Re: [Xen-users] Xen and LVS Direct Routing

["Jason Goodwin" <jason.m.goodwin@xxxxxxxxx>]

I've been experimenting with LVS under domU servers (my first LVS
experience actually). I had issues using LVS-NAT (TCP checksum errors
for any client off of the Xen server, though it worked ok from dom0) so
I switched to direct routing. It seems to work ok for me.

At the moment, I have two directors (failover using ultramonkey /
heartbeat) that are both also the webservers. I've setup the real IP of
each server on eth0. The VIP is also set on eth0 of whichever director
is active. On the failover node, the VIP is added to the loopback
address. This seems to work fine, no need for the dummy driver. The
webserver in my case is listening on all IPs, not just the real. Not
sure if I'll run things this way if I setup production servers, but it
works for testing.

I set /etc/sysctl.conf entries of the following:

net.2ipv4.ip_forward = 1
net.ipv4.conf.eth0.arp_ignore = 1
net.ipv4.conf.eth0.arp_announce = 2

The arp_ignore and arp_announce take care of making sure that the
failover server that has the VIP on it's loopback won't reply to arps
for that IP.

root@lvs1# ip addr
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1300 qdisc pfifo_fast qlen 1000
    link/ether 00:16:3e:41:51:c0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.16/24 brd 192.168.0.255 scope global eth0
    inet 192.168.0.46/24 brd 192.168.0.255 scope global secondary eth0

root@lvs2# ip addr
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet 192.168.0.46/32 brd 255.255.255.255 scope global lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1300 qdisc pfifo_fast qlen 1000
    link/ether 00:16:3e:64:34:5e brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.17/24 brd 192.168.0.255 scope global eth0


--
Jason
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