From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bifrost.lang.hm (mail.lang.hm [64.81.33.126]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 8F6FD21F18E for ; Mon, 9 Mar 2015 09:04:12 -0700 (PDT) Received: from asgard.lang.hm (asgard.lang.hm [10.0.0.100]) by bifrost.lang.hm (8.13.4/8.13.4/Debian-3) with ESMTP id t29G4AEt007441; Mon, 9 Mar 2015 08:04:11 -0800 Date: Mon, 9 Mar 2015 09:04:10 -0700 (PDT) From: David Lang X-X-Sender: dlang@asgard.lang.hm To: "Steinar H. Gunderson" In-Reply-To: <20150309154330.GA4134@sesse.net> Message-ID: References: <20150309154330.GA4134@sesse.net> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] [Bulk] Re: Motivating commercial entities? tell the sales manager (fwd) X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Mar 2015 16:04:41 -0000 On Mon, 9 Mar 2015, Steinar H. Gunderson wrote: > On Mon, Mar 09, 2015 at 08:40:52AM -0700, David Lang wrote: >> why does IPv6 rely on multicast? >> >> multicast is never going to work that well on a busy wireless >> network, especially one that's encrypted with a different key to >> each station. > > It relies on multicast the same way IPv4 relies on broadcast > (ARP, DHCP). If you like broadcast better than multicast, you're > free to simply treat it as such. DHCP only needs to get to the dhcp server(s), not to all nodes. It's unusual for the DHCP server to be wireless rather than wired For ARP, it only needs to get to other wireless nodes if you are doing wireless <-> wireless communication, which is relatively rare. And even there, the access point can 'cheat' if it has an ARP entry for the IP and reply directly rather than contacting every wireless node. Explicit multicast, where the devices that want to listen to the multicast have to tell the access point that they want to listen to a particular multicast aren't too bad. It's the same overhead as unicast to each node. But this doesn't scale to lots of wireless nodes using multicast. It's fairly common for wireless networks to not allow wireless <-> wireless communication, which cuts this off entirely. David Lang