Internet DRAFT - draft-ietf-nvo3-bfd-geneve
draft-ietf-nvo3-bfd-geneve
NVO3 Working Group X. Min
Internet-Draft ZTE Corp.
Intended status: Standards Track G. Mirsky
Expires: 25 February 2024 Ericsson
S. Pallagatti
VMware
J. Tantsura
Nvidia
S. Aldrin
Google
24 August 2023
BFD for Geneve
draft-ietf-nvo3-bfd-geneve-13
Abstract
This document describes the use of the Bidirectional Forwarding
Detection (BFD) protocol in point-to-point Generic Network
Virtualization Encapsulation (Geneve) unicast tunnels used to make up
an overlay network.
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
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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 25 February 2024.
Copyright Notice
Copyright (c) 2023 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.
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Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. BFD Packet Transmission over Geneve Tunnel . . . . . . . . . 4
4. BFD Encapsulation With Inner Ethernet/IP/UDP Header . . . . . 4
4.1. Demultiplexing BFD packet when payload is Ethernet . . . 6
5. BFD Encapsulation With Inner IP/UDP Header . . . . . . . . . 7
5.1. Demultiplexing BFD packet when payload is IP . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
"Generic Network Virtualization Encapsulation" (Geneve) [RFC8926]
provides an encapsulation scheme that allows building an overlay
network of tunnels by decoupling the address space of the attached
virtual hosts from that of the network.
This document describes the use of Bidirectional Forwarding Detection
(BFD) protocol [RFC5880] to enable monitoring the continuity of the
path between two Geneve tunnel endpoints, which may be a NVE (Network
Virtualization Edge) or another device acting as a Geneve tunnel
endpoint. Specifically, the asynchronous mode of BFD, as defined in
[RFC5880], is used to monitor a P2P Geneve tunnel. The support for
BFD Echo function is outside the scope of this document. For
simplicity, NVE is used to represent the Geneve tunnel endpoint. TS
(Tenant System) is used to represent the physical or virtual device
attached to a Geneve tunnel endpoint from the outside. VAP (Virtual
Access Point) is the NVE side of the interface between the NVE and
the TS, and a VAP is a logical network port (virtual or physical)
into a specific virtual network. For detailed definitions and
descriptions of NVE, TS and VAP, please refer to [RFC7365] and
[RFC8014].
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The use cases and the deployment of BFD for Geneve are mostly
consistent with what's described in Section 1 and 3 of [RFC8971]
("Bidirectional Forwarding Detection (BFD) for Virtual eXtensible
Local Area Network (VXLAN)"). One exception is on the usage of
Management VNI, which is described in [I-D.ietf-nvo3-geneve-oam] and
outside the scope of this document.
As specified in Section 4.2 of [RFC8926], Geneve MUST be used with
congestion-controlled traffic or within a traffic-managed controlled
environment (TMCE) to avoid congestion, that requirement applies to
BFD traffic too. Specifically, considering the complexity and
immaturity of BFD congestion control mechanism, BFD for Geneve MUST
be used within a TMCE unless BFD is really congestion controlled. As
an alternative to a real congestion control, an operator of a TMCE
deploying BFD for Geneve is required to provision the rates at which
BFD is transmitted to avoid congestion and false failure detection.
2. Conventions Used in This Document
2.1. Abbreviations
BFD: Bidirectional Forwarding Detection
FCS: Frame Check Sequence
Geneve: Generic Network Virtualization Encapsulation
NVE: Network Virtualization Edge
TMCE: Traffic-Managed Controlled Environment
TS: Tenant System
VAP: Virtual Access Point
VNI: Virtual Network Identifier
VXLAN: Virtual eXtensible Local Area Network
2.2. 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.
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3. BFD Packet Transmission over Geneve Tunnel
Since the Geneve data packet payload may be either an Ethernet frame
or an IP packet, this document defines two formats of BFD packet
encapsulation in Geneve. The BFD session is originated and
terminated at the VAP of an NVE. The selection of the BFD packet
encapsulation is based on how the VAP encapsulates the data packets.
If the payload is IP, then BFD over IP is carried in the payload. If
the payload is Ethernet, then BFD over IP over Ethernet is carried in
the payload, in the same manner as BFD over IP in the IP payload
case, regardless of what the Ethernet payload might normally carry.
4. BFD Encapsulation With Inner Ethernet/IP/UDP Header
If the VAP that originates the BFD packets is used to encapsulate
Ethernet data frames, then the BFD packets are encapsulated in Geneve
as described below. The Geneve packet formats over IPv4 and IPv6 are
defined in Section 3.1 and 3.2 of [RFC8926] respectively. The Outer
IP/UDP and Geneve headers are encoded by the sender as defined in
[RFC8926]. Note that the outer IP header and the inner IP header may
not be of the same address family. In other words, an outer IPv6
header accompanied by an inner IPv4 header and an outer IPv4 header
accompanied by an inner IPv6 header are both possible.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Outer Ethernet Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Outer IPvX Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Outer UDP Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Geneve Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner Ethernet Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner IPvX Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner UDP Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ BFD Control Packet ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outer Ethernet FCS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Geneve Encapsulation of BFD Control Packet With the Inner
Ethernet/IP/UDP Header
The BFD packet MUST be carried inside the inner Ethernet frame of the
Geneve packet. The inner Ethernet frame carrying the BFD Control
packet has the following format:
Inner Ethernet Header:
- Destination MAC: MAC address of a VAP of the terminating NVE.
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- Source MAC: MAC address of a VAP of the originating NVE.
IP Header:
- Source IP: IP address of a VAP of the originating NVE. If the
VAP of the originating NVE has no IP address, then the IP
address 0.0.0.0 for IPv4 or ::/128 for IPv6 MUST be used.
- Destination IP: IP address of a VAP of the terminating NVE. If
the VAP of the terminating NVE has no IP address, then the IP
address 127.0.0.1 for IPv4 or ::1/128 for IPv6 MUST be used.
- TTL or Hop Limit: MUST be set to 255 in accordance with
[RFC5881] that specifies the IPv4/IPv6 single-hop BFD.
The fields of the UDP header and the BFD Control packet are
encoded as specified in [RFC5881].
When the BFD packets are encapsulated in Geneve in this way, the
Geneve header defined in [RFC8926] follows the value set below.
Opt Len field MUST be set consistent with the Geneve specification
[RFC8926] depending on whether or not Geneve options are present
in the frame. The use of Geneve options with BFD is beyond the
scope of this document.
O bit MUST be set to 1, which indicates this packet contains a
control message.
C bit MUST be set to 0, which indicates there isn't any critical
option.
Protocol Type field MUST be set to 0x6558 (Ethernet frame).
Virtual Network Identifier (VNI) field MUST be set to the VNI
number that the originating VAP is mapped to.
4.1. Demultiplexing BFD packet when payload is Ethernet
Once a packet is received, the NVE validates the packet as described
in [RFC8926]. When the payload is Ethernet, the Protocol Type field
equals 0x6558. The Destination MAC address of the inner Ethernet
frame matches the MAC address of a VAP which is mapped to the same
VNI as the received VNI. Then the Destination IP, the UDP
destination port and the TTL or Hop Limit of the inner IP packet MUST
be validated to determine whether the received packet can be
processed by BFD, i.e., the three field values of the inner IP packet
MUST be in compliance with what's defined in Section 4 of this
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document, as well as Section 4 of [RFC5881]. If the validation
fails, the received packet MUST NOT be processed by BFD.
In BFD over Geneve, a BFD session is originated and terminated at a
VAP. Usually one NVE owns multiple VAPs. Since multiple BFD
sessions may be running between two NVEs, there needs to be a
mechanism for demultiplexing received BFD packets to the proper
session. Furthermore, due to the fact that [RFC8014] allows for
N-to-1 mapping between VAP and VNI at one NVE, multiple BFD sessions
between two NVEs for the same VNI are allowed. Also note that a BFD
session can only be established between two VAPs that are mapped to
the same VNI and use the same way to encapsulate data packets.
If the BFD packet is received with Your Discriminator equals to 0,
then the BFD session SHOULD be identified using the VNI number and
the inner Ethernet/IP header. The inner Ethernet/IP header stands
for the source MAC, the source IP, the destination MAC, and the
destination IP. An implementation MAY use the inner UDP port source
number to aid in demultiplexing incoming BFD Control packets. If it
fails to identify the BFD session, the incoming BFD Control packets
MUST be dropped, and an exception event indicating the failure should
be reported to the management.
If the BFD packet is received with non-zero Your Discriminator, then
the BFD session MUST be demultiplexed only with Your Discriminator as
the key.
5. BFD Encapsulation With Inner IP/UDP Header
If the VAP that originates the BFD packets is used to encapsulate IP
data packets, then the BFD packets are encapsulated in Geneve as
described below. The Geneve packet formats over IPv4 and IPv6 are
defined in Section 3.1 and 3.2 of [RFC8926] respectively. The Outer
IP/UDP and Geneve headers are encoded by the sender as defined in
[RFC8926]. Note that the outer IP header and the inner IP header may
not be of the same address family. In other words, an outer IPv6
header accompanied by an inner IPv4 header and an outer IPv4 header
accompanied by an inner IPv6 header are both possible.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Ethernet Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Outer IPvX Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Outer UDP Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Geneve Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner IPvX Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner UDP Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ BFD Control Packet ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Geneve Encapsulation of BFD Control Packet With the
Inner IP/UDP Header
The BFD packet MUST be carried inside the inner IP packet of the
Geneve packet. The inner IP packet carrying the BFD Control packet
has the following format:
Inner IP header:
- Source IP: IP address of a VAP of the originating NVE.
- Destination IP: IP address of a VAP of the terminating NVE.
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- TTL or Hop Limit: MUST be set to 255 in accordance with
[RFC5881] that specifies the IPv4/IPv6 single-hop BFD.
The fields of the UDP header and the BFD Control packet are
encoded as specified in [RFC5881].
When the BFD packets are encapsulated in Geneve in this way, the
Geneve header defined in [RFC8926] follows the value set below.
Opt Len field MUST be set consistent with the Geneve specification
[RFC8926] depending on whether or not Geneve options are present
in the frame. The use of Geneve options with BFD is beyond the
scope of this document.
O bit MUST be set to 1, which indicates this packet contains a
control message.
C bit MUST be set to 0, which indicates there isn't any critical
option.
Protocol Type field MUST be set to 0x0800 (IPv4) or 0x86DD (IPv6),
depending on the address family of the inner IP packet.
Virtual Network Identifier (VNI) field MUST be set to the VNI
number that the originating VAP is mapped to.
5.1. Demultiplexing BFD packet when payload is IP
Once a packet is received, the NVE validates the packet as described
in [RFC8926]. When the payload is IP, the Protocol Type field equals
0x0800 or 0x86DD. The Destination IP address of the inner IP packet
matches the IP address of a VAP which is mapped to the same VNI as
the received VNI. Then the UDP destination port and the TTL or Hop
Limit of the inner IP packet MUST be validated to determine whether
the received packet can be processed by BFD, i.e., the two field
values of the inner IP packet MUST be in compliance with what's
defined in Section 5 of this document, as well as Section 4 of
[RFC5881]. If the validation fails, the received packet MUST NOT be
processed by BFD.
If the BFD packet is received with Your Discriminator equals to 0,
then the BFD session SHOULD be identified using the VNI number and
the inner IP header. The inner IP header stands for the source IP
and the destination IP. An implementation MAY use the inner UDP port
source number to aid in demultiplexing incoming BFD Control packets.
If it fails to identify the BFD session, the incoming BFD Control
packets MUST be dropped, and an exception event indicating the
failure should be reported to the management.
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If the BFD packet is received with non-zero Your Discriminator, then
the BFD session MUST be demultiplexed only with Your Discriminator as
the key.
6. Security Considerations
Security issues discussed in [RFC8926] and [RFC5880] apply to this
document. Particularly, the BFD is an application that is run at the
two Geneve tunnel endpoints. The IP underlay network and/or the
Geneve option can provide security between the peers, which are
subject to the issue of overload described below. The BFD introduces
no security vulnerabilities when run in this manner. Considering
Geneve does not have any inherent security mechanisms, BFD
authentication as specified in [RFC5880] is RECOMMENDED to be
utilized.
This document supports establishing multiple BFD sessions between the
same pair of NVEs, each BFD session over a pair of VAPs residing in
the same pair of NVEs, there SHOULD be a mechanism to control the
maximum number of such sessions that can be active at the same time.
Particularly, assuming an example that each NVE of the pair of NVEs
has N VAPs using Ethernet as the payload, then there could be N
squared BFD sessions running between the pair of NVEs. Considering N
could be a high number, the N squared BFD sessions could result in
overload of the NVE. In this case, it's recommended that N BFD
sessions covering all N VAPs are run for the pair of NVEs. Generally
speaking, the number of BFD sessions is supposed to be enough as long
as all VAPs of the pair of NVEs are covered.
7. IANA Considerations
This document has no IANA action requested.
8. Acknowledgements
The authors would like to acknowledge Reshad Rahman, Jeffrey Haas,
and Matthew Bocci for their guidance on this work.
The authors would like to acknowledge David Black for his explanation
on the mapping relation between VAP and VNI.
The authors would like to acknowledge Stewart Bryant, Anoop Ghanwani,
Jeffrey Haas, Reshad Rahman, Matthew Bocci, Andrew Alston, Magnus
Westerlund, Paul Kyzivat, Sheng Jiang, Carl Wallace, Roman Danyliw,
John Scudder, Donald Eastlake, Eric Vyncke, Zaheduzzaman Sarker, and
Lars Eggert for their thorough review and very helpful comments.
9. References
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9.1. 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>.
[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>.
[RFC8926] Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
"Geneve: Generic Network Virtualization Encapsulation",
RFC 8926, DOI 10.17487/RFC8926, November 2020,
<https://www.rfc-editor.org/info/rfc8926>.
9.2. Informative References
[I-D.ietf-nvo3-geneve-oam]
Mirsky, G., Boutros, S., Black, D. L., and S. Pallagatti,
"OAM for use in GENEVE", Work in Progress, Internet-Draft,
draft-ietf-nvo3-geneve-oam-07, 27 June 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-nvo3-
geneve-oam-07>.
[RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
Rekhter, "Framework for Data Center (DC) Network
Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
2014, <https://www.rfc-editor.org/info/rfc7365>.
[RFC8014] Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
Narten, "An Architecture for Data-Center Network
Virtualization over Layer 3 (NVO3)", RFC 8014,
DOI 10.17487/RFC8014, December 2016,
<https://www.rfc-editor.org/info/rfc8014>.
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[RFC8971] Pallagatti, S., Ed., Mirsky, G., Ed., Paragiri, S.,
Govindan, V., and M. Mudigonda, "Bidirectional Forwarding
Detection (BFD) for Virtual eXtensible Local Area Network
(VXLAN)", RFC 8971, DOI 10.17487/RFC8971, December 2020,
<https://www.rfc-editor.org/info/rfc8971>.
Authors' Addresses
Xiao Min
ZTE Corp.
Nanjing
China
Phone: +86 18061680168
Email: xiao.min2@zte.com.cn
Greg Mirsky
Ericsson
United States of America
Email: gregimirsky@gmail.com
Santosh Pallagatti
VMware
India
Email: santosh.pallagatti@gmail.com
Jeff Tantsura
Nvidia
United States of America
Email: jefftant.ietf@gmail.com
Sam Aldrin
Google
United States of America
Email: aldrin.ietf@gmail.com
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