[Pacemaker] Wrong system send arp reply when using IPaddr

[David Coulson]

Last movement of the ip was six days before issue when we patched and rebooted one of the nodes. 

Resource is a simple ipaddr (not ipaddr2) with an ip and net mask. Like I said, really simple config so confused :)

Sent from my iPhone

On Mar 17, 2013, at 9:01 PM, Andrew Beekhof <andrew at beekhof.net> wrote:

> On Mon, Mar 18, 2013 at 3:17 AM, David Coulson <david at davidcoulson.net> wrote:
>> First off, I'm going to preface this with the realization that what I am
>> explaining makes no sense, doesn't follow normal logic and I'm not a
>> complete idiot. I've beaten my head against a wall with this issue for two
>> days, and have made no progress, yet we've had a couple of production system
>> outages because of it.
>> 
>> Environment is a pair of IBM x-series systems in a DMZ connected to an
>> ASA5500. Each IBM box has two interfaces in a mode=4 bond connected to two
>> switches, which connected to the pri/sec firewall and are interconnected -
>> Poor man's redundancy I support. Both boxes run RHEL6.3 and Pacemaker
>> 1.1.7-6.el6-148fccfd5985c5590cc601123c6c16e966b85d14. ASA has a ARP table
>> timeout of 4hours.
>> 
>> There are about a dozen IPAddr resources in a group which are configured
>> with meta ordered="false" collocated="false" - Each is independent from a
>> service perspective, but the group makes it easy to manage them. Each box
>> runs LVS with mangle rules, then assigns fwm values for routing within LVS -
>> For whatever reason, this still requires the IP to be on the box receiving
>> the packet through LVS, even if the mangle rule is triggered.
>> 
>> We've had a couple of instances for two IPs in this configuration where
>> Pacemaker (and syslog) indicate the IP is assigned to box 01, yet the
>> firewall receives an ARP reply from box 02. Didn't believe it at first until
>> we grabbed packets from a SPAN on the switches. Correct IP address in reply,
>> MAC of one of the bonded interfaces on box 02, yet the IP isn't on it.
>> 
>> We've experienced both 01 arping for an IP on 02, and 02 arping for an IP on
>> 01. Last night when we had the issue, an IP was on 02, 01 arped for it and I
>> tcpdumped on 01 and saw SYN packets coming in for the IP on 01 - Makes
>> sense, but doesn't explain why the box answered the arp in the first place.
> 
> Had pacemaker just failed over the IP?
> Did you set any ARP related options for the resource?
> 
>> 
>> I realize this likely isn't a Pacemaker issue, but I was hoping someone else
>> might have experienced a similar issue, or can at least point me in the
>> right direction. We have a far more complex Pacemaker/LVS environment on our
>> inside network (which isn't link-local to the ASA - goes through an inside
>> router) which works flawlessly, so I'm open to the fact that something is
>> totally screwed up in our DMZ.
>> 
>> Sorry that was long. :)
>> 
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