dhcpv6 on windows server 2008 r2 not sending replies when request is via dhcpv6-relay from router
The environment: - W2K8-R2 Enterprise as VMware clients on same physical server (1 each of retail and vl) and another as a completely standalone computer - Win7 Pro computers (VMclient and standalones) - HP 5400 & 3500 switches configured for IPv6, OSPFv3 routing, and dhcpv6 relay/helper. W2K8-R2 servers configured basically for IPv6 only, and AD, DNS and DHCPv6 services (mainly only using DHCPv6, no IPv4 scopes at all) If I connect a Win7 pro computer to the same subnet (vlan10) as the server, the client will get a dhcpv6 addr as expected. If I connect the Win7 pro client to a different subnet (vlan20) of the switch, the client never gets an IPv6 addr. I can see the switch sending the appropriate dhcpv6 relay-forward request to the server. Using 'netsh int ipv6 sh udp' I see the server is receiving the requests, if I look in the dhcp services appl/ipv6/display statistics I _do not_ see any "solicit" messages coming in. I have verified the communications via wireshark are at least destined to the correct devices. I have read all the posts/blogs here in TechNet and other places on the topic and tried the various netsh config options to no avail. Now, if I use the same dhcpv6 config on a W2K8 (also VMclient, but not R2) server, it works. Additionally, if I use a dibbler dhcpv6 server, it also works. So I am confident that the client and switch configs are working correctly. So my question is, why? I suspect something slightly different between original W2K8 and W28K-R2, as there are a few differences in the netsh options and the IPv6 exclusion configures slightly different. Anyone have any ideas? Thanx...Jeff btw, I accept this could be a case of "clueless Jeff", so don't be afraid to "clue me in" - hahahajeff carrell
September 9th, 2010 8:49pm

Hi, Thank you for your post here. From the description, you have the issue: 1. Windows Server 2008R2 IPv6 DHCP server a. Windows 7 client can get the IP lease when it is in VLAN10 b. Windows 7 client cannot get the IP lease when it is in VLAN20 A Windows Server 2008 DHCP server works well for both VLANs. Since you can verify that there does have relay-forward request to the 2008R2 DHCP server even when the client resides in the VLAN20. I would like to know if there is any difference in the relay-forward requests between from the VLAN10 client (the good one) and from the VLAN20 client (failed one). You can install network monitor tool on the Windows Server 2008R2 DHCP server and capture two copy of the DHCP request and try to find out the difference literally if there is any. By the way, which VLAN is the Windows Server 2008R2 server connected?
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September 10th, 2010 11:11am

Thanx :-) Oops, sorry I wasn't clear about that (too close to it all). The 2008R2 server is in VLAN10. Therefore the dhcp request from the client is "local" when the client is also connected to VLAN10. (no relay-forward by switch) When the client is in VLAN20 and the switch is configured for dhcpv6-relay in VLAN20, and the switch in fact sends the relay request to VLAN10, that is when the server appears to receive the request, but does not reply back. hth...Jeffjeff carrell
September 10th, 2010 5:17pm

Hi, Have you install the following update on the Windows Sever 2008 server? You may paste the captured DHCP relay traffic for further investigation. A DHCPv6 server that is running Windows Server 2008 may drop the DHCP relay-forwarded packets if these packets contain some unknown options http://support.microsoft.com/kb/972962
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October 8th, 2010 3:02am

Thanx for the reply. No, I have not tried this update, as I am running W2K8-R2, not (just) W2K8. Nothing in the doc indicates that the problem is (also) in W2K8-R2. However, I will try it. Regards...Jeffjeff carrell
October 18th, 2010 12:42am

I am having the same issue with my 2008r2 server. Did you ever figure this out?
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December 21st, 2010 4:01pm

I am sorry I did not post the final resolution to the problem I had. My problem was actually related to the code on the HP (ProCurve) switch. If you are running any of the ProVision ASIC switches (3500, 5400, 6200, 6600, 8200) then obtain K.15.04.0003 (which was very recently posted) and DHCPv6 relay now operates correctly. hth...Jeffjeff carrell
May 15th, 2011 9:06pm

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