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Versions: 00                                                            
BFD Working Group                                                R. Wang
Internet-Draft                                                  W. Cheng
Intended status: Informational                              China Mobile
Expires: May 21, 2020                                            Y. Zhao
                                                                  A. Liu
                                                                     ZTE
                                                       November 18, 2019


                   Using One-Arm BFD in Cloud Network
                   draft-wang-bfd-one-arm-use-case-00

Abstract

   Bidirectional Forwarding Detection (BFD) is a fault detection
   protocol that can quickly determine a communication failure between
   devices and notify upper-layer applications [RFC5880].  BFD has
   asynchronous detecting mode and demand detection mode to satisfy
   different scenarios, also supports echo function to reduce the device
   requirement for BFD.  One-Arm BFD this draft descripted supports
   another BFD detecting function rather than the echo as described in
   [RFC5880] [RFC5881], it needs nothing BFD capability to one of the
   devices deployed BFD detecting.  Using One-Arm BFD function, the one
   device works on BFD detecting normally and the other device just
   loopback the BFD packets like echo function.  One-Arm BFD is suitable
   for the cloud virtualization network, the One-Arm BFD is deploy on
   NFV gateways, and NFV virtual machine vNICs just enable the echo/
   loopback process.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 21, 2020.






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Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  One-Arm BFD Use Case  . . . . . . . . . . . . . . . . . . . .   3
   3.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   To minimize the impact of device faults on services and improve
   network availability, a network device must be able to quickly detect
   faults in communication with adjacent devices.  Measures can then be
   taken to promptly rectify the faults to ensure service continuity.

   BFD is a low-overhead, short-duration method to detect faults on the
   path between adjacent forwarding engines.  The faults can be
   interface, data link, and even forwarding engine faults.  It is a
   single, unified mechanism to monitor any media and protocol layers in
   real time.

   BFD has asynchronous detecting mode and demand detection mode to
   satisfy different scenarios, also supports echo function to reduce
   the device requirement for BFD.  BFD echo function is used when two
   devices are connected but only one of them supports full BFD
   capability.  When the echo function is activated, the local system
   sends a BFD control packet and the remote system loops back the



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   packet through the forwarding channel.  If several consecutive echo
   packets are not received, the session is declared to be Down.  BFD
   echo function reduces one of the two devices requirement for BFD.

   With the development of network cloud and NFV virtualization, there
   are many connections between gateway devices and the virtual machine
   devices.  The virtual machine devices don't support BFD capacity at
   all.  There is difficult to deploy BFD between the gateway devices
   and the virtual machine vNICs.  One-Arm BFD supports this scenario,
   it supports gateway enable full BFD capability and virtual machine
   don't support BFD at all, just simply loopback BFD packets on vNICs.

1.1.  Conventions Used in This Document

1.1.1.  Terminology

   BFD: Bidirectional Forwarding Detection

   NFV: Network Function Virtualization

1.1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  One-Arm BFD Use Case

   With the development of network cloud and NFV virtualization, there
   are many connections between gateway devices and the virtual machine
   devices.  The virtual machine(VM) devices don't support BFD capacity
   at all.  If the gateway devices are deployed BFD protocol, there are
   some problems including scalability, detecting period and so on.  And
   the VM can't support BFD protocol currently.  One-Arm echo BFD can
   resolve these problems.  One-arm echo BFD is used when two devices
   are connected and only one of them supports BFD.  A one-arm BFD echo
   session can be established on the device that supports BFD, the other
   device just loopback BFD packets.

   After receiving a one-arm BFD echo session packet, the device that
   does not support BFD immediately loops back the packet, implementing
   quick link failure detection.  As shown in Figure 1, Device A such as
   a NFV gateway supports BFD, whereas Device B such as a virtual
   machine does not.  To rapidly detect faults in the link between
   Device A and Device B, configure a one-arm BFD echo session on Device
   A.  After receiving a one-arm BFD echo session packet from Device A,



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   Device B immediately loops back the packet, implementing rapid link
   fault detection.


   Device A               One-Arm Echo        Device B
   +--------+             BFD session         +---------+
   |   A    |---------------------------------|   B     |
   |        |Inf 1                       Inf 1|         |
   +--------+10.1.1.1/24           10.1.1.2/24+---------+
   BFD is supported.                          BFD is not supported.


                 Figure 1: One-Arm BFD deploying scenario

3.  Discussion

   One-Arm BFD detecting function is better than BFD echo function mode.
   First One-Arm BFD can use full BFD capacity in the BFD-supported
   device.  So One-Arm BFD can also support fast detecting and manage
   BFD sessions effectively.  Second it is scalable using one-arm BFD
   detecting to adapt the NFV virtualization.  Finally, it is the same
   process in the non-BFD-supported devices with echo function.  So one-
   arm BFD can be deployed to the cloud network, and the VMs don't
   require to support BFD capacity.

4.  Security Considerations

   TBD.

5.  IANA Considerations

   This document has no IANA action requested.

6.  Acknowledgements

   TBD.

7.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.




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   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              DOI 10.17487/RFC5881, June 2010,
              <https://www.rfc-editor.org/info/rfc5881>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Ruixue Wang
   China Mobile
   Beijing
   CN

   Email: wangruixue@chinamobile.com


   Weiqiang Cheng
   China Mobile
   Beijing
   CN

   Email: chengweiqiang@chinamobile.com


   Yanhua Zhao
   ZTE
   Nanjing
   CN

   Email: zhao.yanhua3@zte.com.cn


   Aihua Liu
   ZTE
   Shenzhen
   CN

   Email: liu.aihua@zte.com.cn










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