Network MTU size (Jumbo packets)

Discussions about using Windows guests in VirtualBox.
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Astara
Posts: 8
Joined: 11. Sep 2016, 20:30

Network MTU size (Jumbo packets)

Post by Astara »

I setup my WinXP64 guest in bridge mode to one of the interfaces in a linux-bridge -- and that seems to be working fine.
What I was wondering is if there is anyway to set the MTU size to a 9000 (9014?) Jumbo packet which is the size used by anything else on that net.

Since it seems to be working, I guess I don't have to worry about a different MTU size for the guest speaking to 'eth0' (a member of a bridge on my linux box). I am assuming that the guest is using the default 1500 bytes for the MTU on eth0. The host system is using a 9000 byte MTU on eth0.

Still, I was wondering if there was a driver that allowed setting the MTU size to 9000, as that might use less CPU during higher speed network transfers (or give a faster transfer speed).

Thanks much!
A*a
scottgus1
Site Moderator
Posts: 20965
Joined: 30. Dec 2009, 20:14
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: Network MTU size (Jumbo packets)

Post by scottgus1 »

Astara wrote:a driver that allowed setting the MTU size to 9000
The virtual network card put into the guest by Virtualbox uses drivers included with the guest OS itself. It is possible to update the driver inside the guest for that network card using manufacturer's drivers for the same physical card. it is also possible to use another of the virtual network cards for which the guest OS does not have drivers, then provide the drivers from the network card's manufacturer inside the guest.

Whether you can alter the MTU settings is a subject for a google search on the kind of card & drivers you might use. Whether such a change will have any effect in Virtualbox I wouldn't know.

It has been reported on the forum that the "mbps" rating of the virtual card doesn't limit data throughput, the data will flow as fast as the guest can process it. So a guest's 100mbit virtual card will pass data at 1Gbps if the host card is 1Gbps, and possibly faster between two guests on the same host. I have not tested this, but it may be pertinent to your desired experiment.
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