Pong 是什么？见文末~
在写程序代码、运维时经常会使用ping测试连通性，成功时也会看到一个返回值Pong
为什么不返回success呢，如果不了解ICMP协议就不能窥探原因。
下面看看返回Pong的示例：
一、使用java中的Jedis类连接Redis测试时：
Jedis 是 Redis 官方首选的 Java 客户端开发包。
1.测试连通性
public class Demo01 {
public static void main(String[] args) {
//连接本地的 Redis 服务
Jedis jedis = new Jedis("127.0.0.1",6379);
//查看服务是否运行，打出pong表示OK
System.out.println(jedis.ping());
}
java中使用jedis测试连通性返回值pong
二、使用Ansible运维时：
检查指定节点机器是否还能连通，用法很简单，不涉及参数，主机如果在线，则回复pong
[root@localhost ~]# ansible erp -m ping
192.168.10.6 | SUCCESS => {
"changed": false,
"ping": "pong"
}
192.168.10.7 | SUCCESS => {
"changed": false,
"ping": "pong"
}
ping = protocol ICMP, type 8(request), code 0
pong = protocol ICMP, type 0(reply), code 0
Ping is a computer network application used to test whether a particular host is reachable across an IP
network. It is also used to self-test the network interface card of the computer or as a latency test. It works
by sending ICMP “echo reply” packets to the target host and listening for ICMP “echo reply” replies. The
“echo reply” is sometimes called a pong. Ping measures the round-trip time, records packet loss, and
prints a statistical summary of the echo reply packets received (the minimum, maximum, and the mean of
the round-trip times and in some versions the standard deviation of the mean).
参考连接
http://gaia.cs.umass.edu/kurose_ross/programming/Python_code/ICMPping.pdf
