[ipv6hackers] Win7 - no managed flag, DHCP address released?!?

Enno Rey erey at ernw.de
Wed Nov 7 22:32:45 CET 2012


I can confirm this. built a test lab with three (Cisco) routers emitting RAs and a DHCP server. one router emitting RAs with at times O, at times M flag set.
"DHCP based" info (prefix in case of M flag, DNS server in case of O flag) got lost once RA from one of the routers emitting RAs_without_flags received. Win7 clients, (Cisco) default prefix/address lifetime (30/7 days).



On Fri, Oct 19, 2012 at 12:33:28AM +1100, Karl Auer wrote:
> [I sent this to the IETF list and they suggested I repost it here.]
> I have just seen the following demonstrated.
> Two routers, short RA interval, both sending RAs for the same prefix,
> both with the autoconf flag set, one with the managed flag set and one
> without.
> A Windows 7 host gets an address via DHCPv6 when the RA with the managed
> flag comes around - and DROPS IT when an RA without the managed flag
> comes past.
> This is not the valid lifetime expiring normally. I was not able to
> determine whether the Windows host is actually sending a DHCPv6 release
> as well, but it is most certainly dropping the address from the
> interface.
> I will be trying to do my own tests to confirm (or not) this behaviour,
> but has anyone else seen it? Or seen it with other operating systems?
> If it is indeed happening, this behaviour seems very badly broken to me.
> I don't feel the relevant RFCs can reasonably be interpreted as
> supporting this behaviour.
> Regards, K.
> -- 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Karl Auer (kauer at biplane.com.au)
> http://www.biplane.com.au/kauer
> http://www.biplane.com.au/blog
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> Old fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687
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