[LVS-TUN] Squid boxes and connections?

[Johan van den Berg]

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 at epa.gov
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>  
>


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