How to nicely make a neighbors discovery solicitation on Linux?

Solution 1:

ndisc6 -1 fe80::1234 eth0

Replace eth0 with the correct interface name, of course.

Solution 2:

Due to your requirement for this to be reflected in the kernel's neighbors, and your reluctance to install software, try ICMP echo:

ping -c 1 fe80::1234%eth0

Does not really matter what protocol you attempt, so long as it is IP based.

If you are willing to install software, nmap has discovery features. Here is a NDP only scan, output to a XML file (and stdout) which includes the link layer address:

nmap -sn -PR -oX /tmp/lladdr.xml -6 fe80::1234%eth0

Apparently, this type of nmap scan tickles the kernel to do neighbor discovery, as in testing I see it reappear under ip neigh.