ippm F. Brockners
Internet-Draft S. Bhandari
Intended status: Standards Track V. Govindan
Expires: September 12, 2019 C. Pignataro
Cisco
H. Gredler
RtBrick Inc.
J. Leddy
Comcast
S. Youell
JMPC
T. Mizrahi
Huawei Network.IO Innovation Lab
P. Lapukhov
Facebook
B. Gafni
A. Kfir
Mellanox Technologies, Inc.
M. Spiegel
Barefoot Networks
March 11, 2019
Geneve encapsulation for In-situ OAM Data
draft-brockners-ippm-ioam-geneve-02
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
outlines how IOAM data fields are encapsulated in Geneve.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Brockners, et al. Expires September 12, 2019 [Page 1]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
This Internet-Draft will expire on September 12, 2019.
Copyright Notice
Copyright (c) 2019 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
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 defines how IOAM data fields are
transported as part of the Geneve [I-D.ietf-nvo3-geneve]
encapsulation. The IOAM data fields are defined in
[I-D.ietf-ippm-ioam-data].
Brockners, et al. Expires September 12, 2019 [Page 2]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
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]. IOAM data fields are
carried in the Geneve header as a tunnel option, 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.
Brockners, et al. Expires September 12, 2019 [Page 3]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
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].
R (3 bits): Option control flags reserved for future use. MUST be
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].
Brockners, et al. Expires September 12, 2019 [Page 4]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
Multiple IOAM options MAY be included within the Geneve
encapsulation. For example, if a Geneve encapsulation contains two
IOAM options 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
of 15 hops in the IOAM domain, then a maximum of 300 octets of
IOAM data were to be encapsulated in the packet.
Brockners, et al. Expires September 12, 2019 [Page 5]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
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 OAM 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."
5. IANA Considerations
IANA is requested to allocate a Geneve "option class" numbers for
IOAM:
Brockners, et al. Expires September 12, 2019 [Page 6]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
+---------------+-------------+---------------+
| 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,
and Andrew Yourtchenko for the comments and advice.
8. Normative References
[I-D.ietf-ippm-ioam-data]
Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
P., Chang, R., daniel.bernier@bell.ca, d., and J. Lemon,
"Data Fields for In-situ OAM", draft-ietf-ippm-ioam-
data-04 (work in progress), October 2018.
[I-D.ietf-nvo3-geneve]
Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", draft-ietf-
nvo3-geneve-11 (work in progress), March 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>.
Brockners, et al. Expires September 12, 2019 [Page 7]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
[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
Cisco Systems, Inc.
Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany
Email: fbrockne@cisco.com
Shwetha Bhandari
Cisco Systems, Inc.
Cessna Business Park, Sarjapura Marathalli Outer Ring Road
Bangalore, KARNATAKA 560 087
India
Email: shwethab@cisco.com
Vengada Prasad Govindan
Cisco Systems, Inc.
Email: venggovi@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States
Email: cpignata@cisco.com
Brockners, et al. Expires September 12, 2019 [Page 8]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
John Leddy
Comcast
Email: John_Leddy@cable.comcast.com
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
Brockners, et al. Expires September 12, 2019 [Page 9]
Internet-Draft In-situ OAM Geneve encapsulation March 2019
Aviv Kfir
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
U.S.A.
Email: avivk@mellanox.com
Mickey Spiegel
Barefoot Networks
2185 Park Boulevard
Palo Alto, CA 94306
US
Email: mspiegel@barefootnetworks.com
Brockners, et al. Expires September 12, 2019 [Page 10]