[Olsr-users] olsrd (and earlier) ipv6 problems

Henning Rogge (spam-protected)
Tue Mar 25 08:24:23 CET 2014


what kind of IPv6 addresses are assigned on bridges and interfaces
before and after you change the connectivity?

OLSRd use nearly the same codepaths for IPv4 and IPv6, so I expect
there is some "outside event" that triggers this behavior.

Henning Rogge

On Mon, Mar 24, 2014 at 11:44 PM, Russell Senior
<(spam-protected)> wrote:
> We have a network of around 60 nodes, running olsrd (and
> earlier) in a hub and spoke topology, primarily over openvpn tunnels.
> The nodes are running recent trunk openwrt, the hub is a gentoo box.
> The nodes are a mixture of ar71xx, x86 and brcm47xx devices.  We
> provision ipv6 to the nodes through hurricane electric 6in4 tunnel to
> the well-connected hub machine, and then statically provising /64's to
> each of the nodes and let olsrd manage the routing tables.  We also
> run an ipv4 olsrd in parallel.
> Recently, we encountered our first node that had its own native ipv6
> upstream, which is preferable (as it takes the traffic load off our hub
> box).  To avoid routing confusion, we ultimately turned olsrd ipv6 off
> on that node.  Around the same time, we noticed that some of our nodes
> seemed to lose their ipv6 routing.  When I checked the routing tables
> on our hub machine (e.g. "ip -6 r"), all I saw were the local routes.
> I have a set of devices in a test-bed in my basement where I checkout
> newly built images where I have serial console.  My basement network
> has its own ipv6 network through a separate hurricane electric tunnel.
> I noticed that if I unplugged one of the devices in my test-bed, the
> hub machine gradually (over about 30-60 seconds) got all its ipv6
> routes back.  When I plugged in the test-device, boom, in 10-15
> seconds, the hub machine's ipv6 routing table collapsed again.  Unplug
> it, the routes come back.
> Meanwhile, the ipv4 routing table is steady as a rock.
> Eventually, I discover that an openwrt uci option ip6assign seems to
> be causing trouble, and I disable it.  Meanwhile the same image at
> another site does not appear to be causing any trouble, perhaps
> because it does not have an upstream ipv6 network?
> Then a few days ago, I look and notice that all (or virtually all) the
> ipv6 routes are gone from our hub machine again.  This time, I go to
> another of my test-bed devices and turn off the ipv6 olsrd there, and
> after 30-60 seconds the routes all come back again.  This time it is
> an x86 device (an alix2).
> Does this sound at all familiar?  Any suggestion where to start looking?
> --
> Russell Senior, President
> (spam-protected)
> --
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