Internet DRAFT - draft-brockners-ippm-ioam-geneve
draft-brockners-ippm-ioam-geneve
ippm F. Brockners, Ed.
Internet-Draft Cisco
Intended status: Standards Track S. Bhandari
Expires: May 23, 2021 Thoughtspot
V. Govindan
C. Pignataro, Ed.
N. Nainar, Ed.
Cisco
H. Gredler
RtBrick Inc.
J. Leddy
S. Youell
JMPC
T. Mizrahi
Huawei Network.IO Innovation Lab
P. Lapukhov
Facebook
B. Gafni
A. Kfir
Mellanox Technologies, Inc.
M. Spiegel
Barefoot Networks, an Intel company
November 19, 2020
Geneve encapsulation for In-situ OAM Data
draft-brockners-ippm-ioam-geneve-05
Abstract
In-situ Operations, Administration, and Maintenance (IOAM) records
operational and telemetry information in the packet while the packet
traverses a path between two points in the network. This document
proposes a new Geneve tunnel option and outlines how IOAM data fields
are carried in the option data field.
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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Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on May 23, 2021.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirement Language . . . . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
3. IOAM Data Field Encapsulation in Geneve . . . . . . . . . . . 3
4. Considerations . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Discussion of the encapsulation approach . . . . . . . . 5
4.2. IOAM and the use of the Geneve O-bit . . . . . . . . . . 6
4.3. Transit devices . . . . . . . . . . . . . . . . . . . . . 6
4.4. Additional Encapsulation Consideration . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
In-situ OAM (IOAM) records OAM information within the packet while
the packet traverses a particular network domain. The term "in-situ"
refers to the fact that the IOAM data fields are added to the data
packets rather than is being sent within packets specifically
dedicated to OAM. This document proposes a new Geneve tunnel option
and defines how IOAM data fields are transported as part of the
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tunnel option in the Geneve [I-D.ietf-nvo3-geneve] encapsulation.
The IOAM data fields are defined in [I-D.ietf-ippm-ioam-data].
2. Conventions
2.1. Requirement Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Abbreviations
Abbreviations used in this document:
IOAM: In-situ Operations, Administration, and Maintenance
OAM: Operations, Administration, and Maintenance
Geneve: Generic Network Virtualization Encapsulation
3. IOAM Data Field Encapsulation in Geneve
Geneve is defined in [I-D.ietf-nvo3-geneve]. When Geneve
encapsulation header is used, IOAM data fields can either be carried
after the Geneve header, identified by the next protocol field or can
be carried in the Geneve header itself as a tunnel option. The
former approach is defined in [I-D.weis-ippm-ioam-eth] while the
latter approach is defined in this document.
IOAM data fields are carried using a single Geneve Option Class
TBD_IOAM. The different IOAM data fields defined in
[I-D.ietf-ippm-ioam-data] are added as TLVs using that Geneve Option
Class. In an administrative domain where IOAM is used, insertion of
the IOAM header in Geneve is enabled at the Geneve tunnel endpoints,
which also serve as IOAM encapsulating/decapsulating nodes by means
of configuration.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
|Ver| Opt Len |O|C| Rsvd. | Protocol Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Hdr
| Virtual Network Identifier (VNI) | Reserved | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+
| Option Class = TBD_IOAM | Type |R|R|R| Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ I
! | O
! | A
~ IOAM Option and Data Space ~ M
| | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| |
| |
| Payload + Padding (L2/L3/ESP/...) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: IOAM data encapsulation in Geneve
The Geneve header and fields are defined in [I-D.ietf-nvo3-geneve].
The Geneve Option Class value for use with IOAM is TBD_IOAM.
The fields related to the encapsulation of IOAM data fields in Geneve
are defined as follows:
Option Class: 16-bit unsigned integer that determines the IOAM
option class. The value is from the IANA registry setup for
Geneve option classes as defined in [I-D.ietf-nvo3-geneve].
Type: 8-bit field defining the IOAM Option type, as defined in
Section 7.2 of [I-D.ietf-ippm-ioam-data]. The 'C' bit MUST be set
to zero.
R (3 bits): Option control flags reserved for future use. The flags
MUST be set to zero on transmission and ignored on receipt.
Length: 5-bit unsigned integer. Length of the IOAM HDR in 4-octet
units.
IOAM Option and Data Space: IOAM option header and data is present
as defined by the Type field, and is defined in Section 4 of
[I-D.ietf-ippm-ioam-data].
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Multiple distinct IOAM Option-Types MAY be included within the same
Geneve encapsulation. Each IOAM Option-Type MUST occur at most once
within the same Geneve encapsulation. For example, if a Geneve
encapsulation contains two IOAM Option-Types before a data payload,
there would be two fields with TBD_IOAM Option Class each,
differentiated by the Type field which specifies the type of the IOAM
data included.
4. Considerations
This section summarizes a set of considerations on the overall
approach taken for IOAM data encapsulation in Geneve, as well as
deployment considerations.
4.1. Discussion of the encapsulation approach
This section is to support the working group discussion in selecting
the most appropriate approach for encapsulating IOAM data fields in
Geneve.
An encapsulation of IOAM data fields in Geneve should be friendly to
an implementation in both hardware as well as software forwarders and
support a wide range of deployment cases, including large networks
that desire to leverage multiple IOAM data fields at the same time.
Hardware and software friendly implementation: Hardware forwarders
benefit from an encapsulation that minimizes iterative look-ups of
fields within the packet: Any operation which looks up the value
of a field within the packet, based on which another lookup is
performed, consumes additional gates and time in an implementation
- both of which are desired to be kept to a minimum. This means
that flat TLV structures are to be preferred over nested TLV
structures. IOAM data fields are grouped into three option
categories: Trace, proof-of-transit, and edge-to-edge. Each of
these three options defines a TLV structure. A hardware-friendly
encapsulation approach avoids grouping these three option
categories into yet another TLV structure, but would rather carry
the options as a serial sequence.
Total length of the IOAM data fields: The total length of IOAM
data can grow quite large in case multiple different IOAM data
fields are used and large path-lengths need to be considered. If
for example an operator would consider using the IOAM trace option
and capture node-id, app_data, egress/ingress interface-id,
timestamp seconds, timestamps nanoseconds at every hop, then a
total of 20 octets would be added to the packet at every hop. In
case this particular deployment would have a maximum path length
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of 15 hops in the IOAM domain, then a maximum of 300 octets of
IOAM data were to be encapsulated in the packet.
Concerns with the current encapsulation approach:
Hardware support: Using Geneve tunnel options to encapsulate IOAM
data fields leads to a nested TLV structure. Each IOAM data field
option (trace, proof-of-transit, and edge-to-edge) represents a
type, with the different IOAM data fields being TLVs within this
the particular option type. Nested TLVs require iterative look-
ups, a fact that creates potential challenges for implementations
in hardware. It would be desirable to offer a way to encapsulate
IOAM in a way that keeps TLV nesting to a minimum.
Length: Geneve tunnel option length is a 5-bit field in the
current specification [I-D.ietf-nvo3-geneve] resulting in a
maximum option length of 128 (2^5 x 4) octets which constrains the
use of IOAM to either small domains or a few IOAM data fields
only. Support for large domains with a variety of IOAM data
fields would be desirable.
4.2. IOAM and the use of the Geneve O-bit
[I-D.ietf-nvo3-geneve] defines an "O bit" for Control packets. Per
[I-D.ietf-nvo3-geneve] the O bit indicates that the packet contains a
control message instead of data payload. Packets that carry IOAM
data fields in addition to regular data payload / customer traffic
must not set the O bit. Packets that carry only IOAM data fields
without any payload must set the O bit.
4.3. Transit devices
If IOAM is deployed in domains where UDP port numbers are not
controlled and do not have a domain-wide meaning, such as on the
global Internet, transit devices MUST NOT attempt to modify the IOAM
data contained in the IOAM option class. In case UDP port numbers
are not controlled there might be UDP packets, which leverage the UDP
port number that Geneve utilizes, i.e. 6081, but the payload of these
packets isn't Geneve. The scenario and associated reasoning is
discussed in [RFC7605] which states that "it is important to
recognize that any interpretation of port numbers -- except at the
endpoints -- may be incorrect, because port numbers are meaningful
only at the endpoints."
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4.4. Additional Encapsulation Consideration
Geneve encapsulation header supports carrying IOAM data fields either
as part of the tunnel option or as the protocol data unit that
follows the Geneve header. An operator may choose to enable either
of the options but it is not recommended to include both in the same
data packet.
5. IANA Considerations
IANA is requested to allocate a Geneve "option class" numbers for
IOAM:
+---------------+-------------+---------------+
| Option Class | Description | Reference |
+---------------+-------------+---------------+
| x | TBD_IOAM | This document |
+---------------+-------------+---------------+
6. Security Considerations
The security considerations of Geneve are discussed in
[I-D.ietf-nvo3-geneve], and the security considerations of IOAM in
general are discussed in [I-D.ietf-ippm-ioam-data].
IOAM is considered a "per domain" feature, where one or several
operators decide on leveraging and configuring IOAM according to
their needs. Still, operators need to properly secure the IOAM
domain to avoid malicious configuration and use, which could include
injecting malicious IOAM packets into a domain.
7. Acknowledgements
The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari
Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya
Nadahalli, Stefano Previdi, Hemant Singh, Erik Nordmark, LJ Wobker,
Andrew Yourtchenko and Nagendra Kumar Nainar for the comments and
advice.
8. Normative References
[I-D.ietf-ippm-ioam-data]
Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields
for In-situ OAM", draft-ietf-ippm-ioam-data-10 (work in
progress), July 2020.
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[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.
[I-D.weis-ippm-ioam-eth]
Weis, B., Brockners, F., Hill, C., Bhandari, S., Govindan,
V., Pignataro, C., Gredler, H., Leddy, J., Youell, S.,
Mizrahi, T., Kfir, A., Gafni, B., Lapukhov, P., and M.
Spiegel, "EtherType Protocol Identification of In-situ OAM
Data", draft-weis-ippm-ioam-eth-04 (work in progress), May
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>.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
DOI 10.17487/RFC2784, March 2000,
<https://www.rfc-editor.org/info/rfc2784>.
[RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
by an On-line Database", RFC 3232, DOI 10.17487/RFC3232,
January 2002, <https://www.rfc-editor.org/info/rfc3232>.
[RFC7605] Touch, J., "Recommendations on Using Assigned Transport
Port Numbers", BCP 165, RFC 7605, DOI 10.17487/RFC7605,
August 2015, <https://www.rfc-editor.org/info/rfc7605>.
Authors' Addresses
Frank Brockners (editor)
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany
Email: fbrockne@cisco.com
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Shwetha Bhandari
Thoughtspot
3rd Floor, Indiqube Orion, 24th Main Rd, HSR Layout
Bangalore, KARNATAKA 560 102
India
Email: shwetha.bhandari@thoughtspot.com
Vengada Prasad Govindan
Cisco Systems, Inc.
Email: venggovi@cisco.com
Carlos Pignataro (editor)
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States
Email: cpignata@cisco.com
Nagendra Kumar Nainar (editor)
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States
Email: naikumar@cisco.com
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
John Leddy
United States
Email: john@leddy.net
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Stephen Youell
JP Morgan Chase
25 Bank Street
London E14 5JP
United Kingdom
Email: stephen.youell@jpmorgan.com
Tal Mizrahi
Huawei Network.IO Innovation Lab
Israel
Email: tal.mizrahi.phd@gmail.com
Petr Lapukhov
Facebook
1 Hacker Way
Menlo Park, CA 94025
US
Email: petr@fb.com
Barak Gafni
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
U.S.A.
Email: gbarak@mellanox.com
Aviv Kfir
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
U.S.A.
Email: avivk@mellanox.com
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Mickey Spiegel
Barefoot Networks, an Intel company
4750 Patrick Henry Drive
Santa Clara, CA 95054
US
Email: mickey.spiegel@intel.com
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