[radvd-devel-l] Advertise different router?

STARNES, CURTIS Curtis.Starnes at granburyisd.org
Wed Jun 1 09:20:18 EDT 2011

In your Cisco router make sure the 'M' and 'O' flags are both set.

ipv6 nd managed-config-flag
ipv6 nd other-config-flag

The managed-config-flag - 'M' flag tells the router to use a DHCP server.
The other-config-flag - 'O' flag tells the router to send the "Other" DHCP configuration options set in the DHCP scope, including the DNS servers.

If you use radvd to send out the advertisements, then the RA's will originate from the radvd box and then the clients will believe that the radvd box is the router.

I am running the M and O flags set in our Cisco sup720/msfc3 core to deliver the RDNSS information in the DHCP packets.
I am also using the ipv6 dhcp relay destination command in the above Cisco config to request ipv6 DHCP addresses across VLAN's.


-----Original Message-----
From: radvd-devel-l-bounces at litech.org [mailto:radvd-devel-l-bounces at litech.org] On Behalf Of Dyonisius Visser
Sent: Wednesday, June 01, 2011 3:10 AM
To: radvd-devel-l at litech.org
Subject: [radvd-devel-l] Advertise different router?

Hi guys

I am in the process of setting up an IPv6 only network.
I have a dedicated VLAN for this, and assigned a /64 to it.
Our Cisco 3750 sends RAs on this network.

I have set-up a VM with Ecdysis to do nat64, and installed bind-9.8.0 to do dns64. Installed dibbler as well on this VM to do DHCPv6.

So far it seems to work great, Windows 7 and iOS can connect and everything (except Skype) works fine.

Now it would also like to have RFC5006 RDNSS being announced in the RAs.
Unfortunately our Cisco does not support that.

So my idea was to run radvd on the VM, so that does the RAs, and stop doing it on the Cisco.

However radvd advertises the prefix but with itself as the router. This works, but now all traffic is going through the VM, which is not what I want, since we Cisco has native IPv6.

Maybe I'm asking a totally stupid question, but is it possible for radvd to advertise a prefix with a different router? In my case I would like radvd to announce the prefix with the Cisco as the router.

If this can work, I would 'only' have to run two autoconfiguration systems.


Dyonisius Visser
System & Networking Engineer
TERENA Secretariat
Singel 468 D, 1017 AW Amsterdam
The Netherlands
T +31 20 530 44 88 F +31 20 530 44 99
visser at terena.org | www.terena.org

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