Hi, On Sun, May 05, 2013 at 06:53:50PM +0100, Robert Bradley wrote: > On 05/05/13 16:59, Juliusz Chroboczek wrote: > >>Robert bradley has been working on making atomic route updates work > >>and possibly better route cache flushing. > >[...] > >>get the patchset from: git://github.com/rb12345/babeld.git > >While it hasn't rained yet, I've looked at the code. > > > >1. The commit "Atomic route modification in kernel_netlink" contains > >both the atomic route modification code and code for flushing the > >routing cache. I'd like the two to be separated. (I can do that if > >you want, Robert, and leave your name as the original author of the > >commit.) > > Yes, that's fine. I think that the cache-flushing part may not be > needed anyway. > > >4. Is the cache flushing still needed with Baptiste's patch? I'd > >rather not be tweaking /proc files at runtime. > > > >-- Juliusz > > I think the cache flushing is a misunderstanding on my part. I > added the cache flushing since > http://linux-ip.net/html/linux-ip.html and > http://lartc.org/howto/lartc.rpdb.html appeared to imply it might be > needed after local route updates. Looking at the iproute2 manpages > closely though, it appears that it is only needed if source-policy > rules ("ip rule" equivalents) are involved. Without source-policy > rules, cache flushing looks to be completely unnecessary. > > The only interaction between this and Baptiste's patch is that the > emptier caches mean it has fewer routes to filter out. >
Today I had some time to play with this code and 1.4.0. In my simple/stupid/silly ? test case it performed worse. The Babel 1.4.0 running on Ubuntu 13.04 / Linux 3.8.0 generic amd64 can detect when 2 way communication is not possible. But the one at https://github.com/rb12345/babeld does not do this. It will just keep sending traffic to a gateway that can't receive any traffic. I looked if there is any other change between 1.4.0 and the other code and there was one, but it didn't improve things. ___ Ignore IPv6 routing cache on linux 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). https://github.com/jech/babeld/commit/73d8f6621425c624864e63df98c7e49893da09a3 ___ My test-case is: I create 2 VMs with 2 NICs eth1 and eth2 (eth0 is the 3rd NIC for SSH) and connect them to 2 networks. Then I run these commands: (i'm impatient so my intervals are really low) On both VMs: ifconfig eth1 up ifconfig eth2 up ./babeld - -u -d 1 -H 0.3 -C redistribute proto 4 eth1 eth2 (proto 4 is static) on VM1: ip -6 addr add 2001:200::1/64 dev lo ping6 -i 0.1 -n 2001:200::2 on VM2: ip -6 addr add 2001:200::2/64 dev lo Then with tcpdump I check on what interface traffic is coming in. If it's eth2 I drop incoming traffic on eth2: ip6tables -I INPUT -i eth2 -j DROP It detects it as a failed 2-way communication and the routes in the VMs change to reflect that. Then I run: iptables -F INPUT #flush all ip6tables -I INPUT -i eth1 -j DROP Again it detects it as a failed 2-way communication and the routes in the VMs change to reflect that. I hope this is useful to you. Have a nice weekend, Leen. > -- > Robert Bradley > > > _______________________________________________ > Babel-users mailing list > [email protected] > http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users _______________________________________________ Babel-users mailing list [email protected] http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users
