>> The next question I have is about the behavior of the new setting >> in the presence of an RA MTU option. It seems like the sysctl >> doesn't override that RA MTU option, but rather just clamps it. >> >> And then if it's in range, this controls only whether the default >> route has it's MTU adjusted. >> >> That doesn't make any sense to me if we then go and do the >> rt6_mtu_change() call unconditionally. The route metric update >> and the rt6_mtu_change() go hand in hand. > > Agreed but that gets interesting: > > I guess during testing the cnf.mtu6 value was equal to the newly > announced mtu value, so the rt6_mtu_change call does not happen. We > update cnf.mtu6 so a second RA packet would actually bring the system > into the desired state but we have a moment where the default route > carries a too big MTU. That's not good.
Agreed. > Easiest solution is to reorder those calls but that also leaves us with > a time frame where we carry the incorrect MTU on the default route. > Otherwise we must conditionally filter out the default routes. > Roman, any ideas? I think, such approach will work on practise, but looks not very beatiful. May be, a better idea is to serarate per-route and per-device MTU, so an updating of per-device MTU will not affect per-route MTU. Actual MTU can always been calculated as min(route_mtu, device_mtu), but we wouldn't need to update mtu on each route on receiving RA MTU option, for instance. Do you see any problems with such approach? Thanks, Roman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
