06-30-2016 02:28 PM - edited 03-01-2019 05:51 PM
Hi!,
I am slightly confused as to what IP to use in the Neighbor Solicitation (NS) as the source and in the Neighbor Advertisement packet (NA) as the destination.
If the client is requesting for the MAC of a specific IPv6 address, it sends an NS out destined to the Solicited Multicast Address, but which one of its two IPs (Global Unicast Address or Link Local Address) should it use? Same question applies for DAD and IND.
The internet shows examples for both cases: NS packets sourced from an LLA and a Global Unicast Address.
Best Regards
Daniel Seijas
CCNA
07-01-2016 04:53 PM
Hi Daniel,
RFC 4861 Section 7.2.2 says:
If the source address of the packet prompting the solicitation is the same as one of the addresses assigned to the outgoing interface, that address SHOULD be placed in the IP Source Address of the outgoing solicitation. Otherwise, any one of the addresses assigned to the interface should be used.
This description is somewhat hard to digest, so let's do an example: Assume that your interface has a link-local IPv6 address of FE80::1 and a global address 2001:DB8:1:1::1/64. Now, assume you have a data packet whose next hop (perhaps the final destination, perhaps just the nearest router) is the IPv6 address X, and you need to translate X into its MAC address. This packet is not a Neighbor Solicitation itself , but because of this packet, you need to send a Neighbor Solicitation for X. Now:
Best regards,
Peter
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide