Internet DRAFT - draft-mizrahi-ippm-ioam-flags
draft-mizrahi-ippm-ioam-flags
IPPM T. Mizrahi
Internet-Draft Huawei Network.IO Innovation Lab
Intended status: Standards Track F. Brockners
Expires: January 5, 2020 S. Bhandari
R. Sivakolundu
C. Pignataro
Cisco
A. Kfir
B. Gafni
Mellanox Technologies, Inc.
M. Spiegel
Barefoot Networks
J. Lemon
Broadcom
July 04, 2019
In-situ OAM Flags
draft-mizrahi-ippm-ioam-flags-00
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
presents new flags in the IOAM Trace Option headers. Specifically,
the document defines the Loopback, Active, and Immediate Export
flags.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 5, 2020.
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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
(https://trustee.ietf.org/license-info) in effect on the date of
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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. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. New IOAM Trace Option Flags . . . . . . . . . . . . . . . . . 3
4. Loopback in IOAM . . . . . . . . . . . . . . . . . . . . . . 3
5. Active Measurement with IOAM . . . . . . . . . . . . . . . . 4
6. Immediate Exporting . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Performance Considerations . . . . . . . . . . . . . . . . . 6
9. Security Considerations . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
IOAM [I-D.ietf-ippm-ioam-data] is used for monitoring traffic in the
network by incorporating IOAM data fields into in-flight data
packets.
IOAM data may be represented in one of four possible IOAM options:
Pre-allocated Trace Option, Incremental Trace Option, Proof of
Transit (POT) Option, and Edge-to-Edge Option. This document defines
three new flags in the Pre-allocated and Incremental Trace options:
the Loopback, Active, and Immediate Export flags.
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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. Terminology
Abbreviations used in this document:
IOAM: In-situ Operations, Administration, and Maintenance
OAM: Operations, Administration, and Maintenance
3. New IOAM Trace Option Flags
This document defines three new flags in the Pre-allocated and
Incremental Trace options:
Bit 1 "Loopback" (L-bit). Loopback mode is used to send a copy of a
packet back towards the source, as further described in Section 4.
Bit 2 "Active" (A-bit). When set, this indicates that this is an
active IOAM packet, where "active" is used in the sense defined in
[RFC7799], rather than a data packet. The packet may be an IOAM
probe packet, or a replicated data packet (the second and third
use cases of Section 5).
Bit 3 "Immediate Export" (I-bit). Immediate export mode is used to
export IOAM data fields immediately at every IOAM supported
network node, instead of adding the IOAM data fields to the packet
traversing the network. Further details are provided in
Section 6.
4. Loopback in IOAM
Loopback is used for trigerring each transit device along the path to
loop back a copy of the data packet. Loopback mode assumes that a
return path from transit nodes and destination nodes towards the
source exists. The encapsulating node decides (e.g., using a filter)
which packets loopback mode is enabled for by setting the loopback
bit. The encapsulating node also needs to ensure that sufficient
space is available in the IOAM header for loopback operation, which
includes intermediate nodes adding trace data on the original path
and then again on the return path. A loopback bit that is set
indicates to the transit nodes processing this option that they are
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to create a copy of the received packet and send the copy back to the
source of the packet. The copy has its metadata added after being
copied in order to allow any egress-dependent information to be set
based on the egress of the copy rather than the original. The
original packet continues towards its destination. The source
address of the original packet is used as the destination address in
the copied packet. The address of the node performing the copy
operation is used as the source address. The L-bit MUST be cleared
in the copy of the packet that a node sends back towards the source.
On its way back towards the source, the copied packet is processed
like any other packet with IOAM information, including adding any
requested data at each transit node (assuming there is sufficient
space). Once the return packet reaches the IOAM domain boundary,
IOAM decapsulation occurs as with any other packet containing IOAM
information. Because any intermediate node receiving such a packet
would not know how to process the original packet, and because there
would be a risk of the original packet leaking past the initiator of
the IOAM loopback, the initiator of an IOAM loopback MUST be the
initiator of the packet. Once a loopback packet is received back at
the initiator, it is a local matter how it is recognized as a
loopback packet.
5. Active Measurement with IOAM
Active measurement methods [RFC7799] make use of synthetically
generated packets in order to facilitate the measurement. This
section presents use cases of active measurement using the IOAM
Active flag.
The active flag indicates that a packet is used for active
measurement. An IOAM decapsulating node that receives a packet with
the Active flag set in one of its Trace options must terminate the
packet.
An example of an IOAM deployment scenario is illustrated in Figure 1.
The figure depicts two endpoints, a source and a destination. The
data traffic from the source to the destination is forwarded through
a set of network devices, including an IOAM encapsulating node, which
incorporates one or more IOAM option, a decapsulating node, which
removes the IOAM options, optionally one or more transit nodes. The
IOAM options are encapsulated in one of the IOAM encapsulation types,
e.g., [I-D.ietf-sfc-ioam-nsh], or
[I-D.ioametal-ippm-6man-ioam-ipv6-options].
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+--------+ +--------+ +--------+ +--------+ +--------+
| | | IOAM |.....| IOAM |.....| IOAM | | |
+--------+ +--------+ +--------+ +--------+ +--------+
| L2/L3 |<===>| L2/L3 |<===>| L2/L3 |<===>| L2/L3 |<===>| L2/L3 |
+--------+ +--------+ +--------+ +--------+ +--------+
Source Encapsulating Transit Decapsulating Destination
Node Node Node
Figure 1: Network using IOAM.
This draft focuses on three possible use cases of active measurement
using IOAM. These use cases are described using the example of
Figure 1.
o Endpoint active measurement: synthetic probe packets are sent
between the source and destination, traversing the IOAM domain.
Since the probe packets are sent between the endpoints, these
packets are treated as data packets by the IOAM domain, and do not
require special treatment at the IOAM layer.
o IOAM active measurement using probe packets: probe packets are
generated and transmitted by the IOAM encapsulating node, and are
expected to be terminated by the decapsulating node. IOAM data
related to probe packets may be exported by one or more nodes
along its path, by an exporting protocol that is outside the scope
of this document (e.g., [I-D.spiegel-ippm-ioam-rawexport]). Probe
packets include a Trace Option which has its Active flag set,
indicating that the decapsulating node must terminate them.
o IOAM active measurement using replicated data packets: probe
packets are created by the encapsulating node by selecting some or
all of the en route data packets and replicating them. A selected
data packet that is replicated, and its (possibly truncated) copy
is forwarded with one or more IOAM option, while the original
packet is forwarded normally, without IOAM options. To the extent
possible, the original data packet and its replica are forwarded
through the same path. The replica includes a Trace Option that
has its Active flag set, indicating that the decapsulating node
should terminate it.
6. Immediate Exporting
Immediate exporting can be used to export IOAM data to a collector
instead of incorporating this data into en route data packets. The
various types of IOAM nodes MUST process packets with the I-bit set
as follows:
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1. An encapsulating IOAM node configured to set the I-bit
encapsulates the packet with the IOAM header and sets the I-bit,
leaving the IOAM header without locally collected data, and
exports the requested IOAM data immediately. The encapsulating
IOAM node is the only type of node allowed to set the I-bit.
2. A transit node that processes a packet with the I-bit set is
expected to export the requested IOAM data, and not incorporate
it into the IOAM header.
3. A decapsulating IOAM node that processes a packet with the I-bit
set is expected to export the requested IOAM data, and
decapsulate the IOAM header.
Note that in case of "Immediate Export" being employed, no IOAM trace
data is added to the packets traversing the network. As a means to
support correlation of exported IOAM data different nodes in the
network, a deployment could consider attaching an IOAM E2E option in
addition to the trace option, that includes a sequence number. See
Bit 1 in the IOAM-E2E-Types. Please refer to
[I-D.ietf-ippm-ioam-data] for a discussion of IOAM data export and
associated formats.
7. IANA Considerations
IANA is requested to allocate the following bits in the "IOAM Trace
Flags Registry" as follows:
Bit 1 "Loopback" (L-bit)
Bit 2 "Active" (A-bit)
Bit 3 "Immediate Export" (I-bit)
Note that bit 0 is the most significant bit in the Flags Registry.
8. Performance Considerations
Each of the three flags that are defined in this document may have
performance implications. When using the loopback mechanism a copy
of the data packet is sent back to the sender, thus generating more
traffic than originally sent by the endpoints. Using active
measurement with the active flag requires the use of synthetic
(overhead) traffic. The Immediate Export flag triggers exported
packets to be exported to a collector, which in some cases may impact
the collector's performance, or the performance along the paths
leading to the collector.
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Each of the three mechanisms has a cost in terms of the network
bandwidth, and may potentially load the node that analyzes the data.
Therefore, rate limiting may be enabled so as to ensure that the
three mechanisms are used at a rate that does not significantly
affect the network bandwidth, and does not overload the collector (or
the source node in the case of loopback). It should be possible to
use each of the three mechanisms on a subset of the data traffic.
9. Security Considerations
The security considerations of IOAM in general are discussed in
[I-D.ietf-ippm-ioam-data]. Specifically, an attacker may try to use
the functionality that is defined in this document to attack the
network.
An attacker may attempt to overload network devices by injecting
synthetic packets that include an IOAM Trace Option with one or more
of the flags defined in this document. Similarly, an on-path
attacker may maliciously set one or more of the flags of transit
packets.
o Loopback flag: an attacker that sets this flag, either in
synthetic packets or transit packet, can potentially cause an
amplification, since each device along the path creates a copy of
the data packet and sends it back to the source. The attacker can
potentially leverage the loopback flag for a Distributed Denial of
Service (DDoS) attack, as multiple devices send looped-back copies
of a packet to a single source.
o Active flag: the impact of synthetic packets with the active flag
is no worse than synthetic data packets in which the Active flag
is not set. By setting the active flag in en route packets an
attacker can prevent these packets from reaching their
destination, since the packet is terminated by the decapsulating
device; however, note that an on-path attacker may achieve the
same goal by changing the destination address of a packet.
Another potential threat is amplification; if an attacker causes
transit switches to replicate more packets than they are intended
to replicate, either by setting the Active flag or by sending
synthetic packets, then traffic is amplified, causing bandwidth
degredation.
o Immediate Export flag: setting this flag, either in synthetic
packets or in transit packets may overload the collector or
analyzer devices. Since this flag affects multiple devices along
the network path, it potentially amplifies the effect on the
network bandwidth and on the collector's load.
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In order to mitigate the attacks described above, it should be
possible for IOAM-enabled devices to limit each of the three
mechanisms to a configurable rate; Network devices should be able to
limit the rate of: (i) looped-back traffic, (ii) replicated active
packets, and (iii) exported packets.
IOAM is assumed to be deployed in a restricted administrative domain,
thus limiting the scope of the threats above and their affect. This
is a fundamental assumtion with respect to the security aspects of
IOAM, as further discussed in [I-D.ietf-ippm-ioam-data].
10. References
10.1. 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-05 (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>.
10.2. Informative References
[I-D.ietf-sfc-ioam-nsh]
Brockners, F., Bhandari, S., Govindan, V., Pignataro, C.,
Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Mozes,
D., Lapukhov, P., and R. Chang, "Network Service Header
(NSH) Encapsulation for In-situ OAM (IOAM) Data", draft-
ietf-sfc-ioam-nsh-01 (work in progress), March 2019.
[I-D.ioametal-ippm-6man-ioam-ipv6-options]
Bhandari, S., Brockners, F., Pignataro, C., Gredler, H.,
Leddy, J., Youell, S., Mizrahi, T., Kfir, A., Gafni, B.,
Lapukhov, P., Spiegel, M., Krishnan, S., and R. Asati,
"In-situ OAM IPv6 Options", draft-ioametal-ippm-6man-ioam-
ipv6-options-02 (work in progress), March 2019.
[I-D.spiegel-ippm-ioam-rawexport]
Spiegel, M., Brockners, F., Bhandari, S., and R.
Sivakolundu, "In-situ OAM raw data export with IPFIX",
draft-spiegel-ippm-ioam-rawexport-01 (work in progress),
October 2018.
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[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>.
Authors' Addresses
Tal Mizrahi
Huawei Network.IO Innovation Lab
Israel
Email: tal.mizrahi.phd@gmail.com
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
Ramesh Sivakolundu
Cisco Systems, Inc.
170 West Tasman Dr.
SAN JOSE, CA 95134
U.S.A.
Email: sramesh@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States
Email: cpignata@cisco.com
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Aviv Kfir
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
U.S.A.
Email: avivk@mellanox.com
Barak Gafni
Mellanox Technologies, Inc.
350 Oakmead Parkway, Suite 100
Sunnyvale, CA 94085
U.S.A.
Email: gbarak@mellanox.com
Mickey Spiegel
Barefoot Networks
4750 Patrick Henry Drive
Santa Clara, CA 95054
US
Email: mspiegel@barefootnetworks.com
John Lemon
Broadcom
270 Innovation Drive
San Jose, CA 95134
US
Email: john.lemon@broadcom.com
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