From owner-freebsd-net@FreeBSD.ORG Tue Feb 1 18:37:36 2005 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C0F9C16A4CF for ; Tue, 1 Feb 2005 18:37:36 +0000 (GMT) Received: from mx0.nttmcl.com (MX0.nttmcl.com [216.69.68.201]) by mx1.FreeBSD.org (Postfix) with ESMTP id 827FC43D2F for ; Tue, 1 Feb 2005 18:37:36 +0000 (GMT) (envelope-from henrysu@nttmcl.com) Received: from nttmcljlsjk7s3 (dhcp227.nttmcl.com [216.69.69.227]) j11IbKtD007456; Tue, 1 Feb 2005 10:37:20 -0800 From: "Henry Su" To: , Date: Tue, 1 Feb 2005 10:37:20 -0800 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal In-Reply-To: <1107281496.809.48.camel@spirit> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 Subject: RE: Two NIC's connected to same subnet: routing question X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: henrysu@nttmcl.com List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Feb 2005 18:37:36 -0000 You can configure both NIC as /32. You also need proxy arp installed and listen on both NIC. Then the traffic should be able to follow between two NICs. Since Proxy ARP always answers its MAC to clients, so the clients can always send traffic to em1 or em0. Based on client's mac entry in the ARP table, client to client traffic is easily transferred. Other traffic should be able to direct to default gateway. If you know other options, I am interested to hear. Thanks. -----Original Message----- From: owner-freebsd-net@freebsd.org [mailto:owner-freebsd-net@freebsd.org]On Behalf Of Xin LI Sent: Tuesday, February 01, 2005 10:12 AM To: freebsd-net@freebsd.org Subject: Two NIC's connected to same subnet: routing question Dear folks, I think I got confused with the routing problem we will have when at least two NIC's are connected into the same subnet. The scenario: em0: 192.168.0.1/24 em1: 192.168.0.2/24 We can't simply configure like this, since 192.168.0.0/24 network route exists as soon as either em0 or em1 is up. A workaround for this is that we assign 192.168.0.2/32 for em1, but that has another issue that all traffics will go through em0 for "outgoing", say, outside the current network. A google of the issue has indicated that the "Move ARP out of routing table" work done last April should have resolved this, as "With this change it is possible to have more than one interface in the same IP subnet and layer 2 broadcast domain.". However, what I have found from our mailing list archive says only to assign /32 IP address, or remove routing item from route table, which is essentially identical to the /32 solution. So is there any way to utilize the both NIC's? I think I have been confused :-( Cheers, -- Xin LI http://www.delphij.net/