Internet DRAFT - draft-ietf-nvo3-geneve-oam
draft-ietf-nvo3-geneve-oam
NVO3 Working Group G. Mirsky
Internet-Draft Ericsson
Intended status: Standards Track S. Boutros
Expires: 8 June 2024 Ciena
D. Black
Dell EMC
S. Pallagatti
VMware
6 December 2023
OAM for use in GENEVE
draft-ietf-nvo3-geneve-oam-09
Abstract
This document lists a set of general requirements for active OAM
protocols in the Geneve overlay network. Based on the requirements,
IP encapsulation for active Operations, Administration, and
Maintenance protocols in Geneve protocol is defined. Considerations
for using ICMP and UDP-based protocols are discussed.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Acronyms . . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. Active OAM Protocols in Geneve Networks . . . . . . . . . . . 3
2.1. Defect Detection and Troubleshooting in Geneve Network with
Active OAM . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. OAM Encapsulation in Geneve . . . . . . . . . . . . . . . 6
3. Echo Request and Echo Reply in Geneve Tunnel . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Additional Considerations for OAM Encapsulation Method
in Geneve . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Geneve [RFC8926] is intended to support various scenarios of network
virtualization. In addition to carrying multi-protocol payload,
e.g., Ethernet, IPv4/IPv6, the Geneve message includes metadata.
Operations, Administration, and Maintenance (OAM) protocols support
fault management and performance monitoring functions necessary for
comprehensive network operation. Active OAM protocols, as defined in
[RFC7799], use specially constructed packets that are injected into
the network. To ensure that the measured performance metric or the
detected failure of the transport layer are related to a particular
Geneve flow, it is critical that these test packets share fate with
overlay data packets for that flow when traversing the underlay
network.
A set of general requirements for active OAM protocols in the Geneve
overlay network is listed in Section 2. IP encapsulation conforms to
these requirements and is a suitable encapsulation of active OAM
protocols in a Geneve overlay network. Active OAM in a Geneve
overlay network are exchanged between two Geneve tunnel endpoints,
which may be an NVE (Network Virtualization Edge) or another device
acting as a Geneve tunnel endpoint. For simplicity, NVE is used to
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represent the Geneve tunnel endpoint. Please refer to [RFC7365] and
[RFC8014] for detailed definitions and descriptions of NVE. The IP
encapsulation of Geneve OAM defined in this document applies to an
overlay service by introducing a Management Virtual Network
Identifier (VNI) that could be used in combination with various
values of the Protocol Type field in the Geneve header, i.e.,
Ethertypes for IPv4 or IPv6. Analysis and definition of other types
of OAM encapsulation in Geneve are outside the scope of this
document.
1.1. Conventions used in this document
1.1.1. Acronyms
Geneve Generic Network Virtualization Encapsulation
NVO3 Network Virtualization Overlays
OAM Operations, Administration, and Maintenance
VNI Virtual Network Identifier
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. Active OAM Protocols in Geneve Networks
OAM protocols, whether part of fault management or performance
monitoring, are intended to provide reliable information that can be
used to detect a failure, identify the defect and localize it, thus
helping to identify and apply corrective actions to minimize the
negative impact on service. Several OAM protocols are used to
perform these functions; these protocols require demultiplexing at
the receiving instance of Geneve. To improve the accuracy of the
correlation between the condition experienced by the monitored Geneve
tunnel and the state of the OAM protocol the OAM encapsulation is
required to comply with the following requirements:
REQ#1: Geneve OAM test packets MUST share the fate with data
traffic of the monitored Geneve tunnel, i.e., be in-band with the
monitored traffic, follow the same overlay and transport path as
packets with data payload, in the forward direction, i.e. from
ingress toward egress endpoint(s) of the OAM test.
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An OAM protocol MAY be used to monitor the particular Geneve tunnel
as a whole. In that case, test packets could be fate-sharing with a
sub-set of tenant flows transported over the Geneve tunnel. If the
goal is to monitor the condition experienced by the flow of a
particular tenant, the test packets MUST be fate-sharing with that
specific flow in the Geneve tunnel. Both scenarios are discussed in
detail in Section 2.1.
REQ#2: Encapsulation of OAM control message and data packets in
underlay network MUST be indistinguishable from the underlay
network IP forwarding point of view.
REQ#3: Presence of OAM control message in Geneve packet MUST be
unambiguously identifiable to Geneve functionality, e.g., at
endpoints of Geneve tunnels.
REQ#4: OAM test packets MUST NOT be forwarded to a tenant system.
A test packet generated by an active OAM protocol, either for a
defect detection or performance measurement, according to REQ#1, MUST
be fate-sharing with the tunnel or data flow being monitored. In an
environment where multiple paths through the domain are available,
underlay transport nodes can be programmed to use characteristic
information to balance the load across known paths. It is essential
that test packets follow the same route, i.e., traverses the same set
of nodes and links, as a data packet of the monitored flow. Thus,
the following requirement to support OAM packet fate-sharing with the
data flow:
REQ#5: It MUST be possible to express entropy for underlay Equal
Cost Multipath in the Geneve encapsulation of OAM packets.
2.1. Defect Detection and Troubleshooting in Geneve Network with Active
OAM
Figure 1 presents an example of a Geneve domain. In this section, we
consider two scenarios of active OAM being used to detect and
localize defects in the Geneve network.
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+--------+ +--------+
| Tenant +--+ +----| Tenant |
| VNI 28 | | | | VNI 35 |
+--------+ | ................ | +--------+
| +----+ . . +----+ |
| | NVE|--. .--| NVE| |
+--| A | . . | B |---+
+----+ . . +----+
/ . .
/ . Geneve .
+--------+ / . Network .
| Tenant +--+ . .
| VNI 35 | . .
+--------+ ................
|
+----+
| NVE|
| C |
+----+
|
|
=====================
| |
+--------+ +--------+
| Tenant | | Tenant |
| VNI 28 | | VNI 35 |
+--------+ +--------+
Figure 1: An example of a Geneve domain
In the first case, consider when a communication problem between
Network Virtualization Edge (NVE) device A and NVE C exists. Upon
the investigation, the operator discovers that the forwarding in the
underlay, e.g., the IP network, is working well. Still, the Geneve
connection is unstable for all NVE A and NVE C tenants. Detection,
troubleshooting, and localization of the problem can be done
irrespective of the VNI value.
In the second case, traffic on VNI 35 between NVE A and NVE B has no
problems, as on VNI 28 between NVE A and NVE C. But traffic on VNI
35 between NVE A and NVE C experiences problems, for example,
excessive packet loss.
The first case can be detected and investigated using any VNI value,
whether it connects tenant systems or not; however, to conform to
REQ#4 (Section 2) OAM test packets SHOULD be transmitted on a VNI
that doesn't have any tenants. Such a Geneve tunnel is dedicated to
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carrying only control and management data between the tunnel
endpoints, hence it is referred to as a Geneve control channel and
that VNI is referred to as the Management VNI. A configured VNI MAY
be used to identify the control channel, but it is RECOMMENDED that
the default value 1 be used as the Management VNI. Encapsulation of
test packets using the Management VNI is discussed in Section 2.2.
The control channel of a Geneve tunnel MUST NOT carry tenant data.
As no tenants are connected using the control channel, a system that
supports this specification, MUST NOT forward a packet received over
the control channel to any tenant. A packet received over the
control channel MAY be forwarded if and only if it is sent onto the
control channel of the a concatenated Geneve tunnel. The Management
VNI SHOULD be terminated on the tenant-facing side of the Geneve
encap/decap functionality, not the DC-network-facing side (per
definitions in Section 4 of [RFC8014]) so that Geneve encap/decap
functionality is included in its scope. This approach causes an
active OAM packet, e.g., an ICMP echo request, to be decapsulated in
the same fashion as any other received Geneve packet. In this
example, the resulting ICMP packet is handed to NVE's local
management functionality for the processing which generates an ICMP
echo reply. The ICMP echo reply is encapsulated in Geneve as
specified in Section 2.2. for forwarding back to the NVE that sent
the echo request. One advantage of this approach is that a repeated
ping test could detect an intermittent problem in Geneve encap/decap
hardware, which would not be tested if the Management VNI were
handled as a "special case" at the DC-network-facing interface.
The second case is when a test packet is transmitted using the VNI
value associated with the monitored service flow. By doing that, the
test packet experiences network treatment as the tenant's packets.
Details of that use case are outside the scope of this specification.
2.2. OAM Encapsulation in Geneve
Active OAM over a Management VNI in the Geneve network uses an IP
encapsulation. Protocols such as BFD [RFC5880] or STAMP [RFC8762]
use UDP transport. The destination UDP port number in the inner UDP
header (Figure 2) identifies the OAM protocol. This approach is
well-known and has been used, for example, in MPLS networks
[RFC8029]. To use IP encapsulation for an active OAM protocol the
Protocol Type field of the Geneve header MUST be set to the IPv4
(0x0800) or IPv6 (0x86DD) value.
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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 IPvX Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Outer UDP Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Geneve Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner IPvX Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Inner UDP Header ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Active OAM Packet ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: An Example of Geneve IP/UDP Encapsulation of an Active
OAM Packet
Inner IP header:
Destination IP: The IP address MUST be set to the loopback address
127.0.0.1/32 for IPv4, or the loopback address ::1/128 for IPv6
[RFC4291].
Source IP: IP address of the NVE.
TTL or Hop Limit: MUST be set to 255 per [RFC5082].
3. Echo Request and Echo Reply in Geneve Tunnel
ICMP and ICMPv6 ([RFC0792] and [RFC4443] respectively) provide
required on-demand defect detection and failure localization. ICMP
control messages immediately follow the inner IP header encapsulated
in Geneve. ICMP extensions for Geneve networks use mechanisms
defined in [RFC4884].
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4. IANA Considerations
This document has no requirements for IANA. This section can be
removed before the publication.
5. Security Considerations
As part of a Geneve network, active OAM inherits the security
considerations discussed in [RFC8926]. Additionally, a system MUST
provide control to limit the rate of Geneve OAM packets punted to the
Geneve control plane for processing in order to avoid overloading
that control plane.
OAM in GENEVE packets uses the General TTL Security Mechanism
[RFC5082] and any packet received with an inner TTL / Hop Count other
than 255 MUST be discarded.
6. Acknowledgments
The authors express their appreciation to Donald E. Eastlake 3rd for
his suggestions that improved the readability of the document.
7. References
7.1. 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>.
[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385,
February 2006, <https://www.rfc-editor.org/info/rfc4385>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<https://www.rfc-editor.org/info/rfc5586>.
[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>.
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[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>.
7.2. Informative References
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, DOI 10.17487/RFC0792, September 1981,
<https://www.rfc-editor.org/info/rfc792>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", STD 89,
RFC 4443, DOI 10.17487/RFC4443, March 2006,
<https://www.rfc-editor.org/info/rfc4443>.
[RFC4884] Bonica, R., Gan, D., Tappan, D., and C. Pignataro,
"Extended ICMP to Support Multi-Part Messages", RFC 4884,
DOI 10.17487/RFC4884, April 2007,
<https://www.rfc-editor.org/info/rfc4884>.
[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., Ed., and C.
Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, DOI 10.17487/RFC5082, October 2007,
<https://www.rfc-editor.org/info/rfc5082>.
[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>.
[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>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
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[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>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
Two-Way Active Measurement Protocol", RFC 8762,
DOI 10.17487/RFC8762, March 2020,
<https://www.rfc-editor.org/info/rfc8762>.
Appendix A. Additional Considerations for OAM Encapsulation Method in
Geneve
Several other options for OAM encapsulation were considered. Those
are listed in the Appendix solely for informational purposes. These
options were discarded in favor of the approach described in the main
body of this document.
A Protocol Type field might be used to demultiplex active OAM
protocols directly. Such method avoids the use of additional
intermediate header but requires that each active OAM protocol be
assigned unique identifier from the Ether Types registry maintained
by IANA.
The alternative to using the Protocol Type directly is to use a shim
that, in turn, identifies the OAM Protocol and, optionally, includes
additional information. [RFC5586] defines how the Generic Associated
Channel Label (GAL) can be used to identify that the Associated
Channel Header (ACH), defined in [RFC4385], immediately follows the
Bottom-of-the-Stack label. Thus, the MPLS Generic Associated Channel
can be identified, and protocols are demultiplexed based on the
Channel Type field's value. Number of channel types, e.g., for
continuity check and performance monitoring, already have been
defined and are listed in IANA MPLS Generalized Associated Channel
Types (including Pseudowire Associated Channel Types) registry. The
value of the Protocol Type field in the Geneve header MUST be set to
MPLS to use this approach. The Geneve header MUST be immediately
followed by the GAL label with the S flag set to indicate that GAL is
the Bottom-of-the-stack label. Then ACH MUST follow the GAL label
and the value of the Channel Type identifies which of active OAM
protocols being encapsulated in the packet.
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Authors' Addresses
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
Sami Boutros
Ciena
Email: sboutros@ciena.com
David Black
Dell EMC
176 South Street
Hopkinton, MA, 01748
United States of America
Email: david.black@dell.com
Santosh Pallagatti
VMware
Email: santosh.pallagatti@gmail.com
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