NVO3 Working Group X. Min
Internet-Draft G. Mirsky
Intended status: Standards Track ZTE Corp.
Expires: August 20, 2020 S. Pallagatti
VMware
February 17, 2020
BFD for Geneve
draft-xiao-nvo3-bfd-geneve-02
Abstract
This document describes the use of the Bidirectional Forwarding
Detection (BFD) protocol in point-to-point Generic Network
Virtualization Encapsulation (Geneve) tunnels used to make up an
overlay network.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. BFD Packet Transmission over Geneve Tunnel . . . . . . . . . 3
3.1. BFD Encapsulation With Inner Ethernet/IP/UDP Header . . . 3
3.2. BFD Encapsulation With Inner IP/UDP Header . . . . . . . 6
4. Reception of BFD packet from Geneve Tunnel . . . . . . . . . 8
4.1. Demultiplexing of the BFD packet . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
"Generic Network Virtualization Encapsulation" (Geneve)
[I-D.ietf-nvo3-geneve] provides an encapsulation scheme that allows
building an overlay network 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 continuity of the path
between two Geneve tunnel endpoints, which may be NVE (Network
Virtualization Edge) or other 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, and support for
echo BFD is outside the scope of this document. For simplicity, in
this document, NVE is used to represent 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].
The use cases and the deployment of BFD for Geneve are consistent
with what's described in Section 1 and 3 of [I-D.ietf-bfd-vxlan].
The major difference between Geneve and "Virtual eXtensible Local
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Area Network" (VXLAN) [RFC7348] encapsulation is that Geneve supports
multi-protocol payload and variable length options.
2. Conventions Used in This Document
2.1. Terminology
BFD: Bidirectional Forwarding Detection
Geneve: Generic Network Virtualization Encapsulation
NVE: Network Virtualization Edge
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.
3. BFD Packet Transmission over Geneve Tunnel
Concerning whether the Geneve data packets include an Ethernet frame
or an IP packet, this document defines two formats of BFD packet
encapsulation in Geneve. BFD session is originated and terminated at
VAP of an NVE, selection of the BFD packet encapsulation is based on
how the VAP encapsulates the data packets.
3.1. BFD Encapsulation With Inner Ethernet/IP/UDP Header
If the VAP that originates the BFD packets is used to encapsulate
Ethernet data frames, then BFD packets are encapsulated in Geneve as
described below. The Geneve packet format over IPv4 is defined in
Section 3.1 of [I-D.ietf-nvo3-geneve]. The Geneve packet format over
IPv6 is defined in Section 3.2 of [I-D.ietf-nvo3-geneve]. The Outer
IP/UDP and Geneve headers MUST be encoded by the sender as defined in
[I-D.ietf-nvo3-geneve]. Note that the outer IP header and the inner
IP header may not be of the same address family, in other words,
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outer IPv6 header accompanied with inner IPv4 header and outer IPv4
header accompanied with inner IPv6 header are both possible.
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
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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:
Ethernet Header:
Source MAC: MAC address of a VAP of the originating NVE.
Destination MAC: MAC address of a VAP of the terminating 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 of the originating NVE is 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 MUST be chosen from the 127/8 range for IPv4, and from
the ::ffff:127.0.0.0/104 range for IPv6.
TTL or Hop Limit: MUST be set to 255.
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 [I-D.ietf-nvo3-geneve] follows the value set
below.
Opt Len field SHOULD be set to 0, which indicates there isn't any
variable length option.
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 SHOULD be set to the VNI
number that the originating VAP is mapped to.
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3.2. BFD Encapsulation With Inner IP/UDP Header
If the VAP that originates the BFD packets is used to encapsulate IP
data packets, then BFD packets are encapsulated in Geneve as
described below. The Geneve packet format over IPv4 is defined in
Section 3.1 of [I-D.ietf-nvo3-geneve]. The Geneve packet format over
IPv6 is defined in Section 3.2 of [I-D.ietf-nvo3-geneve]. The Outer
IP/UDP and Geneve headers MUST be encoded by the sender as defined in
[I-D.ietf-nvo3-geneve]. Note that the outer IP header and the inner
IP header may not be of the same address family, in other words,
outer IPv6 header accompanied with inner IPv4 header and outer IPv4
header accompanied with 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:
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.
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 [I-D.ietf-nvo3-geneve] follows the value set
below.
Opt Len field SHOULD be set to 0, which indicates there isn't any
variable length option.
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 SHOULD be set to the VNI
number that the originating VAP is mapped to.
4. Reception of BFD packet from Geneve Tunnel
Once a packet is received, the NVE MUST validate the packet as
described in [I-D.ietf-nvo3-geneve].
If the Protocol Type field equals 0x6558 (Ethernet frame), and the
Destination MAC of the inner Ethernet frame matches the MAC
address of a VAP which is mapped to the same as 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.
If the Protocol Type field equals 0x0800 (IPv4) or 0x86DD (IPv6),
and the Destination IP of the inner IP packet matches the IP
address of a VAP which is mapped to the same as 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.
4.1. Demultiplexing of the BFD packet
In BFD over Geneve, a BFD session is originated and terminated at
VAP, usually one NVE owns multiple VAPs, so multiple BFD sessions may
be running between two NVEs, there needs to be a mechanism for
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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,
for different BFD encapsulation, the procedure for demultiplexing the
received BFD packets is different.
When the BFD Encapsulation With Inner Ethernet/IP/UDP Header is
used, the BFD session MUST be identified using the VNI number, and
the inner Ethernet/IP/UDP Header, i.e., the source MAC, the source
IP, the destination MAC, the destination IP, and the source UDP
port number present in the inner Ethernet/IP/UDP header.
When the BFD Encapsulation With Inner IP/UDP Header is used, the
BFD session MUST be identified using the VNI number, and the inner
IP/UDP header, i.e., the source IP, the destination IP, and the
source UDP port number present in the inner IP/UDP header.
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. Security Considerations
This document does not raise any additional security issues beyond
those of the specifications referred to in the list of references.
6. IANA Considerations
This document has no IANA action requested.
7. 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.
8. References
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8.1. Normative References
[I-D.ietf-nvo3-geneve]
Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", draft-ietf-
nvo3-geneve-14 (work in progress), September 2019.
[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>.
[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>.
[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>.
8.2. Informative References
[I-D.ietf-bfd-vxlan]
Networks, J., Paragiri, S., Govindan, V., Mudigonda, M.,
and G. Mirsky, "BFD for VXLAN", draft-ietf-bfd-vxlan-10
(work in progress), January 2020.
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[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>.
Authors' Addresses
Xiao Min
ZTE Corp.
Nanjing
China
Phone: +86 25 88013062
Email: xiao.min2@zte.com.cn
Greg Mirsky
ZTE Corp.
USA
Email: gregimirsky@gmail.com
Santosh Pallagatti
VMware
Email: santosh.pallagatti@gmail.com
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