$ cat /etc/network/interfaces
auto eth0
iface eth0 inet dhcp
hwaddress 52:54:00:12:34:00
auto eth1
iface eth1 inet manual
bond-master bond0
bond-mode active-backup
hwaddress 52:54:00:12:34:02
auto eth2
iface eth2 inet manual
bond-master bond0
bond-mode active-backup
hwaddress 52:54:00:12:34:04
auto bond0
iface bond0 inet static
gateway 10.0.2.1
address 10.0.2.68/24
bond-mode active-backup
hwaddress 52:54:00:12:34:06
bond-slaves none
$ ls -altr --full-time /var/log/upstart/*net*
-rw-r----- 1 root root 433 2015-09-04 17:56:38.984656000 +0000 /var/log/upstart
/procps-static-network-up.log
-rw-r----- 1 root root 114 2015-09-04 18:20:32.470715000 +0000 /var/log/upstart
/network-interface-eth2.log
-rw-r----- 1 root root 114 2015-09-04 18:20:32.470715000 +0000 /var/log/upstart
/network-interface-eth1.log
-rw-r----- 1 root root 1025 2015-09-04 18:20:32.614715000 +0000 /var/log/upstart
/network-interface-eth0.log
-rw-r----- 1 root root 119 2015-09-04 18:20:32.678715000 +0000 /var/log/upstart
/network-interface-bond0.log
-rw-r----- 1 root root 140 2015-09-04 18:20:38.578715000 +0000 /var/log/upstart
/networking.log
$ ls -altr --full-time /run/network
total 4
-rw-r--r-- 1 root root 0 2015-09-04 18:20:32.334715000 +0000 .ifstate.lock
-rw-r--r-- 1 root root 0 2015-09-04 18:20:32.554715000 +0000 ifup.lo
-rw-r--r-- 1 root root 0 2015-09-04 18:20:32.654715000 +0000 ifup.eth0
-rw-r--r-- 1 root root 0 2015-09-04 18:20:32.726715000 +0000 ifup.eth2
-rw-r--r-- 1 root root 0 2015-09-04 18:20:32.738715000 +0000 ifup.eth1
-rw-r--r-- 1 root root 0 2015-09-04 18:20:38.562715000 +0000 ifenslave.bond0
-rw-r--r-- 1 root root 36 2015-09-04 18:20:38.566715000 +0000 ifstate
drwxr-xr-x 2 root root 180 2015-09-04 18:20:38.566715000 +0000 .
drwxr-xr-x 19 root root 660 2015-09-04 18:27:11.814474704 +0000 ..
$ sudo sh -c 'for f in /var/log/upstart/network*; do echo == $f ==; cat $f; done'
== /var/log/upstart/network-interface-bond0.log ==
Waiting for a slave to join bond0 (will timeout after 60s)
RTNETLINK answers: File exists
Failed to bring up bond0.
== /var/log/upstart/network-interface-eth0.log ==
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/eth0/52:54:00:12:34:00
Sending on LPF/eth0/52:54:00:12:34:00
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0xd771ca6a)
DHCPREQUEST of 10.0.2.15 on eth0 to 255.255.255.255 port 67 (xid=0x6aca71d7)
DHCPOFFER of 10.0.2.15 from 10.0.2.2
DHCPACK of 10.0.2.15 from 10.0.2.2
bound to 10.0.2.15 -- renewal in 41583 seconds.
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/eth0/52:54:00:12:34:00
Sending on LPF/eth0/52:54:00:12:34:00
Sending on Socket/fallback
DHCPREQUEST of 10.0.2.15 on eth0 to 255.255.255.255 port 67 (xid=0x2e935a0d)
DHCPACK of 10.0.2.15 from 10.0.2.2
bound to 10.0.2.15 -- renewal in 36046 seconds.
== /var/log/upstart/network-interface-eth1.log ==
Waiting for bonding kernel module to be ready (will timeout after 5s)
Waiting for bond master bond0 to be ready
== /var/log/upstart/network-interface-eth2.log ==
Waiting for bonding kernel module to be ready (will timeout after 5s)
Waiting for bond master bond0 to be ready
== /var/log/upstart/networking.log ==
sh: echo: I/O error
Waiting for a slave to join bond0 (will timeout after 60s)
RTNETLINK answers: File exists
Failed to bring up bond0.