当我在 linux 上使用 ping 命令时
我得到以下输出：
ping google.com
PING google.com (216.58.205.206) 56(84) bytes of data.
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=2 ttl=128 time=490 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=3 ttl=128 time=1209 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=4 ttl=128 time=702 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=5 ttl=128 time=112 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=6 ttl=128 time=320 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=7 ttl=128 time=137 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=8 ttl=128 time=145 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=9 ttl=128 time=281 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=10 ttl=128 time=138 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=11 ttl=128 time=298 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=12 ttl=128 time=194 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=13 ttl=128 time=395 ms
64 bytes from mil04s29-in-f14.1e100.net (216.58.205.206): icmp_seq=14 ttl=128 time=124 ms
所以第一行它说大小是56字节（这是icmp数据的大小对吗？）+ 8（icmp头）+ 20（ipv4头）= 84字节，这是每个发送数据包的大小对吗？
下一行没有，它说 64 字节（数据 + icmp 标头），为什么重播时是 64 字节，为什么不是 84 字节？！
在最后一行
14 packets transmitted, 13 received, 7% packet loss, time 13607ms
时间是什么 ？以及如何计算？
问候