Internet DRAFT - draft-fmm-nvo3-pm-alt-mark
draft-fmm-nvo3-pm-alt-mark
NVO3 Working Group G. Fioccola
Internet-Draft Huawei Technologies
Intended status: Standards Track G. Mirsky
Expires: April 26, 2019 ZTE Corp.
T. Mizrahi
Huawei Network.IO Innovation Lab
October 23, 2018
Performance Measurement (PM) with Alternate Marking in Network
Virtualization Overlays (NVO3)
draft-fmm-nvo3-pm-alt-mark-03
Abstract
This document describes how the alternate marking method can be used
for performance measurement method in a Network Virtualization
Overlays (NVO3) Domain. The description aims to be general for NVO3
encapsulations, but is focused to Geneve, recommended by the NVO3
design team [I-D.ietf-nvo3-encap].
Status of This Memo
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This Internet-Draft will expire on April 26, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 2
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. OAM Performance Measurement in a NVO3 Domain . . . . . . . . 3
4. The Mark Field in the NVO3 Header . . . . . . . . . . . . . . 5
5. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 6
5.1. Single Mark Enabled Measurement . . . . . . . . . . . . . 6
5.2. Double Mark Enabled Measurement . . . . . . . . . . . . . 7
5.3. Multiplexed Mark Enabled Measurement . . . . . . . . . . 8
6. Multipoint Measurement Considerations . . . . . . . . . . . . 8
7. The Mark Field in Geneve . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8.1. Mark Field in Geneve Header . . . . . . . . . . . . . . . 9
9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
11.1. Normative References . . . . . . . . . . . . . . . . . . 9
11.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
[RFC7365] provides a framework for Data Center (DC) Network
Virtualization over Layer 3 (NVO3) tunnels. It is intended to aid in
standardizing protocols and mechanisms to support large-scale network
virtualization for data centers.
[RFC8321] describes a performance measurement method, which can be
used to measure packet loss, latency, and jitter on live traffic.
Since this method is based on marking consecutive batches of packets
the method often referred to as the Alternate Marking Method (AMM).
This document defines how the alternate marking method can be used to
measure packet loss and delay metrics of an NVO3 Domain.
2. Conventions used in this document
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2.1. Terminology
AMM: Alternate Marking Method
OAM: Operations, Administration and Maintenance
NVO3: Network Virtualization Overlays
NVE: Network Virtualization Edge
VNI: Virtual Network Instance
DC: Data Center
NVA: Network Virtualization Authority
Geneve: Generic Network Virtualization Encapsulation
VXLAN: Virtual Extensible LAN
GUE: Generic UDP Encapsulation
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. OAM Performance Measurement in a NVO3 Domain
Figure 1 shows the generic reference model for a DC network
virtualization over an L3 infrastructure while Figure 2 shows the
generic reference model for the Network Virtualization Edge (NVE).
Both Figures are taken from [RFC7365] and [RFC8014].
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+--------+ +--------+
| Tenant +--+ +----| Tenant |
| System | | (') | System |
+--------+ | ................. ( ) +--------+
| +---+ +---+ (_)
+--|NVE|---+ +---|NVE|-----+
+---+ | | +---+
/ . +-----+ .
/ . +--| NVA |--+ .
/ . | +-----+ \ .
| . | \ .
| . | Overlay +--+--++--------+
+--------+ | . | Network | NVE || Tenant |
| Tenant +--+ . | | || System |
| System | . \ +---+ +--+--++--------+
+--------+ .....|NVE|.........
+---+
|
|
=====================
| |
+--------+ +--------+
| Tenant | | Tenant |
| System | | System |
+--------+ +--------+
Figure 1: Generic Reference Model for DC Network Virtualization
Overlays (RFC7365)
+-------- L3 Network -------+
| |
| Tunnel Overlay |
+------------+---------+ +---------+------------+
| +----------+-------+ | | +---------+--------+ |
| | Overlay Module | | | | Overlay Module | |
| +---------+--------+ | | +---------+--------+ |
| |VN Context| | VN Context| |
| | | | | |
| +--------+-------+ | | +--------+-------+ |
| | |VNI| . |VNI| | | | |VNI| . |VNI| |
NVE1 | +-+------------+-+ | | +-+-----------+--+ | NVE2
| | VAPs | | | | VAPs | |
+----+------------+----+ +----+-----------+-----+
| | | |
| | | |
Tenant Systems Tenant Systems
Figure 2: Generic NVE Reference Model (RFC7365)
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L3 networks provide transport for an emulated Layer 2 created by NVE
devices. The connectivity between the NVE devices is achieved with
unicast and multicast tunneling methods. Then, the NVE devices
present an emulated Layer 2 network to the Tenant End Systems at a
Virtual Network Instance (VNI) through Virtual Access Points (VAPs).
The NVE devices map Layer 2 unicast to Layer 3 unicast point-to-point
tunnels and may either map Layer 2 multicast to Layer 3 multicast
tunnels or may replicate packets onto multiple Layer 3 unicast
tunnels.
The emulated Layer 2 network is provided by the NVE devices to which
the Tenant End Systems are connected. This network of NVE can be
operated by a single service provider or can span across multiple
administrative domains. Likewise, the L3 Overlay Network can be
operated by a single service provider or span across multiple
administrative domains.
Each of the layers is responsible for its own OAM. Complex OAM
relationships exist as a result of the hierarchical layering, but
this is out of scope here.
When we refer to an OAM domain considered in this document we refer
to a set of NVEs and the tunnels which interconnect them.
It is commonly agreed that NVO3 OAM Performance Management supports
measurements (packet loss, latency, and jitter) per VNI between two
NVE devices that support the same VNI within a given NVO3 domain.
4. The Mark Field in the NVO3 Header
This document defines a two-bit long field, referred to as Mark field
(M), as part of the NVO3 Header and designated for the alternate
marking performance measurement method [RFC8321]. The Mark field
MUST NOT be used in defining forwarding and/or quality of service
treatment of an NVO3 packet. The Mark field MUST be used only for
the performance measurement of data traffic in the NVO3 layer. Since
the field does not affect forwarding and/or quality of service
treatment of packets, the alternate marking method in the NVO3 layer
can be viewed as nearly-passive performance measurement method.
Figure 3 displays the format of the Mark field.
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0
0 1
+-+-+-+-+
| L | D |
+-+-+-+-+
Figure 3: Mark field (M) format
where:
o L - Loss bit;
o D - Delay bit.
5. Theory of Operation
The marking method can be used in NVO3. For example, one can
consider the NVO3 reference model presented in Figure 1. AMM can be
applied at either ingress or egress NVE to detect performance
degradation defect and localize it efficiently.
Using AMM, NVE1 creates distinct sub-flows. Each sub-flow consists
of consecutive blocks that are unambiguously recognizable by a
monitoring point at any component of the NVO3, e.g. NVE2 or NVE3,
and can be measured to calculate packet loss and/or packet delay
metrics.
Every NVO3 Header [I-D.ietf-nvo3-geneve], [I-D.ietf-nvo3-vxlan-gpe]
and [I-D.ietf-nvo3-gue] can be considered for the application of AMM.
5.1. Single Mark Enabled Measurement
As explained in the [RFC8321], marking can be applied to delineate
blocks of packets based either on the equal number of packets in a
block or based on equal time interval. The latter method offers
better control as it allows better account for capabilities of
downstream nodes to report statistics related to batches of packets
and, at the same time, time resolution that affects defect detection
interval.
If the Single Mark measurement used, then the D flag MUST be set to
zero on transmit and ignored by monitoring point.
The L flag is used to create alternate flows to measure the packet
loss by switching the value of the L flag every N-th packet or at
certain time intervals. Delay metrics MAY be calculated with the
alternate flow using any of the following methods:
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o First/Last Packet Delay calculation: whenever the marking, i.e.
the value of L flag, changes a component of the NVO3 can store the
timestamp of the first/last packet of the block. The timestamp
can be compared with the timestamp of the packet that arrived in
the same order through a monitoring point at a downstream
component of the NVO3 to compute packet delay. Because timestamps
collected based on order of arrival this method is sensitive to
packet loss and re-ordering of packets
o Average Packet Delay calculation: an average delay is calculated
by considering the average arrival time of the packets within a
single block. A component of the NVO3 may collect timestamps for
each packet received within a single block. Average of the
timestamp is the sum of all the timestamps divided by the total
number of packets received. Then the difference between averages
calculated at two monitoring points is the average packet delay on
that segment. This method is robust to out of order packets and
also to packet loss (only a small error is introduced). This
method only provides a single metric for the duration of the block
and it doesn't give the minimum and maximum delay values. This
limitation could be overcome by reducing the duration of the block
by means of a highly optimized implementation of the method.
5.2. Double Mark Enabled Measurement
Double Mark method allows measurement of minimum and maximum delays
for the monitored flow but it requires more nodal and network
resources. If the Double Mark method used, then the L flag MUST be
used to create the alternate flow, i.e. mark larger batches of
packets. The D flag MUST be used to mark single packets to measure
delay jitter.
The first marking (L flag alternation) is needed for packet loss and
also for average delay measurement. The second marking (D flag is
put to one) creates a new set of marked packets that are fully
identified over NVO3, so that a component can store the timestamps of
these packets; these timestamps can be compared with the timestamps
of the same packets on another component of the NVO3 to compute
packet delay values for each packet. The number of measurements can
be easily increased by changing the frequency of the second marking.
But the frequency of the second marking must be not too high in order
to avoid out of order issues. This method is suitable to have not
only the average delay but also the minimum and maximum delay values
and, in wider terms, to know more about the statistic distribution of
delay values.
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5.3. Multiplexed Mark Enabled Measurement
There is also a scheme that provides the benefits of Double Mark
method, but uses only one bit like Single Mark. This methodology is
described in [I-D.mizrahi-ippm-compact-alternate-marking]. The
concept is that in the middle of each block of packets with a certain
value of the L flag, a single packet has the L flag inverted. So, by
examining the stream, the packets with the inverted bit can be easily
identified and employed for delay measurement. This Alternate
Marking variation is advantageous because it requires only one bit
from each packet, and such bits are always in short supply.
6. Multipoint Measurement Considerations
The Multipoint characteristics of the traffic within a given NVO3
Domain could be considered a valuable Use Case of
[I-D.fioccola-ippm-multipoint-alt-mark].
7. The Mark Field in Geneve
[I-D.ietf-nvo3-geneve] defines the format of the Geneve Header.
The design team recommendations in [I-D.ietf-nvo3-encap] section 7
concluded that Geneve is most suitable as a starting point for the
proposed standard for network virtualization.
In addition, the design team recommended addressing requirements for
OAM considerations for alternate marking and for performance
measurements that need 2 bits in the header. This document clarifies
the need for the current OAM bit in the Geneve Header.
Geneve Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver| Opt Len |O|C| M | Rsvd. | Protocol Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Virtual Network Identifier (VNI) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Geneve Header
This document defines a two-bit long field, referred to as the Mark
field (M in Figure 4, as part of Geneve and designated for the
alternate marking performance measurement method [RFC8321]. The Mark
field MUST NOT be used in defining forwarding and/or quality of
service treatment of a NVO3 packet. The Mark field MUST be used only
for the performance measurement of data traffic in the NVO3 layer.
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Since the field does not affect forwarding and/or quality of service
treatment of packets, the alternate marking method in the NVO3 layer
can be viewed as nearly-passive performance measurement method.
8. IANA Considerations
8.1. Mark Field in Geneve Header
This document requests IANA to allocate Mark field as two bits-long
field from Geneve Header Reserved Bits [I-D.ietf-nvo3-geneve].
This document requests IANA to register values of the Mark field of
Geneve as the following:
+--------------+---------+--------------------------+---------------+
| Bit Position | Marking | Description | Reference |
+--------------+---------+--------------------------+---------------+
| 0 | L | Single Mark Measurement | This document |
| 1 | D | Double Mark Measurement | This document |
+--------------+---------+--------------------------+---------------+
Table 1: Mark field of Geneve
9. Security Considerations
This document lists the OAM requirement for the NVO3 domain and does
not raise any security concerns or issues in addition to ones common
to networking and NVO3.
10. Acknowledgement
The authors would like to thank Dale R. Worley for the contribution.
11. References
11.1. Normative References
[I-D.ietf-nvo3-encap]
Boutros, S., "NVO3 Encapsulation Considerations", draft-
ietf-nvo3-encap-02 (work in progress), September 2018.
[I-D.ietf-nvo3-geneve]
Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", draft-ietf-
nvo3-geneve-08 (work in progress), October 2018.
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[I-D.ietf-nvo3-gue]
Herbert, T., Yong, L., and O. Zia, "Generic UDP
Encapsulation", draft-ietf-nvo3-gue-05 (work in progress),
October 2016.
[I-D.ietf-nvo3-vxlan-gpe]
Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
Extension for VXLAN", draft-ietf-nvo3-vxlan-gpe-06 (work
in progress), April 2018.
[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>.
[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>.
11.2. Informative References
[I-D.fioccola-ippm-multipoint-alt-mark]
Fioccola, G., Cociglio, M., Sapio, A., and R. Sisto,
"Multipoint Alternate Marking method for passive and
hybrid performance monitoring", draft-fioccola-ippm-
multipoint-alt-mark-04 (work in progress), June 2018.
[I-D.mizrahi-ippm-compact-alternate-marking]
Mizrahi, T., Arad, C., Fioccola, G., Cociglio, M., Chen,
M., Zheng, L., and G. Mirsky, "Compact Alternate Marking
Methods for Passive and Hybrid Performance Monitoring",
draft-mizrahi-ippm-compact-alternate-marking-03 (work in
progress), October 2018.
[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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[RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate-Marking Method for Passive and Hybrid
Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
January 2018, <https://www.rfc-editor.org/info/rfc8321>.
Authors' Addresses
Giuseppe Fioccola
Huawei Technologies
Riesstrasse, 25
Munich 80992
Germany
Email: giuseppe.fioccola@huawei.com
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Tal Mizrahi
Huawei Network.IO Innovation Lab
Israel
Email: tal.mizrahi.phd@gmail.com
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