LVS
lvs-users
Google
 
Web LinuxVirtualServer.org

Re: [lvs-users] LVS-NAT dropping connection occasionally at random

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] LVS-NAT dropping connection occasionally at random
From: Jesse Cantara <jesse_cantara@xxxxxxxxxxxx>
Date: Fri, 20 Jul 2007 15:44:25 -0400
Just an update:

This might be a hardware/driver issue. I'm having basically the exact 
same problem when attempting to use IPTABLES on the director just as a 
simple NAT router to one webserver (trying to isolate the problem), and 
I still get the exact same behavior (connection closes randomly). So the 
problem doesn't appear to be limited to IPVS anyway.

The machine I'm using for the director/router is a Dell 860 with a 
Broadcom NetXtreme BCM5721 with the "Tigon3" (tg3.ko) driver.

I don't mean to dissuade anybody with any thoughts or ideas they might 
have though :)

-Jesse

Joseph Mack NA3T wrote:
> On Fri, 20 Jul 2007, Jesse Cantara wrote:
> 
> Hi Jesse,
>       Thanks for the complete problem report. I'm leaving 
> your whole post here so Julian sees it.
> 
>> Hello,
> 
> Hi Julian,
>       Is this a problem with the masquerading code below 
> ip_vs()? If so it seems hard to imagine no-one else has seen 
> it.
> 
>> I'm trying to figure out a problem I'm having with my LVS-NAT setup.
>> It's a very simple setup, one director, two networks (director has two
>> nics, one on lan one on internet), three webservers on LAN only on port
>> 80. The issue I'm having is occasionally and randomly the director will
>> apparently just sever the connection when trying to download a file from
>> the webserver. I have performed these tests just fine without issue:
>> 1) Downloading a file directly from the director to a client
>> 2) Downloading a file from the webserver to the director
>>
>> So it would appear that the physical connection is OK, I can make
>> connections to the individual machines without problem, just when
>> connecting through the director to the webserver.
>>
>> What happens is I will be downloading a file, and it will hang (at
>> random points during the download, sometimes not at all), and not continue.
>>
>> ipvsadm will show "ESTABLISHED" on that connection for quite a long
>> time, then "ERR!" after it times out I believe.
>>
>> Watching the traffic on a packet-sniffer client-side shows that directly
>> before the failure, my client keeps sending the same "ack" message back
>> to the server over and over, and the server appears to not recognize it.
> 
> we had a problem a little like that a while ago and I can't 
> remember if it was fixed or not (most likley we didn't fix 
> it).
> 
>> It must be related, but it makes me question where the problem is: the
>> exact same sort of problem happens when I set up IPTABLES to forward a
>> port on the director to one of the webservers directly. I'm not sure if
>> I'm barking up the wrong tree asking on this mailing list, but hopefully
>> somebody has run into something similar before, or can at least point me
>> in the right direction :)
> 
> no this is the place to ask.
> 
> Joe
> 
>> Here is the config of my machines:
>> CentOS 5
>> latest kernel 2.6.18-8.1.8.el5
>> ipvsadm v1.24
>> IPVS v1.2.0
>>
>> I'm not doing anything "fancy" with the webserver, just downloading a
>> large file for test, from apache. Like I said, the webservers work fine
>> when accessing not through the director.
>>
>> If there's anything I have missed, I apologize. Please let me know
>> anything else that I should provide for information.
>>
>> Thanks in advance,
>> -Jesse
>>
>>
>> _______________________________________________
>> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
>> Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
>> or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>>
> 



<Prev in Thread] Current Thread [Next in Thread>