[gentoo-user] Re: managing local IP's

[Kai Krakow]

Am Fri, 24 Feb 2017 03:42:52 +0000
schrieb "J. Roeleveld" <joost@××××××××.org>:

> On February 24, 2017 12:55:26 AM GMT+01:00, thelma@×××××××××××.com
> wrote:
> >I have two networks connected over VPN
> >
> >1st Network has 3-box (only one active)
> >2nd Remote Network has 4-boxes (only two active at any given time)
> >
> >All boxes are configure to run: Hylafax, Asterisk (but only one at a
> >time act as a server).
> >
> >Various external devises like Sipur, Audiocodes has to be configure
> >(IP change) to register to Asterisk server; if I switch a box that
> >acts as a
> >server, I need to login to each device and change the IP.
> >
> >Hylafax is relatively simple to switch, but "yajhfc" that view the
> >faxes
> >has to have an IP changed.
> >Audiocodes - is a nightmare to change IP.
> >Local Asterisk registers with Remote Network over VPN so IP's need to
> >change as well.
> >
> >Is there an easier way to mange it?
>
> Have the active server add a 2nd IP to its network interface and
> configure the clients to use that IP. When switching to a different
> server (making a different one active), move that 2nd IP to the new
> active server.

This is the best way to go.

> This is how most active/passive failovers actually work.

Yes, plus they send an ARP packet to update the local peers and switches
with the move because usually also a virtual MAC address will be moved
over to the other interface.

This is especially important for the local VPN router so remote peers
are able to immediately reach the moved IP.

Usually, the network stack would generate such ARP packets. I'd ensure
with wireshark that this really takes place in the correct order so you
don't diagnose unexpected troubles later. You need a switch with mirror
port for this to work correctly with wireshark.

See https://wiki.wireshark.org/Gratuitous_ARP


-- 
Regards,
Kai

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