SPRING Working Group R. Gandhi, Ed. Internet-Draft C. Filsfils Intended Status: Standards Track S. Soni P. Khordoc Z. Ali Cisco Systems, Inc. D. Voyer D. Bernier Bell Canada S. Salsano Universita di Roma "Tor Vergata" P. L. Ventre CNIT D. Steinberg Steinberg Consulting March 19, 2018 UDP Path for In-band Performance Measurement for Segment Routing Networks draft-gandhi-spring-udp-pm-00.txt Abstract Segment Routing (SR) is applicable to both MPLS (SR-MPLS) and IPv6 (SRv6) data planes. This document specifies a procedure for using UDP path for sending and processing in-band Performance Measurement (PM) Probe query and response messages. The procedure uses RFC 6374 defined mechanisms for Delay and Loss performance measurement. The procedure defined is applicable to IPv4, IPv6, SR-MPLS and SRv6 data planes. This document also defines Return Path Segment List TLV for bidirectional performance measurement. 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 September 20, 2018 [Page 1] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 Copyright Notice Copyright (c) 2018 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 . . . . . . . . . . . . . . 4 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 3. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 5 3.1.1. Delay Measurement Query Message . . . . . . . . . . . 5 3.1.2. Loss Measurement Query Message . . . . . . . . . . . . 5 3.1.3. Probe Query Message for SR Links . . . . . . . . . . . 6 3.1.4. In-band Probe Query Message for SR Policy . . . . . . 6 3.1.4.1. In-band Probe Query Message for SR-MPLS Policy . . 6 3.1.4.2. In-band Probe Query Message for SRv6 Policy . . . 7 3.1.4.3. In-band Probe Query Message for Segment of SRv6 Policy . . . . . . . . . . . . . . . . . . . . . . 7 3.2. Probe Response Message . . . . . . . . . . . . . . . . . . 8 3.2.1. Probe Response Message for SR Links . . . . . . . . . 8 3.2.2. One-way Performance Measurement . . . . . . . . . . . 8 3.2.2.1. Probe Response Message to Controller . . . . . . . 9 3.3. Two-way Performance Measurement . . . . . . . . . . . . . 9 3.3.1. Return Path Segment List TLV . . . . . . . . . . . . . 9 3.3.2. In-band Probe Response Message for SR-MPLS Policy . . 10 3.3.3. In-band Probe Response Message for SRv6 Policy . . . . 10 3.4. ECMP Support . . . . . . . . . . . . . . . . . . . . . . . 11 4. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1. Normative References . . . . . . . . . . . . . . . . . . . 12 6.2. Informative References . . . . . . . . . . . . . . . . . . 12 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Gandhi, et al. Expires September 20, 2018 [Page 2] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 1. Introduction Segment Routing (SR) technology greatly simplifies network operations for Software Defined Networks (SDNs). SR is applicable to both Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) data planes. SR takes advantage of the Equal-Cost Multipath (ECMP) between source and destination nodes. SR Traffic Engineering (TE) Policies as defined in [I-D.spring-segment-routing-policy] are used to steer traffic through a specific, user-defined path using a stack of Segments. Built-in SR Performance Measurement (PM) is one of the essential requirements to provide Service Level Agreements (SLAs). [RFC6374] specifies protocol mechanisms to enable the efficient and accurate measurement of performance metrics in SR networks with MPLS data plane [I-D.spring-sr-mpls-pm]. However, [RFC6374] requires data plane to support Generic Associated Channel Label (GAL) and Generic Associated Channel (G-Ach), which may be not be supported on all nodes in the network. 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. These protocols rely on control channel signaling to establish a connection over an UDP path to bootstrap PM sessions, and they are not compatible with the mechanisms defined in [RFC6374]. Furthermore, these protocols do not define handling for ECMP forwarding paths in SR networks (e.g. using 128/7 addresses defined in [RFC8029]). [RFC7876] specifies the procedures to be used when sending and processing out-of-band performance measurement Responses over an UDP return path and when receiving performance measurement queries using RFC 6374. [RFC7876] can be used to send out-of-band PM Responses in both SR-MPLS and SRv6 networks. For SR Policies, there is a need to specify a return path in the form of a Segment List in PM query messages for bidirectional measurements. Exiting protocols (e.g. TWAMP, RFC 6374, etc.) do not have such mechanisms to specify return path in the PM query messages. This document specifies a procedure for using UDP path for sending and processing in-band PM Probe query and response messages. The procedure uses RFC 6374 defined mechanisms for Delay and Loss PM and unless otherwise specified, the procedures from RFC 6374 are not modified. The procedure defined is applicable to IPv4, IPv6, SR-MPLS and SRv6 data planes. The procedure does not require to bootstrap PM sessions and can be used for both SR links and SR Policies. This document also defines Return Path Segment List TLV for bidirectional Gandhi, et al. Expires September 20, 2018 [Page 3] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 performance measurement. 2. Conventions Used in This Document 2.1. Requirements 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] [RFC8174]. 2.2. Abbreviations ACH: Associated Channel Header. DFLag: Data Format Flag. DM: Delay Measurement. G-ACh: Generic Associated Channel (G-ACh). GAL: Generic Associated Channel (G-ACh) Label. LM: Loss Measurement. MPLS: Multiprotocol Label Switching. PM: Performance Measurement. PTP: Precision Time Protocol. RPSL: Return Path Segment List. SID: Segment ID. SR: Segment Routing. SRv6: Segment Routing with IPv6 data plane. URO: UDP Return Object. 3. Probe Messages In the reference topology shown in the following Figure, node R1 initiates a query for performance measurement and node R5 sends a response for the query message received. The response may be sent to the querier node R1 or to a controller node R100. The nodes R1 and Gandhi, et al. Expires September 20, 2018 [Page 4] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 R5 may be directly connected via a link enabled with segment routing or there exists an SR Policy [I-D.spring-segment-routing-policy] on node R1 with destination to node R5. Both delay and loss performance measurement is performed for the traffic traversing between node R1 and node R5. ------ |R100| ------ ^ | Response (optional) | +-------+ Query +-------+ | | - - - - - - - - - ->| | | R1 |---------------------| R5 | | |<- - - - - - - - - - | | +-------+ Response +-------+ Reference Topology 3.1. Probe Query Message 3.1.1. Delay Measurement Query Message The message content for Delay Measurement probe query message using UDP header [RFC768] is shown in Figure 1. +---------------------------------------------------------------+ | IP Header | . Source IP Address = Sender IP4 or IPv6 Address . . Destination IP Address = Responder IPv4 or IPv6 Address . . Protocol = UDP . . IP TTL = 1 . . Router Alert Option Not Set . . . +---------------------------------------------------------------+ | UDP Header | . Source Port = As chosen by Sender . . Destination Port = TBA1 by IANA . . . +---------------------------------------------------------------+ | Message as specified in RFC 6374 Section 3.2 | . . +---------------------------------------------------------------+ Figure 1: DM Probe Query Message 3.1.2. Loss Measurement Query Message Gandhi, et al. Expires September 20, 2018 [Page 5] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 The message content for loss measurement probe query message using UDP header is shown in Figure 2. +---------------------------------------------------------------+ | IP Header | . Source IP Address = Sender IPv4 or IPv6 Address . . Destination IP Address = Responder IPv4 or IPv6 Address . . Protocol = UDP . . IP TTL = 1 . . Router Alert Option Not Set . . . +---------------------------------------------------------------+ | UDP Header | . Source Port = As chosen by Sender . . Destination Port = TBA2 by IANA . . . +---------------------------------------------------------------+ | Message as specified in RFC 6374 Section 3.1 | . . +---------------------------------------------------------------+ Figure 2: LM Probe Query Message An LM message carries Data Format Flags (DFlags) as defined in [RFC6374]. New Flag is defined in this document for Color (C) in the DFlags field as follows. +-+-+-+-+ |X|B|C|0| +-+-+-+-+ Data Format Flags The Flag C indicates the Color of the counters in the LM message [RFC8321]. 3.1.3. Probe Query Message for SR Links The query message defined in Figure 1 can be used for delay measurement and Figure 2 for loss measurement for SR links. 3.1.4. In-band Probe Query Message for SR Policy 3.1.4.1. In-band Probe Query Message for SR-MPLS Policy The message content for in-band probe query message using UDP header for an SR-MPLS Policy is shown in Figure 3. Gandhi, et al. Expires September 20, 2018 [Page 6] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List[0] | EXP |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List[n] | EXP |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 1 for DM or Figure 2 for LM | . . +---------------------------------------------------------------+ Figure 3: In-band Probe Query Message for SR-MPLS Policy The Segment List can be empty to indicate Implicit NULL case. 3.1.4.2. In-band Probe Query Message for SRv6 Policy The in-band probe query messages using UDP message for an SRv6 Policy is sent using SRH and Segment List as defined in [I-D.6man-segment-routing-header] as shown in Figure 4. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRH | . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 1 for DM or Figure 2 for LM | . . +---------------------------------------------------------------+ Figure 4: In-band Probe Query Message for SRv6 Policy 3.1.4.3. In-band Probe Query Message for Segment of SRv6 Policy In order to measure performance of a segment of an SRv6 Policy, i.e. from the ingress node of the SRv6 Policy to one of the transit nodes of the SRv6 Policy, SID function END.OTP, as described in the pseudo code in [I-D.spring-srv6-network-programming] can be used. Specifically, SID function END.OTP is inserted just before the target SID in the SRH to punt probe messages on the target node, as shown in Figure 5. 0 1 2 3 Gandhi, et al. Expires September 20, 2018 [Page 7] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRH | . END.OTP Before Target SID . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 1 for DM or Figure 2 for LM | . . +---------------------------------------------------------------+ Figure 5: In-band Probe Query Message for Segment of SRv6 Policy 3.2. Probe Response Message The message format for probe response message using UDP header is shown in Figure 6. +---------------------------------------------------------------+ | IP Header | . Source IP Address = Responder IPv4 or IPv6 Address . . Destination IP Address = Source IP Address from Query . . Protocol = UDP . . Router Alert Option Not Set . . . +---------------------------------------------------------------+ | UDP Header | . Source Port = As chosen by Responder . . Destination Port = Source Port from Query . . . +---------------------------------------------------------------+ | Message as specified in RFC 6374 Section 3.2 for DM, or | . Message as specified in RFC 6374 Section 3.1 for LM . . . +---------------------------------------------------------------+ Figure 6: Probe Response Message 3.2.1. Probe Response Message for SR Links The response message defined in Figure 6 can be used for SR links. 3.2.2. One-way Performance Measurement The PM response message defined in Section 3.2 can be used for one- way delay and loss measurement. Note that for one-way delay measurement, Clock synchronization between the querier and responder nodes using methods detailed in Gandhi, et al. Expires September 20, 2018 [Page 8] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 [RFC6374] such as IEEE 1588 Precision Time Protocol (PTP) [IEEE1588], is required. Two-way delay measurement does not require clock to be synchronized between the querier and responder nodes. 3.2.2.1. Probe Response Message to Controller The PM querier node can receive out-of-band probe responses by properly setting the UDP Return Object (URO) TLV in the probe message. The URO TLV (Type 131) is defined in [RFC7876] and includes the UDP-Destination-Port and IP Address. If the querier node requires the probe response to be sent to the controller, it sets the IP address of the controller in the Address field of the URO TLV of the PM probe query message. 3.3. Two-way Performance Measurement For two-way performance measurement [RFC6374], when using a bidirectional channel, the probe response message is sent back to the querier node using a message similar to the probe query message. In this case, the "control code" in the probe message is set to "in-band response requested". 3.3.1. Return Path Segment List TLV For bidirectional measurement, the responder node needs to send the response message on a specific reverse SR path. The querier node can request in the probe query message to the responder node to send a response back on a given reverse path (e.g. co-routed path). [RFC6374] defines DM and LM Probe query messages that include one or more optional TLVs. New TLV Types are defined in this document for Return Path Segment List (RPSL). The format of the RPSL is shown in Figure 9: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RPSL Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List[0] | . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List[n] | . . Gandhi, et al. Expires September 20, 2018 [Page 9] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9: Return Path Segment List TLV The Segment in Segment List may be SR-MPLS Label (Type TBA3), SRv6 Segment (Type TBA4), SR-MPLS Binding SID of the Reverse SR Policy (Type TBA5) or SRv6 Binding SID of the Reverse SR Policy (Type TBA6). The Segment List[0] may be used by the responder node to compute the next-hop address and outgoing interface for the probe response message. The PM querier MUST only insert one RPSL TLV in the probe query message and the responder node MUST only process the first RPSL TLV in the probe query message and ignore the other RPSL TLVs if present. 3.3.2. In-band Probe Response Message for SR-MPLS Policy The message format for in-band probe response message using UDP header for an SR-MPLS Policy is shown in Figure 7. The SR-MPLS label stack in the packet header is built using the segments received in the RPSL TLV in the probe query message. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List[0] | EXP |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List[n] | EXP |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 6 | . IP TTL = 1 . . . +---------------------------------------------------------------+ Figure 7: In-band Probe Response Message for SR-MPLS Policy 3.3.3. In-band Probe Response Message for SRv6 Policy For SRv6 Policy, the SRv6 segment list in the message SRH is built using the SRv6 segments received in the RPSL TLV in the probe query message as shown in Figure 8. 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 Gandhi, et al. Expires September 20, 2018 [Page 10] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRH | . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 6 | . IP TTL = 1 . . . +---------------------------------------------------------------+ Figure 8: In-band Probe Response Message for SRv6 Policy 3.4. ECMP Support Equal-Cost Multipath (ECMP) mechanisms described in [RFC8029] are equally applicable to the performance measurement procedure defined in this document. Responder IPv4 addresses in the range of 127/8 [RFC8029] can be used in PM probe query messages to take advantage of the hashing function in the forwarding plane. This allows the PM query messages to traverse different ECMP forwarding paths of an SR-MPLS Policy. This is used by the querier node to measure the performance of an individual ECMP forwarding path of the SR Policy. Optionally, the querier node may use different source-address and source-port to influence the ECMP forwarding path taken by the PM query message. Entropy label can also be used to take advantage of the hashing function in the forwarding plane to measure performance of various ECMP forwarding paths of an SR-MPLS Policy. ECMP for SRv6 Policies to be added in a future revision of this document. 4. Security Considerations TBA. 5. IANA Considerations IANA is requested to allocate an UDP port (TBA1) for Performance Delay Measurement and an UDP port (TBA2) for Performance Loss Measurement. IANA is also requested to allocate values for the following Return Path Segment List TLVs for RFC 6374 PM Query messages: o TYPE TBA3: SR-MPLS Segment List Gandhi, et al. Expires September 20, 2018 [Page 11] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 o TYPE TBA4: SRv6 Segment List o TYPE TBA5: SR-MPLS Binding SID of the Reverse SR Policy o TYPE TBA6: SRv6 Binding SID of the Reverse SR Policy 6. References 6.1. Normative References [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems", March 2008. [RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August 1980. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [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. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", RFC 8174, May 2017. 6.2. Informative References [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protoco (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. [RFC8029] Kompella, K., Swallow, G., Pignataro, C., Kumar, N., Aldrin, S. and M. Chen, "Detecting Multiprotocol Label Switched (MPLS) Data-Plane Failures", RFC 8029, March 2017. [RFC8321] Fioccola, G. Ed., "Alternate-Marking Method for Passive and Hybrid Performance Monitoring", RFC 8321, January Gandhi, et al. Expires September 20, 2018 [Page 12] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 2018. [I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment Routing Policy for Traffic Engineering", draft-filsfils-spring-segment-routing-policy, work in progress. [I-D.6man-segment-routing-header] Previdi, S., Filsfils, et al., "IPv6 Segment Routing Header (SRH)", draft-ietf-6man-segment-routing-header, work in progress. [I-D.spring-srv6-network-programming] C. Filsfils, et al., "SRv6 Network Programming", draft-filsfils-spring-srv6-network-programming, work in progress. [I-D.spring-sr-mpls-pm] Filsfils, C., et al. "Performance Measurement in Segment Routing Networks with MPLS Data Plane", draft-gandhi-spring-sr-mpls-pm, work in progress. Gandhi, et al. Expires September 20, 2018 [Page 13] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 Acknowledgments The authors would like to thank Faisal Iqbal, Nagendra Kumar and Carlos Pignataro for the earlier discussions on SRv6 Performance Measurement using TLVs in SRH. Contributors To be added. Authors' Addresses Rakesh Gandhi (editor) Cisco Systems, Inc. Canada Email: rgandhi@cisco.com Clarence Filsfils Cisco Systems, Inc. Email: cfilsfil@cisco.com 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 Daniel Voyer Bell Canada Email: daniel.voyer@bell.ca Daniel Bernier Bell Canada Email: daniel.bernier@bell.ca Gandhi, et al. Expires September 20, 2018 [Page 14] Internet-Draft UDP Path for PM for Segment Routing March 19, 2018 Stefano Salsano Universita di Roma "Tor Vergata" Italy Email: stefano.salsano@uniroma2.it Pier Luigi Ventre CNIT Italy Email: pierluigi.ventre@cnit.it Dirk Steinberg Steinberg Consulting Germany Email: dws@dirksteinberg.de Gandhi, et al. Expires September 20, 2018 [Page 15]