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Usage of additional IP address (failover) and warning email


Kitty
21/01/2014, 18h04
Hi

I know this is late and that you have probably solved the issue, but it may help someone in the future.

The netmask should be 255.255.255.255, and the broadcast address should be the the same as the failover IP address.

On CentOS, it goes something like this:

DEVICE="eth0:0"
BOOTPROTO="static"
IPADDR="IP.FAIL.OVER"
NETMASK="255.255.255.255"
ONBOOT="yes"
BROADCAST="IP.FAIL.OVER"

There's a guide here: http://help.ovh.co.uk/IpAlias

rockj
08/01/2014, 18h37
In short I have two questions:

We use both IP addresses for different services, is this a problem? If so, why?
We lease an additional IP address and we use both of em, shouldn't be a problem.

(Ive replace two last octets with "foo" and target and our_selves in the email below. They are on the same subnet (/24) and ARP traffic is of course natural as traffic won't go thru gateway when two clients are on the same local network .. )

See email history:
---------------------
Bonjour,

There is no access for kimsufi servers to ovh support, i could not answer you. A team is handling demands on our forum:

http://forum.kimsufi.com

You can get answers only for commercial, hardware and network side, for software you'll get answers from our community.

Regards, Maxime D.

| Nouveau:
|
| Suivez l'état des réseaux/machines, les opérations en cours depuis:
| http://travaux.ovh.com/


> Hi!
>
> I got noticed from my friend that he received an email about blocking of our +1 IP address: (IP failover address):
>
> How may I contact you using my email client btw? Emailing back to support@ovh.com didn't seem to reach you guys ..
>
> On 01/06/14 at 01:41pm, x wrote:
> > ---------- Forwarded message ----------
> > From:
> > Date: Jan 6, 2014 1:21 AM
> > Subject: Bad configuration regarding your server foo.our.kimsufi.com
> > To: xxx
> > Cc:
> >
> >
> >
> > Hello,
> >
> > We have detected that your server foo.our.kimsufi.com unnecessarily
> sending
> > a large number of requests over the network via its IP failover
> 94.23.foo.our_ip
> > This is due to a misconfiguration.
> >
> > We ask you kindly to reconfigure the IP failover
> > 94.23.foo.our_ip as soon as possible.
>
> Both IP adresses is in use for different services, with "failover ip" as
> default.
> How is this a problem?
>
> We lease the additional IP address and have them both in use.
> (read: traffic will flow on both IP addresses)
>
> Is this a problem? If so, why?
>
> > You will find below a sample of queries sent by your server:
> >
> > ------- EXTRACT OF REQUESTS -------
> >
> > Sun Jan 5 13:43:11 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 15:23:11 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 15:33:10 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 16:40:55 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 16:50:56 2014 : arp who-has 94.23.foo.X tell 94.23..foo.OUR_IP
> > Sun Jan 5 18:41:02 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 19:10:57 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 21:43:14 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Sun Jan 5 22:23:20 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> > Mon Jan 6 01:21:02 2014 : arp who-has 94.23.foo.X tell 94.23.foo.OUR_IP
> >
> > ------- END OF EXTRACT -------
> >
>
> Yes, another server is on the same local network (/24) and is doing an ARP
> to
> communicate with our server directly as they are on the same subnet. This is
> intended networking behaviour since they are on the same subnet.

Correction, we are doing an ARP to communicate with another server on the same subnet. How is this a problem?

>
> Do we have the wrong netmask? It's supposed to be an /24 according to the
> documentation.
>