Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]

"Hemant Singh (shemant)" <shemant@cisco.com> Sun, 15 November 2015 01:21 UTC

Return-Path: <shemant@cisco.com>
X-Original-To: v6ops@ietfa.amsl.com
Delivered-To: v6ops@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 3E2361B2F74 for <v6ops@ietfa.amsl.com>; Sat, 14 Nov 2015 17:21:23 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -14.511
X-Spam-Level:
X-Spam-Status: No, score=-14.511 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id v4uASPaGM4sN for <v6ops@ietfa.amsl.com>; Sat, 14 Nov 2015 17:21:22 -0800 (PST)
Received: from rcdn-iport-5.cisco.com (rcdn-iport-5.cisco.com [173.37.86.76]) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id DE7861B2F73 for <v6ops@ietf.org>; Sat, 14 Nov 2015 17:21:21 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=2016; q=dns/txt; s=iport; t=1447550481; x=1448760081; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-transfer-encoding:mime-version; bh=rInh+8Uu8h/bFY58rHh4mlrrsSdudnThyt3PGxHLQRY=; b=Td8QtXjoHb1acFeGbZZXPAEgKPkrJcB8GvuQgoefhz+/aygTGqIFxJfF MWOQgNa6PoyiN/5JUtg+eLch4mDahZKDokRy2jjWO5BAosrxJgWw8gKo+ G++u1oPZ0KSezlqpkD8rnJSG3MZe3fYkagWagfhjQSgG5cv5guFxfh5oa w=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0ACAgCZ3UdW/5NdJa1egzuBQga+RQENg?= =?us-ascii?q?WSGEAIcgQs4FAEBAQEBAQGBCoQ0AQEBBCMRRQwEAgEIEQQBAQMCIwMCAgIwFAE?= =?us-ascii?q?ICAIEDgUIiCamcY9+AQEBAQEBAQEBAQEBAQEBAQEBAQEBGIEBilGHdYFEBZZIA?= =?us-ascii?q?Y0fnEsBHwEBQoIRHYFWcoREgQcBAQE?=
X-IronPort-AV: E=Sophos;i="5.20,295,1444694400"; d="scan'208";a="46892145"
Received: from rcdn-core-11.cisco.com ([173.37.93.147]) by rcdn-iport-5.cisco.com with ESMTP; 15 Nov 2015 01:21:21 +0000
Received: from XCH-RTP-005.cisco.com (xch-rtp-005.cisco.com [64.101.220.145]) by rcdn-core-11.cisco.com (8.14.5/8.14.5) with ESMTP id tAF1LKoY023780 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Sun, 15 Nov 2015 01:21:21 GMT
Received: from xch-rtp-005.cisco.com (64.101.220.145) by XCH-RTP-005.cisco.com (64.101.220.145) with Microsoft SMTP Server (TLS) id 15.0.1104.5; Sat, 14 Nov 2015 20:21:20 -0500
Received: from xch-rtp-005.cisco.com ([64.101.220.145]) by XCH-RTP-005.cisco.com ([64.101.220.145]) with mapi id 15.00.1104.000; Sat, 14 Nov 2015 20:21:20 -0500
From: "Hemant Singh (shemant)" <shemant@cisco.com>
To: Owen DeLong <owen@delong.com>
Thread-Topic: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
Thread-Index: AQHRFohEbga31qC+rEetrILg3VHRBZ6LRgsAgAa8AYCAAnb/AIAFJeaAgAAIg4CAAEiPQIAAXDaA//+8puCAAJNfgP//ymfwgABnY4D//75MIAAMrMUAAAokG4D//7ZcAIAAThMA///AA4CAAE9HQIAA4EYAgABMFPCAACUMAIAATzQw
Date: Sun, 15 Nov 2015 01:21:20 +0000
Message-ID: <f3d8339f2bdf4947a632b01382e87ed1@XCH-RTP-005.cisco.com>
References: <D76E6E81-419B-459D-AF5F-A6B8781CF445@delong.com> <a562066cf4d14f80aa94de314c27d632@XCH-RTP-005.cisco.com> <F5469EDB-E8E3-459A-ACF0-C9B2F11A8968@delong.com> <1c64119717ac4cc5a1e88dc8175af92f@XCH-RTP-005.cisco.com> <38D33D99-5075-4A52-9B57-9FEC9B088EF0@delong.com> <dcc3058655eb45319b5f2431db9667b0@XCH-RTP-005.cisco.com> <8A25D382-C4C6-4FBA-B5FF-D10BD4F398A9@delong.com> <158e13b7080a494cb3503476dc378a1e@XCH-RTP-005.cisco.com> <EFB44958-1C5D-4F08-9859-275489392B3D@delong.com> <a4050b82cc954ac8b25f50dc985451c9@XCH-RTP-005.cisco.com> <20151114181240.GI89490@Space.Net> <04d5779d611a4c5abd7db9093b991f81@XCH-RTP-005.cisco.com> <AE864A8C-9E88-4514-A0BA-A371DC3614DF@delong.com>
In-Reply-To: <AE864A8C-9E88-4514-A0BA-A371DC3614DF@delong.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: [10.82.243.16]
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
MIME-Version: 1.0
Archived-At: <http://mailarchive.ietf.org/arch/msg/v6ops/YFjPSqBgZhrabOTMoIokAaG0t8k>
Cc: "v6ops@ietf.org" <v6ops@ietf.org>
Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
X-BeenThere: v6ops@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: v6ops discussion list <v6ops.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/v6ops>, <mailto:v6ops-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/v6ops/>
List-Post: <mailto:v6ops@ietf.org>
List-Help: <mailto:v6ops-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/v6ops>, <mailto:v6ops-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 15 Nov 2015 01:21:23 -0000


-----Original Message-----
From: Owen DeLong [mailto:owen@delong.com] 
Sent: Saturday, November 14, 2015 7:58 PM
To: Hemant Singh (shemant)
Cc: Gert Doering; v6ops@ietf.org
Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]

>I didn’t say you couldn’t bridge the LO and External interfaces… I said that short of doing that, having the same subnet on both interfaces is a misconfiguration.

>You haven’t proven that the interfaces aren’t bridged (or effectively so), nor have you proven that they are actually on the same subnet. Ergo, it is, actually, still a meaningless example.

An app has decides to use the IPv6 address of the lo interface to source the app's packets.   This is what the ping command in my example decides since the command is asked to use the source of the ICMPv6 packets as the lo interface's address.  Then usual data forwarding on the router takes over.  Routing decides from the packet destination, the packet has to egress out an outbound interface, say, eth0.   However, when the packet is to be egressed out eth0, the L2 destination lookup fails.  Eth0 issues a ND address resolution to resolve the destination uses its own source interface IPv6 address.  I forced the ND address resolution by clearing the IPv6 neighbor cache on the router.   Then I proved the packet is forwarded.   There is no bridging involved and packets are sourced fine using the lo interface.

Hemant