[ubuntu] udp packets goes through old default route

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http://ubuntuforums.org – Hello everybody! The problem is: I've got ubuntu server machine with 2 eth interfaces ex: eth0, eth1. eth0-internet, eth1-lan. And also I've got pptp connection to internet connection through eth0. In iptables I've got two nat rules for both eth1->ppp, eth1->eth0(reason: if ppp connection died). In eth1 network I've got audiocodes mp-201 VoIP to analog adapter. It uses external voip server, through nat with UDP packets. Point of problem: if my pptp connection drops for some reason packets from mp-201 starts to go through eth0 iface, and after pptp reconnects voip stop working becaus (Hardware)