On Tue, Oct 27, 2020, 02:49 Strahil Nikolov via Users <users@ovirt.org> wrote:
> Hello All, > > I would like to learn more about OVN and especially the maximum MTU that I > can use in my environment. > > Current Setup 4.3.10 > Network was created via UI -> MTU Custom -> 8976 -> Create on External > Provider -> Connect to Physical Network > > So my physical connection is MTU 9000 and I have read that Geneve uses 24 > bits (maybe that's wrong ?) , thus I have reduced the MTU to 8976. > >From the internet draft it seems that the tunnel header + reserved bits comprise 64 bits. A common practice for Geneve implementations is to use 8900 mtu for VMs when having 9000 mtu physical network. The draft: https://tools.ietf.org/html/draft-ietf-nvo3-geneve-08 > > I did some testing on the VMs and ping with payload of '8914' was the > maximum I could pass without fragmenting and thus the MTU on the VMs was > set to 8942. > > Did I correctly configure the test network's MTU and am I understanding it > correctly that we need extra 34 bits inside the network for encapsulation ? > > I have checked > https://www.ovirt.org/develop/release-management/features/network/managed_mtu_for_vm_networks.html > but I don't see any refference how to calculate the max MTU. > > > Best Regards, > Strahil Nikolov > _______________________________________________ > Users mailing list -- users@ovirt.org > To unsubscribe send an email to users-le...@ovirt.org > Privacy Statement: https://www.ovirt.org/privacy-policy.html > oVirt Code of Conduct: > https://www.ovirt.org/community/about/community-guidelines/ > List Archives: > https://lists.ovirt.org/archives/list/users@ovirt.org/message/CKNS5T5KE2W5EIXBTGQDU3URKHQDVAM4/ >
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