Re: [lvs-users] LVS Setup interfering with connection to other server?

To: "' users mailing list.'" <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] LVS Setup interfering with connection to other server?
From: "Dan Brown" <danb@xxxxxx>
Date: Sat, 28 Jun 2008 10:22:38 -0600
Ah damn nevermind.  I should have spotted this much much earlier but I've
been banging my head on the problem too long.  I just realized that when I
do this:
# ip addr sh lo
    inet brd scope global secondary lo:110
    inet brd scope global secondary lo:111
    inet brd scope global secondary lo:114
    inet brd scope global secondary lo:122
    inet brd scope global secondary lo:003
    inet brd scope global secondary lo:004
    inet brd scope global secondary lo:005
    inet brd scope global secondary lo:006

I should be having the network mask of /32 on everything. :P

Dan Brown

> -----Original Message-----
> From: lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx [mailto:lvs-users-
> bounces@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Dan Brown
> Sent: Saturday, June 28, 2008 09:11
> To: ' users mailing list.'
> Subject: [lvs-users] LVS Setup interfering with connection to other
> server?
> I have a server which I recently migrated a number of sites to and
> subsequently could not connect to a mail list server running mailman
> after
> doing the move.   The problem appears to be caused by the new server
> although I can't figure out why.  I discovered that when the new server
> is
> up and running:
> 1. The maillist server itself cannot reassign itself it's IP address.
> I
> restarted the network interfaces and I get the following:
> [root@iris rc.d]# /etc/init.d/network restart
> Shutting down interface eth0:                              [  OK  ]
> Shutting down interface eth1:                              [  OK  ]
> Shutting down loopback interface:                          [  OK  ]
> Setting network parameters:                                [  OK  ]
> Bringing up loopback interface:                            [  OK  ]
> Bringing up interface eth0:  Error, some other host already uses
> address
>                                                            [FAILED]
> Bringing up interface eth1:                                [  OK  ]
> Awesome eh?  As it happens, the router says the MAC address it is the
> same
> as the server it is supposed to be, even after rebooting the router.
> Why
> would the new server be arp'ing for a server it has no configuration
> for?
> If I assign the interface using:
> ifconfig eth0 netmask broadcast
> up
> it comes up normally.
> 2. The new server is part of the LVS system and has a couple of hundred
> IPs
> on its loopback interface (via DR for, and
> the real IP is on the network block  It cannot
> connect
> to the server in problem 1 when those IPs are in place.  When the
> address is
> assigned, no other servers (almost all part of the LVS) have any
> problems at
> all connecting to it.  Just this one server.  Originally it had some
> arptable rules about not responding to that IP address but that has
> since
> been removed.  It has never had a loopback entry for the IP itself.
> The IP
> of the server itself is on a different network but it's all behind the
> same
> router.  The server is:, the maillist server is
> For some reason, it appears the server is connecting to itself.  A
> tcpdump
> on the loopback address shows:
> 08:15:24.808782 IP > S
> 1356583672:1356583672(0) win 32767 <mss 16396,sackOK,timestamp 50190198
> 0,nop,wscale 2>
> 08:15:24.909467 IP > R
> 0:0(0)
> ack 1356583673 win 0
> None of the other LVS real servers I've setup are having this problem,
> and
> there are no problems connecting to any of the sites on the server...
> so
> what did I miss this time?
> ___________________________________________________
> Dan Brown
> danb@xxxxxx
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