From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0.riseup.net (mx0.riseup.net [198.252.153.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 597A91E86D for ; Wed, 10 Apr 2024 15:49:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.252.153.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712764144; cv=none; b=mxx7eMODvLCER6XjGgpxwXLGYSa2xLwBIAzkcSfc8KTRaWn9tuNyAs2qMXNw5guf5EIMnogHeEdmnwXP4b8LUUJUPHGUAFL8gHLL1aI6WgoljXFyijvKcWJBmx2HC2p7TD/IaYsc/5LoRJ77l/9NuzwyqH/nPNJYxepxTHcocpU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712764144; c=relaxed/simple; bh=KmBcRNBBzl9CUxizaUvIqsY7aU3E7X7wR5wK9XQPIHo=; h=Date:From:To:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Tgtp5BNpldaJA5L2RzJ8MPlNNLP0+w87JA39M6kj206ypdj1B4gFLkxUk46A9MBOvHBBwKzD5Gjjw6dQH37vw056mIyb/6d7XcFShA1ubVHPelBxP5FWvvNbPorkhOwJZKh8drAlkMflpb8DltLrheQHJF2Td4V9FATVxVfYXXI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=riseup.net; spf=pass smtp.mailfrom=riseup.net; dkim=pass (1024-bit key) header.d=riseup.net header.i=@riseup.net header.b=WviOljBx; arc=none smtp.client-ip=198.252.153.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=riseup.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=riseup.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=riseup.net header.i=@riseup.net header.b="WviOljBx" Received: from fews02-sea.riseup.net (fews02-sea-pn.riseup.net [10.0.1.112]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx0.riseup.net (Postfix) with ESMTPS id 4VF6gx4qYJz9wmC for ; Wed, 10 Apr 2024 15:49:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=riseup.net; s=squak; t=1712764141; bh=KmBcRNBBzl9CUxizaUvIqsY7aU3E7X7wR5wK9XQPIHo=; h=Date:From:To:Subject:In-Reply-To:References:Reply-To:From; b=WviOljBxozD5yJc4+ksfTARddoSe3AifmcNM/W+ezgV+I1+z1I6KPGFf5OfOCwggU qtzGNAbQJpjk6NXF+zpJ2UX0MfI7cpqvMnXT7sKHQ35yGbuLsSQ2Xi2XunB3Tsw3ca CuOaiT9fItre4ohPGDXhV8sJwG/YFvG9Vhm9IGxs= X-Riseup-User-ID: C3FDA133CDBEB9A7EB2B33A0770B05660FD368CC08B761059097E643AB85B592 Received: from [127.0.0.1] (localhost [127.0.0.1]) by fews02-sea.riseup.net (Postfix) with ESMTPSA id 4VF6gw2QXDzFpbL for ; Wed, 10 Apr 2024 15:48:59 +0000 (UTC) Date: Wed, 10 Apr 2024 15:48:51 -0000 From: "William N." To: netfilter@vger.kernel.org Subject: Re: Correct way of setting the TCP max segment sizes for IPv4 and IPv6? Message-ID: <20240410154851.6a627134@localhost> In-Reply-To: <9AE2B9F2-FE7D-440F-A595-F015957ECBFF@slavino.sk> References: <20240408192441.657ac116@localhost> <3C74BD22-CFE3-444A-AFEC-C532D7F2AACB@slavino.sk> <20240409193300.2aef4ff7@localhost> <9AE2B9F2-FE7D-440F-A595-F015957ECBFF@slavino.sk> Reply-To: netfilter@riseup.net Precedence: bulk X-Mailing-List: netfilter@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 09 Apr 2024 22:04:41 +0000 Slavko wrote: > RFC 9293, sect. 3.7.1 By asking "What about the RFC" I didn't mean "Which RFC sets the numbers". I meant "Why do you use the same MSS for IPv4 and IPv6, considering the RFC explains they are different?" > AFAIK main problem of too low MSS is CPU increase, This is how I understand it too. Wikipedia calls it "protocol overhead". I don't know if there are other implications though (e.g. OS fingerprinting or something else). > using IPv4 limit for both solves corner cases... How? The two corner cases are different and 1220 is > x2 than 536, i.e. very far from the "corner" (limit), i.e. it would not improve efficiency.