linux 策略路由问题！！！

规则如下：
  ip route add 10.10.0.0/16 via 10.254.254.1 table int1 proto static 
  ip route add throw 0/0 table int1 proto static 
  ip route add 172.18.0.0/16 via 172.17.1.1 table int2 proto static 
  ip route add throw 0/0 table int2 proto static 
  ip route add 0/0 via 172.17.1.254 table main proto static 
  ip rule add pref 15000 table int1 iif eth1 
  ip rule add pref 15001 table int2 iif eth2 
  ip rule add pref 15002 to 10.10.0.0/16 table int1 
  ip rule add pref 15003 to 172.18.0.0/16 table int2

ip route add throw 0/0 table int1 proto static 大侠 这句是什么意思？

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throw 和策略规则(policy rule)一块使用的控制路由。如果选择了这种路由，就会认为没有发现路由，在这个表中的查询就会被终止。没有找到策略路由就相当于在路由表中没有找到路由，数据包会被丢弃，并产生ICMP信息net unreachable。本地发送者会返回ENETUNREACH错误。
  The throw route type is a convenient route type which causes a route lookup in a routing table to fail, returning the routing selection process to the RPDB. This is useful when there are additional routing tables. Note that there is an implicit throw if no default route exists in a routing table, so the route created by the first command in the example is superfluous, although legal.