Public bug reported: ifup failed when we set a static MTU small than 68, and when we change the static configuration and try to run ifdown and then ifup, the interface still with the old MTU and both of ifup and ifdown command fail. when we change the MTU manually by ip tool and then change it in the /etc/network/interfaces to be 1500 the interface get back to work.
root:~# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.10 Release: 16.10 Codename: yakkety root:~# uname -r 4.8.0-26-generic scenario: set the MTU static to 67 root:~# ifdown ens2 root:~# ifup ens2 root:~# ifdown ens2 RTNETLINK answers: No such device root:~# ifup ens2 RTNETLINK answers: No buffer space available Failed to bring up ens2. root:~# cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). auto ens2 iface ens2 inet static address 21.3.5.16 mtu 67 ## change MTU static to 1500 root:~# vim /etc/network/interfaces root:~# ifdown ens2 ifdown: interface ens2 not configured root:~# ifup ens2 RTNETLINK answers: No buffer space available Failed to bring up ens2. root:~# ip link set ens2 mtu 1500 root:~# ifup ens2 ** Affects: ifupdown (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to ifupdown in Ubuntu. https://bugs.launchpad.net/bugs/1638256 Title: ifup fail when use MTU small than 68 Status in ifupdown package in Ubuntu: New Bug description: ifup failed when we set a static MTU small than 68, and when we change the static configuration and try to run ifdown and then ifup, the interface still with the old MTU and both of ifup and ifdown command fail. when we change the MTU manually by ip tool and then change it in the /etc/network/interfaces to be 1500 the interface get back to work. root:~# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.10 Release: 16.10 Codename: yakkety root:~# uname -r 4.8.0-26-generic scenario: set the MTU static to 67 root:~# ifdown ens2 root:~# ifup ens2 root:~# ifdown ens2 RTNETLINK answers: No such device root:~# ifup ens2 RTNETLINK answers: No buffer space available Failed to bring up ens2. root:~# cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). auto ens2 iface ens2 inet static address 21.3.5.16 mtu 67 ## change MTU static to 1500 root:~# vim /etc/network/interfaces root:~# ifdown ens2 ifdown: interface ens2 not configured root:~# ifup ens2 RTNETLINK answers: No buffer space available Failed to bring up ens2. root:~# ip link set ens2 mtu 1500 root:~# ifup ens2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1638256/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp