Hi, during testing with failover of the default gateways we found out the following: /proc/sys/net/ipv4/route/gc_timeout is some sort of timeout value, after which the kernel declares a route to be dead. What is the setup: We have a system that is connected with two NIC's to a switch. These NIC's are in the same lan, but carry different networks: A host with two nics on a switch: ip link set dev eth0 up ip link set dev eth1 up ip addr add 192.168.1.10/24 dev eth0 ip addr add 192.168.2.10/24 dev eth1 ip route add default via 192.168.1.1 ip route add default via 192.168.2.1 echo 0 > /proc/sys/net/ipv4/conf/eth0/rp_filter echo 0 > /proc/sys/net/ipv4/conf/eth1/rp_filter A single router configuration (from a failover cluster): ip link set dev eth0 up ip addr add 192.168.1.1/24 dev eth0 ip addr add 192.168.2.1/24 dev eth0 As long as everything works, you will reach 192.168.2.10 through eth1, and 192.168.1.10 through eth0. If you unplug one of the two devices (simulating a dead nic), it will take some time plus gc_timouet (in seconds) for linux to declare one of the two default gateways as dead, and to start to use the other default gateway. As long as your source address is not within 192.168.1.0/24 or 192.168.2.0/24, the kernel must use a default gateway, and therefore your link will be redundant. Setting gc_timeout to 10 seconds gave us a failover time of about 110 seconds for existing connections. I did not look at the timers of the router etc, so that also is important. -- <ard@telegraafnet.nl> Telegraaf Elektronische Media http://wwwijzer.nl http://leerquoten.monster.org/ http://www.faqs.org/rfcs/rfc1855.html Let your government know you value your freedom. Sign the petition: http://petition.eurolinux.org/
