Quoting r. Hal Rosenstock <[EMAIL PROTECTED]>: > Subject: Re: [PATCH] IB/ipoib: use appropriate path selector > > On Wed, 2006-09-13 at 18:08, Michael S. Tsirkin wrote: > > Quoting r. Roland Dreier <[EMAIL PROTECTED]>: > > > Subject: Re: [PATCH] IB/ipoib: use appropriate path selector > > > > > > Michael> IPoIB in linux needs 2K MTU. Therefore it must set mtu > > > Michael> selector in path record query accordingly. > > > > > > Umm -- why does it need a 2K MTU? As far as I know it should work > > > fine with any MTU, assuming the SA sets the MTU of the broadcast > > > multicast group correctly. > > > > Hmm, you are right, it is just that existing implementations all > > set that to 2K. > > By default yes. It can be configured. > > > But there is a silent assumption that MTU of any path is >= broadcast > > multicast group MTU, and this is what I want to fix. > > The spec says: > "The value (for IB MTU) assigned to the broadcast-GID must not be > greater than any physical link MTU spanned by the IPoIB subnet". > so if the broadcast group is improperly setup not to follow this, there > will be other issues.
Correct. IPoIB uses broadcast group MTU to get the value reported to Linux. If some link has a lower MTU IPoIB can not use it. > It doesn't need to be included in the PR request. I disagree here. If you do not set selector, SA is free to return a path with lower MTU even though physical link allows higher MTU. Does it say otherwise somewhere? -- MST _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
