Bug 579860 - NetworkManager doesn't use configured MTU for DSL connections
Summary: NetworkManager doesn't use configured MTU for DSL connections
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Fedora
Classification: Fedora
Component: NetworkManager
Version: 12
Hardware: All
OS: Linux
low
medium
Target Milestone: ---
Assignee: Dan Williams
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
: 579866 (view as bug list)
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2010-04-06 18:44 UTC by Saikat Guha
Modified: 2010-12-03 16:15 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2010-12-03 16:15:25 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

Description Saikat Guha 2010-04-06 18:44:48 UTC
Description of problem:
Configured MTU is not used for DSL connections.

Version-Release number of selected component (if applicable):
NetworkManager-0.7.998-2.git20100106.fc12.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Create a new DSL connection (PPPoE)
2. Set MTU to 1480
3. Establish DSL connection
4. ifcfg ppp0
  
Actual results:
MTU=1492

Expected results:
MTU=1480

Comment 1 Dan Williams 2010-04-06 20:22:46 UTC
*** Bug 579866 has been marked as a duplicate of this bug. ***

Comment 2 Dan Williams 2010-04-06 20:30:38 UTC
When you say you set the MTU in step #2, do you mean in the "Wired" tab?

Comment 3 Saikat Guha 2010-04-06 22:16:56 UTC
Yes, in the Wired tab.

Comment 4 Jirka Klimes 2010-04-08 13:32:49 UTC
Hmm, 1492 is used as default value when MTU is not set.

Could you post /var/log/messages log?

Comment 5 Saikat Guha 2010-04-08 16:07:37 UTC
2010-04-08T21:33:40.226385+05:18 dent NetworkManager: <info>  Activation (eth0) starting connection 'Home DSL'
2010-04-08T21:33:40.226428+05:18 dent NetworkManager: <info>  (eth0): device state change: 3 -> 4 (reason 0)
2010-04-08T21:33:40.226441+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 1 of 5 (Device Prepare) scheduled...
2010-04-08T21:33:40.226970+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 1 of 5 (Device Prepare) started...
2010-04-08T21:33:40.226989+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 2 of 5 (Device Configure) scheduled...
2010-04-08T21:33:40.227001+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 1 of 5 (Device Prepare) complete.
2010-04-08T21:33:40.227013+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 2 of 5 (Device Configure) starting...
2010-04-08T21:33:40.227025+05:18 dent NetworkManager: <info>  (eth0): device state change: 4 -> 5 (reason 0)
2010-04-08T21:33:40.227150+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 2 of 5 (Device Configure) successful.
2010-04-08T21:33:40.227165+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 3 of 5 (IP Configure Start) scheduled.
2010-04-08T21:33:40.227177+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 2 of 5 (Device Configure) complete.
2010-04-08T21:33:40.227242+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 3 of 5 (IP Configure Start) started...
2010-04-08T21:33:40.227269+05:18 dent NetworkManager: <info>  (eth0): device state change: 5 -> 7 (reason 0)
2010-04-08T21:33:40.227407+05:18 dent NetworkManager: <info>  Starting pppd connection
2010-04-08T21:33:40.229375+05:18 dent dbus-daemon: Rejected send message, 2 matched rules; type="error", sender=":1.393" (uid=0 pid=1570 comm="NetworkManager) interface="(unset)" member="(unset)" error name="org.freedesktop.DBus.Error.UnknownMethod" requested_reply=0 destination=":1.502" (uid=0 pid=20187 comm="/usr/sbin/pppd))
2010-04-08T21:33:40.229456+05:18 dent dbus-daemon: Rejected send message, 2 matched rules; type="error", sender=":1.393" (uid=0 pid=1570 comm="NetworkManager) interface="(unset)" member="(unset)" error name="org.freedesktop.DBus.Error.UnknownMethod" requested_reply=0 destination=":1.502" (uid=0 pid=20187 comm="/usr/sbin/pppd))
2010-04-08T21:33:40.229544+05:18 dent dbus-daemon: Rejected send message, 2 matched rules; type="error", sender=":1.393" (uid=0 pid=1570 comm="NetworkManager) interface="(unset)" member="(unset)" error name="org.freedesktop.DBus.Error.UnknownMethod" requested_reply=0 destination=":1.502" (uid=0 pid=20187 comm="/usr/sbin/pppd))
2010-04-08T21:33:40.229628+05:18 dent dbus-daemon: Rejected send message, 2 matched rules; type="error", sender=":1.393" (uid=0 pid=1570 comm="NetworkManager) interface="(unset)" member="(unset)" error name="org.freedesktop.DBus.Error.UnknownMethod" requested_reply=0 destination=":1.502" (uid=0 pid=20187 comm="/usr/sbin/pppd))
2010-04-08T21:33:40.229722+05:18 dent dbus-daemon: Rejected send message, 2 matched rules; type="error", sender=":1.393" (uid=0 pid=1570 comm="NetworkManager) interface="(unset)" member="(unset)" error name="org.freedesktop.DBus.Error.UnknownMethod" requested_reply=0 destination=":1.502" (uid=0 pid=20187 comm="/usr/sbin/pppd))
2010-04-08T21:33:40.240987+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 4 of 5 (IP6 Configure Get) scheduled...
2010-04-08T21:33:40.241086+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 3 of 5 (IP Configure Start) complete.
2010-04-08T21:33:40.241121+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 4 of 5 (IP6 Configure Get) started...
2010-04-08T21:33:40.241133+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 4 of 5 (IP6 Configure Get) complete.
2010-04-08T21:33:40.242722+05:18 dent pppd[21555]: Plugin rp-pppoe.so loaded.
2010-04-08T21:33:40.242830+05:18 dent pppd[21555]: RP-PPPoE plugin version 3.8p compiled against pppd 2.4.5
2010-04-08T21:33:40.255764+05:18 dent pppd[21555]: Plugin /usr/lib64/pppd/2.4.5/nm-pppd-plugin.so loaded.
2010-04-08T21:33:40.273347+05:18 dent pppd[21555]: pppd 2.4.5 started by root, uid 0
2010-04-08T21:33:40.284596+05:18 dent pppd[20187]: Exit.
2010-04-08T21:33:40.384045+05:18 dent pppd[21555]: PPP session is 47
2010-04-08T21:33:40.384098+05:18 dent pppd[21555]: Connected to 00:0c:42:3d:b4:e0 via interface eth0
2010-04-08T21:33:40.384963+05:18 dent pppd[21555]: Using interface ppp0
2010-04-08T21:33:40.385013+05:18 dent pppd[21555]: Connect: ppp0 <--> eth0
2010-04-08T21:33:40.500952+05:18 dent pppd[21555]: CHAP authentication succeeded
2010-04-08T21:33:40.501149+05:18 dent pppd[21555]: peer from calling number 00:0C:42:3D:B4:E0 authorized
2010-04-08T21:33:40.516042+05:18 dent pppd[21555]: local  IP address 172.16.11.238
2010-04-08T21:33:40.516274+05:18 dent pppd[21555]: remote IP address 202.62.83.3
2010-04-08T21:33:40.516434+05:18 dent pppd[21555]: primary   DNS address 202.62.77.2
2010-04-08T21:33:40.516635+05:18 dent pppd[21555]: secondary DNS address 202.62.64.3
2010-04-08T21:33:40.517837+05:18 dent NetworkManager: <info>  PPP manager(IP Config Get) reply received.
2010-04-08T21:33:40.517985+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 4 of 5 (IP4 Configure Get) scheduled...
2010-04-08T21:33:40.518092+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 4 of 5 (IP4 Configure Get) started...
2010-04-08T21:33:40.518120+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 5 of 5 (IP Configure Commit) scheduled...
2010-04-08T21:33:40.518146+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 4 of 5 (IP4 Configure Get) complete.
2010-04-08T21:33:40.518170+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 5 of 5 (IP Configure Commit) started...
2010-04-08T21:33:40.532021+05:18 dent pppd[21555]: CCP terminated by peer (No compression negotiated)
2010-04-08T21:33:40.532217+05:18 dent pppd[21555]: Compression disabled by peer.
2010-04-08T21:33:41.545518+05:18 dent NetworkManager: <info>  (eth0): device state change: 7 -> 8 (reason 0)
2010-04-08T21:33:41.546939+05:18 dent dnsmasq[20166]: reading /etc/resolv.conf
2010-04-08T21:33:41.547101+05:18 dent dnsmasq[20166]: using nameserver 202.62.64.3#53
2010-04-08T21:33:41.547131+05:18 dent dnsmasq[20166]: using nameserver 202.62.77.2#53
2010-04-08T21:33:41.547228+05:18 dent dnsmasq[20166]: cleared cache
2010-04-08T21:33:41.562441+05:18 dent NetworkManager: <info>  Policy set 'Home DSL' (ppp0) as default for routing and DNS.
2010-04-08T21:33:41.562559+05:18 dent NetworkManager: <info>  Activation (eth0) successful, device activated.
2010-04-08T21:33:41.562609+05:18 dent NetworkManager: <info>  Activation (eth0) Stage 5 of 5 (IP Configure Commit) complete.

Comment 6 Dan Williams 2010-04-08 23:17:06 UTC
The wired tab's MTU applies to the *ethernet* device, not the PPP device.

To make things worse, the PPP interface MTU/MRU is negotiated by pppd, and not available to the plugin since pppd just sets the MTU on ppp0.  So I guess what we need to do is to, in the pppd plugin, grab the MTU off the interface and send that back to NM as the PPP interface MTU, then adjust the underlying device MTU (ie eth0) to be less than that.

That would likely take care of the issue.  Since the PPP MTU is autonegotiated, we shouldn't need to manually adjust it or provide UI for it anywhere.

Comment 7 Saikat Guha 2010-04-09 03:34:10 UTC
(In reply to comment #6)
> we need to do is to, in the pppd plugin, grab the MTU off the interface and
> send that back to NM as the PPP interface MTU, then adjust the underlying
> device MTU (ie eth0) to be less than that.

The problem I am facing is that the MTU for the *ppp* device is being reset to 1492 after pppd negotiates 1480. My current workaround after NM establishes the connection is to run "ifconfig ppp0 mtu 1480" .... the MTU for the ethernet device is still 1500.

Comment 8 Bug Zapper 2010-11-03 17:43:51 UTC
This message is a reminder that Fedora 12 is nearing its end of life.
Approximately 30 (thirty) days from now Fedora will stop maintaining
and issuing updates for Fedora 12.  It is Fedora's policy to close all
bug reports from releases that are no longer maintained.  At that time
this bug will be closed as WONTFIX if it remains open with a Fedora 
'version' of '12'.

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Comment 9 Bug Zapper 2010-12-03 16:15:25 UTC
Fedora 12 changed to end-of-life (EOL) status on 2010-12-02. Fedora 12 is 
no longer maintained, which means that it will not receive any further 
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of 
Fedora please feel free to reopen this bug against that version.

Thank you for reporting this bug and we are sorry it could not be fixed.


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