SPRING Working Group R. Gandhi, Ed. Internet-Draft C. Filsfils Intended Status: Informational Cisco Systems, Inc. Expires: August 18, 2019 D. Voyer Bell Canada S. Salsano Universita di Roma "Tor Vergata" P. L. Ventre CNIT M. Chen Huawei February 14, 2019 In-band Performance Measurement for Segment Routing Networks with MPLS Data Plane draft-gandhi-spring-rfc6374-srpm-mpls-00 Abstract RFC 6374 specifies protocol mechanisms to enable the efficient and accurate measurement of packet loss, one-way and two-way delay, as well as related metrics such as delay variation in MPLS networks using probe messages. This document reviews how these mechanisms can be used for Delay and Loss Performance Measurements (PM) in Segment Routing (SR) networks with MPLS data plane (SR-MPLS), for both SR links and end-to-end SR Policies. The performance measurements for SR links are used to compute extended Traffic Engineering (TE) metrics for delay and loss and are advertised in the network using the routing protocol extensions. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." Gandhi, et al. Expires August 18, 2019 [Page 1] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Reference Topology . . . . . . . . . . . . . . . . . . . . 4 2.3. In-band Probe Messages . . . . . . . . . . . . . . . . . . 5 3. Probe Query and Response Packets . . . . . . . . . . . . . . . 5 3.1. Probe Packet Header for SR-MPLS Policies . . . . . . . . . 5 3.2. Probe Packet Header for SR-MPLS Links . . . . . . . . . . 6 3.3. Probe Response Message for SR-MPLS Links and Policies . . 6 3.3.1. One-way Measurement Probe Response Message . . . . . . 6 3.3.2. Two-way Measurement Probe Response Message . . . . . . 6 4. Performance Delay Measurement . . . . . . . . . . . . . . . . 7 4.1. Delay Measurement Message Format . . . . . . . . . . . . . 7 4.2. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Performance Loss Measurement . . . . . . . . . . . . . . . . . 7 5.1. Loss Measurement Message Format . . . . . . . . . . . . . 8 6. Performance Measurement for P2MP SR Policies . . . . . . . . . 8 7. ECMP for SR-MPLS Policies . . . . . . . . . . . . . . . . . . 8 8. SR Link Extended TE Metrics Advertisements . . . . . . . . . . 8 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 11.1. Normative References . . . . . . . . . . . . . . . . . . 9 11.2. Informative References . . . . . . . . . . . . . . . . . 9 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Gandhi, et al. Expires August 18, 2019 [Page 2] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 1. Introduction Service provider's ability to satisfy Service Level Agreements (SLAs) depend on the ability to measure and monitor performance metrics for packet loss and one-way and two-way delay, as well as related metrics such as delay variation. The ability to monitor these performance metrics also provides operators with greater visibility into the performance characteristics of their networks, thereby facilitating planning, troubleshooting, and network performance evaluation. [RFC6374] specifies protocol mechanisms to enable the efficient and accurate measurement of performance metrics in MPLS networks using probe messages. The One-Way Active Measurement Protocol (OWAMP) defined in [RFC4656] and Two-Way Active Measurement Protocol (TWAMP) defined in [RFC5357] provide capabilities for the measurement of various performance metrics in IP networks. However, mechanisms defined in [RFC6374] are more suitable for Segment Routing (SR) when using MPLS data plane (SR-MPLS). The [RFC6374] also supports IEEE 1588 timestamps [IEEE1588] and "direct mode" Loss Measurement (LM), which are required in SR networks. [RFC7876] specifies the procedures to be used when sending and processing out-of-band performance measurement probe replies over an UDP return path when receiving RFC 6374 based probe queries. These procedures can be used to send out-of-band PM replies for both SR links and SR Policies [I-D.spring-segment-routing-policy] for one-way measurement. This document reviews how probe based mechanisms defined in [RFC6374] can be used for Delay and Loss Performance Measurements (PM) in SR networks with MPLS data plane, for both SR links and end-to-end SR Policies. The performance measurements for SR links are used to compute extended Traffic Engineering (TE) metrics for delay and loss and are advertised in the network using routing protocol extensions. 2. Conventions Used in This Document 2.1. Abbreviations ACH: Associated Channel Header. DM: Delay Measurement. ECMP: Equal Cost Multi-Path. G-ACh: Generic Associated Channel (G-ACh). Gandhi, et al. Expires August 18, 2019 [Page 3] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 GAL: Generic Associated Channel (G-ACh) Label. LM: Loss Measurement. MPLS: Multiprotocol Label Switching. NTP: Network Time Protocol. PM: Performance Measurement. PSID: Path Segment Identifier. PTP: Precision Time Protocol. SID: Segment ID. SL: Segment List. SR: Segment Routing. SR-MPLS: Segment Routing with MPLS data plane. TC: Traffic Class. TE: Traffic Engineering. URO: UDP Return Object. 2.2. Reference Topology In the reference topology shown in Figure 1, the querier node R1 initiates a performance measurement probe query and the responder node R5 sends a probe response for the query message received. The probe response is typically sent to the querier node R1. The nodes R1 and R5 may be directly connected via a link enabled with Segment Routing or there exists a Point-to-Point (P2P) SR Policy [I-D.spring-segment-routing-policy] on node R1 with destination to node R5. In case of Point-to-Multipoint (P2MP), SR Policy originating from source node R1 may terminate on multiple destination leaf nodes [I-D.spring-sr-p2mp-policy]. +-------+ Query +-------+ | | - - - - - - - - - ->| | | R1 |---------------------| R5 | | |<- - - - - - - - - - | | +-------+ Response +-------+ Gandhi, et al. Expires August 18, 2019 [Page 4] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 Figure 1: Reference Topology Both delay and loss performance measurement is performed in-band for the traffic traversing between node R1 and node R5. One-way delay and two-way delay measurements are defined in Section 2.4 of [RFC6374]. Transmit and Receive packet loss measurements are defined in Section 2.2 and Section 2.6 of [RFC6374]. One-way loss measurement provides receive packet loss whereas two-way loss measurement provides both transmit and receive packet loss. 2.3. In-band Probe Messages For both Delay and Loss measurements for links and SR Policies, no PM session is created on the responder node. The probe messages for Delay measurement are sent in-band by the querier node to measure the delay experienced by the actual traffic flowing on the links and SR Policies. For Loss measurement, in-band probe messages are used to collect the traffic counter for the incoming link or incoming SID on which the probe query message is received at the responder node R5 (as it has no PM session state present on the node). 3. Probe Query and Response Packets 3.1. Probe Packet Header for SR-MPLS Policies As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and response messages flow over the MPLS Generic Associated Channel (G- ACh). A probe packet for an end-to-end measurement for SR Policy contains SR-MPLS label stack [I-D.spring-segment-routing-policy], with the G-ACh Label (GAL) at the bottom of the stack. The GAL is followed by an Associated Channel Header (ACH), which identifies the message type and the message payload following the ACH as shown in Figure 2. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label(0) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label(n) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | GAL (value 13) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|Version| Reserved | GAL Channel Type | Gandhi, et al. Expires August 18, 2019 [Page 5] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Probe Packet Header for an End-to-end SR-MPLS Policy The SR-MPLS label stack can be empty to indicate Implicit NULL label case. 3.2. Probe Packet Header for SR-MPLS Links As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and response messages flow over the MPLS Generic Associated Channel (G-ACh). A probe packet for SR-MPLS links contains G-ACh Label (GAL). The GAL is followed by an Associated Channel Header (ACH), which identifies the message type, and the message payload following the ACH as shown in Figure 3. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | GAL (value 13) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|Version| Reserved | GAL Channel Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Probe Packet Header for an SR-MPLS Link 3.3. Probe Response Message for SR-MPLS Links and Policies 3.3.1. One-way Measurement Probe Response Message For one-way performance measurement [RFC7679], the PM querier node can receive "out-of-band" probe replies by properly setting the UDP Return Object (URO) TLV in the probe query message. The URO TLV (Type=131) is defined in [RFC7876] and includes the UDP-Destination-Port and IP Address. In particular, if the querier sets its own IP address in the URO TLV, the probe response is sent back by the responder node to the querier node. In addition, the "control code" in the probe query message is set to "out-of-band response requested". The "Source Address" TLV (Type 130), and "Return Address" TLV (Type 1), if present in the probe query message, are not used to send probe response message. 3.3.2. Two-way Measurement Probe Response Message For two-way performance measurement [RFC6374], when using a bidirectional channel, the probe response message is sent back to the querier node in-band on the reverse direction SR Link or SR Policy Gandhi, et al. Expires August 18, 2019 [Page 6] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 using a message with format similar to their probe query message. In this case, the "control code" in the probe query message is set to "in-band response requested". A Path Segment Identifier [I-D.spring-mpls-path-segment] of the forward SR Policy can be used to find the reverse SR Policy and to send back the probe response message. 4. Performance Delay Measurement 4.1. Delay Measurement Message Format As defined in [RFC6374], MPLS DM probe query and response messages use Associated Channel Header (ACH) (value 0x000C for delay measurement) [RFC6374], which identifies the message type, and the message payload following the ACH. For both SR links and end-to-end measurement for SR Policies, the same MPLS DM ACH value is used. The DM message payload as defined in Section 3.2 of [RFC6374] is used for SR-MPLS delay measurement, for both SR links and end-to-end SR Policies. 4.2. Timestamps The Section 3.4 of [RFC6374] defines timestamp format that can be used for delay measurement. The IEEE 1588 Precision Time Protocol (PTP) timestamp format [IEEE1588] is used by default as described in Appendix A of [RFC6374], but it may require hardware support. As an alternative, Network Time Protocol (NTP) timestamp format can also be used [RFC6374]. Note that for one-way delay measurement, clock synchronization between the querier and responder nodes using the methods detailed in [RFC6374] is required. The two-way delay measurement does not require clock synchronization between the querier and responder nodes. 5. Performance Loss Measurement The LM protocol can perform two distinct kinds of loss measurement as described in Section 2.9.8 of [RFC6374]. o In inferred mode, LM will measure the loss of specially generated test messages in order to infer the approximate data plane loss level. Inferred mode LM provides only approximate loss accounting. Gandhi, et al. Expires August 18, 2019 [Page 7] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 o In direct mode, LM will directly measure data plane packet loss. Direct mode LM provides perfect loss accounting, but may require hardware support. For both of these modes of LM, Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] is used for accounting received traffic on the egress node of the SR-MPLS Policy. 5.1. Loss Measurement Message Format As defined in [RFC6374], MPLS LM probe query and response messages use Associated Channel Header (ACH) (value 0x000A for direct loss measurement or value 0x000B for inferred loss measurement), which identifies the message type, and the message payload following the ACH. For both SR links and end-to-end measurement for SR Policies, the same MPLS LM ACH value is used. The LM message payload as defined in Section 3.1 of [RFC6374] is used for SR-MPLS loss measurement, for both SR links and end-to-end SR Policies. 6. Performance Measurement for P2MP SR Policies The procedures for delay and loss measurement reviewed in this document for Point-to-Point (P2P) SR-MPLS Policies are also equally applicable to the Point-to-Multipoint (P2MP) SR Policies. The responder node adds the "Source Address" TLV (Type 130) [RFC6374] in the probe response message. This TLV allows the querier node to identify the responder nodes of the P2MP SR Policy. 7. ECMP for SR-MPLS Policies An SR Policy can have ECMPs between the source and transit nodes, between transit nodes and between transit and destination nodes. Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP paths via transit nodes part of that Anycast group. The PM messages using [RFC6374] can not traverse all ECMP paths to measure performance delay of all paths of an SR Policy. 8. SR Link Extended TE Metrics Advertisements The extended TE metrics for SR link delay and loss computed using the performance measurement procedures reviewed in this document can be advertised in the routing domain as follows: Gandhi, et al. Expires August 18, 2019 [Page 8] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 o For OSPF, ISIS, and BGP-LS, protocol extensions defined in [RFC7471], [RFC7810] [I-D.lsr-isis-rfc7810bis], and [I-D.idr-te-pm-bgp] are used, respectively for advertising the extended TE link metrics in the network. o The extended TE link delay metrics advertised are minimum-delay, maximum-delay, average-delay, and delay-variance for one-way. o The delay-variance metric is computed as specified in Section 4.2 of [RFC5481]. o The one-way delay metrics can be computed using two-way measurement by dividing the measured delay values by 2. o The extended TE link loss metric advertised is one-way percentage packet loss. 9. Security Considerations This document reviews the procedures for performance delay and loss measurement for SR-MPLS networks, for both links and end-to-end SR Policies using the mechanisms defined in [RFC6374]. This document does not introduce any additional security considerations other than those covered in [RFC6374], [RFC7471], [RFC7810], and [RFC7876]. 10. IANA Considerations This document does not require any IANA actions. 11. References 11.1. Normative References [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS networks', RFC 6374, September 2011. [RFC7876] Bryant, S., Sivabalan, S., and Soni, S., "UDP Return Path for Packet Loss and Delay Measurement for MPLS Networks", RFC 7876, July 2016. 11.2. Informative References [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems", March 2008. Gandhi, et al. Expires August 18, 2019 [Page 9] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, September 2006. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008. [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation Applicability Statement", RFC 5481, March 2009. [RFC7679] Almes, G., et al., "A One-Way Delay Metric for IP Performance Metrics (IPPM)', RFC 7679, January 2016. [RFC7471] Giacalone, S., et al., "OSPF Traffic Engineering (TE) Metric Extensions", RFC 7471, March 2015. [RFC7810] Previdi, S., et al., "IS-IS Traffic Engineering (TE) Metric Extensions", RFC 7810, May 2016. [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018, . [I-D.lsr-isis-rfc7810bis] Ginsberg, L., et al., "IS-IS Traffic Engineering (TE) Metric Extensions", draft-ietf-lsr-isis-rfc7810bis, work in progress. [I-D.idr-te-pm-bgp] Ginsberg, L. Ed., et al., "BGP-LS Advertisement of IGP Traffic Engineering Performance Metric Extensions", draft-ietf-idr-te-pm-bgp, work in progress. [I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment Routing Policy Architecture", draft-ietf-spring-segment-routing-policy, work in progress. [I-D.spring-sr-p2mp-policy] Voyer, D. Ed., et al., "SR Replication Policy for P2MP Service Delivery", draft-voyer-spring-sr-p2mp-policy, work in progress. [I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in MPLS Based Segment Routing Network", draft-cheng-spring-mpls-path-segment, work in progress. Gandhi, et al. Expires August 18, 2019 [Page 10] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 Acknowledgments The authors would like to thank Greg Mirsky for providing many useful comments and suggestions. Contributors Sagar Soni Cisco Systems, Inc. Email: sagsoni@cisco.com Patrick Khordoc Cisco Systems, Inc. Email: pkhordoc@cisco.com Zafar Ali Cisco Systems, Inc. Email: zali@cisco.com Authors' Addresses Rakesh Gandhi (editor) Cisco Systems, Inc. Canada Email: rgandhi@cisco.com Clarence Filsfils Cisco Systems, Inc. Email: cfilsfil@cisco.com Daniel Voyer Bell Canada Email: daniel.voyer@bell.ca Stefano Salsano Universita di Roma "Tor Vergata" Italy Email: stefano.salsano@uniroma2.it Gandhi, et al. Expires August 18, 2019 [Page 11] Internet-Draft RFC 6374 for SR-MPLS February 14, 2019 Pier Luigi Ventre CNIT Italy Email: pierluigi.ventre@cnit.it Mach(Guoyi) Chen Huawei Email: mach.chen@huawei.com Gandhi, et al. Expires August 18, 2019 [Page 12]