kern.log
    2019-01-08T20:15:05.820 compute-1 kernel: info [ 120.136433] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216
    2019-01-08T20:15:13.249 compute-1 kernel: info [ 127.565644] ixgbe 0000:83:00.1 ens801f1: changing MTU from 9216 to 1500
    2019-01-09T16:46:57.116 compute-1 kernel: info [ 38.450255] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216
    2019-01-09T16:47:04.038 compute-1 kernel: info [ 45.372024] ixgbe 0000:83:00.1 ens801f1: changing MTU from 9216 to 1500
    2019-01-10T19:32:28.146 compute-1 kernel: info [ 38.470733] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216
    2019-01-10T19:32:38.194 compute-1 kernel: info [ 48.517861] ixgbe 0000:83:00.1 ens801f1: changing MTU from 9216 to 1500
    2019-01-10T21:36:43.011 compute-1 kernel: info [ 38.362522] ixgbe 0000:83:00.1 ens801f1: changing MTU from 1500 to 9216

Ghada Khalil (gkhalil) wrote :

Marking as release gating -- Issue introduced by Generalized Network config feature; unclear why this bug didn't cause any issues before.

Changed in starlingx:
importance: Undecided → Medium
assignee: nobody → Teresa Ho (teresaho)
status: New → Triaged
tags: added: stx.2019.03 stx.networking
Ken Young (kenyis) 15 hours ago
tags: added: stx.2019.05
removed: stx.2019.03
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