SPRING Working Group R. Gandhi, Ed. Internet-Draft C. Filsfils Intended Status: Standards Track Cisco Systems, Inc. Expires: April 6, 2020 D. Voyer Bell Canada S. Salsano Universita di Roma "Tor Vergata" M. Chen Huawei October 4, 2019 Performance Measurement Using UDP Path for Segment Routing Networks draft-gandhi-spring-rfc6374-srpm-udp-02 Abstract Segment Routing (SR) leverages the source routing paradigm. Segment Routing (SR) is applicable to both Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) data planes. This document specifies procedures for using UDP path for sending and processing probe query and response messages for Performance Measurement (PM). The procedure uses the mechanisms defined in RFC 6374 for Performance Delay and Loss Measurement. The procedure specified is applicable to SR-MPLS and SRv6 data planes for both links and end-to-end measurement for SR Policies. 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." Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the Gandhi, et al. Expires April 6, 2020 [Page 1] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 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 2.3. Reference Topology . . . . . . . . . . . . . . . . . . . . 5 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Example Provisioning Model . . . . . . . . . . . . . . . . 7 4. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 7 4.1.1. Delay Measurement Probe Query Message . . . . . . . . 8 4.1.2. Loss Measurement Probe Query Message . . . . . . . . . 8 4.1.3. Probe Query for SR Links . . . . . . . . . . . . . . . 9 4.1.4. Probe Query for End-to-end Measurement for SR Policy . 9 4.1.4.1. Probe Query Message for SR-MPLS Policy . . . . . . 9 4.1.4.2. Probe Query Message for SRv6 Policy . . . . . . . 10 4.2. Probe Response Message . . . . . . . . . . . . . . . . . . 11 4.2.1. One-way Measurement Mode . . . . . . . . . . . . . . . 12 4.2.1.1. SR Links and End-to-end Measurement for SR Policy . . . . . . . . . . . . . . . . . . . . . . 12 4.2.1.2. Probe Response Message to Controller . . . . . . . 12 4.2.2. Two-way Measurement Mode . . . . . . . . . . . . . . . 12 4.2.2.1. SR Links . . . . . . . . . . . . . . . . . . . . . 12 4.2.2.2. End-to-end Measurement for SR Policy . . . . . . . 12 4.2.2.3. Return Path TLV . . . . . . . . . . . . . . . . . 13 4.2.2.4. Probe Response Message for SR-MPLS Policy . . . . 13 4.2.2.5. Probe Response Message for SRv6 Policy . . . . . . 14 4.2.3. Loopback Measurement Mode . . . . . . . . . . . . . . 14 5. Performance Measurement for P2MP SR Policies . . . . . . . . . 14 6. ECMP Support for SR Policies . . . . . . . . . . . . . . . . . 15 7. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . . 15 7.1. Sequence Number TLV in Unauthenticated Mode . . . . . . . 16 7.2. Sequence Number TLV in Authenticated Mode . . . . . . . . 16 8. Additional Message Processing Rules . . . . . . . . . . . . . 18 Gandhi, et al. Expires April 6, 2020 [Page 2] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 8.1. TTL Value . . . . . . . . . . . . . . . . . . . . . . . . 18 8.2. Router Alert Option . . . . . . . . . . . . . . . . . . . 18 8.3. UDP Checksum . . . . . . . . . . . . . . . . . . . . . . . 18 9. Security Considerations . . . . . . . . . . . . . . . . . . . 18 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 11.1. Normative References . . . . . . . . . . . . . . . . . . 19 11.2. Informative References . . . . . . . . . . . . . . . . . 20 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 23 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23 1. Introduction Segment Routing (SR) leverages the source routing paradigm and 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 Multipaths (ECMPs) between source and transit nodes, between transit nodes and between transit and destination nodes. SR Policies as defined in [I-D.spring-segment-routing-policy] are used to steer traffic through a specific, user-defined paths using a stack of Segments. Built-in SR Performance Measurement (PM) is one of the essential requirements to provide Service Level Agreements (SLAs). 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 test-channel over an UDP path. These protocols lack support for IEEE 1588 timestamp [IEEE1588] format and direct-mode Loss Measurement (LM), which are required in SR networks [RFC6374]. The Simple Two-way Active Measurement Protocol (STAMP) [I-D.ippm-stamp] alleviates the control-channel signaling by using configuration data model to provision a test-channel. In addition, the STAMP supports IEEE 1588 timestamp format for Delay Measurement (DM). The TWAMP Light [Appendix I in RFC5357] [BBF.TR-390] provides simplified mechanisms for active performance measurement in Customer IP networks by provisioning UDP paths and eliminates the control-channel signaling. [Y1731] specifies the mechanisms to carry OAM messages specifically for Ethernet networks that include Ethernet Frame Delay and Loss measurements. [RFC6374] specifies protocol mechanisms to enable the efficient and accurate measurement of performance metrics and can be used in SR networks with MPLS data plane [I-D.spring-rfc6374-srpm-mpls]. Gandhi, et al. Expires April 6, 2020 [Page 3] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 [RFC6374] addresses the limitations of the IP based performance measurement protocols as specified in Section 1 of [RFC6374]. The [RFC6374] requires data plane to support MPLS Generic Associated Channel Label (GAL) and Generic Associated Channel (G-Ach), which may not be supported on all nodes in the network. [RFC7876] specifies the procedures to be used when sending and processing out-of-band performance measurement probe response messages over an UDP return path for RFC 6374 based probe queries. [RFC7876] can be used to send out-of-band PM probe responses in both SR-MPLS and SRv6 networks for one-way performance measurement. For SR Policies, there are ECMPs between the source and transit nodes, between transit nodes and between transit and destination nodes. Existing PM protocols (e.g. RFC 6374) do not define handling for ECMP forwarding paths in SR networks. For two-way measurements for SR Policies, there is a need to specify a return path in the form of a Segment List in PM probe query messages without requiring any SR Policy state on the destination node. Existing protocols do not have such mechanisms to specify return path in the PM probe query messages. This document specifies a procedure for sending and processing probe query and response messages using UDP paths for Performance Measurement in SR networks. The procedure uses RFC 6374 defined mechanisms for Performance Delay and Loss Measurement and unless otherwise specified, the procedures from RFC 6374 are not modified. The procedure specified is applicable to both SR-MPLS and SRv6 data planes. The procedure can be used for both SR links and end-to-end performance measurement for SR Policies and it does not require to bootstrap PM sessions. 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] when, and only when, they appear in all capitals, as shown here. 2.2. Abbreviations ACH: Associated Channel Header. BSID: Binding Segment ID. Gandhi, et al. Expires April 6, 2020 [Page 4] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 DFLag: Data Format Flag. DM: Delay Measurement. ECMP: Equal Cost Multi-Path. G-ACh: Generic Associated Channel (G-ACh). GAL: Generic Associated Channel (G-ACh) Label. LM: Loss Measurement. MPLS: Multiprotocol Label Switching. NTP: Network Time Protocol. OWAMP: One-Way Active Measurement 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. SRv6: Segment Routing with IPv6 data plane. STAMP: Simple Two-way Active Measurement Protocol. TC: Traffic Class. TWAMP: Two-Way Active Measurement Protocol. URO: UDP Return Object. 2.3. Reference Topology In the reference topology shown below, the sender node R1 initiates a probe query for performance measurement and the responder node R5 sends a probe response for the query message received. The probe Gandhi, et al. Expires April 6, 2020 [Page 5] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 response may be sent to the sender node R1 or to a controller node R100. 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]. ------ |R100| ------ ^ | Response | +-------+ Query +-------+ | | - - - - - - - - - ->| | | R1 |---------------------| R5 | | |<- - - - - - - - - - | | +-------+ Response +-------+ Sender Responder Reference Topology 3. Overview One-way delay and two-way delay measurement procedure defined in Section 2.4 of [RFC6374] are used. Transmit and Receive packet loss measurement procedures defined in Section 2.2 and Section 2.6 of [RFC6374] are used. One-way loss measurement provides receive packet loss whereas two-way loss measurement provides both transmit and receive packet loss. Separate UDP destination port numbers are user-configured for delay and loss measurements from the range specified in [I-D.ippm-stamp]. The sender uses the destination UDP port number following the guidelines specified in Section 6 in [RFC6335]. For both links and end-to-end SR Policies, no PM session for delay or loss measurement is created on the responder node R5 [RFC6374]. For Performance Measurement, probe query and response messages are sent as following: o For Delay Measurement, the probe messages are sent on the congruent path of the data traffic by the sender node, and are used to measure the delay experienced by the actual data traffic flowing on the links and SR Policies. o For Loss Measurement, the probe messages are sent on the congruent Gandhi, et al. Expires April 6, 2020 [Page 6] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 path of the data traffic by the sender node, and are used to collect the receive traffic counters for the incoming link or incoming SID where the probe query messages are received at the responder node (incoming link or incoming SID needed since the responder node does not have PM session state present). The In-Situ Operations, Administration, and Maintenance (IOAM) mechanisms for SR-MPLS defined in [I-D.spring-ioam-sr-mpls] and for SRv6 defined in [I-D.spring-ioam-srv6] are used to carry PM information such as timestamp in-band as part of the data packets, and are outside the scope of this document. 3.1. Example Provisioning Model An example of a provisioning model and typical measurement parameters for performance delay and loss measurements is shown in the following Figure: +------------+ | Controller | +------------+ Measurement Protocol / \ Measurement Protocol Destination UDP Port / \ Destination UDP port Measurement Type / \ Measurement Type Delay/Loss / \ Delay/Loss Authentication Mode & Key / \ Authentication Mode & Key Timestamp Format / \ Delay Measurement Mode / \ Loss Measurement Mode / \ v v +-------+ +-------+ | | | | | R1 |-----------| R5 | | | | | +-------+ +-------+ Sender Responder Provisioning Model The mechanisms used to provision the sender and responder nodes are outside the scope of this document. 4. Probe Messages 4.1. Probe Query Message Gandhi, et al. Expires April 6, 2020 [Page 7] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 In this document, UDP path is used for Delay and Loss measurements for SR links and end-to-end SR Policies for the probe messages defined in [RFC6374]. The user-configured destination UDP ports (separate UDP ports for different delay and loss message formats) are used for identifying the PM probe packets. 4.1.1. Delay Measurement Probe Query Message The message content for Delay Measurement for probe query message using UDP header [RFC768] is shown in Figure 1. The DM probe query message is sent with user-configured Destination UDP port number for DM. The Destination UDP port can also be used as Source port for two-way delay measurement, since the message has a flag to distinguish between query and response. The DM probe query message contains the payload format for delay measurement defined in Section 3.2 of [RFC6374]. +---------------------------------------------------------------+ | IP Header | . Source IP Address = Sender IPv4 or IPv6 Address . . Destination IP Address = Responder IPv4 or IPv6 Address . . Protocol = UDP . . . +---------------------------------------------------------------+ | UDP Header | . Source Port = As chosen by Sender . . Destination Port = User-configured Port for Delay Measurement. . . +---------------------------------------------------------------+ | Payload = Message as specified in Section 3.2 of RFC 6374 | . . +---------------------------------------------------------------+ Figure 1: DM Probe Query Message It is recommended to use the IEEE 1588v2 Precision Time Protocol (PTP) truncated 64-bit timestamp format [IEEE1588] as a default format as specified in Appendix A of [RFC6374], preferred with hardware support. As an alternative, Network Time Protocol (NTP) timestamp format can also be used [RFC6374]. 4.1.2. Loss Measurement Probe Query Message The message content for Loss measurement probe query message using UDP header [RFC768] is shown in Figure 2. As shown, the LM probe query message is sent with user-configured Destination UDP port number for LM. Separate Destination UDP ports are used for direct-mode and inferred-mode loss measurements. The Destination UDP port can also be used as Source port for two-way loss measurement, Gandhi, et al. Expires April 6, 2020 [Page 8] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 since the message has a flag to distinguish between query and response. The LM probe query message contains the payload format for loss measurement defined in Section 3.1 of [RFC6374]. +---------------------------------------------------------------+ | IP Header | . Source IP Address = Sender IPv4 or IPv6 Address . . Destination IP Address = Responder IPv4 or IPv6 Address . . Protocol = UDP . . . +---------------------------------------------------------------+ | UDP Header | . Source Port = As chosen by Sender . . Destination Port = User-configured Port for Loss Measurement . . . +---------------------------------------------------------------+ | Payload = Message as specified in Section 3.1 of RFC 6374 | . . +---------------------------------------------------------------+ Figure 2: LM Probe Query Message The Loss Measurement using Alternate-Marking method defined in [RFC8321] requires to identify the Block Number (or color) of the traffic counters carried by the probe query and response messages. Block Number TLV defined in [I-D.spring-rfc6374-srpm-mpls] is used to carry Block Number for the counters in the probe query and response messages for loss measurement. 4.1.3. Probe Query for SR Links The probe query message as defined in Figure 1 is sent on the congruent path of the data traffic for performance Delay measurement. Similarly, the probe query message as defined in Figure 2 is sent on the congruent path of the data traffic for performance Loss measurement. 4.1.4. Probe Query for End-to-end Measurement for SR Policy The performance delay and loss measurement for segment routing is applicable to both SR-MPLS and SRv6 Policies. 4.1.4.1. Probe Query Message for SR-MPLS Policy The probe query message for end-to-end performance measurement of an SR-MPLS Policy is sent using its SR-MPLS header containing the MPLS Gandhi, et al. Expires April 6, 2020 [Page 9] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 segment list 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List(1) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List(n) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PSID | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 1 for DM or Figure 2 for LM | . . +---------------------------------------------------------------+ Figure 3: Probe Query Message for SR-MPLS Policy The Segment List (SL) can be empty to indicate Implicit NULL label case for a single-hop SR Policy. The Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of the SR-MPLS Policy is used for accounting received traffic on the egress node for loss measurement. The PSID is not added for end-to- end SR Policy delay measurement. 4.1.4.2. Probe Query Message for SRv6 Policy An SRv6 Policy is setup using the SRv6 Segment Routing Header (SRH) and a Segment List as defined in [I-D.6man-segment-routing-header]. The probe query messages using UDP header for end-to-end performance measurement of an SRv6 Policy is sent using its SRv6 Segment Routing Header (SRH) and Segment List as shown in Figure 4. +---------------------------------------------------------------+ | SRH | . END.OTP (DM) or END.OP (LM) with Target SRv6 SID . . . +---------------------------------------------------------------+ | Message as shown in Figure 1 for DM or Figure 2 for LM | . (Using IPv6 Source and Destination Addresses) . . . +---------------------------------------------------------------+ Figure 4: Probe Query Message for SRv6 Policy Gandhi, et al. Expires April 6, 2020 [Page 10] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 For delay measurement of SRv6 Policy using SRH, END function END.OTP [I-D.6man-srv6-oam] is used with the target SRv6 SID to punt probe messages on the target node, as shown in Figure 4. Similarly, for loss measurement of SRv6 Policy, END function END.OP [I-D.6man-srv6-oam] is used with target SRv6 SID to punt probe messages on the target node. 4.2. Probe Response Message When the received probe query message does not contain any UDP Return Object (URO) TLV [RFC7876], the probe response message is sent using the IP/UDP information from the received probe query message. The content of the probe response message is shown in Figure 5. +---------------------------------------------------------------+ | 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 Section 3.2 of RFC 6374 for DM, or | . Message as specified in Section 3.1 of RFC 6374 for LM . . . +---------------------------------------------------------------+ Figure 5: Probe Response Message When the received probe query message contains UDP Return Object (URO) TLV [RFC7876], the probe response message uses the IP/UDP information from the URO in the probe query message. The content of the probe response message is shown in Figure 6. +---------------------------------------------------------------+ | IP Header | . Source IP Address = Responder IPv4 or IPv6 Address . . Destination IP Address = URO.Address . . Protocol = UDP . . Router Alert Option Not Set . . . +---------------------------------------------------------------+ | UDP Header | Gandhi, et al. Expires April 6, 2020 [Page 11] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 . Source Port = As chosen by Responder . . Destination Port = URO.UDP-Destination-Port . . . +---------------------------------------------------------------+ | Message as specified in Section 3.2 of RFC 6374 for DM, or | . Message as specified in Section 3.1 of RFC 6374 for LM . . . +---------------------------------------------------------------+ Figure 6: Probe Response Message Using URO from Probe Query 4.2.1. One-way Measurement Mode 4.2.1.1. SR Links and End-to-end Measurement for SR Policy In one-way performance measurement mode, the probe response message as defined in Figure 5 or Figure 6 is sent out-of-band to the sender node, for both SR links and SR Policies. The PM sender node can receive probe response message back by setting its own IP address as Source Address of the header or by adding URO TLV in the probe query message and setting its own IP address in the IP Address in the URO TLV (Type=131) [RFC7876]. 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. 4.2.1.2. Probe Response Message to Controller As shown in the Reference Topology, if the sender node requires the probe response message to be sent to the controller R100, it adds URO TLV in the probe query message and sets the IP address of R100 in the IP Address field and user-configured UDP port for DM and for LM in the UDP-Destination-Port field of the URO TLV (Type=131) [RFC7876]. 4.2.2. Two-way Measurement Mode 4.2.2.1. SR Links In two-way performance measurement mode, when using a bidirectional link, the probe response message as defined in Figure 5 or Figure 6 is sent back on the congruent path of the data traffic to the sender node for SR links. In this case, the "control code" in the probe query message is set to "in-band response requested" [RFC6374]. 4.2.2.2. End-to-end Measurement for SR Policy Gandhi, et al. Expires April 6, 2020 [Page 12] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 In two-way performance measurement mode, when using a bidirectional path, the probe response message is sent back on the congruent path of the data traffic to the sender node for end-to-end measurement of SR Policies. In this case, the "control code" in the probe query message is set to "in-band response requested" [RFC6374]. 4.2.2.3. Return Path TLV For two-way performance measurement, the sender node can request the responder node to send a response message back on a given reverse path (e.g. co-routed path for two-way measurement). Return Path TLV defined in [I-D.spring-rfc6374-srpm-mpls] is used to carry reverse SR path information as part of the payload of the probe query message. Additional Segment List Sub-TLVs are defined in this document for the Return Path TLV for the following Types: o Type (value TBD4): SRv6 Segment List of the Reverse SR Path o Type (value TBD5): SRv6 Binding SID [I-D.pce-binding-label-sid] of the Reverse SR Policy 4.2.2.4. Probe Response Message for SR-MPLS Policy The message content for sending probe response message on the congruent path of the data traffic for two-way end-to-end performance measurement of an SR-MPLS Policy is shown in Figure 8. The SR-MPLS label stack in the packet header is built using the Segment List received in the Return Path 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(1) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Segment List(n) | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message as shown in Figure 5 or 6 | . . +---------------------------------------------------------------+ Figure 8: Probe Response Message for SR-MPLS Policy Gandhi, et al. Expires April 6, 2020 [Page 13] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 The Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of the forward SR-MPLS Policy can be used to find the reverse SR-MPLS Policy to send the probe response message for two-way measurement in the absence of Return Path TLV defined in the following Section. 4.2.2.5. Probe Response Message for SRv6 Policy The message content for sending probe response message on the congruent path of the data traffic for two-way end-to-end performance measurement of an SRv6 Policy is shown in Figure 9. For SRv6 Policy using SRH, the SRv6 SID list in the SRH of the probe response message is built using the SRv6 Segment List received in the Return Path TLV in the probe query message. +---------------------------------------------------------------+ | SRH | . END.OTP (DM) or END.OP (LM) with Target SRv6 SID . . . +---------------------------------------------------------------+ | Message as shown in Figure 5 or 6 | . (Using IPv6 Source and Destination Addresses) . . . +---------------------------------------------------------------+ Figure 9: Probe Response Message for SRv6 Policy 4.2.3. Loopback Measurement Mode The Loopback measurement mode defined in Section 2.8 of [RFC6374] can be used to measure round-trip delay of a bidirectional SR Path. The IP header of the probe query message contains the destination address equals to the sender address and the source address equals to the responder address. Optionally, the probe query message can carry the reverse path information (e.g. reverse path label stack for SR-MPLS) as part of the SR header. The responder node does not process the PM probe messages and generate response messages. 5. Performance Measurement for P2MP SR Policies The procedures for delay and loss measurement described in this document for Point-to-Point (P2P) SR Policies [I-D.spring-segment-routing-policy] are also equally applicable to the Point-to-Multipoint (P2MP) SR Policies [I-D.spring-sr-p2mp-policy] as following: o The sender root node sends probe query messages using the either Gandhi, et al. Expires April 6, 2020 [Page 14] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 Spray P2MP segment or TreeSID P2MP segment defined in [I-D.spring-sr-p2mp-policy] over the P2MP SR Policy. o The sender root node sets the PM probe query message Destination IPv4 Address from the 127/8 range for SR-MPLS Policy. o Each responder leaf node sends its IP address in the Source Address of the probe response messages. This allows the sender root node to identify the responder leaf nodes of the P2MP SR Policy. o The P2MP root node measures the end-to-end delay and loss performance for each P2MP leaf node. 6. ECMP Support for SR 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 probe messages need to be sent to traverse different ECMP paths to measure performance delay of an SR Policy. Forwarding plane has various hashing functions available to forward packets on specific ECMP paths. Following mechanisms can be used in PM probe messages to take advantage of the hashing function in forwarding plane to influence the path taken by them. o The mechanisms described in [RFC8029] and [RFC5884] for handling ECMPs are also applicable to the performance measurement. In the IP/UDP header of the PM probe messages, Destination Addresses in 127/8 range for IPv4 or 0:0:0:0:0:FFFF:7F00/104 range for IPv6 can be used to exercise a particular ECMP path. As specified in [RFC6437], 3-tuple of Flow Label, Source Address and Destination Address fields in the IPv6 header can also be used. o For SR-MPLS Policy, entropy label [RFC6790] can be used in the PM probe messages. o For SRv6 Policy using SRH, Flow Label in the SRH [I-D.6man-segment-routing-header] of the PM probe messages can be used. 7. Sequence Numbers The message formats for DM and LM [RFC6374] can carry either Gandhi, et al. Expires April 6, 2020 [Page 15] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 timestamp or sequence number but not both. There are case where both timestamp and sequence number are desired for both DM and LM. Sequence numbers can be useful when some probe query messages are lost or they arrive out of order. In addition, the sequence numbers can be useful for detecting denial-of-service (DoS) attacks on UDP ports. 7.1. Sequence Number TLV in Unauthenticated Mode [RFC6374] defines DM and LM probe query and response messages that can include one or more optional TLVs. New TLV Type (value TBA1) is defined in this document to carry sequence number for probe query and response messages for delay and loss measurement. The format of the Sequence Number TLV in unauthenticated mode is shown in Figure 10. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type TBA1 | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 10: Sequence Number TLV - Unauthenticated Mode o The sequence numbers start with 0 and are incremented by one for each subsequent probe query packet. o The sequence number are independent for DM and LM messages. o The sequence number can be of any length determined by the sender node. o The Sequence Number TLV is optional. o The PM sender node SHOULD only insert one Sequence Number TLV in the probe query message and the responder node in the probe response message SHOULD return the first Sequence Number TLV from the probe query message and ignore the other Sequence Number TLVs if present. o When Sequence Number TLV is added, the DM and LM messages SHOULD NOT carry sequence number in the timestamp field of the message. 7.2. Sequence Number TLV in Authenticated Mode Gandhi, et al. Expires April 6, 2020 [Page 16] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 The PM probe query and response packet format in authenticated mode includes a key Hashed Message Authentication Code (HMAC) ([RFC2104]) hash. Each probe query and response messages are authenticated by adding Sequence Number with Hashed Message Authentication Code (HMAC) TLV. It can use HMAC-SHA-256 truncated to 128 bits (similarly to the use of it in IPSec defined in [RFC4868]); hence the length of the HMAC field is 16 octets. In authenticated mode, only the sequence number is encrypted, and the other payload fields are sent in clear text. The probe packet MAY include Comp.MBZ (Must Be Zero) variable length field to align the packet on 16 octets boundary. The computation of HMAC field using HMAC-SHA1 [RFC5357] can be used with the procedure defined in this document. HMAC uses own key and the definition of the mechanism to distribute the HMAC key is outside the scope of this document. Both the authentication type and key can be user-configured on both the sender and responder nodes. The format of the Sequence Number TLV in authentication mode is shown in Figure 11. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type TBA2 | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Comp.MBZ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | HMAC (16 octets) | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11: Sequence Number TLV - Authenticated Mode o This TLV is mandatory in the authenticated mode. o The node MUST discard the probe message if HMAC is invalid. o The Sequence Number follows the same processing rule as defined in the unauthenticated mode. Gandhi, et al. Expires April 6, 2020 [Page 17] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 8. Additional Message Processing Rules 8.1. TTL Value The TTL or the Hop Limit field in the IP, MPLS and SRH headers of the probe query messages are set to 255. When using the Destination IPv4 Address from the 127/8 range, the TTL in the IPv4 header is set to 1 [RFC8029]. Similarly, when using the Destination IPv6 Address from the 0:0:0:0:0:FFFF:7F00/104 range, the Hop Limit field in the inner IPv6 header is set to 1 whereas in the outer IPv6 header is set to 255. 8.2. Router Alert Option The Router Alert IP option is not set when using the routable Destination IP Address in the probe messages. When using the Destination IPv4 Address from the 127/8 range, the Router Alert IP Option of value 0x0 [RFC2113] for IPv4 is set in the IP header [RFC8029]. Similarly, when using the Destination IPv6 Address from the 0:0:0:0:0:FFFF:7F00/104 range, the Router Alert IP Option of value 69 [RFC7506] for IPv6 is set in the IP header. 8.3. UDP Checksum The Checksum Complement for delay and loss measurement messages follows the procedure defined in [RFC7820] and can be optionally used with the procedures defined in this document. For IPv4 and IPv6 probe messages, where the hardware is not capable of re-computing the UDP checksum or adding checksum complement [RFC7820], the sender node sets the UDP checksum to 0 [RFC6936] [RFC8085]. The receiving node bypasses the checksum validation and accepts the packets with UDP checksum of 0 for the UDP port being used for PM. 9. Security Considerations The performance measurement is intended for deployment in well-managed private and service provider networks. As such, it assumes that a node involved in a measurement operation has previously verified the integrity of the path and the identity of the far end responder node. The security considerations described in Section 8 of [RFC6374] are applicable to this specification, and particular attention should be paid to the last three paragraphs. Gandhi, et al. Expires April 6, 2020 [Page 18] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 If desired, attacks can be mitigated by performing basic validation and sanity checks, at the sender, of the counter or timestamp fields in received measurement response messages. The minimal state associated with these protocols also limits the extent of measurement disruption that can be caused by a corrupt or invalid message to a single query/response cycle. Use of HMAC-SHA-256 in the authenticated mode defined in this document protects the data integrity of the probe messages. SRv6 has HMAC protection authentication defined for SRH [I-D.6man-segment-routing-header]. Hence, PM probe messages for SRv6 may not need authentication mode. Cryptographic measures may be enhanced by the correct configuration of access-control lists and firewalls. 10. IANA Considerations IANA is requested to allocate the values for the following Sub-TLV Types for the Return Path TLV for RFC 6374. o Type TBD4: SRv6 Segment List of the Reverse SR Path o Type TBD5: SRv6 Binding SID of the Reverse SR Policy IANA is also requested to allocate the values for the following Sequence Number TLV Types for RFC 6374 to be carried in the PM probe query and response messages for delay and loss measurement: o Type TBA1: Sequence Number TLV in Unauthenticated Mode o Type TBA2: Sequence Number TLV in Authenticated Mode 11. References 11.1. Normative References [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. Gandhi, et al. Expires April 6, 2020 [Page 19] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 [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. [I-D.spring-rfc6374-srpm-mpls] Gandhi, R. Ed., et al. "Performance Measurement in Segment Routing Networks with MPLS Data Plane", draft-gandhi-spring-rfc6374-srpm-mpls, work in progress. [I-D.6man-srv6-oam] Ali, Z., et al., "Operations, Administration, and Maintenance (OAM) in Segment Routing Networks with IPv6 Data plane (SRv6)", draft-ietf-6man-spring-srv6-oam, work in progress. 11.2. Informative References [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems", March 2008. [Y1731] ITU-T Recommendation Y.1731 (02/08), "OAM functions and mechanisms for Ethernet based networks", February 2008. [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- Hashing for Message Authentication", RFC 2104, DOI 10.17487/RFC2104, February 1997, . [RFC2113] Katz, D., "IP Router Alert Option", RFC 2113, February 1997. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, September 2006. [RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA- 384, and HMAC-SHA-512 with IPsec", RFC 4868,DOI 10.17487/RFC4868, May 2007, . [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008. [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, Gandhi, et al. Expires April 6, 2020 [Page 20] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 "Bidirectional Forwarding Detection (BFD) for MPLS Label Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884, June 2010. [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", BCP 165,RFC 6335, August 2011. [RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, November 2011. [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. Yong, "The Use of Entropy Labels in MPLS Forwarding", RFC 6790, November 2012. [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement for the Use of IPv6 UDP Datagrams with Zero Checksums", RFC 6936, April 2013. [RFC7506] Raza, K., Akiya, N., and C. Pignataro, "IPv6 Router Alert Option for MPLS Operations, Administration, and Maintenance (OAM)", RFC 7506, DOI 10.17487/RFC7506, April 2015, . [RFC7820] Mizrahi, T., "UDP Checksum Complement in the One-Way Active Measurement Protocol (OWAMP) and Two-Way Active Measurement Protocol (TWAMP)", RFC 7820, March 2016. [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. [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, March 2017, . [RFC8321] Fioccola, G. Ed., "Alternate-Marking Method for Passive and Hybrid Performance Monitoring", RFC 8321, January 2018. [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, . Gandhi, et al. Expires April 6, 2020 [Page 21] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 [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.6man-segment-routing-header] Filsfils, C., et al., "IPv6 Segment Routing Header (SRH)", draft-ietf-6man-segment-routing-header, work in progress. [I-D.pce-binding-label-sid] Filsfils, C., et al., "Carrying Binding Label/Segment-ID in PCE-based Networks", draft-ietf-pce-binding-label-sid, work in progress. [I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in MPLS Based Segment Routing Network", draft-ietf-spring-mpls-path-segment, work in progress. [I-D.ippm-stamp] Mirsky, G. et al. "Simple Two-way Active Measurement Protocol", draft-ietf-ippm-stamp, work in progress. [BBF.TR-390] "Performance Measurement from IP Edge to Customer Equipment using TWAMP Light", BBF TR-390, May 2017. [I-D.spring-ioam-sr-mpls] Gandhi, R. Ed., et al., "Segment Routing with MPLS Data Plane Encapsulation for In-situ OAM Data", draft-gandhi-spring-ioam-sr-mpls, work in progress. [I-D.spring-ioam-srv6]. Ali, Z., et al., "Segment Routing Header encapsulation for In-situ OAM Data", draft-ali-spring-ioam-srv6, work in progress. Gandhi, et al. Expires April 6, 2020 [Page 22] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 Acknowledgments The authors would like to thank Nagendra Kumar and Carlos Pignataro for the discussion on SRv6 Performance Measurement. The authors would like to thank Thierry Couture for the discussions on the use-cases for the performance measurement in segment routing networks. The authors would also like to thank Stewart Bryant for the discussion on UDP port allocation for Performance Measurement and Greg Mirsky for providing 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 Pier Luigi Ventre CNIT Italy Email: pierluigi.ventre@cnit.it Authors' Addresses Rakesh Gandhi (editor) Cisco Systems, Inc. Canada Email: rgandhi@cisco.com Clarence Filsfils Cisco Systems, Inc. Email: cfilsfil@cisco.com Gandhi, et al. Expires April 6, 2020 [Page 23] Internet-Draft RFC 6374 UDP Path for Segment Routing October 4, 2019 Daniel Voyer Bell Canada Email: daniel.voyer@bell.ca Stefano Salsano Universita di Roma "Tor Vergata" Italy Email: stefano.salsano@uniroma2.it Mach(Guoyi) Chen Huawei Email: mach.chen@huawei.com Gandhi, et al. Expires April 6, 2020 [Page 24]