Решил следующим способом:
написал скрипт:
set iface up-script /usr/local/up.sh

---cat /usr/local/up.sh ---
#!/bin/sh
iface1=`/sbin/ifconfig |grep -A 1 ng | grep -B 1 *.*.*.194 | grep ng | awk '{print $1}' | sed s/://`
route add *.*.*.224/29 -interface "$iface1"
iface2=`/sbin/ifconfig |grep -A 1 ng | grep -B 1 *.*.*.195 | grep ng | awk '{print $1}' | sed s/://`
route add *.*.*.216/29 -interface "$iface2"
iface3=`/sbin/ifconfig |grep -A 1 ng | grep -B 1 *.*.*.196 | grep ng | awk '{print $1}' | sed s/://`
route add *.*.*.212/30 -interface "$iface3"