hi, My system is Ubuntu 13.04, kernel version is 3.8.0-21-generic, bird version is 1.3.10. In order to achieve two functions in r0: Use ecmp functions to achieve load balancing. Using iptables connmark modules in solving the problem of address overlap. I have two devices r0-1, I used the bird's ospf and ecmp function, r0 can learn from r1 to the twodefault route. As follows: default proto bird nexthop via 192.168.0.1 dev tun1 weight 3 nexthop via 192.168.0.2 dev tun2 weight 1 I use tcpdump, Ethereal found on r0 data is based per_packet forwarded to r1. But I'm on r0 configured conntrack. If I use conntrack, so my data from r0 to r1 will generate about connection problems. How do I solve it. Whether per_connection function can solve this connection problem? How to open per_connection on ubuntu system? Thanks for the help you provided earlier, thanks again ...