| ippm | F. Brockners |
| Internet-Draft | S. Bhandari |
| Intended status: Standards Track | C. Pignataro |
| Expires: March 14, 2020 | Cisco |
| H. Gredler | |
| RtBrick Inc. | |
| J. Leddy | |
| S. Youell | |
| JPMC | |
| T. Mizrahi | |
| Huawei Network.IO Innovation Lab | |
| D. Mozes | |
| P. Lapukhov | |
| R. Chang | |
| Barefoot Networks | |
| D. Bernier | |
| Bell Canada | |
| J. Lemon | |
| Broadcom | |
| September 11, 2019 |
Data Fields for In-situ OAM
draft-ietf-ippm-ioam-data-07
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 discusses the data fields and associated data types for in-situ OAM. In-situ OAM data fields can be embedded into a variety of transports such as NSH, Segment Routing, Geneve, native IPv6 (via extension header), or IPv4. In-situ OAM can be used to complement OAM mechanisms based on e.g. ICMP or other types of probe packets.
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This document defines data fields for "in-situ" Operations, Administration, and Maintenance (IOAM). 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 data is added to the data packets rather than is being sent within packets specifically dedicated to OAM. IOAM is to complement mechanisms such as Ping or Traceroute, or more recent active probing mechanisms as described in [I-D.lapukhov-dataplane-probe]. In terms of "active" or "passive" OAM, "in-situ" OAM can be considered a hybrid OAM type. "In-situ" mechanisms do not require extra packets to be sent. IOAM adds information to the already available data packets and therefore cannot be considered passive. In terms of the classification given in [RFC7799] IOAM could be portrayed as Hybrid Type 1. IOAM mechanisms can be leveraged where mechanisms using e.g. ICMP do not apply or do not offer the desired results, such as proving that a certain traffic flow 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 in which probe traffic is potentially handled differently from regular data traffic by the network devices.
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:
IOAM deployment assumes a set of constraints, requirements, and guiding principles which are described in this section.
Scope: This document defines the data fields and associated data types for in-situ OAM. The in-situ OAM data field can be transported by a variety of transport protocols, including NSH, Segment Routing, Geneve, IPv6, or IPv4. Specification details for these different transport protocols are outside the scope of this document.
Deployment domain (or scope) of in-situ OAM deployment: IOAM is a network domain focused feature, with "network domain" being a set of network devices or entities within a single administration. For example, a network domain can include an enterprise campus using physical connections between devices or an overlay network using virtual connections / tunnels for connectivity between said devices. A network domain is defined by its perimeter or edge. Designers of protocol encapsulations for IOAM must specify mechanisms to ensure that IOAM data stays within an IOAM domain. In addition, the operator of such a domain is expected to put provisions in place to ensure that IOAM data does not leak beyond the edge of an IOAM domain, e.g. using for example packet filtering methods. The operator should consider the potential operational impact of IOAM to mechanisms such as ECMP processing (e.g. load-balancing schemes based on packet length could be impacted by the increased packet size due to IOAM), path MTU (i.e. ensure that the MTU of all links within a domain is sufficiently large to support the increased packet size due to IOAM) and ICMP message handling (i.e. in case of a native IPv6 transport, IOAM support for ICMPv6 Echo Request/Reply could desired which would translate into ICMPv6 extensions to enable IOAM-Data-Fields to be copied from an Echo Request message to an Echo Reply message).
IOAM control points: IOAM-Data-Fields are added to or removed from the live user traffic by the devices which form the edge of a domain. Devices which form an IOAM-Domain can add, update or remove IOAM-Data-Fields. Edge devices of an IOAM-Domain can be hosts or network devices.
Traffic-sets that IOAM is applied to: IOAM can be deployed on all or only on subsets of the live user traffic. It SHOULD be possible to enable IOAM on a selected set of traffic (e.g., per interface, based on an access control list or flow specification defining a specific set of traffic, etc.) The selected set of traffic can also be all traffic.
Encapsulation independence: Data formats for IOAM SHOULD be defined in a transport-independent manner. IOAM applies to a variety of encapsulating protocols. A definition of how IOAM-Data-Fields are encapsulated into "parent" protocols, like NSH or IPv6 is outside the scope of this document.
Layering: If several encapsulation protocols (e.g., in case of tunneling) are stacked on top of each other, IOAM-Data-Fields could be present at multiple layers. The behavior follows the ships-in-the-night model, i.e. IOAM-Data-Fields in one layer are independent from IOAM-Data-Fields in another layer. Layering allows operators to instrument the protocol layer they want to measure. The different layers could, but do not have to share the same IOAM encapsulation mechanisms.
IOAM implementation: The definition of the IOAM-Data-Fields take the specifics of devices with hardware data-plane and software data-plane into account.
This section details IOAM-related nomenclature and describes data types such as IOAM-Data-Fields, IOAM-Types, IOAM-Namespaces as well as the different types of IOAM nodes.
An IOAM-Data-Field is a set of bits with a defined format and meaning, which can be stored at a certain place in a packet for the purpose of IOAM.
To accommodate the different uses of IOAM, IOAM-Data-Fields fall into different categories. In IOAM these categories are referred to as IOAM-Option-Types. A common registry is maintained for IOAM-Option-Types, see Section 7.2 for details. Corresponding to these IOAM-Option-Types, different IOAM-Data-Fields are defined. IOAM-Data-Fields can be encapsulated into a variety of protocols, such as NSH, Geneve, IPv6, etc. The definition of how IOAM-Data-Fields are encapsulated into other protocols is outside the scope of this document.
This document defines four IOAM-Option-Types:
IOAM is expected to be deployed in a specific domain. The part of the network which employs IOAM is referred to as the "IOAM-Domain". One or more IOAM-Option-Types are added to a packet upon entering the IOAM-Domain and are removed from the packet when exiting the domain. Within the IOAM-Domain, the IOAM-Data-Fields MAY be updated by network nodes that the packet traverses. An IOAM-Domain consists of "IOAM encapsulating nodes", "IOAM decapsulating nodes" and "IOAM transit nodes". The role of a node (i.e. encapsulating, transit, decapsulating) is defined within an IOAM-Namespace (see below). A node can have different roles in different IOAM-Namespaces.
A device which adds at least one IOAM-Option-Type to the packet is called the "IOAM encapsulating node", whereas a device which removes an IOAM-Option-Type is referred to as the "IOAM decapsulating node". Nodes within the domain which are aware of IOAM data and read and/or write or process the IOAM data are called "IOAM transit nodes". IOAM nodes which add or remove the IOAM-Data-Fields can also update the IOAM-Data-Fields at the same time. Or in other words, IOAM encapsulating or decapsulating nodes can also serve as IOAM transit nodes at the same time. Note that not every node in an IOAM domain needs to be an IOAM transit node. For example, a deployment might require that packets traverse a set of firewalls which support IOAM. In that case, only the set of firewall nodes would be IOAM transit nodes rather than all nodes.
An "IOAM encapsulating node" incorporates one or more IOAM-Option-Types (from the list of IOAM-Types, see Section 7.2) into packets that IOAM is enabled for. If IOAM is enabled for a selected subset of the traffic, the IOAM encapsulating node is responsible for applying the IOAM functionality to the selected subset.
An "IOAM transit node" updates one or more of the IOAM-Data-Fields. If both the Pre-allocated and the Incremental Trace Option-Types are present in the packet, each IOAM transit node will update at most one of these Option-Types. A transit node MUST NOT add new IOAM-Option-Types to a packet, and MUST NOT change the IOAM-Data-Fields of an IOAM Edge-to-Edge Option-Type.
An "IOAM decapsulating node" removes IOAM-Option-Type(s) from packets.
A subset or all of the IOAM-Option-Types and their corresponding IOAM-Data-Fields can be associated to an IOAM-Namespace. IOAM-Namespaces add further context to IOAM-Option-Types and associated IOAM-Data-Fields. Any IOAM-Namespace MUST interpret the IOAM-Option-Types and associated IOAM-Data-Fields per the definition in this document. IOAM-Namespaces group nodes to support different deployment approaches of IOAM (see a few example use-cases below) as well as resolve issues which can occur due to IOAM-Data-Fields not being globally unique (e.g. IOAM node identifiers do not have to be globally unique). IOAM-Data-Fields significance is always within a particular IOAM-Namespace.
An IOAM-Namespace is identified by a 16-bit namespace identifier (Namespace-ID). IOAM-Namespace identifiers MUST be present and populated in all IOAM-Option-Types. The Namespace-ID value is divided into two sub-ranges:
The IANA-assigned range is intended to allow future extensions to have new and interoperable IOAM functionality, while the operator-assigned range is intended to be domain specific, and managed by the network operator. The Namespace-ID value of 0x0000 is default and known to all the nodes implementing IOAM.
Namespace identifiers allow devices which are IOAM capable to determine:
IOAM-Namespaces support several different uses:
"IOAM tracing data" is expected to be collected at every IOAM transit node that a packet traverses to ensure visibility into the entire path a packet takes within an IOAM-Domain. I.e., in a typical deployment all nodes in an IOAM-Domain would participate in IOAM and thus be IOAM transit nodes, IOAM encapsulating or IOAM decapsulating nodes. If not all nodes within a domain are IOAM capable, IOAM tracing information (i.e., node data, see below) will only be collected on those nodes which are IOAM capable. Nodes which are not IOAM capable will forward the packet without any changes to the IOAM-Data-Fields. The maximum number of hops and the minimum path MTU of the IOAM domain is assumed to be known.
To optimize hardware and software implementations IOAM tracing is defined as two separate options. Any deployment MAY choose to configure and support one or both of the following options.
A particular implementation of IOAM MAY choose to support only one of the two trace option types. In the event that both options are utilized at the same time, the Incremental Trace-Option MUST be placed before the Pre-allocated Trace-Option. Deployments which mix devices which either the Incremental Trace-Option or the Pre-allocated Trace-Option could result in both Option-Types being present in a packet. Given that the operator knows which equipment is deployed in a particular IOAM, the operator will decide by means of configuration which type(s) of trace options will be used for a particular domain.
Every node data entry holds information for a particular IOAM transit node that is traversed by a packet. The IOAM decapsulating node removes the IOAM-Option-Type(s) and processes and/or exports the associated data. IOAM-Data-Fields are defined in the context of an IOAM-Namespace. This allows for a namespace-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).
IOAM tracing can collect the following types of information:
The IOAM Pre-allocated Trace-Option and the IOAM Incremental Trace-Option have similar formats. Except where noted below, the internal formats and fields of the two trace options are identical. Both Trace-Options consist of a fixed size "trace option header" and a variable data space to store gathered data, the "node data list":
Pre-allocated and incremental trace option headers: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Namespace-ID |NodeLen | Flags | RemainingLen| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IOAM-Trace-Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The trace option data MUST be 4-octet aligned: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ | | | | 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] | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
All the IOAM-Data-Fields MUST be 4-octet aligned. If a node which is supposed to update an IOAM-Data-Field is not capable of populating the value of a field set in the IOAM-Trace-Type, the field value MUST be set to 0xFFFFFFFF for 4-octet fields or 0xFFFFFFFFFFFFFFFF for 8-octet fields, indicating that the value is not populated, except when explicitly specified in the field description below.
Some IOAM-Data-Fields defined below, such as interface identifiers or IOAM-Namespace specific data, are defined in both "short format" as well as "wide format". Their use is not exclusive. A deployment could choose to leverage both. For example, ingress_if_id_(short format) could be an identifier for the physical interface, whereas ingress_if_id_(wide format) could be an identifier for a logical sub-interface of that physical interface.
Data field and associated data type for each of the IOAM-Data-Fields is shown below:
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | namespace specific data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | namespace specific data ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ namespace specific data (contd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | buffer occupancy | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Checksum Complement | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 |
~ ~
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note that due to the fact that IOAM uses its own IOAM-Namespaces for IOAM-Data-Fields, data fields like interface identifiers can be used in a flexible way to represent system resources that are associated with ingressing or egressing packets, i.e. ingress_if_id could represent a physical interface, a virtual or logical interface, or even a queue.
IOAM decapsulating nodes MUST recompute the UDP Checksum field, since they do not know whether previous hops modified the UDP Checksum field or the Checksum Complement field.
When this field is part of the data field but a node populating the field has no opaque state data to report, the Length must be set to 0 and the Schema ID must be set to 0xFFFFFF to mean no schema.
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 provides example entries of the "node data list".
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 subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| namespace specific data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 subseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop_Lim | node_id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| node_id(contd) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Schema Id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Opaque data |
~ ~
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IOAM Proof of Transit Option-Type is to support path or service function chain [RFC7665] verification use cases. Proof-of-transit uses methods like nested hashing or nested encryption of the IOAM data or mechanisms such as Shamir's Secret Sharing Schema (SSSS). While details on how the IOAM data for the proof of transit option is processed at IOAM 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 IOAM-Data-Fields to the packet:
The IOAM Proof of Transit Option-Type consist of a fixed size "IOAM proof of transit option header" and "IOAM proof of transit option data fields":
IOAM proof of transit option header:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Namespace-ID |IOAM POT Type | IOAM POT flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IOAM proof of transit Option-Type IOAM-Data-Fields MUST be
4-octet aligned:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| POT Option data field determined by IOAM-POT-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IOAM proof of transit option of IOAM POT Type 0: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Namespace-ID |IOAM POT Type=0|P|R R R R R R R| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+ | Random | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ P | Random(contd) | O +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ T | Cumulative | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | Cumulative (contd) | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<-+
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".
The IOAM Edge-to-Edge Option-Type is to carry data that is added by the IOAM encapsulating node and interpreted by IOAM decapsulating node. The IOAM transit nodes MAY process the data but MUST NOT modify it.
The IOAM Edge-to-Edge Option-Type consist of a fixed size "IOAM Edge-to-Edge Option-Type header" and "IOAM Edge-to-Edge Option-Type data fields":
IOAM Edge-to-Edge Option-Type header: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Namespace-ID | IOAM-E2E-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IOAM Edge-to-Edge Option-Type IOAM-Data-Fields MUST be 4-octet aligned: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | E2E Option data field determined by IOAM-E2E-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The IOAM-Data-Fields include a timestamp field which is represented in one of three possible timestamp formats. It is assumed that the management plane is responsible for determining which timestamp format is used.
The Precision Time Protocol (PTP) [IEEE1588v2] uses an 80-bit timestamp format. The truncated timestamp format is a 64-bit field, which is the 64 least significant bits of the 80-bit PTP timestamp. The PTP truncated format is specified in Section 4.3 of [I-D.ietf-ntp-packet-timestamps], and the details are presented below for the sake of completeness.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nanoseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: PTP [IEEE1588v2] Truncated Timestamp Format
Timestamp field format:
Epoch:
Resolution:
Wraparound:
Synchronization Aspects:
The Network Time Protocol (NTP) [RFC5905] timestamp format is 64 bits long. This format is specified in Section 4.2.1 of [I-D.ietf-ntp-packet-timestamps], and the details are presented below for the sake of completeness.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: NTP [RFC5905] 64-bit Timestamp Format
Timestamp field format:
Epoch:
Resolution:
Wraparound:
Synchronization Aspects:
This timestamp format is based on the POSIX time format [POSIX]. The detailed specification of the timestamp format used in this document is presented below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Microseconds |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: POSIX-based Timestamp Format
Timestamp field format:
Epoch:
Resolution:
Wraparound:
Synchronization Aspects:
IOAM nodes collect information for packets traversing a domain that supports IOAM. IOAM decapsulating nodes as well as IOAM transit nodes can choose to retrieve IOAM information from the packet, process the information further and export the information using e.g., IPFIX. The mechanisms and associated data formats for exporting IOAM data is outside the scope of this document.
Raw data export of IOAM data using IPFIX is discussed in [I-D.spiegel-ippm-ioam-rawexport].
This document requests the following IANA Actions.
IANA is requested to create a new protocol registry for "In-Situ OAM (IOAM) Protocol Parameters". This is the common registry that will include registrations for all IOAM-Namespaces. Each Registry, whose names are listed below:
will contain the current set of possibilities defined in this document. New registries in this name space are created via RFC Required process as per
The subsequent sub-sections detail the registries herein contained.
This registry defines 128 code points for the IOAM Option-Type field for identifying IOAM Option-Types as explained in Section 4. The following code points are defined in this draft:
4 - 127 are available for assignment via RFC Required process as per
This registry defines code point for each bit in the 24-bit IOAM-Trace-Type field for Pre-allocated trace option and Incremental trace option defined in Section 4.4. The meaning of Bits 0 - 11 for trace type are defined in this document in Paragraph 5 of Section 4.4.1:
The meaning for Bits 12 - 21 are available for assignment via RFC Required process as per
This registry defines code points for each bit in the 4 bit flags for the Pre-allocated trace option and for the Incremental trace option defined in Section 4.4. The meaning of Bit 0 (the most significant bit) for trace flags is defined in this document in Paragraph 3 of Section 4.4.1:
This registry defines 256 code points to define IOAM POT Type for IOAM proof of transit option Section 4.5. The code point value 0 is defined in this document:
1 - 255 are available for assignment via RFC Required process as per
This registry defines code points for each bit in the 8 bit flags for IOAM POT option defined in Section 4.5. The meaning of Bit 0 for IOAM POT flags is defined in this document in Section 4.5:
The meaning for Bits 1 - 7 are available for assignment via RFC Required process as per
This registry defines code points for each bit in the 16 bit IOAM-E2E-Type field for IOAM E2E option Section 4.6. The meaning of Bit 0 - 3 are defined in this document:
The meaning of Bits 4 - 15 are available for assignment via RFC Required process as per
IANA is requested to set up an "IOAM Namespace-ID Registry", containing 16-bit values. The meaning of Bit 0 is defined in this document. IANA is requested to reserve the values 0x0001 to 0x7FFF for private use (managed by operators), as specified in Section 4.3 of the current document. Registry entries for the values 0x8000 to 0xFFFF are to be assigned via the "Expert Review" policy defined in [RFC8126].
As discussed in [RFC7276], a successful attack on an OAM protocol in general, and specifically on IOAM, can prevent the detection of failures or anomalies, or create a false illusion of nonexistent ones.
The Proof of Transit Option-Type (Section Section 4.5) is used for verifying the path of data packets. The security considerations of POT are further discussed in [I-D.ietf-sfc-proof-of-transit].
The data elements of IOAM can be used for network reconnaissance, allowing attackers to collect information about network paths, performance, queue states, buffer occupancy and other information. Note that in case IOAM is used in "immediate export" mode (reference to be added in a future revision), the IOAM related trace information would not be available in the customer data packets, but would trigger export of packet related IOAM information at every node. IOAM data export and securing IOAM data export is outside the scope of this document.
IOAM can be used as a means for implementing Denial of Service (DoS) attacks, or for amplifying them. For example, a malicious attacker can add an IOAM header to packets in order to consume the resources of network devices that take part in IOAM or collectors that analyze the IOAM data. Another example is a packet length attack, in which an attacker pushes headers associated with IOAM Option-Types into data packets, causing these packets to be increased beyond the MTU size, resulting in fragmentation or in packet drops.
Since IOAM options may include timestamps, if network devices use synchronization protocols then any attack on the time protocol [RFC7384] can compromise the integrity of the timestamp-related data fields.
At the management plane, attacks may be implemented by misconfiguring or by maliciously configuring IOAM-enabled nodes in a way that enables other attacks. Thus, IOAM configuration should be secured in a way that authenticates authorized users and verifies the integrity of configuration procedures.
Notably, IOAM is expected to be deployed in specific network domains, thus confining the potential attack vectors to within the network domain. Indeed, in order to limit the scope of threats to within the current network domain the network operator is expected to enforce policies that prevent IOAM traffic from leaking outside of the IOAM domain, and prevent IOAM data from outside the domain to be processed and used within the domain. Note that the Immediate Export mode (reference to be added in a future revision) can mitigate the potential threat of IOAM data leaking through data packets.
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, Vengada Prasad Govindan, Andrew Yourtchenko, Aviv Kfir, Tianran Zhou and Zhenbin (Robin) 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.
The authors would like to gracefully acknowledge useful review and insightful comments received from Joe Clarke, Al Morton, Tom Herbet, Haoyu song, and Mickey Spiegel.
The authors would like to acknowledge the contribution of "Immediate export" of IOAM trace by Barak Gafni.
| [IEEE1588v2] | Institute of Electrical and Electronics Engineers, "IEEE Std 1588-2008 - IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems", IEEE Std 1588-2008, 2008. |
| [POSIX] | Institute of Electrical and Electronics Engineers, "IEEE Std 1003.1-2008 (Revision of IEEE Std 1003.1-2004) - IEEE Standard for Information Technology - Portable Operating System Interface (POSIX(R))", IEEE Std 1003.1-2008, 2008. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC5905] | Mills, D., Martin, J., Burbank, J. and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010. |
| [RFC8126] | Cotton, M., Leiba, B. and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017. |
| [I-D.ietf-ntp-packet-timestamps] | Mizrahi, T., Fabini, J. and A. Morton, "Guidelines for Defining Packet Timestamps", Internet-Draft draft-ietf-ntp-packet-timestamps-07, August 2019. |
| [I-D.ietf-nvo3-geneve] | Gross, J., Ganga, I. and T. Sridhar, "Geneve: Generic Network Virtualization Encapsulation", Internet-Draft draft-ietf-nvo3-geneve-13, March 2019. |
| [I-D.ietf-nvo3-vxlan-gpe] | Maino, F., Kreeger, L. and U. Elzur, "Generic Protocol Extension for VXLAN", Internet-Draft draft-ietf-nvo3-vxlan-gpe-07, April 2019. |
| [I-D.ietf-sfc-proof-of-transit] | Brockners, F., Bhandari, S., Dara, S., Pignataro, C., Leddy, J., Youell, S., Mozes, D., Mizrahi, T., Aguado, A. and D. Lopez, "Proof of Transit", Internet-Draft draft-ietf-sfc-proof-of-transit-02, March 2019. |
| [I-D.kitamura-ipv6-record-route] | Kitamura, H., "Record Route for IPv6 (PR6) Hop-by-Hop Option Extension", Internet-Draft draft-kitamura-ipv6-record-route-00, November 2000. |
| [I-D.lapukhov-dataplane-probe] | Lapukhov, P. and r. remy@barefootnetworks.com, "Data-plane probe for in-band telemetry collection", Internet-Draft draft-lapukhov-dataplane-probe-01, June 2016. |
| [I-D.spiegel-ippm-ioam-rawexport] | Spiegel, M., Brockners, F., Bhandari, S. and R. Sivakolundu, "In-situ OAM raw data export with IPFIX", Internet-Draft draft-spiegel-ippm-ioam-rawexport-02, July 2019. |
| [RFC7276] | Mizrahi, T., Sprecher, N., Bellagamba, E. and Y. Weingarten, "An Overview of Operations, Administration, and Maintenance (OAM) Tools", RFC 7276, DOI 10.17487/RFC7276, June 2014. |
| [RFC7384] | Mizrahi, T., "Security Requirements of Time Protocols in Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384, October 2014. |
| [RFC7665] | Halpern, J. and C. Pignataro, "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, October 2015. |
| [RFC7799] | Morton, A., "Active and Passive Metrics and Methods (with Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799, May 2016. |
| [RFC7820] | Mizrahi, T., "UDP Checksum Complement in the One-Way Active Measurement Protocol (OWAMP) and Two-Way Active Measurement Protocol (TWAMP)", RFC 7820, DOI 10.17487/RFC7820, March 2016. |
| [RFC7821] | Mizrahi, T., "UDP Checksum Complement in the Network Time Protocol (NTP)", RFC 7821, DOI 10.17487/RFC7821, March 2016. |
| [RFC8300] | Quinn, P., Elzur, U. and C. Pignataro, "Network Service Header (NSH)", RFC 8300, DOI 10.17487/RFC8300, January 2018. |