[radvd-devel-l] Multiple IPv6 Routers

[Pekka Savola]

On Fri, 26 Nov 2010, Iain J. Watson wrote:
> Also, when I hard power-off one of the routers to simulate a failure I
> can no longer ping in either direction. If I run radvdump on either of
> the test servers I see nothing being received. If I then restart radvd
> on the remaining router I become able to ping again.

Some thoughts:

  1) please note that your client OS may not support high/low 
preferences.
  2) the amount of time it takes to remove a dead default gw is 
governed by AdvDefaultLifetime which you have not set.
  3) AdvReachableTime might help but than again it might not. RFC4861 
also specifies how the client should delete non-working neighbors or 
routers, but I have not tested this myself.

To get more accurate info on what is happening, you will need to look 
at the routing and neighbor table (/sbin/ip -6 r l, n l) and tcpdump 
-e (the MAC addresses used).

Your remainder point about having to restart radvd on the remaining 
router is likely a combination of 1) and 2) but it could also be a bug 
(and more radvd debug log could be useful).

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings