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Hello,
On Wed, 16 Jan 2002, Joseph Mack wrote:
> > > I've to handle the ARP problem so I've put two NIC on the two
> > > realservers...
> >
> > Please, don't do it in this way. This works may be only with
> > Linux 2.0. For 2.2+ you need specific kind of ARP control:
>
> that straightens me out a bit. Does the ARP control require the
> hidden patch (in which case there's no point to an extra NIC)
> or can I do it with an unmodified kernel?
If the real server/any Linux 2.2+ host (without hidden flag
enabled) receives a broadcast ARP probe about any local IP
address (VIP in our case) then it is replied no matter on what device
is configured the local IP address. I don't see the trick to add
unused NIC for VIPs as solution. IMO, it should not work. Of course,
there are conditions that can lead to drop the probe. Ah, I now see
3.2.3. Put an extra NIC on the real-server to carry the VIP (on eth1)
in my v1.1, Mar 2001 LVS-HOWTO (should I upgrade? No, I see it
in the version on the site, without 3.2.3 prefix):
---
With 2.2.x kernels you can't stop
this device (eth1) from replying to arp requests, but if you don't
connect the cable to it or don't put a route to it in the real-
server's routing table, then the client won't be able to send it an
arp request.
---
Note that unconnected eth1 will not reply but eth0
can reply for addresses configured on eth1, in some cases even
when eth1 is marked down. So, the above solution can't work for 2.2+.
Or may be there is a working variant based on some way for filtering
the probes? We know that eth0 is used to talk with the network
where VIP is participating, so eth0 can freely reply.
> Joe
Regards
--
Julian Anastasov <ja@xxxxxx>
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