From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lang.hm (045-059-245-186.biz.spectrum.com [45.59.245.186]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 091113CB37 for ; Wed, 28 Feb 2024 07:17:24 -0500 (EST) Received: from dlang-mobile (unknown [10.2.3.133]) by mail.lang.hm (Postfix) with ESMTP id 056E61C624C; Wed, 28 Feb 2024 04:17:23 -0800 (PST) Date: Wed, 28 Feb 2024 04:17:23 -0800 (PST) From: David Lang To: Juliusz Chroboczek cc: Rich Brown , bloat@lists.bufferbloat.net In-Reply-To: <874jdsizp5.wl-jch@irif.fr> Message-ID: <8s2q08r1-p4s0-2pns-3s2q-334s7np6947o@ynat.uz> References: <30F7E4EF-906B-41CD-9EDE-179106E8BFCF@gmail.com> <874jdsizp5.wl-jch@irif.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Re: [Bloat] mDNS X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Feb 2024 12:17:24 -0000 On Wed, 28 Feb 2024, Juliusz Chroboczek via Bloat wrote: >> But my point is that the OpenWrt router has no way to predict what >> address/subnet will be assigned to its WAN port. > > In principle, the ISP should assign either a global address, or an address in > the range 100.64.0.0/10 (RFC 6598). This range was deliberately chosen to > not collide with RFC 1918 space, so that the NAT box can choose any RFC 1918 > prefix on its downstream interfaces. > > In practice, however, ISPs don't necessarily obey the RFCs, and people do > chain NAT boxes, so none of the above is guaranteed. chaining NAT boxes is very common, too many ISPs don't give you anything other than a NAT address from their router >> Consequently, at boot-time, OpenWrt should simply choose some different >> subnet for its LAN subnet(s), and then advertise an mDNS name. > > I'm not sure how that could happen at boot time, it would need to happen > whenever a DHCPv4 lease changes. This implies that the router might need > to renumber if the ISP changes its allocation, and there are no > renumbering procedures for IPv4 (I'm not sure if anyone implements RFC 3203). it's unusual for the network block to change on a renewal, and in that rare case you could reboot the router. > It would also make addressing non-deterministic, which would make > debugging slightly more difficult. But then, we already have > non-deterministic addressing in IPv6, so I guess that's something we can > live with. remember, you don't need to randomly pick something, you just need to have a couple networks, figure out if one is in use by the WAN and if so pick the other. I will say that 192.168.0 and 192.168.1 are very commonly used, so anything other than those a better default personally, I like 192.168.255 as people tend to forget that's a valid network. David Lang > -- Juliusz > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat