Re: BIRD ripng default gateway route strange behavior

29 Apr 2015


      Follow up : Nobody has ideas about that ?
On Apr 18, 2015 7:14 PM, "olivier a" <oatech7402@gmail.com> wrote:
...
Hello all ^^
I'm puzzled with a really weird RIPng default gateway propagation problem.
I don't quite understand what's happening. Here is what happens ...
Network topology :
PC1---Router1---Router2----InternetGateway---z
RIPng enabled on PC1, Router1, Router2
Router2 has a static IPv6 DG ( Default Gateway ) to InternetGateway
Router1 has no static IPv6 DG, and no kernel{learn} directive.
Router2=Ubuntu14.04 LTS, Router1=raspbian Wheezy, bird = last version,
compiled from sources
...
link-local addresses replaces with symbolic names ( ie [fe80::Router1] )
Something really strange seems to happen :
. Router2 gets this routing table :
default via InternetGateway dev eth0  proto static  metric 1
default via [fe80::Router1] dev eth1  proto bird  metric 1024
But Router1 isn't announcing any IPv6 DefaultGateway, just ::/0 metric 16
( ie it is poisoning the route ).
( I checked using Wireshark ).
Is there a bug that transforms a received "::/0 metric 16" into a
"default via [fe80::Router1] dev eth1  proto bird  metric 1024" route ?
Here is Router2 bird6.conf file :
-------------------------------------------------
log syslog all;
debug protocols all;
#log stderr all;
#log "tmp" all;
router id 192.168.4.1;
protocol kernel {
learn;
scan time 20;
export all;
import all;
}
protocol direct {
#interface "eth0";
}
protocol device {
scan time 10;
}
protocol rip {
debug all;
port 521;
interface "*" { mode multicast; ttl security on; };
honor neighbor;
authentication none;
import all;
export all;
}
-------------------------------------------------------------
I managed to solve the problem, by having Router2 drop incomming ::/0
announcements :
---------------------------------------------------------
import filter {   # This block filters ::/0 in
                if net ~ [ ::/0 ] then
                        reject "ripng:rejected:DG";
                else
                        accept "ripng:accepted:not-DG";
        };
export all;
---------------------------------------------------------
the problem is solved, yet it puzzles me.
This is really strange. Does anybody understand what is happening ??