[lkml]   [2001]   [Sep]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] strict interface arp patch for Linux 2.4.2

Julian Anastasov <> on 09/20/2001 06:19:04 PM

To: Allen Lau/Raleigh/IBM@IBMUS
cc: linux-kernel <>
Subject: Re: [PATCH] strict interface arp patch for Linux 2.4.2


On Thu, 20 Sep 2001, Allen Lau wrote:

>> I want to bring your attention to a Linux ARP patch we plan to use for
load balancing and server
>> clustering. The available arp filter and hidden patch are not
completely satisfactory. The following

> Can you explain what setup can't be build using arp_filter,
> hidden or rp_filter and particulary where "hidden" fails for clusters,
> it is very interesting?

The function provided by "hidden" is a necessary element but not
sufficient. I suppose arp_filter
has to be combined with the hidden patch. I dislike hiding an interface,
and the hidden patch is no
longer included in the major distributions which makes delivering a
solution difficult.

In this example, are virtual ip's which can float between
boxes and interfaces.
I want virtual ip to be known to clients through eth0 node1
( eth1 node2). Node1
can redirect traffic to eth0 node2.
node1 node2
lo:1 lo:1
lo:2 lo:2

eth0 eth1 eth0 eth1

On node1, does hiding loopback hide and can be advertised
as source ip in arp
requests from eth0?

>> To generalize, each real server may have multiple nic's of different
types. The task becomes one of
?> maintaining strict identity of each of the real and virtual ip
addresses. The Linux ARP has the
>> following behaviors which are problematic for maintaining strict
interface identify.
>> 1) box responds to arp on all interfaces on the same wire for an IP
address (arp race)

> rp_filter and arp_filter can help here but this "arp race" is not
> an evil in some setups

I believe "arp race" may cause purges in a switched network. It certainly
is counter to maintaining
strict interface identity.

Allen Lau
Julian Anastasov <>

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:03    [W:0.027 / U:3.240 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site