Re: Ultramonkey Ping problem

On Thu, Dec 21, 2006 at 06:00:57PM +0100, Lars Roland wrote:
> Hi all
> 
> I have just configured a Debian SpamAssassin cluster according to the
> "Streamline High Availability and Load Balancing" topology
> (http://www.ultramonkey.org/3/topologies/sl-ha-lb-eg.html), but I am
> having some IP/VIP problems. My IP setup is:
> 
> ----
> VIP 10.10.20.10
> Director_1/real_1: 10.10.20.11
> Director_2/real_2: 10.10.20.12
> ----
> 
> The problem is that I can ping director_1 from director_2 but not the
> other way aound, thus since I use ping as check method, director 1
> shows director_2 as down i.e.
> 
> ----
> TCP  10.10.20.10:783 wlc
>  -> 10.10.20.11:783              Local   1      0          460
>  -> 10.10.20.12:783              Route   0      0          0
> ----
> 
> If I however run the following on director_1
> 
> ----
> ipvsadm -e -t 10.10.20.10:783 -r 10.10.20.12 -w 1
> ----
> 
> then ipvsadm shows
> 
> ----
> TCP  10.10.20.10:783 wlc
>  -> 10.10.20.11:783              Local   1      0          460
>  -> 10.10.20.12:783              Route   1      0          24
> ----
> 
> and it begins routing traffic successfully (i.e. spamassassin on
> 10.10.20.12 (director_2) receives connections). I can however still
> not contact director_2 directly from director_1 i.e.
> 
> ----
> telnet 10.10.20.12 783
> ----
> 
> gives no reply, I am running kernel 2.6.18 and I have configured
> sysctl according to the article in order to fix the Linux arp problem.
> I hope some one has an idea on what is wrong, because I am in the
> blind here.

That is quite curious. I guess that the best thing to do is
to use tcpdump or similar to try and debug the problem.
Is 10.10.20.11 seeing packets from 10.10.20.12,
does it send a reply packet?

If you have ipvs enabled on one host, it really ought
to be disabled on the other host (at that time). 
But I don't think that is the cause of the problem.

I wonder if for soem reason 10.10.20.11 is sending packets to
10.10.20.12 with 10.10.20.10 as the source address, which
is valid for it to do. This would explain the problem.

-- 
Horms
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/


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