[dhcwg] Clarification of RFC3315 : using multiple IA_NAs within one DHCPv6 Message

ip admin <ipmanx@googlemail.com> Tue, 08 December 2015 20:44 UTC

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Date: Tue, 08 Dec 2015 21:44:50 +0100
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Subject: [dhcwg] Clarification of RFC3315 : using multiple IA_NAs within one DHCPv6 Message
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Dear all,

 (please let me know if I’m supposed to submit this somewhere else)

 is DHCPv6 supposed to be used to assign  multiple IPs to a client by using
multiple IA_NAs within one DHCP message?

 For example is it possible to assign both Unique Local and Global Unicast
IPs at the same time via DHCP? Assigning multiple IPs from the same scope
(e.g. multiple Global Unicast IPs) might also be useful to support
renumbering (as SLAAC does).

 While RFC 3315 mentions that there might be multiple IA_NA options within
a DHCP message it does not explicitly mention if a client is supposed to
include multiple IA_NA options to request multiple IPs. On the other side
it’s unclear what a server should do if the client does include multiple
IA_Nas but the server has only one scope to satisfy the request – should it
assign two IPs with the same prefix or ignore all but one IA_NA?

 RFC 3315 mentions explicitly the co-existence of IA_NA and IA_TA in one
DHCP message, e.g. in section 17.1.1

“Either IA_NA or IA_TA options, or a combination of both, can be included
in DHCP messages.”

 which IMHO means that a client might at least get both a permanent and a
temporary IP at the same time.

 However I do not find any references that confirm that shared networks -
two prefixes on the same (V)LAN – should be possible.

 Any pointers to clarify this are welcome.

Thanks & Regards
 Thomas