[Pkg-utopia-maintainers] Bug#418023: Interfaces managed by NetworkManager have MTU 576

[Michel Dänzer]

On Mon, 2007-04-16 at 15:01 +0200, Michael Biebl wrote:
> Michel Dänzer wrote:
> > Package: network-manager
> > Version: 0.6.4-7
> > Severity: important
> > 
> > 
> > I noticed that all interfaces managed by NetworkManager seem to
> > have an MTU of 576 bytes (the minimum). This seems to have a negative
> > effect on download speed, or certainly not a positive one. As
> > nm_system_get_mtu() in src/backends/NetworkManagerDebian.c returns 0,
> > NetworkManager doesn't seem to set the MTU explicitly though, so I'm not
> > sure where the default is coming from. I verified that hacking the above
> > function to return 1500 results in interfaces managed by NetworkManager
> > having an MTU of 1500, with a line like
> > 
> > Apr  6 12:18:52 thor NetworkManager: <information>^ISetting MTU of
> > interface 'sungem' to 1500
> > 
> > in syslog.
> 
> Hi Michel,
> 
> do you have the same problem when you manage your devices with ifupdown?

No, the desktop machines which don't use NetworkManager set the MTU to
1500 by default.

> Basically, nm_system_get_mtu() returning 0, means that the system
> default is used and network-manager does not mess with it.

I understand that, but it doesn't seem to be handled quite correctly
yet.

> Is there an authoritive config file, where we could read the mtu
> configuration? 

I don't know, but grep can't seem to find anything in /etc.

> Otherwise I would refrain from setting the MTU to any
> arbitrary fixed number.

Sure, I didn't (mean to) suggest that. I think the default MTU should be
determined the same way as without NetworkManager.


-- 
Earthling Michel Dänzer           |          http://tungstengraphics.com
Libre software enthusiast         |          Debian, X and DRI developer