Internet DRAFT - draft-mmbb-nvo3-geneve-oam
draft-mmbb-nvo3-geneve-oam
NVO3 Working Group G. Mirsky
Internet-Draft ZTE Corp.
Intended status: Standards Track S. Boutros
Expires: March 29, 2021 Ciena
D. Black
Dell EMC
S. Pallagatti
VMware
September 25, 2020
OAM for use in GENEVE
draft-mmbb-nvo3-geneve-oam-04
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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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 . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Geneve [I-D.ietf-nvo3-geneve] 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 defined as a suitable encapsulation of
active OAM protocols in a Geneve overlay network. Note that the IP
encapsulation of OAM is applicable to those VNIs that support the use
of the necessary values of the Protocol Type field in the Geneve
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header, i.e., Ethertypes of IPv4 or IPv6. It does not apply to VNIs
that lack that support, e.g., VNIs that only support Ethernet
Ethertypes. 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
CC Continuity Check
CV Connectivity Verification
FM Fault Management
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
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packets with data payload, in the forward direction, i.e. from
ingress toward egress endpoint(s) of the OAM test.
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. In the latter case, the test
packet MUST use the same Geneve encapsulation as the data packet
(except for the value in the Protocol Type field
[I-D.ietf-nvo3-geneve]), including the value in the Virtual Network
Identifier (VNI) field. 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 forwaded 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, a communication problem between Network
Virtualization Edge (NVE) device A and NVE C was observed. The
underlay, e.g., IP network, forwarding is working well but the Geneve
connection is unstable for all tenants of NVE A and NVE C.
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. To conform to REQ#4
(Section 2) OAM test packets could be transmitted on VNI that doesn't
have any tenant. That VNI in a Geneve tunnel is dedicated to
carrying only control and management data between the tunnel
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endpoints, hence communication that uses that VNI is also and
referred to as a Geneve control channel. Thus, 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 concatenated Geneve tunnel. A specific VNI MAY be used to
identify the control channel. The value that is associated with this
function is referred to as Management VNI. It is RECOMMENDED that
the value 1 be used as the default value of Management VNI.
Encapsulation of test packets, in this case, is discussed in
Section 2.2. 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 [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 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 requires that a test packet be transmitted using the
VNI value for the traffic that is encountering problems. The
encapsulation of the test packet, i.e., inner encapsulation, MUST be
the same as the tenant packet's encapsulation in the Geneve tunnel
and use the same VNI number. Encapsulation of test packets in this
case, is discussed in Section 2.2.
2.2. OAM Encapsulation in Geneve
Active OAM in Geneve network uses an IP encapsulation. Protocols
such as BFD [RFC5880] or STAMP [RFC8762] use UDP transport.
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]. The UDP source
port can be used to provide entropy, e.g., for Equal Cost Multipath.
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: Geneve IP/UDP Encapsulation of an Active OAM Packet
Inner IP header:
Destination IP: IP address MUST NOT be of one of tenant's IP
addresses. The IP address SHOULD be set to the loopback address
127.0.0.1/32 for IPv4, or the loopback address ::1/128 for IPv6
[RFC4291]. Alternatively, the destination IP address MAY be set
to VAP's IP address.
Source IP: IP address of the originating VAP.
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
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in Geneve. ICMP extensions for Geneve networks use mechanisms
defined in [RFC4884].
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 [I-D.ietf-nvo3-geneve]. 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.
6. Acknowledgments
TBD
7. References
7.1. Normative References
[I-D.ietf-nvo3-geneve]
Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", draft-ietf-
nvo3-geneve-16 (work in progress), March 2020.
[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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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>.
[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>.
[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>.
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[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 of OAM encapsulation were considered. Those
are listed in the Appendix solely for the informational purpose.
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.
Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Sami Boutros
Ciena
Email: sboutros@ciena.com
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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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