[141893] in North American Network Operators' Group
Re: The stupidity of trying to "fix" DHCPv6
daemon@ATHENA.MIT.EDU (Ricky Beam)
Mon Jun 13 15:51:11 2011
To: nanog@nanog.org
Date: Mon, 13 Jun 2011 15:50:09 -0400
From: "Ricky Beam" <jfbeam@gmail.com>
In-Reply-To: <20110612134501.GA25078@ussenterprise.ufp.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Sun, 12 Jun 2011 09:45:01 -0400, Leo Bicknell <bicknell@ufp.org> wrote:
> In a message written on Sun, Jun 12, 2011 at 01:04:41PM +0200, Iljitsch
> van Beijnum wrote:
>> Like I said before, that would pollute the network with many multicasts
>> which can seriously degrade wifi performance.
>
> Huh? This is no worse than IPv4 where a host comes up and sends a
> subnet-broadcast to get DHCP.
Broadcast != Multicast. esp. when talking about wireless chipsets. I've
yet to find a wifi chipset that didn't completely fuck-up when presented
with even a low pps of multicast traffic. Broadcast traffic doesn't seem
to bother them -- it doesn't attempt to filter them in any way, or really
pay them any attention. If I had to guess, the chip firmware is
individually transmitting multicast packets to each peer; a broadcast
packet is sent once to all peers.
I've not had any wireless networks disrupted by broadcast traffic -- and
with Radware load balancers in the network, there are *plenty* of
broadcasts (ARP). Just a few 100pps of multicast and the AP fails.
(linksys, netgear, even cisco... all broadcom crap radios.)
--Ricky
