On Thu, Mar 22, 2018 at 9:53 PM, Roopa Prabhu <ro...@cumulusnetworks.com> wrote: > On Thu, Mar 22, 2018 at 8:34 AM, Chas Williams <3ch...@gmail.com> wrote: >> If the bridge is allowing multiple VLANs, some VLANs may have >> different MTUs. Instead of choosing the minimum MTU for the >> bridge interface, choose the maximum MTU of the bridge members. >> With this the user only needs to set a larger MTU on the member >> ports that are participating in the large MTU VLANS. >> >> Signed-off-by: Chas Williams <3ch...@gmail.com> >> --- > > Acked-by: Roopa Prabhu <ro...@cumulusnetworks.com> > > This or an equivalent fix is necessary: as stated above, today the > bridge mtu capped at min port mtu limits all > vlan devices on top of the vlan filtering bridge to min port mtu.
On further thought, since this patch changes default behavior, it may upset people. ie with this patch, a vlan device on the bridge by default will now use the bridge max mtu and that could cause unexpected drops in the bridge driver if the xmit port had a lower mtu. This may surprise users. The other equivalent fix i was thinking about is to keep the default behavior as is, and allow a max mtu to be configured on the bridge. This will allow a sys admin to fix the current mtu limitations if deployments require it. we will submit an incremental patch to re-work this patch to restore default behavior.
