修改IP头部校验的计算方式加速路由器转发速率

Recall that the checksum in the IPv4 header covers only the header (i.e., it does not cover any data in the IP packet) and is recomputed at each IP hop (required because the IPv4 TTL field is decremented by routers when the datagram is forwarded). ————《TCP IP Illustrated, Vol1》 p476

ipv4的头部校验每跳都要重新计算，是因为TTL会发生变化，那么能不能直接忽略TTL来计算头部校验？

首先发生bit flip的概率就很低，再发生到TTL字段就更低了。即使是最高位反转，最多也是增加128跳的寿命。