Re: [LARTC] arp control in a multihomes host

From: "Martin A. Brown" <mabrown-lartc@securepipe.com>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] arp control in a multihomes host
Date: Mon, 02 Sep 2002 02:50:05 +0000	[thread overview]
Message-ID: <marc-lartc-103093504022450@msgid-missing> (raw)
In-Reply-To: <marc-lartc-103093408322077@msgid-missing>

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
 : 
 : 
 : 
 : 
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 : 

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

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