IETF Logo Mail Archive

Re: DAD question

sthaug@nethelp.no Sat, 11 August 2012 21:48 UTC

Return-Path: <sthaug@nethelp.no>
X-Original-To: ipv6@ietfa.amsl.com
Delivered-To: ipv6@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 701BE11E809A for <ipv6@ietfa.amsl.com>; Sat, 11 Aug 2012 14:48:50 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.041
X-Spam-Level:
X-Spam-Status: No, score=-6.041 tagged_above=-999 required=5 tests=[AWL=0.558, BAYES_00=-2.599, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id s+afyNe5Wvbu for <ipv6@ietfa.amsl.com>; Sat, 11 Aug 2012 14:48:50 -0700 (PDT)
Received: from bizet.nethelp.no (bizet.nethelp.no [195.1.209.33]) by ietfa.amsl.com (Postfix) with SMTP id 7F22C11E8087 for <ipv6@ietf.org>; Sat, 11 Aug 2012 14:48:49 -0700 (PDT)
Received: (qmail 97321 invoked from network); 11 Aug 2012 21:48:46 -0000
Received: from bizet.nethelp.no (HELO localhost) (195.1.209.33) by bizet.nethelp.no with SMTP; 11 Aug 2012 21:48:46 -0000
Date: Sat, 11 Aug 2012 23:48:46 +0200
Message-Id: <20120811.234846.71124335.sthaug@nethelp.no>
To: kauer@biplane.com.au
Subject: Re: DAD question
From: sthaug@nethelp.no
In-Reply-To: <1344721144.6453.29.camel@karl>
References: <5FAE0128-DDE7-45C4-8632-F56EAA1BE362@gmail.com> <20120811.180104.41668882.sthaug@nethelp.no> <1344721144.6453.29.camel@karl>
X-Mailer: Mew version 3.3 on Emacs 21.3 / Mule 5.0 (SAKAKI)
Mime-Version: 1.0
Content-Type: Text/Plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Cc: ipv6@ietf.org
X-BeenThere: ipv6@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: "IPv6 Maintenance Working Group \(6man\)" <ipv6.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ipv6>, <mailto:ipv6-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/ipv6>
List-Post: <mailto:ipv6@ietf.org>
List-Help: <mailto:ipv6-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ipv6>, <mailto:ipv6-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sat, 11 Aug 2012 21:48:50 -0000

> > Duplicate MAC addresses are regularly seen in the wild.
> 
> It's important to remember that DAD is link local. It is only checking
> whether the same address occurs on the local link. Duplicate MAC
> addresses are not actually a problem as long as the duplicates are not
> on the same link. If the duplicates ARE on the same link, then you have
> a real problem at layer 2 anyway. The same link local address, based on
> a MAC, is also a real problem if it's duplicated, for much the same
> reason.

We use the 1:1 VLAN model for our customers, so in that sense I agree
with you - these duplicates would not be a problem in our case. If we
had used the N:1 VLAN model instead, it could be a very real problem.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no

v2.23.0 | Report a Bug | By Email