RS or NS?

[LanceLee]

for a host directly connected to a router in a IPv6 network, should it be using NS or RS IPv6message to find out the MAC address of that router?

[Martin L]

RS is send by PC, Router replies with RA

NS is similar to ARP in IPv4

see Stateless address autoconfig https://en.wikipedia.org/wiki/Neighbor_Discovery_Protocol

Regards, ML
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[Giuseppe Larosa]

Hello @LanceLee ,

the host can use the RS message to trigger an RA. Then it can use the NS process to resolve the MAC address of the router.

The main property of the NS process managed by ICMPv6 is that it is able to provide MAC address resolution without using frames with a broadcast destination at MAC level. The "query" message is sent using a multicast ethernet address that has the last less significant 24 bits equal to the last significant 24 bits of the IPv6 address for which the resolution is taking place.

When I studied IPv6 for the first time I was puzzled about this. It was hard to believe it was possible to perform address resolution without using broadcast.

Hope to help

Giuseppe