[Babel-users] [PATCH] Ignore IPv6 routing cache on linux

[Dave Taht]

On Wed, Apr 24, 2013 at 2:31 AM, Baptiste Jonglez
<baptiste.jonglez at ens-lyon.fr> wrote:
> Recent linux kernels (roughly 3.x) keep a routing cache for IPv6: each
> time a host is contacted, a temporary /128 route is added. These
> routes are visible using “ip -6 route show cache”.
>
> Asking babeld to redistribute all IPv6 routes known to the host, using
> "redistribute ip ::/0", causes it to announce and de-announce these
> /128 routes frequently, leading other nodes to mark them as
> unreachable (thus preventing communication with the host described by
> the /128 route, even though less specific routes are available).
> ---
>  kernel_netlink.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/kernel_netlink.c b/kernel_netlink.c
> index 0a85009..fc6519b 100644
> --- a/kernel_netlink.c
> +++ b/kernel_netlink.c
> @@ -1106,6 +1106,10 @@ filter_kernel_routes(struct nlmsghdr *nh, void *data)
>      if(rtm->rtm_src_len != 0)
>          return 0;
>
> +    /* Ignore cached routes, advertised by some kernels (linux 3.x). */
> +    if(rtm->rtm_flags & RTM_F_CLONED)
> +      return 0;
> +
>      if(data)
>          current_route = &routes[*found];
>      else
> --
> 1.8.2.1

I am a little confused here, the routing cache was eliminated in linux
as of version 3.6, I believe. Does this happen on 3.6 and later? (sure
if the above fixes it for older kernels, goferit)

>
>
> _______________________________________________
> Babel-users mailing list
> Babel-users at lists.alioth.debian.org
> http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users



-- 
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html