在IPv4网络中，arping是一款用户态用来探测host link-layer address的常用工具；
在IPv6网络中，同样有一款类似的工具ndisc6, 用来探测链路上任意node的link-layer address,
接下来简单介绍下如何安装及使用ndisc6这款工具。
sudo yum install ndisc6 -y
Usage: ndisc6 [options] <IPv6 address> <interface>
Looks up an on-link IPv6 node link-layer address (Neighbor Discovery)
-1, --single display first response and exit
-h, --help display this help and exit
-m, --multiple wait and display all responses
-n, --numeric don’t resolve host names
-q, --quiet only print the link-layer address (mainly for scripts)
-r, --retry maximum number of attempts (default: 3)
-s, --source specify source IPv6 address
-V, --version display program version and exit
-v, --verbose verbose display (this is the default)
-w, --wait how long to wait for a response [ms] (default: 1000)
ndisc6 240e:1:2:3::1 eth0