From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: mail@danrl.com Received: from krantz.zx2c4.com (localhost [127.0.0.1]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 0daffa1d for ; Sat, 8 Apr 2017 09:33:27 +0000 (UTC) Received: from mx.cakelie.net (mx.cakelie.net [45.76.39.236]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id e6490050 for ; Sat, 8 Apr 2017 09:33:27 +0000 (UTC) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [RFC] Multicast and IPv6 Link Local Addresses From: =?utf-8?Q?Dan_L=C3=BCdtke?= In-Reply-To: Date: Sat, 8 Apr 2017 11:39:54 +0200 Message-Id: References: To: "Jason A. Donenfeld" Cc: Juliusz Chroboczek , =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , =?utf-8?Q?Dave_T=C3=A4ht?= , WireGuard mailing list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi everyone, I am very excited that we have this discussion, as I am one of those = IPv6-first/IPv6-only guys who like poking the topic. I try to keep it short: - Scalability: I agree with what George said. Broadcast does not scale = nicely, and IPv6 multicast is intended to help scaling things by = reaching exactly the node that need to get a copy of a particular = packet. Downgrading IPv6 multicast to broadcast hurts scalability and I = for one, would rather not see multicast in WireGuard if it does not = scale. I am afraid it would be counterproductive to the goal of having a = widely accepted and used protocol. - Multicast is not the everyday use case, so if multicast requires an = extra knob or an extra option, that would be fine I guess. I am in favor = of intentionally enabling multicast. I am still wrapping my head around = static vs. dynamic (read: magic) configuration of multicast addresses = and groups. Will let you know once I end up with something worth = sharing. In the meantime, I think "solicited node multicast = addresses/groups" are the one thing that comes with the least amount of = trouble. Especially if IPv6 LL addressing is also there. - IPv6 link-local addressing: For me it is a perfect example for "the = right amount of magic". It would make (at least my) life so much easier. = Filling the neighbor cache would require WireGuard to provide (simulated = or real) solicited node multicast addresses routing, right? Or is it = feasible to fill the neighbor cache based on the peer configuration? The = last thing sounds wrong to me. So much for my first thoughts. Cheers, Dan=