IPPM H. Song Internet-Draft Futurewei Intended status: Standards Track B. Gafni Expires: May 5, 2021 Mellanox Technologies, Inc. T. Zhou Z. Li Huawei F. Brockners S. Bhandari R. Sivakolundu Cisco T. Mizrahi, Ed. Huawei Smart Platforms iLab November 1, 2020 In-situ OAM Direct Exporting draft-ietf-ippm-ioam-direct-export-02 Abstract In-situ Operations, Administration, and Maintenance (IOAM) is used for recording and collecting operational and telemetry information. Specifically, IOAM allows telemetry data to be pushed into data packets while they traverse the network. This document introduces a new IOAM option type called the Direct Export (DEX) option, which is used as a trigger for IOAM data to be directly exported without being pushed into in-flight data 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 https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on May 5, 2021. Song, et al. Expires May 5, 2021 [Page 1] Internet-Draft IOAM Direct Exporting November 2020 Copyright Notice Copyright (c) 2020 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 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirement Language . . . . . . . . . . . . . . . . . . 3 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 3. The Direct Exporting (DEX) IOAM Option Type . . . . . . . . . 3 3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. The DEX Option Format . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4.1. IOAM Type . . . . . . . . . . . . . . . . . . . . . . . . 6 4.2. IOAM DEX Flags . . . . . . . . . . . . . . . . . . . . . 6 5. Performance Considerations . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . 8 Appendix A. Hop Limit and Hop Count in Direct Exporting . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction IOAM [I-D.ietf-ippm-ioam-data] is used for monitoring traffic in the network, and for incorporating IOAM data fields into in-flight data packets. IOAM makes use of four possible IOAM options, defined in [I-D.ietf-ippm-ioam-data]: Pre-allocated Trace Option, Incremental Trace Option, Proof of Transit (POT) Option, and Edge-to-Edge Option. This document defines a new IOAM option type (also known as an IOAM type) called the Direct Export (DEX) option. This option is used as a trigger for IOAM nodes to export IOAM data to a receiving entity Song, et al. Expires May 5, 2021 [Page 2] Internet-Draft IOAM Direct Exporting November 2020 (or entities). A "receiving entity" in this context can be, for example, an external collector, analyzer, controller, decapsulating node, or a software module in one of the IOAM nodes. This draft has evolved from combining some of the concepts of PBT-I from [I-D.song-ippm-postcard-based-telemetry] with immediate exporting from [I-D.ietf-ippm-ioam-flags]. 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 DEX: Direct EXporting 3. The Direct Exporting (DEX) IOAM Option Type 3.1. Overview The DEX option is used as a trigger for exporting telemetry data to a receiving entity (or entities). This option is incorporated into data packets by an IOAM encapsulating node, and removed by an IOAM decapsulating node, as illustrated in Figure 1. The option can be read but not modified by transit nodes. Note: the terms IOAM encapsulating, decapsulating and transit nodes are as defined in [I-D.ietf-ippm-ioam-data]. Song, et al. Expires May 5, 2021 [Page 3] Internet-Draft IOAM Direct Exporting November 2020 ^ |Exported IOAM data | | | +--------------+------+-------+--------------+ | | | | | | | | User +---+----+ +---+----+ +---+----+ +---+----+ packets |Encapsu-| | Transit| | Transit| |Decapsu-| --------->|lating |====>| Node |====>| Node |====>|lating |----> |Node | | A | | B | |Node | +--------+ +--------+ +--------+ +--------+ Insert DEX Export Export Remove DEX option and IOAM data IOAM data option and export data export data Figure 1: DEX Architecture The DEX option is used as a trigger to export IOAM data. The trigger applies to transit nodes, the decapsulating node, and the encapsulating node: o An IOAM encapsulating node configured to incorporate the DEX option encapsulates the packet with the DEX option, and MAY export the requested IOAM data immediately. The IOAM encapsulating node is the only type of node allowed to push the DEX option. o A transit node that processes a packet with the DEX option MAY export the requested IOAM data. o An IOAM decapsulating node that processes a packet with the DEX option MAY export the requested IOAM data, and MUST decapsulate the IOAM header. As in [I-D.ietf-ippm-ioam-data], the DEX option may be incorporated into all or a subset of the traffic that is forwarded by the encapsulating node. Moreover, IOAM nodes MAY export data for all traversing packets that carry the DEX option, or MAY selectively export data only for a subset of these packets. The DEX option specifies which data fields should be exported, as specified in Section 3.2. The format and encapsulation of the packet that contains the exported data is not within the scope of the current document. For example, the export format can be based on [I-D.spiegel-ippm-ioam-rawexport]. Song, et al. Expires May 5, 2021 [Page 4] Internet-Draft IOAM Direct Exporting November 2020 A transit IOAM node that does not support the DEX option SHOULD ignore it. A decapsulating node that does not support the DEX option MUST remove it, along with any other IOAM options carried in the packet if such exist. 3.2. The DEX Option Format The format of the DEX option is depicted in Figure 2. The length of the DEX option is either 8 octets or 16 octets, as the Flow ID and the Sequence Number fields (summing up to 8 octets) are optional. It is assumed that the lower layer protocol indicates the length of the DEX option, thus indicating whether the two optional fields are present. 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 | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IOAM-Trace-Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flow ID (optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number (Optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: DEX Option Format Namespace-ID A 16-bit identifier of the IOAM namespace, as defined in [I-D.ietf-ippm-ioam-data]. Flags A 16-bit field, comprised of 16 one-bit subfields. Flags are allocated by IANA, as defined in Section 4.2. IOAM-Trace-Type A 24-bit identifier which specifies which data fields should be exported. The format of this field is as defined in [I-D.ietf-ippm-ioam-data]. Specifically, bit 23, which corresponds to the Checksum Complement data field, should be assigned to be zero by the IOAM encapsulating node, and ignored by transit and decapsulating nodes. The reason for this is that the Checksum Complement is intended for in-flight packet modifications and is not relevant for direct exporting. Song, et al. Expires May 5, 2021 [Page 5] Internet-Draft IOAM Direct Exporting November 2020 Reserved This field SHOULD be ignored by the receiver. Flow ID A 32-bit flow identifier. If the actual Flow ID is shorter than 32 bits, it is zero padded in its most significant bits. The field is set at the encapsulating node. The Flow ID can be uniformly assigned by a central controller or algorithmically generated by the encapsulating node. The latter approach cannot guarantee the uniqueness of Flow ID, yet the conflict probability is small due to the large Flow ID space. The Flow ID can be used to correlate the exported data of the same flow from multiple nodes and from multiple packets. Sequence Number A 32-bit sequence number starting from 0 and increasing by 1 for each following monitored packet from the same flow at the encapsulating node. The Sequence Number, when combined with the Flow ID, provides a convenient approach to correlate the exported data from the same user packet. 4. IANA Considerations 4.1. IOAM Type The "IOAM Type Registry" was defined in Section 7.2 of [I-D.ietf-ippm-ioam-data]. IANA is requested to allocate the following code point from the "IOAM Type Registry" as follows: TBD-type IOAM Direct Export (DEX) Option Type If possible, IANA is requested to allocate code point 4 (TBD-type). 4.2. IOAM DEX Flags IANA is requested to define an "IOAM DEX Flags" registry. This registry includes 16 flag bits. Allocation should be performed based on the "RFC Required" procedure, as defined in [RFC8126]. 5. Performance Considerations The DEX option triggers exported packets to be exported to a receiving entity (or entities). In some cases this may impact the receiving entity's performance, or the performance along the paths leading to it. Therefore, rate limiting may be enabled so as to ensure that direct exporting is used at a rate that does not significantly affect the Song, et al. Expires May 5, 2021 [Page 6] Internet-Draft IOAM Direct Exporting November 2020 network bandwidth, and does not overload the receiving entity (or the source node in the case of loopback). It should be possible to use each DEX on a subset of the data traffic, and to load balance the exported data among multiple receiving entities. 6. 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 the DEX option. Similarly, an on-path attacker may maliciously incorporate the DEX option into transit packets, or maliciously remove it from packets in which it is incorporated. Forcing DEX, either in synthetic packets or in transit packets may overload the receiving entity (or entities). Since this mechanism affects multiple devices along the network path, it potentially amplifies the effect on the network bandwidth and on the receiving entity's load. In order to mitigate the attacks described above, it should be possible for IOAM-enabled devices to limit the exported IOAM data to a configurable rate. 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 assumption with respect to the security aspects of IOAM, as further discussed in [I-D.ietf-ippm-ioam-data]. 7. References 7.1. Normative References [I-D.ietf-ippm-ioam-data] Brockners, F., Bhandari, S., and T. Mizrahi, "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-data-10 (work in progress), July 2020. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Song, et al. Expires May 5, 2021 [Page 7] Internet-Draft IOAM Direct Exporting November 2020 7.2. Informative References [I-D.ietf-ippm-ioam-flags] Mizrahi, T., Brockners, F., Bhandari, S., Sivakolundu, R., Pignataro, C., Kfir, A., Gafni, B., Spiegel, M., and J. Lemon, "In-situ OAM Flags", draft-ietf-ippm-ioam-flags-03 (work in progress), October 2020. [I-D.song-ippm-postcard-based-telemetry] Song, H., Zhou, T., Li, Z., Mirsky, G., Shin, J., and K. Lee, "Postcard-based On-Path Flow Data Telemetry using Packet Marking", draft-song-ippm-postcard-based- telemetry-08 (work in progress), October 2020. [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-03 (work in progress), March 2020. [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, . Appendix A. Hop Limit and Hop Count in Direct Exporting In order to help correlate and order the exported packets, it is possible to include the Hop_Lim/Node_ID data field in exported packets; if the IOAM-Trace-Type [I-D.ietf-ippm-ioam-data] has the Hop_Lim/Node_ID bit set, then exported packets include the Hop_Lim/ Node_ID data field, which contains the TTL/Hop Limit value from a lower layer protocol. An alternative approach was considered during the design of this document, according to which a 1-octet Hop Count field would be included in the DEX header (presumably by claiming some space from the Flags field). The Hop Limit would starts from 0 at the encapsulating node and be incremented by each IOAM transit node that supports the DEX option. In this approach the Hop Count field value would also be included in the exported packet. The main advantage of the Hop_Lim/Node_ID approach is that it provides information about the current hop count without requiring each transit node to modify the DEX option, thus simplifying the data plane functionality of Direct Exporting. The main advantage of the Hop Count approach that was considered is that it counts the number of IOAM-capable nodes without relying on the lower layer TTL, Song, et al. Expires May 5, 2021 [Page 8] Internet-Draft IOAM Direct Exporting November 2020 especially when the lower layer cannot prvide the accurate TTL information, e.g., Layer 2 Ethernet or hierarchical VPN. The Hop Count approach would also explicitly allow to detect a case where an IOAM-capable node fails to export packets. It would also be possible to use a flag to indicate an optional Hop Count field, which enables to control the tradeoff. On one hand it would address the use cases that the Hop_Lim/Node_ID cannot cover, and on the other hand it would not require transit switches to update the option if it was not supported or disabled. For the sake of simplicity the Hop Count approach was not pursued, and this field is not incorporated in the DEX header. Authors' Addresses Haoyu Song Futurewei 2330 Central Expressway Santa Clara 95050 USA Email: haoyu.song@huawei.com Barak Gafni Mellanox Technologies, Inc. 350 Oakmead Parkway, Suite 100 Sunnyvale, CA 94085 U.S.A. Email: gbarak@mellanox.com Tianran Zhou Huawei 156 Beiqing Rd. Beijing 100095 China Email: zhoutianran@huawei.com Zhenbin Li Huawei 156 Beiqing Rd. Beijing 100095 China Email: lizhenbin@huawei.com Song, et al. Expires May 5, 2021 [Page 9] Internet-Draft IOAM Direct Exporting November 2020 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 Tal Mizrahi (editor) Huawei Smart Platforms iLab 8-2 Matam Haifa 3190501 Israel Email: tal.mizrahi.phd@gmail.com Song, et al. Expires May 5, 2021 [Page 10]