Hi everyone After configuring bonding eth0 and eth1 in domU, "cat /proc/net/bonding/bond0" showed it was configured correctly. ----------------------------------------------------------------------------------------- Bonding Mode: fault-tolerance (active-backup) Primary Slave: eth1 Currently Active Slave: eth1 MII Status: up MII Polling Interval (ms): 0 Up Delay (ms): 0 Down Delay (ms): 0 ARP Polling Interval (ms): 1000 ARP IP target/s (n.n.n.n form): 10.25.81.1, 10.24.22.70 Slave Interface: eth0 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:16:3e:46:90:bb Slave Interface: eth1 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:16:3e:74:81:2f ----------------------------------------------------------------------------------------------- and /etc/modprobe.conf file was edited for bonding like below ----------------------------------------------------------------------------------------------- alias eth0 xennet alias scsi_hostadapter xenblk alias eth1 xennet alias bond0 bonding #options bond0 miimon=100 mode=1 primary=eth0 options bond0 arp_interval=1000 arp_ip_target=10.25.81.1,10.24.22.70 mode=1 primary=eth1 ----------------------------------------------------------------------------------------------- When switch port which currently active slave is connected (via eth1 in dom0) was down, this domU detected eth1 was no longer connected and changed primary interface to backup slave (eth0). It was observed by /var/log/message ----------------------------------------------------------------------------------------------- kernel: bonding: bond0: changing from interface eth0 to primary interface eth1 kernel: bonding: bond0: making interface eth1 the new active one. kernel: bonding: bond0: link status down for active interface eth1, disabling it kernel: bonding: bond0: making interface eth0 the new active one. kernel: bonding: bond0: backup interface eth1 is now up ----------------------------------------------------------------------------------------------- the problem was that last message "kernel: bonding: bond0: backup interface eth1 is now up" keep repeating in domU and network did not work. At this time, I tcpdumped eth0 in dom0 and domU and showed domU keep sending/receiving arp message properly. tcpdump message in domU ----------------------------------------------------------------------------------------------- 15:32:03.592087 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:04.592047 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:04.593386 arp reply 10.25.81.1 is-at 00:00:0c:07:ac:16 15:32:05.592228 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:06.592252 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:07.592237 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:07.592810 arp reply 10.25.81.1 is-at 00:00:0c:07:ac:16 15:32:08.592456 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:09.592457 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:10.592417 arp who-has 10.25.81.1 tell 10.25.81.100 15:32:10.593041 arp reply 10.25.81.1 is-at 00:00:0c:07:ac:16 15:32:11.592588 arp who-has 10.25.81.1 tell 10.25.81.100 ----------------------------------------------------------------------------------------------- In conclusion, domU network was not working but arp networking seems working. Any guess/suggestion? Thank you in advance. System Info Xen Version : 3.4.1 Dom0 OS : Centos 5.3 x64 DomU OS : Centos 5.3 x64 _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users