Re: Service Redundancy using BFD

Greg Mirsky <> Tue, 28 November 2017 22:13 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id A41B112878D for <>; Tue, 28 Nov 2017 14:13:24 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -0.709
X-Spam-Status: No, score=-0.709 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, HTTPS_HTTP_MISMATCH=1.989, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id dth9K6fd_ZyF for <>; Tue, 28 Nov 2017 14:13:20 -0800 (PST)
Received: from ( [IPv6:2a00:1450:4010:c07::233]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 513F01201F8 for <>; Tue, 28 Nov 2017 14:13:20 -0800 (PST)
Received: by with SMTP id a12so1602979lfe.4 for <>; Tue, 28 Nov 2017 14:13:20 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=JVwCShwprURIK1NjMn6KhYdWPAahexXTrhBg83kaB6w=; b=oB743LBsmhBI80y5uDPs6b2sQjBjLwcQibuzjtdmeUkcFiciPmUh0naVBch3Iv17AS zqIH/mYSt0H8PWljiSsvorlG5LlK/wVKafXmddlZW2qci0WHsTecWtkLVN2raxnQLuN5 /7M20o0H5K8guHdJw9/spSSEZZcnwuANYYM0EsZjc/E3cyVVCuzsZaJJT0BsdwFKEv+k aQCKMc9aIsTY7vZF64H2IGFWrj2DBQ/NmQ7wMQSeO89svw0n3V//Cf48KoEL+pAHQfGM 1Q33KQeba3vQ+xhzHP0Pkif0CfzRmf1RYInnzwmkWUuNI1uQ0s2ugGcIZbp3k0pFZepA DYgw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=JVwCShwprURIK1NjMn6KhYdWPAahexXTrhBg83kaB6w=; b=sqRqGMbyjgaQv6xZK6eYB0b1bddrDQShdg0B1RKFtPfN8UAPp2uAAL+gSWaWSglLSL n8bzj4MMxi7aBBA/dockv5rb9GwNVhM92L+PHa0b01891JTnJgmX2tZ0YlrcImk6QGse dATZn8iYHdXUxQqLSYwiZcSK/SdmsJLVBdMD946k7Hvyr53Lqj4u9PHcGk7VMh6nhnKn Qo3vxCxMwdpE46sd+Vz+6B3c7HrhGdu0ZfAW/MAvyLKGct/FtMWCMrEW3l0IhPShJ7rS amQsM2NszcvNiky84UhpgEExzAx2PEMu4AEPaJiFXU8xDIb1q75ALl5pAWZMSrxUjoF7 fapg==
X-Gm-Message-State: AJaThX7tnTTt3oE4LM07mNg+6Ee+0c6dgJH2W4Ba7/D12cKtlqvQh0H/ d/dsn9WFTbyu/UjhrmPTklr8irisej99zJFU9I0=
X-Google-Smtp-Source: AGs4zMZEP47czf3IvU16Q7GkcVwQEpYn28Uv9pOmNajtkcPgkAc6G67kTRQLsbWXQrRyTfdsqdaG0W7PlyGNBQ7N31U=
X-Received: by with SMTP id h29mr324641ljb.144.1511907198504; Tue, 28 Nov 2017 14:13:18 -0800 (PST)
MIME-Version: 1.0
Received: by with HTTP; Tue, 28 Nov 2017 14:13:17 -0800 (PST)
In-Reply-To: <>
References: <> <> <>
From: Greg Mirsky <>
Date: Tue, 28 Nov 2017 14:13:17 -0800
Message-ID: <>
Subject: Re: Service Redundancy using BFD
To: Sami Boutros <>
Cc: Ankur Dubey <>, "" <>, Reshad Rahman <>
Content-Type: multipart/alternative; boundary="94eb2c1ce7fa801867055f125361"
Archived-At: <>
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: "RTG Area: Bidirectional Forwarding Detection DT" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 28 Nov 2017 22:13:24 -0000

Hi Sami,
I was not suggesting that it is either MPLS or Ethernet. I was pointing
that protection mechanisms use protection coordination for a reason and had
pointed to one example. But for the case you're presenting in the draft, I
think, the VRRP-like protocol may work quite nicely. In our draft to use
p2mp BFD to support faster VRRP convergence
extension to the VRRP already has been proposed. Why not add indication of
"stickiness", i.e. whether role of the designated forwarder is revertive or
non-revertive, to the VRRP? I took liberty to add RTGWG to the discussion.


On Tue, Nov 28, 2017 at 10:34 AM, Sami Boutros <>; wrote:

> Hi Greg,
> The network in which the draft apply is neither an MPLS-TP or a G.8031
> network.
> It is for an IP packet network, and the mechanism described that we
> beleive is useful is when a BFD session used to monitor liveness between 2
> nodes (doing active/standby redundancy for L2/L3 or L4-L7 services) goes
> down, it is useful when the BFD session comes back up that the node that
> didn’t fail tell the other node. This notification will allow
> non-preemptive services to continue to run on the node that didn’t fail.
> Thanks,
> Sami
> From: Greg Mirsky <>;
> Date: Tuesday, November 28, 2017 at 8:16 AM
> To: Ankur Dubey <>;
> Cc: ""; <>;, Reshad Rahman <
>>;, Sami Boutros <>;
> Subject: Re: Service Redundancy using BFD
> Hi Ankur,
> usually this problem, as I understand it from the document, is handled by
> the special protection coordination protocol as, for example, in RFC 6378
> or G.8031. PSC or APS reflect roles of working and protecting paths and
> communicate over the protecting path.
> Regards,
> Greg
> On Mon, Nov 27, 2017 at 6:47 PM, Ankur Dubey <>; wrote:
>> Hi all,
>> Please review and provide comments for the following draft:
>> <>
>> *Summary of draft:*
>> This draft proposes a new BFD diag code via which a node running a BFD
>> session with another node, can inform the other node after a BFD session
>> times out, that it didn’t go down and did live through the failure.
>> Such notification is useful for a set of nodes providing Active/Standby
>> redundancy. When these nodes are running multiple L2/L3/L4-L7 services  in
>> non-revertive mode of redundancy, the standby node taking over as active
>> for non-revertive services after BFD times out needs to indicate in the BFD
>> packet that it outlived the other failed old active node. The new diag code
>> will be used for this purpose. When this diag code is set in the BFD
>> packets, it will provide an indication to the failed old active node that
>> it MUST NOT activate the non-revertive services when it comes up.
>> For providing a per service level failover, a node activating certain
>> non-revertive services needs to indicate that it is Active ONLY for those
>> non-revertive services. This can be done by using a unique bitmap where
>> each bit position is uniquely identifying a service. This unique bitmap is
>> configured on all nodes by a network controller. When there is at least one
>> non-revertive service for which a node is not active AND it is active for
>> at least 1 non-revertive service, this node will set bits identifying the
>> active services in the bitmap and send it in the payload of the BFD packet.
>> Thanks,
>> --Ankur