Re: [Idr] TCP & BGP: Some don't send terminate BGP when holdtimer expired, because TCP recv window is 0

Job Snijders <job@fastly.com> Wed, 20 January 2021 19:09 UTC

Return-Path: <job@fastly.com>
X-Original-To: idr@ietfa.amsl.com
Delivered-To: idr@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id AFC763A1262 for <idr@ietfa.amsl.com>; Wed, 20 Jan 2021 11:09:26 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.099
X-Spam-Level:
X-Spam-Status: No, score=-2.099 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=fastly.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yLketGmIAypH for <idr@ietfa.amsl.com>; Wed, 20 Jan 2021 11:09:25 -0800 (PST)
Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 2B8D23A12AC for <idr@ietf.org>; Wed, 20 Jan 2021 11:09:25 -0800 (PST)
Received: by mail-wr1-x442.google.com with SMTP id l12so18905040wry.2 for <idr@ietf.org>; Wed, 20 Jan 2021 11:09:24 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastly.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=oOogRIx9ISTUs8IYkBZybcHEVGNOiA3IaldfW0w39rw=; b=AdxMF8A2dcwDOkGYjw3CCf/IZIzkIC2a/K+7d+XYzFRE5qc4SQF+ApaBbqCD2ftaZR N4INSzTrTHWpiroJhfH54sFTprMHLzFx1lPpvS9BfZtjMK2ne9+mlAu6YlGPoBgel+va 2Y8pJypb4/uVijBxXrdDYi7Db27iXLEoUrb8c=
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=oOogRIx9ISTUs8IYkBZybcHEVGNOiA3IaldfW0w39rw=; b=XkEcEAmPVftpCkxQ/sz9J3CgalWBapLbSy/DH2Cr4jtZ0HnqVTaB24Gew6e1yn0V9b m+avtR+7MSxvvhXDAcirDOMNYgzd3nGflYSLPmxcKaQ5vooo+RU4cWUDMG9Lz4nwnCTe qh8ArTNzr+hKvjvjNfn40Hi5Hxn6+ywoD7//bDFyV//uLNxTPHZHu7f+0djn5gSoSbis 8J0BQzRGzMyX9mQtZcCioc31i9RUspKtO8o7Cqga8L0fLHQUWfLXJ87malIbvDMVwj7+ B9NhGXWVGU28+DbLUxhFBzQLwy3sKyU6xE78llq7NZQhWyRnoj2XM/CEtfG0rJ5SBd72 5R3A==
X-Gm-Message-State: AOAM532v367+MQsO6E6twk5kreCHR7k8HOryVCjZ1gr0d/O/NbjoLBjt fC0TyitbmVKcPzKdcTAIVAGk6g==
X-Google-Smtp-Source: ABdhPJzD3L5A/pd6SDJlSu/Fl4QItAI8Dfv4X5T79yY/QVIYDrVXKpXcPfH8iHTXaqWVgpr7T9fJLw==
X-Received: by 2002:a5d:4f0e:: with SMTP id c14mr10793972wru.84.1611169763360; Wed, 20 Jan 2021 11:09:23 -0800 (PST)
Received: from snel (mieli.sobornost.net. [45.138.228.4]) by smtp.gmail.com with ESMTPSA id u205sm5382913wme.42.2021.01.20.11.09.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Jan 2021 11:09:22 -0800 (PST)
Date: Wed, 20 Jan 2021 20:09:21 +0100
From: Job Snijders <job@fastly.com>
To: Enke Chen <enchen@paloaltonetworks.com>
Cc: John Scudder <jgs@juniper.net>, "idr@ietf. org" <idr@ietf.org>
Message-ID: <YAh/4dDQaJGcIAYf@snel>
References: <CANJ8pZ-WMDotkQvhN-NuP7ivZkPRR-9S2KJSar=6463U0VKkow@mail.gmail.com> <EFC56A31-1276-4DAB-9526-9C2F24814D2C@pfrc.org> <CANJ8pZ_LnDna_jtipcLJq9rrS3MM32rLdxRW8ntC2aEi9VvzMg@mail.gmail.com> <722A787A-5B83-4802-A9F4-AB2957BB3305@juniper.net> <CANJ8pZ9K2+MS9cksczt2G4OTAiNwR5iBQp=0-UEXMS=nUNqLAQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CANJ8pZ9K2+MS9cksczt2G4OTAiNwR5iBQp=0-UEXMS=nUNqLAQ@mail.gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
Archived-At: <https://mailarchive.ietf.org/arch/msg/idr/gORi7kyDOgDDNgefPykzGVM0F8E>
Subject: Re: [Idr] TCP & BGP: Some don't send terminate BGP when holdtimer expired, because TCP recv window is 0
X-BeenThere: idr@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Inter-Domain Routing <idr.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/idr>, <mailto:idr-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/idr/>
List-Post: <mailto:idr@ietf.org>
List-Help: <mailto:idr-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/idr>, <mailto:idr-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 20 Jan 2021 19:09:27 -0000

Dear Enke, group, 

On Wed, Jan 20, 2021 at 10:20:47AM -0800, Enke Chen wrote:
> Here is an update on the TCP_USER_TIMEOUT option in Linux for the
> zero-window case:
> 
> 1) There is a bug in the code, and a fix has been committed to Linux's
> networking git:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=9d9b1ee0b2d1c9e02b2338c4a4b0a062d2d3edac
> 
> 2) A patch has been committed to Linux's man-page repo to clarify that the
> option also covers the case that buffered data remain untransmitted:
> 
> https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=1942e41202aa5cc39dd8970ab62cd1b288277753
> 
> Thanks.   -- Enke

Wow, thank you, this is a welcome development!

Two follow-up questions for the group:

1) Should the *default* BGP HoldTimer value be the input to mechanisms
   such as the Linux TCP_USER_TIMEOUT option? (a 'Send Hold Timer') Earlier
   on in the thread Tony Li suggested "For robustness, it makes sense that
   the transmitter also close the connection."
   ref: https://mailarchive.ietf.org/arch/msg/idr/CS7VOx42V76RfGLmXhQqM8DyNjk/

2) Should we request IANA to assign a new "BGP Error Notification Code"
   for the purpose of locally correctly logging the reason the remote
   peer was shutdown, or also use Code 4 (Hold Timer Expired) for this
   case?

John Scudder brought up that in the current version of the FSM this
would be a 'ManualStop', but I'd like to explore the option of an
automated termination of the connection (until IdleTimer expires).

Kind regards,

Job