Ubuntu
linux package

per route mtu settings are broken in linux kernel 3.2

Bug #1177507 reported by Yura Pakhuchiy on 2013-05-07

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	linux (Ubuntu)	Invalid	Medium	Unassigned

Bug Description

Hello,

Looks like setting per route mtu (as described in [1]) is broken in linux kernel 3.2 (default kernel from ubuntu 12.04).
I made script to illustrate this:

root@germany7:~# cat route-mtu
#!/bin/bash

uname -a
ip tuntap add dev test mode tun
ifconfig test 10.1.1.1/16 mtu 1500
echo =============================================================
echo No per route mtu entry
ping -c1 -Mdo -s2000 10.1.1.2
echo =============================================================
echo Per route MTU is set to 800
ip route add 10.1.1.2 dev test proto static src 10.1.1.1 mtu lock 800
ip route flush cache
ping -c1 -Mdo -s2000 10.1.1.2
ip route del 10.1.1.2 dev test proto static src 10.1.1.1 mtu lock 800
echo =============================================================
echo Per route MTU is set to 600
ip route add 10.1.1.2 dev test proto static src 10.1.1.1 mtu lock 600
ip route flush cache
ping -c1 -Mdo -s2000 10.1.1.2
ip route del 10.1.1.2 dev test proto static src 10.1.1.1 mtu lock 600
echo =============================================================
echo No per route mtu entry
ip route flush cache
ping -c1 -Mdo -s2000 10.1.1.2
ip tuntap del dev test mode tun

With kernel 3.2 I get following output:
Linux germany7 3.2.0-41-generic-pae #66-Ubuntu SMP Thu Apr 25 03:50:20 UTC 2013 i686 i686 i386 GNU/Linux
=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

=============================================================
Per route MTU is set to 800
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 800)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

=============================================================
Per route MTU is set to 600
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 800)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 800)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

After once set to 800, MTU is always 800, even if you add different route and clean routing cache.

It looks like that problem is fixed in ubuntu kernel 3.5. With it, everything works like expected:
root@germany7:~# ./route-mtu
Linux germany7 3.5.0-28-generic #48~precise1-Ubuntu SMP Wed Apr 24 21:43:05 UTC 2013 i686 i686 i386 GNU/Linux
=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

I also tested with kernels 2.6.35 (in lucid) and 3.8 (in precise), results are same to 3.5.

Is there any chance to get fixes from 3.5/3.8 backported to the default precise kernel 3.2?

1. http://lartc.org/howto/lartc.cookbook.mtu-discovery.html
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu17.2
Architecture: i386
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC268 Analog [ALC268 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: yura 2759 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'Intel'/'HDA Intel at 0xf4800000 irq 45'
   Mixer name : 'Intel Cantiga HDMI'
   Components : 'HDA:10ec0268,1025013c,00100101 HDA:14f12c06,10250093,00100000 HDA:80862802,80860101,00100000'
   Controls : 23
   Simple ctrls : 10
CheckboxSubmission: 02f685f3381c5341bcbab31fdf0318b9
CheckboxSystem: 8278c9e6a57f68452a782d8924c0633a
DistroRelease: Ubuntu 12.04
HibernationDevice: RESUME=UUID=2d28cf13-ba1f-4394-9958-51ed5ccb4dd3
MachineType: Acer Extensa 5630
MarkForUpload: True
Package: linux (not installed)
PccardctlIdent:
Socket 0:
   no product info available
PccardctlStatus:
Socket 0:
   no card
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: root=UUID=8f05626d-62de-43a5-87f9-1e51af186021 ro quiet splash resume=UUID=70081498-3f3e-4d20-8ccb-c31aebd900d6
ProcVersionSignature: Ubuntu 3.2.0-41.66-generic 3.2.42
RelatedPackageVersions:
linux-restricted-modules-3.2.0-41-generic N/A
linux-backports-modules-3.2.0-41-generic N/A
linux-firmware 1.79.4
Tags: precise
Uname: Linux 3.2.0-41-generic i686
UpgradeStatus: Upgraded to precise on 2013-05-09 (0 days ago)
UserGroups: adm admin disk fuse pulse-access src sudo users wireshark
WpaSupplicantLog:

dmi.bios.date: 08/05/2008
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: V1.19
dmi.board.name: Homa
dmi.board.vendor: Acer
dmi.board.version: Rev
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrV1.19:bd08/05/2008:svnAcer:pnExtensa5630:pvr0100:rvnAcer:rnHoma:rvrRev:cvnAcer:ct10:cvrN/A:
dmi.product.name: Extensa 5630
dmi.product.version: 0100
dmi.sys.vendor: Acer

See original description

Tags:

Yura Pakhuchiy (yura-p) on 2013-05-07

description:

updated

Brad Figg (brad-figg) on 2013-05-07

affects:

linux-meta (Ubuntu) → linux (Ubuntu)

Revision history for this message

Brad Figg (brad-figg) wrote on 2013-05-07: Missing required logs.

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1177507

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

Changed in linux (Ubuntu):
status:	New → Incomplete
tags:	added: precise

Joseph Salisbury (jsalisbury) on 2013-05-07

Changed in linux (Ubuntu):
importance:	Undecided → Medium
status:	Incomplete → Triaged
tags:	added: kernel-da-key kernel-fixed-upstream

Revision history for this message

Yura Pakhuchiy (yura-p) wrote on 2013-05-10: AcpiTables.txt

AcpiTables.txt Edit (217.8 KiB, text/plain)

apport information

tags:	added: apport-collected
description:	updated

Revision history for this message

Yura Pakhuchiy (yura-p) wrote on 2013-05-10: AlsaDevices.txt

AlsaDevices.txt Edit (543 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: AplayDevices.txt

AplayDevices.txt Edit (257 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: BootDmesg.txt

BootDmesg.txt Edit (67.1 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: CRDA.txt

CRDA.txt Edit (257 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: Card0.Amixer.values.txt

Card0.Amixer.values.txt Edit (1.9 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: Card0.Codecs.codec.0.txt

Card0.Codecs.codec.0.txt Edit (8.3 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: Card0.Codecs.codec.1.txt

Card0.Codecs.codec.1.txt Edit (160 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: Card0.Codecs.codec.3.txt

#10

Card0.Codecs.codec.3.txt Edit (1.3 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: CurrentDmesg.txt

#11

CurrentDmesg.txt Edit (29.2 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: IwConfig.txt

#12

IwConfig.txt Edit (545 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: Lspci.txt

#13

Lspci.txt Edit (15.5 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: Lsusb.txt

#14

Lsusb.txt Edit (650 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: PciMultimedia.txt

#15

PciMultimedia.txt Edit (609 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: ProcCpuinfo.txt

#16

ProcCpuinfo.txt Edit (1.5 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: ProcEnviron.txt

#17

ProcEnviron.txt Edit (108 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: ProcInterrupts.txt

#18

ProcInterrupts.txt Edit (1.6 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: ProcModules.txt

#19

ProcModules.txt Edit (3.8 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: PulseList.txt

#20

PulseList.txt Edit (19.9 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: RfKill.txt

#21

RfKill.txt Edit (124 bytes, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: UdevDb.txt

#22

UdevDb.txt Edit (122.7 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: UdevLog.txt

#23

UdevLog.txt Edit (276.2 KiB, text/plain)

apport information

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Yura Pakhuchiy (yura-p) wrote on 2013-05-10: WifiSyslog.txt

#24

WifiSyslog.txt Edit (337.8 KiB, text/plain)

apport information

Yura Pakhuchiy (yura-p) on 2013-06-24

Changed in linux (Ubuntu):
status:	Triaged → Confirmed

Revision history for this message

penalvch (penalvch) wrote on 2013-07-21:

#25

Yura Pakhuchiy, as per http://us.acer.com/ac/en/US/content/drivers an update is available for your BIOS (1.36). If you update to this, does it change anything?

If not, could you please both specify what happened, and provide the output of the following terminal command:
sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

Thank you for your understanding.

tags:	added: bios-outdated-v1.36
Changed in linux (Ubuntu):
status:	Confirmed → Incomplete

Revision history for this message

Yura Pakhuchiy (yura-p) wrote on 2013-07-22:

#26

I'm pretty sure this problem is not depends on hardware. I tried not only on mine laptop, but on several servers with different hardware configurations. You can run attached script and will see that it happens on your system too (if you are running ubuntu kernel 3.2).

Changed in linux (Ubuntu):
status:	Incomplete → Confirmed

Revision history for this message

Yura Pakhuchiy (yura-p) wrote on 2013-07-22:

#27

Also Joseph Salisbury (jsalisbury) already marked this change as Triaged. I reverted this to Verified by accident before.

Revision history for this message

Yura Pakhuchiy (yura-p) wrote on 2013-07-22:

#28

I meant: this bug

penalvch (penalvch) on 2013-07-22

tags:

added: refused-troubleshooting

Revision history for this message

Yura Pakhuchiy (yura-p) wrote on 2013-07-22:

#29

Oh, really? I think appreciate tag would be developer-emulating-work. Anyone can check that problem with ubuntu kernel 3.2 on every system, independently of hw configuration and bios version. More over, problem is fixed upstream.

Revision history for this message

Richard Laager (rlaager) wrote on 2016-08-25:

#30

Download full text (3.9 KiB)

First, let me say I'm not an Ubuntu developer.

Second, is this still a problem for you?

On a system running Precise, this seems to work for me:
Linux yak 3.2.0-107-generic #148-Ubuntu SMP Mon Jul 18 20:22:08 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
From 10.1.1.1 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 10.1.1.2 ping statistics ---
0 packets transmitted, 0 received, +1 errors

On a system running Trusty, it also seems to work:
Linux tuna 3.13.0-93-generic #140-Ubuntu SMP Mon Jul 18 21:21:05 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
ping: local error: Message too long, mtu=1500

--- 10.1.1.2 ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

=============================================================
Per route MTU is set to 800
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
ping: local error: Message too long, mtu=800

--- 10.1.1.2 ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

=============================================================
Per route MTU is set to 600
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
ping: local error: Message too long, mtu=600

--- 10.1.1.2 ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
ping: local error: Message too long, mtu=1500

--- 10.1.1.2 ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

On Xenial, it also seems to work:
Linux grape 4.4.0-34-generic #53-Ubuntu SMP Wed Jul 27 16:06:39 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
=============================================================
No per route mtu entry
PING 10.1.1.2 (10.1.1.2) 2000(2028) bytes of data.
ping: local error: Message too long, mtu=1500

--- 10.1.1.2 ping statistics ---
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

=============================================================
Per route MTU is s...

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per route mtu settings are broken in linux kernel 3.2

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