----- Original Message ----- > From: "Igor Lvovsky" <[email protected]> > To: "VDSM Project Development" <[email protected]> > Cc: "Simon Grinberg" <[email protected]> > Sent: Wednesday, November 28, 2012 2:58:52 PM > Subject: [vdsm] MTU setting according to ifcfg files. > > Hi, > > I am working on one of the vdsm bugs that we have and I found that > initscripts (initscripts-9.03.34-1.el6.x86_64) > behaviour doesn't fits our needs. > So, I would like to raise this issue in the list. > > The issue is MTU setting according to ifcfg files. > I'll try to describe the flow below. > > 1. I started with ifcfg file for the interface without MTU keyword at > all > and the proper interface (let say eth0) had the *default* MTU=1500 > (according to /sys/class/net/eth0/mtu). > 2. I created a bridge with MTU=9000 on top of this interface. > Everything went OK. > After I wrote MTU=9000 on ifcfg-eth0 and ifdown/ifup it, eth0 got > the proper MTU. > 3. Now, I removed the bridge and deleted MTU keyword from the > ifcfg-eth0. > But after ifup/ifdown the actual MTU of the eth0 stayed 9000. > > The only way to change it back to 1500 (or something else) is > explicitly set MTU in ifcfg file. > According to Bill Nottingham it is intentional behaviour.
Right. The network should not push what not configured. > If so, we have a problem in vdsm, because we never set MTU value > until user ask it explicitly. > It means that if we have interface with MTU=9000 on it just because > once there was a bridge with such MTU > attached to it and now we want to attach regular bridge with > *default* MTU=1500 we have a problem. > The only thing we can do to avoid this it's set explicitly MTU=1500 > in interface's ifcfg file. > IMHO it's a bit ugly, but it looks like we have no choice. > > As usual comments more than welcome... For the long run have total control over our resources, and push whatever configuration we require... skipping distribution specific behaviour. Regards, Alon. _______________________________________________ vdsm-devel mailing list [email protected] https://lists.fedorahosted.org/mailman/listinfo/vdsm-devel
