Re: [lvs-users] No Application data in LVS

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] No Application data in LVS
From: Michael Schwartzkopff <misch@xxxxxxxxxxx>
Date: Mon, 26 Nov 2007 12:22:19 +0100
Am Montag, 26. November 2007 12:01 schrieb Graeme Fowler:
> On Mon, 2007-11-26 at 11:49 +0100, Michael Schwartzkopff wrote:
> > TCP Syn, Syn ACK, ACK (3-way handshake) works. So NAT shold work in my
> > environment.
> You should see the following at the client - CIP is client IP, VIP is
> virtual IP, DIP is director IP, RIP is realserver IP:
> then several packets transferring data - the request and the response.
> It appears your problem stems from the fact that the client is seeing a
> response from the RIP, not the VIP. I'm surmising a bit at this point
> because I can't see, nor have you described, your network layout.

All communication of course with the virtual IP. No response from the DIP. IF 
I tcpdump on the real server I see the same (!) packets, except NATed IP 

Real client (

Director on xen
Two IP addresses on eth0: and
Routing to the attached nets and default route.

Real Server on XEN
one IP address on eth0
Routing to the attached net and a default route back to the director.

> The client should normally see *nothing* from the DIP or RIP. If it
> does, it's not working properly.


> What do you see on the director and the realserver at the same time? Is
> the realserver responding directly to the client? Come to that, is the
> realserver's default gw set to be the director?

tcpdump on the real server shows the same packets except for the translated 
NAT Addresses.

I think the problem is in some other direction. 
- NAT works. 3 way handshake pooves that.
- Applikation data are sent back from the real server to the client.
- Applikation data are received on the network interface on the client. 
Prooven by tcpdump.
- Somehow these applikation data are not proceeded further on in the network 
stack of the client.

Thanks for further ideas.

Dr. Michael Schwartzkopff
MultiNET Services GmbH
Addresse: Bretonischer Ring 7; 85630 Grasbrunn; Germany
Tel: +49 - 89 - 45 69 11 0
Fax: +49 - 89 - 45 69 11 21
mob: +49 - 174 - 343 28 75

mail: misch@xxxxxxxxxxx

Sitz der Gesellschaft: 85630 Grasbrunn
Registergericht: Amtsgericht München HRB 114375
Geschäftsführer: Günter Jurgeneit, Hubert Martens


PGP Fingerprint: F919 3919 FF12 ED5A 2801 DEA6 AA77 57A4 EDD8 979BSkype: 

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