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DHCP relay agent IPv6 RRS feed

  • Question

  • Hello,

    I would like to have some help setting up an ipv6 dhcp relay agent in our network. Unfortunately, (AND I DON'T KNOW FOR WHAT REASON) when I configure the dhcp relay agent (on Windows Server 2008-R2), the address for the DHCP server MUST be a GLOBAL ipv6 address.

    Well, in our INTRANET, we use "ipv6 unique local addresses" as it should be (NO?). So the DHCP server is sitting in one of those FD01:.... networks and not on the INTERNET and has an address of FD01:101:101:2::2.

    Q1: why (suddenly) the DHCP server must have a GLOBAL address in order to be relay-able by a Microsoft Windows Server 2008-R2 Relay Agent?

    Q2: because this is not changeable, how would YOU do it?

    Thank you in advance!


    Thomas.

    Friday, June 22, 2012 6:39 AM

Answers

  • Bad news: replying to myself...

    Good news: "silently" MS fixed this in Windows server 2012-R2 (see attachment).

    - I do not know why since +5  years (w2008, w2008-R2, w2012) this wasn't working

    - Why this is not on the "new features" list for 2012-R2 then?

    Sad & frustrated about the time spent to try to figure out why this wasn't working, without success...


    Thomas.

    • Marked as answer by Thomas M.T. _ Friday, November 22, 2013 6:25 PM
    Friday, November 22, 2013 6:25 PM

All replies

  • Is everything else working properly with Unique Local Addressing only in place?  Default routes are correct?  Router advertisements?

    If yes, then I'd guess it was a Microsoft 'lazy code checking" type bug.

    “The validity of link-local addresses is limited to a single link; e.g. to all computers connected to a switch, or to one wireless network. Hosts on different sides of a bridge are also on the same link, whereas hosts on different sides of a router are on different links.”
    All Link Local Addresses are of the form,
    FE80::/10

    So if they only check for the 'F' portion of the address (rather than FE80) and then reject..  Or possibly checking for 2800 prefix and rejecting all others.

    Either way, your simplest solution is to give the systems needing them valid global addresses as well.


    Tuesday, July 3, 2012 1:56 PM
  • Hi,

    Yes, everything else works perfectly.

    I don't know why you wrote all that stuff regarding link.local addresses? This is out of the scope of the question.

    I'm not looking for the simplest solution but to understand an unpredictable message...

    The "Q2: because this is not changeable, how would YOU do it?" question should be read like "..." + with ULAddresses...

    Please see attachment...

    DHCPv6 Relay Agent WANTS DHCPv6 Server to use GLOBAL Addresses...

    DHCPv6 Server accepts Unique Local Addresses and works just fine on the locally attached subnet...


    Thomas.






    Tuesday, July 3, 2012 2:19 PM
  • BTW: Just checked in Windows Server 2012. Same story.

    Why? Because!

    I think I have to get along with that....


    Thomas.

    Thursday, July 12, 2012 9:22 AM
  • A long time since this thread is open.
    Still do not know why the DHCPv6 server MUST have global addresses in order to be relay-able by a Microsoft Windows Server 2008-2 or 2012 RTM relay agent...

    If someone knows the guy @ MS who decided this, it would be nice to forward this question.

    Thanks.


    Thomas.

    Thursday, November 22, 2012 6:39 PM
  • Hi Thomas --

    No disrespect intended, but it looks like your address is a couple of fields short. Your Unique Unicas address set breaks down to:

    prefix: FD

    random Global ID: 0101010101

    subnet: 0002

    CID: FD01:0101:0101:0002::64

    That looks fine, as you indicate. It's the node number I'm not so sure about. I'm pretty sure that you have to put the all of the separators in even when collapsing all 4 zeros in a field. Try entering:

    FD01:0101:0101:0002::::2

    Let me know if it works --

    Robert

    Wednesday, March 27, 2013 12:53 AM
  • Hi, it wants a "global ipV6" not a "local unique ipV6" address or anything else as the target dhcp server's address, anyhow you might write it... and I still do not know why.

    When I think that one person @ MS programmed this and wrote the error message and there is no one since month to give an answer??? It must be a big secret... Starting to wonder if it's dangerous to ask...

    Thanks.


    Thomas.


    Wednesday, March 27, 2013 2:00 PM
  • Hi Thomas --

    One detail I forgot about when replying -- what subnet is your relay agent on? Being an RRAS box, shouldn't it be multihomed to the 0002 subnet and also to another subnet (0003 or something)? It should be listening for DHCPv6 Solicit messages on the reserved local multicast FF02:0:0:0:0:1:2 on the (not the 0002) subnet and relaying them to the DHCPv6 server on the 0002 subnet, yes?

    BTW -- this subject is of great interest to me -- I have a 150-subnet test lab that needs IPv6 with central address management and the lack of an IP Helper-like capability in v6 is a real show stopper --

    Tnx!

    Robert

    Wednesday, March 27, 2013 7:29 PM
  • Yes, the network setup was correct. After having changed all the addressing to IpV6 GLOBAL addresses, I was able to configure the DHCP Relay Agent that worked as expected (expected, except the Global Address Space requirement for the relay setup).


    Thomas.

    Thursday, March 28, 2013 9:44 AM
  • Interesting...   I am having a similar issue....  A Cisco 10K CMTS hasn no problem relaying FDF8, but an Arris C4 CMTS reports it is and illegal relay address..

    Friday, April 12, 2013 1:05 PM
  • Having the same problem on a Windows Server 2012 Essentials.
    I also do not understand why it is not possible to connect to a DHCP server with a "local unique ipV6" address.

    Thomas, means that that you got an IPv6 range from your ISP (or from a tunnel broker) which are you using now?

    Thursday, May 9, 2013 12:03 AM
  • Bad news: replying to myself...

    Good news: "silently" MS fixed this in Windows server 2012-R2 (see attachment).

    - I do not know why since +5  years (w2008, w2008-R2, w2012) this wasn't working

    - Why this is not on the "new features" list for 2012-R2 then?

    Sad & frustrated about the time spent to try to figure out why this wasn't working, without success...


    Thomas.

    • Marked as answer by Thomas M.T. _ Friday, November 22, 2013 6:25 PM
    Friday, November 22, 2013 6:25 PM
  • Oh yes... It does. But in wrong way as usual.

    Finally we can assing DHCP server with unique local IPv6 (fc00/7) as target of DHCP v6 relay agent. But it anyway doesn't work in Win 2016/2019.

    DHCP v6 relay agent still relay DHCP request only from 2000::/3

    With any other addresses it doesn't work. For example:

    CLI(FD50::/64) <--> [FD50::10 + DHCP v6 RA] RRAS [FD51::10/64] <--> [FD51::20] DHCPv6 SRV

    FD51::20 is specified as target of DHCPv6 RA

    In this config CLI[FD50:/64] send DHCPv6 requests to FF02::1:2 (which is correct) but FD50::10 doesn't have such join. It looks odd. And even wrong.

    Let's make one more config:

    CLI(3050::/64) <--> [3050::10 + DHCP v6 RA] RRAS [FD51::10/64] <--> [FD51::20] DHCPv6 SRV

    Oh shi... It is working magically... ???

    Why? Why I need use global IPv6 addresses in test labs? Why I can't use local unique addresses? Is it a bug which Microsoft missed in public releases?

    Also:

    netsh routing ipv6 relayv6 add dhcpserver

    still accepts only 2000::/3

    • Edited by ns.88.ns Monday, December 2, 2019 12:12 PM
    Sunday, December 1, 2019 11:56 PM