[LARTC] arp control in a multihomes host

[LARTC] arp control in a multihomes host

[Geoff Steer]

I have a problem involing arp table entries that I'm hoping someone can
help with.

I'm working on a mail system that utilises multiple Linux servers in a
redundant configuration.
The configuration has pairs of Linux servers running as MTAs. Each pair
of real servers hides behind a virtual server name. The virtual server
name and load balancing of real servers is handled by an Alteon AD3 switch.
Each of the Linux servers has two ethernet interfaces with the second
interface also connected to a (second) Alteon. The two Alteons are
configured in an active-standby arrangement using VRRP.
The IP addresses of each linux servers' ethernet interfaces are on the
same subnet (172.16.180.0/128),

The configuration of the Alteon causes each of the Alteon IP
addresses to appear on each interface of the Linux box, with the same
MAC address i.e.

alteon1 (172.16.180.2) at 00:00:E8:D7:4F:5D [ether] on eth0
alteon2 (172.16.180.3) at 00:50:BA:CB:DD:D8 [ether] on eth0
alteon1 (172.16.180.2) at 00:00:E8:D7:4F:5D [ether] on eth1
alteon2 (172.16.180.3) at 00:50:BA:CB:DD:D8 [ether] on eth1

What I'm looking to do is to not have the second entry for any host
appear in the arp table if it's already there for another interface.
i.e. if alteon1 has an arp entry pointing to eth0, don't add one for
eth1 - which I guess means, don't issue arp requests/responses on the
other interface for an Alteon if we have an arp table entry.
The solution doesn't need to be tailored to the Alteon IP
addresses, just a general rule of not issuing arp requests/responses
on a second interface if we already have a similiar entry pointing to
the first interface.

Regards
Geoff Steer




_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] arp control in a multihomes host

[Martin A. Brown]

Geoff,

Frankly, I'm not sure if this is the answer to your question, but Julian 
Anastasov has written a very handy utility called "ip arp".  You may find 
that this is just the trick.

Check out Julian's work here:

  http://www.linuxvirtualserver.org/~julian/
  http://www.linuxvirtualserver.org/~julian/iparp.txt

Hopefully, there is somebody else on this list who has specific experience 
with the problem you are trying to solve.

Anyway, best of luck,

-Martin

On Mon, 2 Sep 2002, Geoff Steer wrote:

 : I have a problem involing arp table entries that I'm hoping someone can
 : help with.
 : 
 : I'm working on a mail system that utilises multiple Linux servers in a
 : redundant configuration.
 : The configuration has pairs of Linux servers running as MTAs. Each pair
 : of real servers hides behind a virtual server name. The virtual server
 : name and load balancing of real servers is handled by an Alteon AD3 switch.
 : Each of the Linux servers has two ethernet interfaces with the second
 : interface also connected to a (second) Alteon. The two Alteons are
 : configured in an active-standby arrangement using VRRP.
 : The IP addresses of each linux servers' ethernet interfaces are on the
 : same subnet (172.16.180.0/128),
 : 
 : The configuration of the Alteon causes each of the Alteon IP
 : addresses to appear on each interface of the Linux box, with the same
 : MAC address i.e.
 : 
 : alteon1 (172.16.180.2) at 00:00:E8:D7:4F:5D [ether] on eth0
 : alteon2 (172.16.180.3) at 00:50:BA:CB:DD:D8 [ether] on eth0
 : alteon1 (172.16.180.2) at 00:00:E8:D7:4F:5D [ether] on eth1
 : alteon2 (172.16.180.3) at 00:50:BA:CB:DD:D8 [ether] on eth1
 : 
 : What I'm looking to do is to not have the second entry for any host
 : appear in the arp table if it's already there for another interface.
 : i.e. if alteon1 has an arp entry pointing to eth0, don't add one for
 : eth1 - which I guess means, don't issue arp requests/responses on the
 : other interface for an Alteon if we have an arp table entry.
 : The solution doesn't need to be tailored to the Alteon IP
 : addresses, just a general rule of not issuing arp requests/responses
 : on a second interface if we already have a similiar entry pointing to
 : the first interface.
 : 
 : Regards
 : Geoff Steer
 : 
 : 
 : 
 : 
 : _______________________________________________
 : LARTC mailing list / LARTC@mailman.ds9a.nl
 : http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
 : 

-- 
Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com


_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] arp control in a multihomes host

[M.F. PSIkappa]

Hello,
you can use ebtables (http://users.pandora.be/bart.de.schuymer/ebtables/).

On Mon, 2 Sep 2002, Geoff Steer wrote:

> I have a problem involing arp table entries that I'm hoping someone can
> help with.
>
> I'm working on a mail system that utilises multiple Linux servers in a
> redundant configuration.
> The configuration has pairs of Linux servers running as MTAs. Each pair
> of real servers hides behind a virtual server name. The virtual server
> name and load balancing of real servers is handled by an Alteon AD3 switch.
> Each of the Linux servers has two ethernet interfaces with the second
> interface also connected to a (second) Alteon. The two Alteons are
> configured in an active-standby arrangement using VRRP.
> The IP addresses of each linux servers' ethernet interfaces are on the
> same subnet (172.16.180.0/128),
>
> The configuration of the Alteon causes each of the Alteon IP
> addresses to appear on each interface of the Linux box, with the same
> MAC address i.e.
>
> alteon1 (172.16.180.2) at 00:00:E8:D7:4F:5D [ether] on eth0
> alteon2 (172.16.180.3) at 00:50:BA:CB:DD:D8 [ether] on eth0
> alteon1 (172.16.180.2) at 00:00:E8:D7:4F:5D [ether] on eth1
> alteon2 (172.16.180.3) at 00:50:BA:CB:DD:D8 [ether] on eth1
>
> What I'm looking to do is to not have the second entry for any host
> appear in the arp table if it's already there for another interface.
> i.e. if alteon1 has an arp entry pointing to eth0, don't add one for
> eth1 - which I guess means, don't issue arp requests/responses on the
> other interface for an Alteon if we have an arp table entry.
> The solution doesn't need to be tailored to the Alteon IP
> addresses, just a general rule of not issuing arp requests/responses
> on a second interface if we already have a similiar entry pointing to
> the first interface.
>
> Regards
> Geoff Steer

--
`)_|_('       PSIkappa
   I k        psi _at_ atlantis.sk

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/