MTU setting doesn't work as expected with Ubuntu for vlan interfaces

[Alexander Evseev]

# fuel --fuel-version
api: '1.0'
astute_sha: 04ebab96d57b0e8acbf2d7f3ba05e4fbf31b741e
auth_required: true
build_id: 2015-04-29_07-55-19
build_number: '361'
feature_groups:
- mirantis
fuel-library_sha: 0e5b82d24853304befb22145ac4aaf3545d295e1
fuel-ostf_sha: b38602c841deaa03ddffc95c02f319360462cbe3
fuelmain_sha: ee112acfdd0f9017ef40be53e8e51bb5c429e97c
nailgun_sha: e660b1c09d7d4d07bdd48d424ce9aed3b6facd6e
openstack_version: 2014.2.2-6.1
production: docker
python-fuelclient_sha: 8cd6cf575d3c101dee1032abb6877dfa8487e077
release: '6.1'
release_versions:
  2014.2.2-6.1:
    VERSION:
      api: '1.0'
      astute_sha: 04ebab96d57b0e8acbf2d7f3ba05e4fbf31b741e
      build_id: 2015-04-29_07-55-19
      build_number: '361'
      feature_groups:
      - mirantis
      fuel-library_sha: 0e5b82d24853304befb22145ac4aaf3545d295e1
      fuel-ostf_sha: b38602c841deaa03ddffc95c02f319360462cbe3
      fuelmain_sha: ee112acfdd0f9017ef40be53e8e51bb5c429e97c
      nailgun_sha: e660b1c09d7d4d07bdd48d424ce9aed3b6facd6e
      openstack_version: 2014.2.2-6.1
      production: docker
      python-fuelclient_sha: 8cd6cf575d3c101dee1032abb6877dfa8487e077
      release: '6.1'

Fuel, one controller, and one compute — all virtualized using KVM. Ubuntu via IBP, Neutron + VLANs, Ceph for all.

For private network used host-only bridge with MTU on host set to 9000.

Setting MTU in Fuel UI changes MTU only for main interface but not for subinterfaces like management and storage VLANs/bridges even after nodes reboot.

# ifconfig
br-ex Link encap:Ethernet HWaddr 06:db:6c:bf:ba:65
          inet addr:192.168.122.13 Bcast:192.168.122.255 Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe47:7ea6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:851 errors:0 dropped:0 overruns:0 frame:0
          TX packets:610 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:57960 (57.9 KB) TX bytes:55314 (55.3 KB)

br-ex-hapr Link encap:Ethernet HWaddr f6:47:20:d6:2d:8d
          inet6 addr: fe80::f447:20ff:fed6:2d8d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:255 errors:0 dropped:0 overruns:0 frame:0
          TX packets:480 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:25746 (25.7 KB) TX bytes:36296 (36.2 KB)

br-ex-vrouter Link encap:Ethernet HWaddr 26:cb:8f:0f:fc:58
          inet6 addr: fe80::24cb:8fff:fe0f:fc58/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:365 errors:0 dropped:0 overruns:0 frame:0
          TX packets:625 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:33594 (33.5 KB) TX bytes:47900 (47.9 KB)

br-fw-admin Link encap:Ethernet HWaddr 52:54:00:3e:ba:9f
          inet addr:10.20.1.1 Bcast:10.20.255.255 Mask:255.255.0.0
          inet6 addr: fe80::5054:ff:fe3e:ba9f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:6135 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6571 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:384037 (384.0 KB) TX bytes:1755241 (1.7 MB)

br-mgmt Link encap:Ethernet HWaddr 52:54:00:3e:ba:9f
          inet addr:192.168.0.4 Bcast:192.168.0.255 Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe3e:ba9f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:26569 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25572 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:20051381 (20.0 MB) TX bytes:27865239 (27.8 MB)

br-mgmt-hapr Link encap:Ethernet HWaddr ba:14:d0:1e:9c:64
          inet6 addr: fe80::b814:d0ff:fe1e:9c64/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:21498 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22047 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:18391534 (18.3 MB) TX bytes:18827922 (18.8 MB)

br-mgmt-vrouter Link encap:Ethernet HWaddr c2:c2:10:18:0a:72
          inet6 addr: fe80::c0c2:10ff:fe18:a72/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:313 errors:0 dropped:0 overruns:0 frame:0
          TX packets:800 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:29250 (29.2 KB) TX bytes:53358 (53.3 KB)

br-storage Link encap:Ethernet HWaddr 52:54:00:3e:ba:9f
          inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe3e:ba9f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:8513 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9401 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:11508950 (11.5 MB) TX bytes:9801797 (9.8 MB)

eth0 Link encap:Ethernet HWaddr 52:54:00:47:7e:a6
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:403 errors:0 dropped:0 overruns:0 frame:0
          TX packets:214 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:25246 (25.2 KB) TX bytes:15568 (15.5 KB)

eth1 Link encap:Ethernet HWaddr 52:54:00:3e:ba:9f
          UP BROADCAST RUNNING MULTICAST MTU:9000 Metric:1
          RX packets:19045 errors:0 dropped:0 overruns:0 frame:0
          TX packets:20281 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:14136310 (14.1 MB) TX bytes:20678487 (20.6 MB)

eth1.101 Link encap:Ethernet HWaddr 52:54:00:3e:ba:9f
          inet6 addr: fe80::5054:ff:fe3e:ba9f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:4391 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4296 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1924765 (1.9 MB) TX bytes:9065591 (9.0 MB)

eth1.102 Link encap:Ethernet HWaddr 52:54:00:3e:ba:9f
          inet6 addr: fe80::5054:ff:fe3e:ba9f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:8513 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9409 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:11508950 (11.5 MB) TX bytes:9802445 (9.8 MB)

hapr-host Link encap:Ethernet HWaddr 22:12:41:42:e4:60
          inet addr:240.0.0.1 Bcast:0.0.0.0 Mask:255.255.255.252
          inet6 addr: fe80::2012:41ff:fe42:e460/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:19 errors:0 dropped:0 overruns:0 frame:0
          TX packets:19 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1418 (1.4 KB) TX bytes:1749 (1.7 KB)

lo Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING MTU:65536 Metric:1
          RX packets:30513 errors:0 dropped:0 overruns:0 frame:0
          TX packets:30513 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:22732431 (22.7 MB) TX bytes:22732431 (22.7 MB)

mgmt-conntrd Link encap:Ethernet HWaddr 76:5d:b9:93:e6:6f
          inet6 addr: fe80::745d:b9ff:fe93:e66f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:465 errors:0 dropped:0 overruns:0 frame:0
          TX packets:92 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:23514 (23.5 KB) TX bytes:4536 (4.5 KB)

p_br-floating-0 Link encap:Ethernet HWaddr 06:db:6c:bf:ba:65
          inet6 addr: fe80::4db:6cff:febf:ba65/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:15 errors:0 dropped:0 overruns:0 frame:0
          TX packets:311 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1074 (1.0 KB) TX bytes:16470 (16.4 KB)

p_br-prv-0 Link encap:Ethernet HWaddr 5a:38:a6:b3:b5:fd
          inet6 addr: fe80::5838:a6ff:feb3:b5fd/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B) TX bytes:788 (788.0 B)

vrouter-host Link encap:Ethernet HWaddr 72:78:a2:62:ac:c6
          inet addr:240.0.0.5 Bcast:0.0.0.0 Mask:255.255.255.252
          inet6 addr: fe80::7078:a2ff:fe62:acc6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:29 errors:0 dropped:0 overruns:0 frame:0
          TX packets:29 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:2020 (2.0 KB) TX bytes:2020 (2.0 KB)

MTU setting has only one config file /etc/network/interfaces.d/ifcfg-eth1 (as set via Fuel).

Here is part of network scheme:

network_scheme:
  endpoints:
    br-ex:
      IP:
      - 192.168.122.13/24
      gateway: 192.168.122.1
      vendor_specific:
        phy_interfaces:
        - eth0
    br-floating:
      IP: none
    br-fw-admin:
      IP:
      - 10.20.1.1/16
      gateway: 10.20.0.2
      gateway-metric: 65000
    br-mgmt:
      IP:
      - 192.168.0.4/24
      vendor_specific:
        phy_interfaces:
        - eth1
        vlans: 101
    br-prv:
      IP: none
      vendor_specific:
        phy_interfaces:
        - eth1
        vlans: 1000:1030
    br-storage:
      IP:
      - 192.168.1.2/24
      vendor_specific:
        phy_interfaces:
        - eth1
        vlans: 102
  interfaces:
    eth0: {}
    eth1:
      mtu: 9000

CentOS + Fedora LT kernel installed via classic install (some issues with my virtualized environment prevents VLAN working with stock kernel, and IBP doesn't installs Fedora LT kernel) works fine. MTU setting as with Ubuntu has only one interface — /etc/sysconfig/network-scripts/ifcfg-eth1

[Sergey Vasilenko (xenolog)]

It's a feature of current ubuntu-kernel.

[Nastya Urlapova (aurlapova)]

@Vova, Sergey, correct status for 6.1 what is?

[Vladimir Kuklin (vkuklin)]

It is possible to manually assign these values to subinterfaces, so this issue should be documented - there is an easy w/a available

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/183970

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/183970
Committed: https://git.openstack.org/cgit/stackforge/fuel-library/commit/?id=6071511de21f1fcdaa88b9899dfc495b224246cd
Submitter: Jenkins
Branch: master

commit 6071511de21f1fcdaa88b9899dfc495b224246cd
Author: Sergey Vasilenko <email address hidden>
Date: Fri May 15 15:48:22 2015 -0700

    Adjust MTU for child interfaces if it possible

    For network scheme, like
    ---
    network_scheme:
      version: 1.1
      provider: lnx
      interfaces:
        eth1:
          mtu: 9000
      transformations:
        - action: add-port
          name: eth1
        - action: add-port
          name: eth1.101
      endpoints:
        eth1.101:
          IP:
            - 192.168.34.56/24
      roles:
        xxx: eth1.101

    interface 'eth1.101' should be created with MTU=9000

    Closes-bug: #1453027
    Change-Id: I170e9088d5e3bcd241da7e56dfa7b7934d6d810d

[Bogdan Dobrelya (bogdando)]

Why the status for 7.0 is confirmed?

[Stanislav Makar (smakar)]

for 6.1 is fixed

[Stanislav Makar (smakar)]

Verified

VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "6.1"
  openstack_version: "2014.2.2-6.1"
  api: "1.0"
  build_number: "478"
  build_id: "2015-05-28_20-55-26"
  nailgun_sha: "4344fe68b5c93d2e7f7254076aab62aa3a612e42"
  python-fuelclient_sha: "e19f1b65792f84c4a18b5a9473f85ef3ba172fce"
  astute_sha: "5d570ae5e03909182db8e284fbe6e4468c0a4e3e"
  fuel-library_sha: "09822a44c2298437882062a43c8ab0bcef952524"
  fuel-ostf_sha: "6b4ddbfd3126b77f79759721e86d395bf106b177"
  fuelmain_sha: "6b5712a7197672d588801a1816f56f321cbceebd"