[Xen-users] Re: Problem setting up LVS (Linux Virtual Server) in Xen Virtual

["Andersen, Erling " <erling.andersen@xxxxxxxxxxxxxxx>]

I'm seeing the same problem running the LVS load-balancer and a couple of real 
servers as virtual machines. My setup is based on Ubuntu 6.10.

However, the problem only appears when the load-balancer and the real servers 
are running on the same physical machine (dom0). When migrating the 
load-balancer live to another physical computer on the same subnet, the network 
traffic all of a sudden starts to work! This leads me to believe there is a 
problem with the bridge in dom0. There are some indications on this in the 
document http://en.opensuse.org/Xen3_and_a_Virtual_Network which discusses 
moving the bridge/router to a virtual machine.

I'm not a bridge expert and do not understand why the brouter setup in the 
document above would be necessary. Is there some way to make our setup with the 
bridge in dom0 work?

-Erling

Original posting:

To:  xen-users@xxxxxxxxxxxxxxxxxxx 
Subject:  [Xen-users] Problem setting up LVS (Linux Virtual Server) in Xen 
Virtual Machine 
From:  cifroes <cifroes@xxxxxxxxxx> 
Date:  Mon, 06 Nov 2006 19:29:22 +0000 

Hi all,


I'm trying to setup 3 virtual machines, 1 with LVS (Linux Virtual Server) 
load-balancing and 2 with Tomcat+Axis (webserver and stuff). 


I'm using openSUSE 10.1 (xen 3.0.2) in all VMs and Dom0. rcSuseFirewall is 
stopped, iptables -l report everything "accept"'ing. 

Here's my IP configuration:
http://pwp.netcabo.pt/pformoso/network.gif

You can see there are 3VMs running.


In the LB virtual machine I configure Linux Virtual Server (ipvsadm):
ipvsadm -A -t 192.168.200.180:8080 -s rr
ipvsadm -a -t 192.168.200.180:8080 -r 192.168.200.185:8080 -m
ipvsadm -a -t 192.168.200.180:8080 -r 192.168.200.190:8080 -m

I also set ip_forward:
echo "1" > /proc/sys/net/ipv4/ip_forward


Then, in dom0 I try my LVS:
lynx http://192.168.200.180:8080
but I only get "making http connection to xxxx..."


Tomcat logs in both VMs don't report the connection.
TCP sniffer in VM10/20 reports:
Capturing on eth0

1 0.000000 192.168.200.150 -> 192.168.200.185 TCP 44000 > http-alt [SYN] Seq=0 
Ack=0 Win=5840 Len=0 MSS=1460 TSV=19301554 TSER=0 WS=2 2 0.009607 
192.168.200.185 -> 192.168.200.150 TCP http-alt > 44000 [SYN, ACK] Seq=0 Ack=1 
Win=5792 Len=0 MSS=1460 TSV=19273803 TSER=19301554 WS=2 3 0.009658 
192.168.200.150 -> 192.168.200.185 TCP 44000 > http-alt [RST] Seq=1 
Ack=4283853535 Win=0 Len=0 


TCP sniffer in LB reports:

1 0.000000 192.168.200.150 -> 192.168.200.180 TCP 44000 > http-alt [SYN] Seq=0 
Ack=0 Win=5840 Len=0 MSS=1460 TSV=19301554 TSER=0 WS=2 2 0.009344 
192.168.200.150 -> 192.168.200.185 TCP 44000 > http-alt [SYN] Seq=0 Ack=0 
Win=5840 Len=0 MSS=1460 TSV=19301554 TSER=0 WS=2 




Any ideas why this doesn't work? How should I do it? Any tutorial/howto help is 
appreciated. 


Thanks in advance,
--cifroes

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