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CPE IPv6 Issue

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  • 1.  CPE IPv6 Issue

    Posted 08-06-2018 05:23



    I expect this is not the right place to ask this question but thought someone may have seen a similar issue before.


    I don't necessarily think that it is the CPE at fault here, but you all know the layout, I think, but here it is again from an end laptop perspective:


    Laptop LAN --> CPE LAN - CPE WAN --> SRX340 --> Core --> Upstream ISP.


    If I ping, for example, facebook IPv6 address from SRX340, it all works fine. If I ping facebook IPv6 from the CPE it works fine. If I try and ping from the Windows 10 laptop I cannot even ping the WAN interface on the CPE. When I complete an "ipconfig" on the Laptop, I notice that the IPv6 address given is not even in the range or derivative of the WAN assigned address.


    The CPE is a Draytek Vigor 2860 and I have configured it as per their manual for IPv6.


    If anyone has come across this type of error before, would be good to know how you resolved it.


  • 2.  RE: CPE IPv6 Issue

    Posted 08-06-2018 06:13

    Check if delegated prefix is installed for dhcp client cpe. After that you need enable slacc or dhcp server in cpe lan though I think It should be automatic.

  • 3.  RE: CPE IPv6 Issue
    Best Answer

    Posted 08-06-2018 07:46

    Hi Hugleo,


    As an add on, because this is the Ethernet Core side, I am manually configuring the device (as we will have to initially before they are sent out).


    So, the static WAN address is a /126 so that it can have the same prefix as the SRX340 CPE Facing interface. As I mentioned, if I ping any internet address from the WAN of the CPE it is all working perfectly. So, I looked up the draytek IPv6 LAN config page here:



    Which seems to involve PD but then, I don't normally deal with the CPE end points. The guy that does is back tomorrow so maybe he knows.


    There is an entry area where I have defined the /56 and then CPE should automatically assign the /64s from this /56 as per the DHCPv6-PD auto config on the CPE. But, as I mentioned, it is assigning some strange, unknow address range.... hence why the laptop cannot communicate with the outside World... 😞


  • 4.  RE: CPE IPv6 Issue

    Posted 08-06-2018 08:37

    As always. after a little investigation I have found a little more information.


    The laptop has several "preferred" addresses, of which one of them (from a wireshark trace) is the one it is using and it is an old address. Now just need to figure out how to clear these addresses and use the new one.

  • 5.  RE: CPE IPv6 Issue

    Posted 08-07-2018 01:54

    I cleared the preferred addresses and set DHCPv6 but the laptop is not getting an address from the DHCPv6 enabled Draytek CPE.


    As I can ping everywhere on the internet from the CPE WAN interface, then it proves the working SRX340. So, I can close this as resolved from that perspective. I shall work on with the CPE.