xen domU net working problems
pinging to domU often get package loss, and sometime get timeout
but pinging to dom0 always normally

when dom0 rebooted, all domUs' network recovered 

but I can not always reboot dom0,

is there some one kindly to help me to resolved this problem,

partial system logs from dom0

    

        avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv4 with address 67.215.231.210.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv4 for mDNS.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: Registering new address record for fe80::230:48ff:fef0:751 on eth1.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv6 with address fe80::230:48ff:fef0:751.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv6 for mDNS.
        Jan  5 07:15:52 vps3 avahi-daemon[5001]: Registering new address record for 172.16.103.131 on eth0.
        Jan  5 07:15:52 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth0.IPv4 with address 172.16.103.131.
        Jan  5 07:15:52 vps3 avahi-daemon[5001]: New relevant interface eth0.IPv4 for mDNS.
        Jan  5 07:15:49 vps3 avahi-daemon[5001]: Registering new address record for fe80::230:48ff:fef0:750 on eth0.
        Jan  5 07:15:49 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::230:48ff:fef0:750.
        Jan  5 07:15:49 vps3 avahi-daemon[5001]: New relevant interface eth0.IPv6 for mDNS.
        Jan  5 07:15:48 vps3 kernel: 8021q: adding VLAN 0 to HW filter on device eth0
        Jan  5 07:15:48 vps3 kernel: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth1.IPv6 no longer relevant for mDNS.
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth1.IPv6 with address fe80::230:48ff:fef0:751.
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for 
    
    fe80::230:48ff:fef0:751 on eth1.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth1.IPv4 no longer relevant for mDNS.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth1.IPv4 with address 67.215.231.210.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for 67.215.231.210 on eth1.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth0.IPv6 no longer relevant for mDNS.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::230:48ff:fef0:750.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for fe80::230:48ff:fef0:750 on eth0.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth0.IPv4 no longer relevant for mDNS.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth0.IPv4 with address 172.16.103.131.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for 172.16.103.131 on eth0.
    Jan  5 07:10:03 vps3 avahi-daemon[5001]: Registering new address record for 67.215.231.210 on eth1.
    Jan  5 07:10:03 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv4 with address 67.215.231.210.
    Jan  5 07:10:03 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv4 for mDNS.
    Jan  5 07:10:02 vps3 avahi-daemon[5001]: Registering new address record for fe80::230:48ff:fef0:751 on eth1.
    Jan  5 07:10:02 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv6 with address fe80::230:48ff:fef0:751.
    Jan  5 07:10:02 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv6 for mDNS.
    Jan  5 07:10:01 vps3 avahi-daemon[5001]: Registering new address record for 172.16.103.131 on eth0.
    Jan  5 07:10:01 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth0.IPv4 with address 172.16.103.131.
    Jan  5 07:10:01 vps3 avahi-daemon[5001]: New relevant interface eth0.IPv4 for mDNS.


xen domU net working problems
===

pinging to domU often get package loss, and sometime get timeout
but pinging to dom0 always normally

when dom0 rebooted, all domUs' network recovered 

but I can not always reboot dom0,

is there some one kindly to help me to resolved this problem,

partial system logs from dom0

    

        avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv4 with address 67.215.231.210.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv4 for mDNS.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: Registering new address record for fe80::230:48ff:fef0:751 on eth1.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv6 with address fe80::230:48ff:fef0:751.
        Jan  5 07:15:53 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv6 for mDNS.
        Jan  5 07:15:52 vps3 avahi-daemon[5001]: Registering new address record for 172.16.103.131 on eth0.
        Jan  5 07:15:52 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth0.IPv4 with address 172.16.103.131.
        Jan  5 07:15:52 vps3 avahi-daemon[5001]: New relevant interface eth0.IPv4 for mDNS.
        Jan  5 07:15:49 vps3 avahi-daemon[5001]: Registering new address record for fe80::230:48ff:fef0:750 on eth0.
        Jan  5 07:15:49 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::230:48ff:fef0:750.
        Jan  5 07:15:49 vps3 avahi-daemon[5001]: New relevant interface eth0.IPv6 for mDNS.
        Jan  5 07:15:48 vps3 kernel: 8021q: adding VLAN 0 to HW filter on device eth0
        Jan  5 07:15:48 vps3 kernel: igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth1.IPv6 no longer relevant for mDNS.
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth1.IPv6 with address fe80::230:48ff:fef0:751.
        Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for 
    
    fe80::230:48ff:fef0:751 on eth1.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth1.IPv4 no longer relevant for mDNS.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth1.IPv4 with address 67.215.231.210.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for 67.215.231.210 on eth1.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth0.IPv6 no longer relevant for mDNS.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::230:48ff:fef0:750.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for fe80::230:48ff:fef0:750 on eth0.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Interface eth0.IPv4 no longer relevant for mDNS.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: iface.c: interface_mdns_mcast_join() called but no local address available.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Leaving mDNS multicast group on interface eth0.IPv4 with address 172.16.103.131.
    Jan  5 07:15:44 vps3 avahi-daemon[5001]: Withdrawing address record for 172.16.103.131 on eth0.
    Jan  5 07:10:03 vps3 avahi-daemon[5001]: Registering new address record for 67.215.231.210 on eth1.
    Jan  5 07:10:03 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv4 with address 67.215.231.210.
    Jan  5 07:10:03 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv4 for mDNS.
    Jan  5 07:10:02 vps3 avahi-daemon[5001]: Registering new address record for fe80::230:48ff:fef0:751 on eth1.
    Jan  5 07:10:02 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth1.IPv6 with address fe80::230:48ff:fef0:751.
    Jan  5 07:10:02 vps3 avahi-daemon[5001]: New relevant interface eth1.IPv6 for mDNS.
    Jan  5 07:10:01 vps3 avahi-daemon[5001]: Registering new address record for 172.16.103.131 on eth0.
    Jan  5 07:10:01 vps3 avahi-daemon[5001]: Joining mDNS multicast group on interface eth0.IPv4 with address 172.16.103.131.
    Jan  5 07:10:01 vps3 avahi-daemon[5001]: New relevant interface eth0.IPv4 for mDNS.

