Re: Unable to forward packets

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Unable to forward packets
From: Joseph Mack NA3T <jmack@xxxxxxxx>
Date: Wed, 22 Feb 2006 05:13:33 -0800 (PST)
On Tue, 21 Feb 2006, Bill Omer wrote:

I'm doing the following

my short answer it that I don't know what's wrong. You're going to have to figure it out and tell us so I can put it in the HOWTO. However here's some comments

The server running lvs with eth0 being its rip and the vip is bound to

aliased ethernet devices have been deprecated since 2.4.0. They may or may not work in your situation, but we don't know and we aren't going to debug it.

ipvsadm -A -t lvs-vip:23 -s wlc
ipvsadm -a -t lvs-vip:23 -r test-rs -g
echo 1 > /proc/sys/net/ipv4/ip_forward
route add -host dev eth0:0

This is guaranteed to give unpredictable results.

On the box I'm calling test-rs, I'm doing the following
ifconfig lo:0 lvs-vip netmask broadcast lvs-vip up
echo 1 >/proc/sys/net/ipv4/ip_forward
route add -host lvs-vip dev lo:0

I don't know why people run this last route command. They say that it makes their machines work. I've never needed it.

You're also running a RedHat kernel. You're going to have to look on the archives to see if it works. It probably does, but we only support the standard kernel here. There are plenty of people running market enhanced kernels with LVS. You can always go back to your RH kernel after you get it to work with the standard kernel.

lo:0      Link encap:Local Loopback
         inet addr:  Mask:
         UP LOOPBACK RUNNING  MTU:16436  Metric:1
         RX packets:15 errors:0 dropped:0 overruns:0 frame:0
         TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:0
         RX bytes:900 (900.0 b)  TX bytes:0 (0.0 b)

To troubleshoot this, I'm running 'tcpdump -ln port 23'    on the lvs server
and the test-rs machine.  On the lvs server, I get the following when I try
to telnet to the vip from a 3 machine

I assume a 3 machine is your client.

21:14:04.278916 > S
2084871663:2084871663(0) win 5840 <mss 1460,sackOK,timestamp 101529036
0,nop,wscale 0> (DF) [tos 0x10]
21:14:04.278929 > S
2084871663:2084871663(0) win 5840 <mss 1460,sackOK,timestamp 101529036
0,nop,wscale 0> (DF) [tos 0x10]

so you can't get there. Any firewall rules?

nfs-101$ telnet lvs-vip
telnet: connect to address No route to host
telnet: Unable to connect to remote host: No route to host

you can't get there. I'd look at routing or firewall rules first.


Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at Homepage It's GNU/Linux!

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