** Description changed: + [Impact] + GRE overlay networks can't carry traffic with MTU > 1500 + + [Test Case] + + [Regression Potential] + + + [Bug Report] + Under Linux 4.13 its not possible to configure GRE tunnel devices with a MTU larger than 1500; this impacts on Open vSwitch (which creates tunnel devices for GRE overlay networking) and the ip tools. The kernel will error with: - gre_sys: Invalid MTU 65000 requested, hw max 1500 + gre_sys: Invalid MTU 65000 requested, hw max 1500 The side effect of this is that if overlay networks are configured with high MTUs, the gre devices fragment the packets and networking is generally slow/broken. This is resolved as part of the upcoming 4.15 kernel under: https://github.com/torvalds/linux/commit/cfddd4c33c254954927942599d299b3865743146
** Description changed: [Impact] GRE overlay networks can't carry traffic with MTU > 1500 [Test Case] + sudo add-apt-repository cloud-archive:pike + sudo apt update + sudo apt install openvswitch-switch + sudo ovs-vsctl add-br br-tun + sudo ovs-vsctl add-port br-tun gre0 -- set interface gre0 type=gre options:remote_ip=10.100.1.1 + + gre_sys device will be configured with MTU 1472. + + sudo ip link set gre_sys mtu 65000 + + will fail with EINVAL. [Regression Potential] - [Bug Report] Under Linux 4.13 its not possible to configure GRE tunnel devices with a MTU larger than 1500; this impacts on Open vSwitch (which creates tunnel devices for GRE overlay networking) and the ip tools. The kernel will error with: gre_sys: Invalid MTU 65000 requested, hw max 1500 The side effect of this is that if overlay networks are configured with high MTUs, the gre devices fragment the packets and networking is generally slow/broken. This is resolved as part of the upcoming 4.15 kernel under: https://github.com/torvalds/linux/commit/cfddd4c33c254954927942599d299b3865743146 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1743746 Title: 4.13: unable to increase MTU configuration for GRE devices To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1743746/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
