From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 20 Sep 2001 19:35:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 20 Sep 2001 19:35:38 -0400 Received: from e21.nc.us.ibm.com ([32.97.136.227]:16862 "EHLO e21.nc.us.ibm.com") by vger.kernel.org with ESMTP id ; Thu, 20 Sep 2001 19:35:30 -0400 Importance: Normal Subject: Re: [PATCH] strict interface arp patch for Linux 2.4.2 To: linux-kernel X-Mailer: Lotus Notes Release 5.0.3 March 21, 2000 Message-ID: From: "Allen Lau" Date: Thu, 20 Sep 2001 19:34:21 -0400 X-MIMETrack: Serialize by Router on D04NMS38/04/M/IBM(Release 5.0.8 |June 18, 2001) at 09/20/2001 07:35:47 PM MIME-Version: 1.0 Content-type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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 Hello, 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, 1.1.1.11 2.2.2.22 are virtual ip's which can float between boxes and interfaces. I want virtual ip 1.1.1.11 to be known to clients through eth0 node1 (2.2.2.22 eth1 node2). Node1 can redirect 1.1.1.11 traffic to eth0 node2. node1 node2 lo:1 1.1.1.11 lo:1 1.1.1.11 lo:2 2.2.2.22 lo:2 2.2.2.22 eth0 1.1.1.1 eth1 2.2.2.1 eth0 1.1.1.2 eth1 2.2.2.2 eth0:1 1.1.1.11 eth1:1 2.2.2.22 On node1, does hiding loopback hide 1.1.1.11? and can 2.2.2.1 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. Regards Allen Lau -- Julian Anastasov