Network Working Group F. Brockners
Internet-Draft S. Bhandari
Intended status: Experimental C. Pignataro
Expires: May 3, 2017 Cisco
H. Gredler
RtBrick Inc.
J. Leddy
Comcast
S. Youell
JMPC
T. Mizrahi
Marvell
D. Mozes
Mellanox Technologies Ltd.
P. Lapukhov
Facebook
R. Chang
Barefoot Networks
October 30, 2016
Data Formats for In-situ OAM
draft-brockners-inband-oam-data-02
Abstract
In-situ Operations, Administration, and Maintenance (OAM) records
operational and telemetry information in the packet while the packet
traverses a path between two points in the network. This document
discusses the data types and data formats for in-situ OAM data
records. In-situ OAM data records can be embedded into a variety of
transports such as NSH, Segment Routing, VXLAN-GPE, native IPv6 (via
extension header), or IPv4. In-situ OAM is to complement current
out-of-band OAM mechanisms based on ICMP or other types of probe
packets.
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
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 3, 2017.
Copyright Notice
Copyright (c) 2016 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
3. In-situ OAM Data Types and Data Format . . . . . . . . . . . 4
3.1. In-situ OAM Tracing Options . . . . . . . . . . . . . . . 4
3.1.1. Pre-allocated Trace Option . . . . . . . . . . . . . 6
3.1.2. Incremental Trace Option . . . . . . . . . . . . . . 9
3.1.3. In-situ OAM node data element format . . . . . . . . 11
3.1.4. Examples of In-situ OAM node data . . . . . . . . . . 14
3.2. In-situ OAM Proof of Transit Option . . . . . . . . . . . 16
3.3. In-situ OAM Edge-to-Edge Option . . . . . . . . . . . . . 18
4. In-situ OAM Data Export . . . . . . . . . . . . . . . . . . . 18
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6. Manageability Considerations . . . . . . . . . . . . . . . . 19
7. Security Considerations . . . . . . . . . . . . . . . . . . . 19
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
This document defines data record types for "in-situ" Operations,
Administration, and Maintenance (OAM). In-situ OAM records OAM
information within the packet while the packet traverses a particular
network domain. The term "in-situ" refers to the fact that the OAM
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data is added to the data packets rather than is being sent within
packets specifically dedicated to OAM. A discussion of the
motivation and requirements for in-situ OAM can be found in
[I-D.brockners-inband-oam-requirements]. In-situ OAM is to
complement "out-of-band" or "active" mechanisms such as ping or
traceroute, or more recent active probing mechanisms as described in
[I-D.lapukhov-dataplane-probe]. In-situ OAM mechanisms can be
leveraged where current out-of-band mechanisms do not apply or do not
offer the desired results, such as proving that a certain set of
traffic takes a pre-defined path, SLA verification for the live data
traffic, detailed statistics on traffic distribution paths in
networks that distribute traffic across multiple paths, or scenarios
where probe traffic is potentially handled differently from regular
data traffic by the network devices.
This document defines the data types and data formats for in-situ OAM
data records. The in-situ OAM data records can be transported by a
variety of transport protocols, including NSH, Segment Routing,
VXLAN-GPE, IPv6, IPv4. Encapsulation details for these different
transport protocols are outside the scope of this document.
2. Conventions
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].
Abbreviations used in this document:
MTU: Maximum Transmit Unit
NSH: Network Service Header
OAM: Operations, Administration, and Maintenance
SFC: Service Function Chain
SID: Segment Identifier
SR: Segment Routing
TLV: Type-Length-Value
VXLAN-GPE: Virtual eXtensible Local Area Network, Generic Protocol
Extension
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3. In-situ OAM Data Types and Data Format
This section defines in-situ OAM data types and data formats of the
data records required for in-situ OAM. The different uses of in-situ
OAM require the definition of different types of data. The in-situ
OAM data format for the data being carried corresponds to the three
main categories of in-situ OAM data defined in
[I-D.brockners-inband-oam-requirements], which are : edge-to-edge,
per node, and for selected nodes only.
Transport options for in-situ OAM data are found in
[I-D.brockners-inband-oam-transport]. In-situ OAM data is defined as
options in Type-Length-Value (TLV) format. The TLV format for each
of the three different types of in-situ OAM data is defined in this
document.
In-situ OAM is expected to be deployed in a specific domain rather
than on the overall Internet. The part of the network which employs
in situ OAM is referred to as the "in-situ OAM-domain". In-situ OAM
data is added to a packet upon entering the in-situ OAM-domain and is
removed from the packet when exiting the domain. Within the in-situ
OAM-domain, the in-situ OAM data may be updated by network nodes that
the packet traverses. The device which adds in-situ OAM data
container to the packet to capture in-situ OAM data is called the
"in-situ OAM encapsulating node", whereas the device which removes
the in-situ OAM data container is referred to as the "in-situ OAM
decapsulating node". Nodes within the domain which are aware of in-
situ OAM data and read and/or write or process the in-situ OAM data
are called "in-situ OAM transit nodes". Note that not every node in
an in-situ OAM domain needs to be an in-situ OAM transit node. For
example, a Segment Routing deployment might require the segment
routing path to be verified. In that case, only the SR nodes would
also be in-situ OAM transit nodes rather than all nodes.
3.1. In-situ OAM Tracing Options
"In-situ OAM tracing data" is expected to be collected at every node
that a packet traverses, i.e., in a typical deployment all nodes in
an in-situ OAM-domain would participate in in-situ OAM and thus be
in-situ OAM transit nodes, in-situ OAM encapsulating or in-situ OAM
decapsulating nodes. The maximum network diameter of the in-situ OAM
domain is assumed to be known.
To optimize hardware and software implementations tracing is defined
as two separate options. Any deployment MAY choose to configure and
support one or both of the following options. An implementation of
the transport protocol that carries these in-situ OAM data MAY choose
to support only one of the options. In the event that both options
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are utilized at the same time, the Incremental Trace Option MUST be
placed before the Pre-allocated Trace Option.
Pre-allocated Trace Option: This trace option is defined as a
container of node-data elements with pre-allocated space for each
node to populate its information. This option is useful for
software implementations where it is efficient to allocate the
space once and index into the array to populate the data during
transit. The in-situ OAM encapsulating node allocates the option
header and sets the fields in the option header. The in situ OAM
encapsulating node allocates an array which is to store
operational data retrieved from every node while the packet
traverses the domain. In-situ OAM transit nodes update the
content of the array. A pointer which is part of the in-situ OAM
trace data points to the next empty slot in the array, which is
where the next in-situ OAM transit node fills in its data.
Incremental Trace Option: This trace options is defined as a
container of node-data elements where each node allocates and
pushes its node data immediately following the option header. The
number of node-data recorded and maximum number of node data that
can be recorded are written into the option header. This format
of trace recording is useful for some of the hardware
implementations as this eliminates the need for the transit
network elements to read the full array in the option and allows
for arbitrarily long packets as the MTU allows. The in-situ OAM
encapsulating node allocates the option header. The in-situ OAM
encapsulating node based on operational state and configuration
sets the fields in the header to control how large the node data
list can grow. In-situ OAM transit nodes pushes its node data to
the node data list and increments the number of node data records
in the header.
Every node data entry is to hold information for a particular in situ
OAM transit node that is traversed by a packet. The in-situ OAM
decapsulating node removes the in-situ OAM data and process and/or
export the metadata. In-situ OAM data uses its own name-space for
information such as node identifier or interface identifier. This
allows for a domain-specific definition and interpretation. For
example: In one case an interface-id could point to a physical
interface (e.g., to understand which physical interface of an
aggregated link is used when receiving or transmitting a packet)
whereas in another case it could refer to a logical interface (e.g.,
in case of tunnels).
The following in-situ OAM data is defined for in-situ OAM tracing:
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o Identification of the in-situ OAM node. An in-situ OAM node
identifier can match to a device identifier or a particular
control point or subsystem within a device.
o Identification of the interface that a packet was received on.
o Identification of the interface that a packet was sent out on.
o Time of day when the packet was processed by the node. Different
definitions of processing time are feasible and expected, though
it is important that all devices of an in-situ OAM domain follow
the same definition.
o Generic data: Format-free information where syntax and semantic of
the information is defined by the operator in a specific
deployment. For a specific deployment, all in-situ OAM nodes
should interpret the generic data the same way. Examples for
generic in-situ OAM data include geo-location information
(location of the node at the time the packet was processed),
buffer queue fill level or cache fill level at the time the packet
was processed, or even a battery charge level.
o A mechanism to detect whether in-situ OAM trace data was added at
every hop or whether certain hops in the domain weren't in-situ
OAM transit nodes.
The "Node data List" array in the packet is populated iteratively as
the packet traverses the network, starting with the last entry of the
array, i.e., "Node data List [n]" is the first entry to be populated,
"Node data List [n-1]" is the second one, etc.
3.1.1. Pre-allocated Trace Option
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In-situ OAM Pre-allocated Trace Option:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Elements-left | Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OAM-Trace-Type | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| | |
| Node data List [0] | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ D
| | a
| Node data List [1] | t
| | a
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~ S
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ p
| | a
| Node data List [n-1] | c
| | e
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | |
| Node data List [n] | |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
Option Type: 8-bit identifier of the type of option. Option number
is defined based on the encapsulation protocol.
Opt Data Len: 8-bit unsigned integer. Length of the Option Data
field of this option, in octets.
Elements-left: 8-bit unsigned integer. A pointer that indicates the
next data recording point in the data space of the packet in
octets. It is the index into the "Node data List" array shown
above.
Reserved1: 8-bit unused field in this document and MUST be set to
zero.
OAM-trace-type: 16-bit identifier of a particular trace element
variant.
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The trace type value is a bit field. The following bit fields are
defined in this document, with details on each field described in
the Section 3.1.3. The order of packing the trace data in each
Node-data element follows the bit order for setting each trace
data element.
Bit 0 When set indicates presence of Hop_Lim and node_id in the
Node data.
Bit 1 When set indicates presence of ingress_if_id and
egress_if_id in the Node data.
Bit 2 When set indicates presence of timestamp seconds in the
Node data
Bit 3 When set indicates presence of timestamp nanoseconds in
the Node data.
Bit 4 When set indicates presence of transit delay in the Node
data.
Bit 5 When set indicates presence of app_data in the Node data.
Bit 6 When set indicates presence of queue depth in the Node
data.
Bit 7 - 14 Undefined in this document.
Bit 15 When set indicates wide data format for all the node data
elements that are present. When unset indicates short
data format for all the node data elements that are
present.
Section 3.1.4 describes the format of a number of trace types.
Reserved2: 16-bit unused field in this document and MUST be set to
zero.
Node data List [n]: Variable-length field. The format of which is
determined by the OAM Type representing the n-th Node data in the
Node data List. The Node data List is encoded starting from the
last Node data of the path. The first element of the node data
list (Node data List [0]) contains the last node of the path while
the last node data of the Node data List (Node data List[n])
contains the first Node data of the path traced. The index
contained in "Elements-left" identifies the current active Node
data to be populated.
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3.1.2. Incremental Trace Option
In-situ OAM Incremental Trace Option:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Maximum Length| Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OAM Trace Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node data List [0] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node data List [1] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node data List [n-1] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Node data List [n] |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type: 8-bit identifier of the type of option. Option number
is defined based on the encapsulation protocol.
Opt Data Len: 8-bit unsigned integer. Length of the Option Data
field of this option, in octets.
Maximum Length: 8-bit unsigned integer. This field specifies the
maximum length of the node data list in octets. Given that the
sender knows the minimum path MTU, the sender can set the maximum
of node data bytes allowed before exceeding the MTU. Thus, a
simple comparison between "Opt data Len" and "Max Length" allows
to decide whether or not data could be added.
Flags 8-bit field. Following flags are defined:
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1 "Overflow" (O-bit) (least significant bit). This bit is set by
the network element if the number of records on the packet is
at the maximum limit as specified by the packet: i.e., the
packet is already "full" of telemetry information. This is
useful for transit nodes to ignore further processing of the
option. If inserting a new node data record would cause "Opt
Data Len" to exceed "Max Length", no record is added and the
overflow "O-bit" must be set to "1" in the header.
OAM-trace-type: 16-bit identifier of a particular trace element
variant.
The trace type value is a bit field. The following bit fields are
defined in this document, with details on each field described in
the Section 3.1.3. The order of packing the trace data in each
Node-data element follows the bit order for setting each trace
data element.
Bit 0 When set indicates presence of Hop_Lim and node_id in the
Node data.
Bit 1 When set indicates presence of ingress_if_id and
egress_if_id in the Node data.
Bit 2 When set indicates presence of timestamp seconds in the
Node data
Bit 3 When set indicates presence of timestamp nanoseconds in
the Node data.
Bit 4 When set indicates presence of transit delay in the Node
data.
Bit 5 When set indicates presence of app_data in the Node data.
Bit 6 When set indicates presence of queue depth in the Node
data.
Bit 7 When set indicates presence of variable length Opaque
State Snapshot field.
Bit 8-14 Undefined in this draft.
Bit 15 When set indicates wide data format for all the node data
elements that are present. When unset indicates short
data format for all the node data elements that are
present.
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Section 3.1.4 describes the format of a number of trace types.
Reserved: 2 bytes unused field in this document and MUST be set to
zero.
Node data List [n]: Variable-length field. The format of which is
determined by the OAM Type representing the n-th Node data in the
Node data List. The Node data List is encoded starting from the
last Node data of the path. The first element of the node data
list (Node data List [0]) contains the last node of the path while
the last node data of the Node data List (Node data List[n])
contains the first Node data of the path traced.
3.1.3. In-situ OAM node data element format
The in-situ OAM node data elements are defined in 2 formats - short
and wide that is selected by bit 15 in the OAM-trace-type field. All
the data records MUST be 4-byte aligned in both the formats.
Data type and format for each of the data records in short format is
shown below:
Hop_Lim and node_id: 4-octet field defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Hop_Lim: 1-octet unsigned integer. It is set to the Hop Limit
value in the packet at the node that records this data. Hop
Limit information is used to identify the location of the node
in the communication path. This is copied from the lower layer
for e.g. TTL value in IPv4 header or hop limit field from IPv6
header of the packet.
node_id: 3-octet unsigned integer. Node identifier field to
uniquely identify a node within in-situ OAM domain. The
procedure to allocate, manage and map the node_ids is beyond
the scope of this document.
ingress_if_id and egress_if_id: 4-octet field defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id | egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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ingress_if_id: 2-octet unsigned integer. Interface identifier to
record the ingress interface the packet was received on.
egress_if_id: 2-octet unsigned integer. Interface identifier to
record the egress interface the packet is forwarded out of.
timestamp seconds: 4-octet unsigned integer. Absolute timestamp in
seconds that specifies the time at which the packet was received
by the node. The format of this field is identical to the most
significant 32 bits of 64 least significant bits of the
[IEEE1588v2]. This truncated format consists of a 32-bit seconds
field. As defined in [IEEE1588v2], the timestamp specifies the
number of seconds elapsed since 1 January 1970 00:00:00 according
to the International Atomic Time (TAI).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
timestamp nanoseconds: 4-octet unsigned integer in the range 0 to
10^9-1. This timestamp specifies the fractional part of the wall
clock time at which the packet was received by the node in units
of nanoseconds. It is nanoseconds that are recorded in 32 least
significant bits of absolute time as per [IEEE1588v2]. This
fields allows for delay computation between any two nodes in the
network when the nodes are time synchronized.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
transit delay: 4-octet unsigned integer in the range 0 to 2^30-1.
It is the time in nanoseconds packet spent in transiting a node.
This can serve to give an indication of queuing delay at the node.
If the transit delay exceeds 2^30-1 nanoseconds then the top bit
'O' is set to indicate overflow.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O| transit delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
app_data: 4-octet placeholder which can be used by the node to add
application specific data
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queue depth: 4-octet unsigned integer field. This field indicates
the length of the egress interface queue of the interface where
the packet is forwarded out of.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| queue depth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data type and format for each of the elements in wide format follows
when Most Significant Bit (MSB) i.e., bit 15 of OAM-Trace-Type is
set:
Hop_Lim and node_id: 8-octet field defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ node_id (contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Hop_Lim: 1-octet unsigned integer. It is set to the Hop Limit
value in the packet at the node that records this data. Hop
Limit information is used to identify the location of the node
in the communication path. This is copied from the lower layer
for e.g. TTL value in IPv4 header or hop limit field from IPv6
header of the packet.
node_id: 7-octet unsigned integer. Node identifier field to
uniquely identify a node within in-situ OAM domain. The
procedure to allocate, manage and map the node_ids is beyond
the scope of this document.
ingress_if_id and egress_if_id: 8-octet field defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ingress_if_id: 4-octet unsigned integer. Interface identifier to
record the ingress interface the packet was received on.
egress_if_id: 4-octet unsigned integer. Interface identifier to
record the egress interface the packet is forwarded out of.
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app_data: 8-octet placeholder which can be used by the node to add
application specific data.
Opaque State Snapshot: Variable length field. It allows the network
element to store arbitrary state in the node data record, without
a pre-defined schema. The schema needs to made known to the
analyzer by some out-of-band means. The 24-bit "Schema Id" field
in the record is supposed to let the analyzer know which
particular schema to use, and it is expected to be configured on
the network element by the operator. This ID is expected to be
configured on the device by the network operator.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Schema ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Opaque data |
~ ~
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Length: 1-octet unsigned integer. It is the length of the Opaque
data field that follows Schema Id. It MUST always be a
multiple of 4.
Schema ID: 3-octet unsigned integer identifying the schema of
Opaque data.
Opaque data: Variable length field. This field is interpreted as
specified by the schema identified by the Schema ID.
The fields - timestamp seconds, timestamp nanoseconds and transit
delay have the same format as defined in short format.
3.1.4. Examples of In-situ OAM node data
An entry in the "Node data List" array can have different formats,
following the needs of the deployment. Some deployments might only
be interested in recording the node identifiers, whereas others might
be interested in recording node identifier and timestamp. The
section defines different formats that an entry in "Node data List"
can take.
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0x002B: In-situ OAM-trace-type is 0x2B then the format of node data
is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id | egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| app_data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x0003: In-situ OAM-trace-type is 0x0003 then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ingress_if_id | egress_if_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x0009: In-situ OAM-trace-type is 0x0009 then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x0021: In-situ OAM-trace-type is 0x0021 then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| app_data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x0029: In-situ OAM-trace-type is 0x0029 then the format is:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| app_data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0x104D: In-situ OAM-trace-type is 0x104D then the format is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| node_id(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Schema Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Opaque data |
~ ~
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2. In-situ OAM Proof of Transit Option
In-situ OAM Proof of Transit data is to support the path or service
function chain [RFC7665] verification use cases. Proof-of-transit
uses methods like nested hashing or nested encryption of the in-situ
OAM data or mechanisms such as Shamir's Secret Sharing Schema (SSSS).
While details on how the in-situ OAM data for the proof of transit
option is processed at in-situ OAM encapsulating, decapsulating and
transit nodes are outside the scope of the document, all of these
approaches share the need to uniquely identify a packet as well as
iteratively operate on a set of information that is handed from node
to node. Correspondingly, two pieces of information are added as in-
situ OAM data to the packet:
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o Random: Unique identifier for the packet (e.g., 64-bits allow for
the unique identification of 2^64 packets).
o Cumulative: Information which is handed from node to node and
updated by every node according to a verification algorithm.
In-situ OAM Proof of Transit option:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | POT type = 0 |P| reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
| Random | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ P
| Random(contd) | O
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ T
| Cumulative | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Cumulative (contd) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
Option Type: 8-bit identifier of the type of option.
Opt Data Len: 8-bit unsigned integer. Length of the Option Data
field of this option, in octets.
POT Type: 8-bit identifier of a particular POT variant that dictates
the POT data that is included. This document defines POT Type 0:
0: POT data is a 16 Octet field as described below.
Profile to use (P): 1-bit. Indicates which POT-profile is used to
generate the Cumulative. Any node participating in POT will have
a maximum of 2 profiles configured that drive the computation of
cumulative. The two profiles are numbered 0, 1. This bit conveys
whether profile 0 or profile 1 is used to compute the Cumulative.
Reserved: 7-bit. Reserved for future use.
Random: 64-bit Per packet Random number.
Cumulative: 64-bit Cumulative that is updated at specific nodes by
processing per packet Random number field and configured
parameters.
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Note: Larger or smaller sizes of "Random" and "Cumulative" data are
feasible and could be required for certain deployments (e.g. in case
of space constraints in the transport protocol used). Future
versions of this document will address different sizes of data for
"proof of transit".
3.3. In-situ OAM Edge-to-Edge Option
The in-situ OAM Edge-to-Edge Option is to carry data which is to be
interpreted only by the in-situ OAM encapsulating and in-situ OAM
decapsulating node, but not by in-situ OAM transit nodes.
Currently only sequence numbers use the in-situ OAM Edge-to-Edge
option. In order to detect packet loss, packet reordering, or packet
duplication in an in-situ OAM-domain, sequence numbers can be added
to packets of a particular tube (see
[I-D.hildebrand-spud-prototype]). Each tube leverages a dedicated
namespace for its sequence numbers.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | OAM-E2E-Type | reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| E2E Option data format determined by iOAM-E2E-Type ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type: 8-bit identifier of the type of option.
Opt Data Len: 8-bit unsigned integer. Length of the Option Data
field of this option, in octets.
OAM-E2E-Type: 8-bit identifier of a particular in situ OAM E2E
variant.
0: E2E option data is a 64-bit sequence number added to a
specific tube which is used to identify packet loss and
reordering for that tube.
Reserved: 8-bit. (Reserved Octet) Reserved octet for future use.
4. In-situ OAM Data Export
In-situ OAM nodes collect information for packets traversing a domain
that supports in-situ OAM. The device at the domain edge (which
could also be an end-host) which receives a packet with in-situ OAM
information chooses how to process the in-situ OAM data collected
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within the packet. This decapsulating node can simply discard the
information collected, can process the information further, or export
the information using e.g., IPFIX.
The discussion of in-situ OAM data processing and export is left for
a future version of this document.
5. IANA Considerations
IANA considerations will be added in a future version of this
document.
6. Manageability Considerations
Manageability considerations will be addressed in a later version of
this document..
7. Security Considerations
Security considerations will be addressed in a later version of this
document. For a discussion of security requirements of in-situ OAM,
please refer to [I-D.brockners-inband-oam-requirements].
8. Acknowledgements
The authors would like to thank Eric Vyncke, Nalini Elkins, Srihari
Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya
Nadahalli, LJ Wobker, Erik Nordmark, and Andrew Yourtchenko for the
comments and advice. This document leverages and builds on top of
several concepts described in [I-D.kitamura-ipv6-record-route]. The
authors would like to acknowledge the work done by the author Hiroshi
Kitamura and people involved in writing it.
9. References
9.1. Normative References
[I-D.brockners-inband-oam-requirements]
Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
Gredler, H., Leddy, J., and S. Youell, "Requirements for
In-band OAM", draft-brockners-inband-oam-requirements-01
(work in progress), July 2016.
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[IEEE1588v2]
Institute of Electrical and Electronics Engineers,
"1588-2008 - IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", IEEE Std 1588-2008, 2008,
<http://standards.ieee.org/findstds/
standard/1588-2008.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References
[I-D.brockners-inband-oam-transport]
Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
Leddy, J., and S. Youell, "Encapsulations for In-band OAM
Data", draft-brockners-inband-oam-transport-01 (work in
progress), July 2016.
[I-D.hildebrand-spud-prototype]
Hildebrand, J. and B. Trammell, "Substrate Protocol for
User Datagrams (SPUD) Prototype", draft-hildebrand-spud-
prototype-03 (work in progress), March 2015.
[I-D.kitamura-ipv6-record-route]
Kitamura, H., "Record Route for IPv6 (PR6) Hop-by-Hop
Option Extension", draft-kitamura-ipv6-record-route-00
(work in progress), November 2000.
[I-D.lapukhov-dataplane-probe]
Lapukhov, P. and r. remy@barefootnetworks.com, "Data-plane
probe for in-band telemetry collection", draft-lapukhov-
dataplane-probe-01 (work in progress), June 2016.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/
RFC7665, October 2015,
<http://www.rfc-editor.org/info/rfc7665>.
Authors' Addresses
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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
Carlos Pignataro
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
United States
Email: cpignata@cisco.com
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
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Tal Mizrahi
Marvell
6 Hamada St.
Yokneam 20692
Israel
Email: talmi@marvell.com
David Mozes
Mellanox Technologies Ltd.
Email: davidm@mellanox.com
Petr Lapukhov
Facebook
1 Hacker Way
Menlo Park, CA 94025
US
Email: petr@fb.com
Remy Chang
Barefoot Networks
2185 Park Boulevard
Palo Alto, CA 94306
US
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