Re: Service Redundancy using BFD

Sami Boutros <> Tue, 28 November 2017 18:23 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id A5B07128CD5 for <>; Tue, 28 Nov 2017 10:23:37 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.71
X-Spam-Status: No, score=-2.71 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, HTTPS_HTTP_MISMATCH=1.989, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-2.8, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id Rjdkayv9skDi for <>; Tue, 28 Nov 2017 10:23:34 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 6319D128C9C for <>; Tue, 28 Nov 2017 10:23:34 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=selector1-vmware-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=SfrgD/ccSTPj6OOjmPMAR6YGu7RFBx0PfzCEUP+UhVk=; b=l7GF1C6HSDdUXZSysL6XsuQ8873mANQmP9gSngePKisiTNtIdrPdCW2yGV4MDl1K5SfYiYIjGviK6rhwN6pjvvsjeG5YC1suLheubK4fvGUfdvdIgcwHJLeojG0gRzG5OO1SjVQIFzD2LN4Mv5URQ+24IkFmYwUUfySDhIZlZCA=
Received: from ( by ( with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id; Tue, 28 Nov 2017 18:23:33 +0000
Received: from ([]) by ([]) with mapi id 15.20.0282.002; Tue, 28 Nov 2017 18:23:32 +0000
From: Sami Boutros <>
To: Ashesh Mishra <>, Ankur Dubey <>, "" <>
CC: Reshad Rahman <>
Subject: Re: Service Redundancy using BFD
Thread-Topic: Service Redundancy using BFD
Thread-Index: AQHTZ/M82vlye4FAgk+FmQYa86ul9aMpXmmAgAA3kIA=
Date: Tue, 28 Nov 2017 18:23:32 +0000
Message-ID: <>
References: <> <>
In-Reply-To: <>
Accept-Language: en-US
Content-Language: en-US
authentication-results: spf=none (sender IP is );
x-originating-ip: []
x-ms-publictraffictype: Email
x-microsoft-exchange-diagnostics: 1; MWHPR05MB3230; 20:sbC7t74H+Ke4WQSPFE44BYa8dGppLfRnp4tRML4yLOTBsgjWedtMxsXR9crLb3mcK9xOYan1bduK4XcATE1Th6sv/4cjRbVNhGIUvrLFL4dQ9ulEAiwJWg7uxQcoG8bOmlp0Ae2iiRUJGGTVsaklTBYhxLW858DM1ygydu5ojA8=
x-ms-exchange-antispam-srfa-diagnostics: SSOS;SSOR;
x-forefront-antispam-report: SFV:SKI; SCL:-1; SFV:NSPM; SFS:(10009020)(39860400002)(346002)(366004)(376002)(189002)(199003)(53754006)(8676002)(54356999)(86362001)(14454004)(110136005)(4326008)(101416001)(97736004)(82746002)(25786009)(77096006)(81166006)(5660300001)(316002)(99286004)(2501003)(50986999)(606006)(81156014)(3846002)(7736002)(6116002)(102836003)(53936002)(229853002)(76176999)(36756003)(8936002)(2906002)(478600001)(3480700004)(2900100001)(6436002)(6506006)(105586002)(6306002)(53546010)(6486002)(68736007)(966005)(66066001)(106356001)(6512007)(39060400002)(33656002)(83716003)(54896002)(236005)(561944003)(45080400002)(3660700001)(6246003)(3280700002)(2950100002)(189998001); DIR:OUT; SFP:1101; SCL:1; SRVR:MWHPR05MB3230;; FPR:; SPF:None; PTR:InfoNoRecords; MX:1; A:1; LANG:en;
x-ms-office365-filtering-correlation-id: 74be3bcd-0fcd-48bf-efc2-08d5368d219e
x-microsoft-antispam: UriScan:; BCL:0; PCL:0; RULEID:(4534020)(4602075)(4627115)(201703031133081)(201702281549075)(5600026)(4604075)(2017052603258); SRVR:MWHPR05MB3230;
x-ms-traffictypediagnostic: MWHPR05MB3230:
x-microsoft-antispam-prvs: <>
x-exchange-antispam-report-test: UriScan:(61668805478150)(10436049006162)(72170088055959)(120809045254105)(189930954265078)(95692535739014)(227612066756510)(21748063052155);
x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(6040450)(2401047)(8121501046)(5005006)(93006095)(93001095)(3002001)(10201501046)(3231022)(6041248)(20161123555025)(20161123558100)(20161123560025)(20161123562025)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(20161123564025)(6072148)(201708071742011); SRVR:MWHPR05MB3230; BCL:0; PCL:0; RULEID:(100000803101)(100110400095); SRVR:MWHPR05MB3230;
x-forefront-prvs: 0505147DDB
received-spf: None ( does not designate permitted sender hosts)
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: multipart/alternative; boundary="_000_6FB7BA5C8ECC433089D08FD7306217F5vmwarecom_"
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 74be3bcd-0fcd-48bf-efc2-08d5368d219e
X-MS-Exchange-CrossTenant-originalarrivaltime: 28 Nov 2017 18:23:32.2802 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR05MB3230
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 18:23:38 -0000

Hi Ashesh,

Thanks for your comments.

For your first comment the draft applies to both single hop or what you call interface BFD and multi hop BFD too. And yes the per service could be per interface too if this is a single hop BFD, we can clarify that in the draft.

For your second comment, I am not sure I understand. The service will be active only on one node, if the service is associated with the whole node, then the BFD session is monitoring the node liveness. And when the service is associated with an interface the BFD session will monitor the interface connectivity as well. So, a primary service can’t be active at the 2 node endpoints hosting the BFD session.


From: Ashesh Mishra <<>>
Date: Tuesday, November 28, 2017 at 4:04 AM
To: Ankur Dubey <<>>, "<>" <<>>
Cc: Reshad Rahman <<>>, Sami Boutros <<>>
Subject: Re: Service Redundancy using BFD

Hi Ankur,

This is a good proposal to pursue within the BFD-wg.

Couple of comments:

-          BFD can only signal this diag code for the interface that it is monitoring (the IP next hop, MPLS LSP, etc.). You mention per-service (which I assume means per-service-per-interface) failover in the draft but it may be worthwhile defining behavior on per-service-type-per-interface as well.

-          There still needs to be a method for the primary and backup pairs (two BFD end-points on primary service and two on backup service) to communicate with each other (primary-to-primary and backup-to-backup) if the service is active or standby. This is useful in the scenario when the primary cannot communicate with backup nodes (it is a failure condition after all).

Again, at 10k ft, I like the idea of signaling active/standby using BFD.


From: Rtg-bfd <<>> on behalf of Ankur Dubey <<>>
Date: Monday, November 27, 2017 at 9:47 PM
To: "<>" <<>>
Cc: Reshad Rahman <<>>, Sami Boutros <<>>
Subject: Service Redundancy using BFD

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.