LVS
lvs-users
Google
 
Web LinuxVirtualServer.org

Re: [LVS-TUN] Squid boxes and connections?

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [LVS-TUN] Squid boxes and connections?
From: Johan van den Berg <vdberj@xxxxxxxxxxx>
Date: Thu, 06 Jan 2005 13:23:19 +0200
Joseph Mack wrote:

Janno de Wit wrote:
- How can I see if connectiontable is full? `dmesg` gives no output.

hmm, don't know. probably you can get it with ipvsadm.

I would really like to find this out too! How do I know if packets or connections are being lost or if something malfunctions, or if the connection table is full?

In my scenario I have LVS-NAT for incoming connections into my cluster, and IPTABLES SNAT outgoing. Now, if none of my servers need to initiate a connection to the outside, then the IPTABLES connection table should be clear, and LVS-NAT table contain entries of all incoming connections. This it actually does, except every now and again, a client would try to establish a connection to the cluster, and IPVS would store the SYN in the IPVS connection table, but the SYN/ACK from the server would be NATted through IPTABLES, as if the original SYN never existed. This would result in the wrong IP on the director being used for the SYN/ACK, meaning the client would respond with a RESET, and resend its SYN to the original IP, as if connection was never established. This happens about once every two days, and then only for a few minutes. One can actually see a SYN in the IPVS connection table that just stays like that until it times out, and an equivalent SYN/ACK using netstat for the response.

I can only assume that some or other limit was reached in one of the connection tables, or that something else went berzerk, but as nothing is reported in syslog or klog, and I couldn't figure out how to find out exactly what I should otherwise be looking at.

Any further advice would be appreciated.

Joe
--

Joseph Mack PhD, High Performance Computing & Scientific Visualization
LMIT, Supporting the EPA Research Triangle Park, NC 919-541-0007
Federal Contact - John B. Smith 919-541-1087 - smith.johnb@xxxxxxx


---------------------------------------------------------------------------
This message (and attachments) is subject to restrictions and a disclaimer. Please refer to http://www.unisa.ac.za/disclaimer for full details.
---------------------------------------------------------------------------
<<<<gwavasig>>>>
<<<< gwavasig >>>>




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