[Bug 1874515] Re: 20.04 does not bring up certain bridges

Tue Apr 28 20:25:02 UTC 2020

The difference between bridges managing to come up correctly and the
ones which does not seem to be that bridges defined as "inet manual"
fails and the ones defined as "inet static" succeeds. An example of a
bridge coming up correctly with a similar setup without the post-up
brctl addbr command;

auto int0.70
iface int0.70 inet manual
        vlan-raw-device int0
        pre-up ifconfig $IFACE up
        post-down ifconfig $IFACE down

auto br_nat
iface br_nat inet static
        bridge_ports int0.70
        bridge_maxwait 5
        address 172.X.X.X/24
        up ip ro add 10.X.X.X/10 via 172.X.X.X dev $IFACE

So two conclusions;

1) Bridges configured with bridge_ports with interfaces defined as "inet
manual" while the bridge is also configured as "inet manual" will fail
to come up correctly.

2) If a bridge fails to come up with the inet manual directive the
dhclient for br_ext_prim also dies after receiving one lease.

Reservation on #1 that this could probably also be true with an "inet static" interface for a bridge configured as "inet manual". 

Both of the above works 100% fine in 18.04.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to ifupdown in Ubuntu.
https://bugs.launchpad.net/bugs/1874515

Title:
  20.04 does not bring up certain bridges

Status in ifupdown package in Ubuntu:
  New

Bug description:
  After upgrading from a fully patched ubuntu-server 18.04 to 20.04 and
  rebooting I noticed that some of my bridge interfaces defined in
  /etc/network/interfaces would not come up while others would.

  Bridges brought up at boot:

  br_ext_prim
  br_ext_sec
  br_int_50
  br_nat

  Bridges missing:

  br_int_500
  br_nat_ext

  Relevant log from 18.04 prior to upgrade:

  Apr 23 19:11:37 fancy systemd-udevd[725]: Could not generate persistent MAC address for br_nat_ext: No such file or directory
  Apr 23 19:11:37 fancy systemd[1]: Found device /sys/subsystem/net/devices/br_nat_ext.
  Apr 23 19:11:37 fancy systemd[1]: Started ifup for br_nat_ext.
  Apr 23 19:11:37 fancy systemd-networkd[2284]: br_nat_ext: Link UP
  Apr 23 19:11:37 fancy sh[2383]: Waiting for br_nat_ext to get ready (MAXWAIT is 5 seconds).
  Apr 23 19:11:37 fancy kernel: [    9.447538] br_nat_ext: port 1(int0.51) entered blocking state
  Apr 23 19:11:37 fancy kernel: [    9.447540] br_nat_ext: port 1(int0.51) entered disabled state
  Apr 23 19:11:37 fancy systemd-networkd[2284]: br_nat_ext: Gained carrier
  Apr 23 19:11:37 fancy kernel: [   10.942682] br_nat_ext: port 1(int0.51) entered blocking state
  Apr 23 19:11:37 fancy kernel: [   10.942683] br_nat_ext: port 1(int0.51) entered forwarding state
  Apr 23 19:11:37 fancy kernel: [   10.943270] IPv6: ADDRCONF(NETDEV_CHANGE): br_nat_ext: link becomes ready
  Apr 23 19:11:39 fancy systemd-networkd[2284]: br_nat_ext: Gained IPv6LL

  Relevant log from 20.04 after upgrade:

  Apr 23 19:39:52 fancy ifup[1845]: br_nat_ext: ERROR while getting interface flags: No such device
  Apr 23 19:39:52 fancy ifup[1066]: ifup: failed to bring up br_nat_ext
  Apr 23 19:40:04 fancy libvirtd[1935]: Cannot get interface MTU on 'br_nat_ext': No such device
  Apr 23 19:40:04 fancy libvirtd[1935]: internal error: Failed to autostart VM 'dns': Cannot get interface MTU on 'br_nat_ext': No such device
  Apr 23 19:43:43 fancy libvirtd[1935]: Cannot get interface MTU on 'br_nat_ext': No such device
  Apr 23 19:39:52 fancy systemd[1]: networking.service: Main process exited, code=exited, status=1/FAILURE
  Apr 23 19:39:52 fancy systemd[1]: networking.service: Failed with result 'exit-code'.
  Apr 23 19:39:52 fancy systemd[1]: Failed to start Raise network interfaces.

  Similar logs show up for br_int_500.

  Some examples of entries of /etc/network/interfaces:

  Not working:

  # NAT via main FW
  auto int0.51
  iface int0.51 inet manual
         vlan-raw-device int0
         pre-up ifconfig $IFACE up
         post-down ifconfig $IFACE down

  auto br_nat_ext
  iface br_nat_ext inet manual
          bridge_ports int0.51
          bridge_maxwait 5
          pre-up ifconfig $IFACE up
          post-down ifconfig $IFACE down

  Working:

  # 1GE
  auto ext0.10
  iface ext0.10 inet manual
          vlan-raw-device ext0
          pre-up ifconfig $IFACE up
          post-down ifconfig $IFACE down

  # Secondary bridge 1GE
  auto br_ext_sec
  iface br_ext_sec inet manual
          bridge_ports ext0.10
          bridge_maxwait 5
          post-up ifconfig $IFACE up
          post-down ifconfig $IFACE down

  Output from syslog in regards to br_ext_sec after upgrade:

  Apr 23 19:39:52 fancy systemd-udevd[1366]: br_ext_sec: Could not generate persistent MAC: No data available
  Apr 23 19:39:52 fancy kernel: [   24.353151] br_ext_sec: port 1(ext0.10) entered blocking state
  Apr 23 19:39:52 fancy kernel: [   24.353156] br_ext_sec: port 1(ext0.10) entered disabled state
  Apr 23 19:39:52 fancy systemd-networkd[620]: br_ext_sec: Link UP
  Apr 23 19:39:52 fancy ifup[1538]: Waiting for br_ext_sec to get ready (MAXWAIT is 5 seconds).
  Apr 23 19:39:52 fancy kernel: [   24.360953] br_ext_sec: port 1(ext0.10) entered blocking state
  Apr 23 19:39:52 fancy kernel: [   24.360956] br_ext_sec: port 1(ext0.10) entered forwarding state
  Apr 23 19:39:52 fancy systemd[1]: Found device /sys/subsystem/net/devices/br_ext_sec.
  Apr 23 19:39:52 fancy systemd[1]: Started ifup for br_ext_sec.
  Apr 23 19:39:52 fancy sh[1547]: ifup: waiting for lock on /run/network/ifstate.br_ext_sec
  Apr 23 19:39:52 fancy sh[1547]: ifup: interface br_ext_sec already configured
  Apr 23 19:39:53 fancy systemd-networkd[620]: br_ext_sec: Gained carrier

  No changes applied to /etc/network/interfaces between boots. No complaints from upgrade process otherwise.

  Attaching a slightly redacted interfaces file from the system in the
  ticket aswell.

  Thanks :)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1874515/+subscriptions