How to enable jumbo frames on LACP ?

[HeinzApfel]

Hi,

can someone please explain how to the set the MTU on an lagg-interface in the GUI?

I would like to set "mtu 9000" and added this in the GUI under "Options" on my "lagg0" interface which is a LACP bundle with two Ethernet adapters.
Using ifconfig I can see that lagg0 is using that mtu but the Ethernet interfaces still use 1500. Also I can verify via ping from another, jumbo frame enabled, system that the mtu is still 1500.

Thanks and best regards,
Heinz

 

[dlavigne]

Did you see this note in the docs?

Note: options can be set at either the lagg level (using the “Edit” button) or the individual parent interface level (using the “Edit Members” button). Typically, changes are made at the lagg level (Figure 7.4c) as each interface member will inherit from the lagg. If you instead configure the interface level (Figure 7.4d), you will have to repeat the configuration for each interface within the lagg. However, some lagg options can only be set by editing the interface. For instance, since the MTU of a lagg is inherited from the interface, in order to set an MTU on a lagg you must set all the interfaces to the same MTU before creating the lagg.

 

[jgreco]

Also be aware that you might need to specify a larger frame size on the parent interfaces to allow for the extra header. Also be aware that jumbo sucks, screw jumbo. Instead of messing around to get a few percent performance increase, you'd be better served by moving to 10GbE or something like that.

 

[HeinzApfel]

Thanks for your quick replies and pointing me to the right place.
I added "mtu 9000 up" to all interfaces and it's working now.