Internet DRAFT - draft-wang-bfd-one-arm-use-case
draft-wang-bfd-one-arm-use-case
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,
<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>.
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,
<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
Wang, et al. Expires May 21, 2020 [Page 5]
