How can IPv6 clients find servers such as NTP, SIP

Question

For IPv6, I understand clients may get an address either statelessly using SLAAC, or statefully using DHCPv6 (although I hear Android doesn't support address assignment via DHCPv6).

My question is, for clients that configure their IPv6 address via SLAAC, what is the way for a network to push other network configuration to them? Can they get such configuration through Router Advertisements, or must the network also deploy DHCPv6 for clients to get this extra information (but not get their IPv6 address)? Eg:

• DNS server
  • I hear RFC 6106 - IPv6 Router Advertisement Options for DNS Configuration is intended to provide a way for communicating DNS servers. In practice, do Windows, Linux, Android, iOS clients use RA or DHCPv6 to find IPv6 DNS servers?
• NTP server
  • I have found a draft for NTP advertising through Router Advertisements. But this draft was not accepted, I guess. So do clients need to find an NTP server via DHCPv6?
• SIP server
  • Do clients need to use DHCPv6 option 21 or 22? Is there any Router Advertisement equivalent?
• Vendor-specific protocols
  • DHCPv6 has option 16 and option 17 for vendor-specific information, which could be used by a client to find a vendor-specific server on a network, if the DHCPv6 administrator has configured it. Is there any Router Advertising equivalent?

If DHCPv6 is the only way to get this sort of server info, is it reasonably straight-forward to configure a client to get its address via SLAAC, and then get this extra configuration via DHCPv6?

Answer 1

DNS can be taken care of by router advertisements, but as for all other options, you're basically stuck with DHCP. However, a stateless DHCPv6 server is one valid deployment, where the DHCPv6 server doesn't track IP assignments, but only advertises services to hosts in the network, and let's SLAAC configure IP addresses.

Options seem to pretty much identical: http://www.networksorcery.com/enp/protocol/dhcpv6.htm

RA seems to only allow you to send basic IP information and the default gateway, DNS might be possible but nothing more.

So TL;DR;

Your options are to either use stateful DHCPv6, which works exactly as DHCPv4, or you can use stateless DHCPv6, which uses SLAAC to do IP configuration, and as such is much more lightweight.