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. Wang, et al. Expires May 21, 2020 [Page 1] Internet-Draft Using One-Arm BFD in Cloud Network November 2019 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 Wang, et al. Expires May 21, 2020 [Page 2] Internet-Draft Using One-Arm BFD in Cloud Network November 2019 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, Wang, et al. Expires May 21, 2020 [Page 3] Internet-Draft Using One-Arm BFD in Cloud Network November 2019 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, . [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, . Wang, et al. Expires May 21, 2020 [Page 4] Internet-Draft Using One-Arm BFD in Cloud Network November 2019 [RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, DOI 10.17487/RFC5881, June 2010, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 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 Wang, et al. Expires May 21, 2020 [Page 5]