< draft-gandhi-spring-rfc6374-srpm-mpls-00.txt   draft-gandhi-spring-rfc6374-srpm-mpls-01.txt >
SPRING Working Group R. Gandhi, Ed. SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils Internet-Draft C. Filsfils
Intended Status: Informational Cisco Systems, Inc. Intended Status: Informational Cisco Systems, Inc.
Expires: August 18, 2019 D. Voyer Expires: November 16, 2019 D. Voyer
Bell Canada Bell Canada
S. Salsano S. Salsano
Universita di Roma "Tor Vergata" Universita di Roma "Tor Vergata"
P. L. Ventre P. L. Ventre
CNIT CNIT
M. Chen M. Chen
Huawei Huawei
February 14, 2019 May 15, 2019
In-band Performance Measurement for Performance Measurement for
Segment Routing Networks with MPLS Data Plane Segment Routing Networks with MPLS Data Plane
draft-gandhi-spring-rfc6374-srpm-mpls-00 draft-gandhi-spring-rfc6374-srpm-mpls-01
Abstract Abstract
RFC 6374 specifies protocol mechanisms to enable the efficient and RFC 6374 specifies protocol mechanisms to enable the efficient and
accurate measurement of packet loss, one-way and two-way delay, as accurate measurement of packet loss, one-way and two-way delay, as
well as related metrics such as delay variation in MPLS networks well as related metrics such as delay variation in MPLS networks
using probe messages. This document reviews how these mechanisms can using synthetic probe messages. This document reviews how these
be used for Delay and Loss Performance Measurements (PM) in Segment mechanisms can be used for Performance Delay and Loss Measurements in
Routing (SR) networks with MPLS data plane (SR-MPLS), for both SR Segment Routing (SR) networks with MPLS data plane (SR-MPLS), for
links and end-to-end SR Policies. The performance measurements for both SR links and end-to-end SR Policies. The Performance
SR links are used to compute extended Traffic Engineering (TE) Measurements (PM) for SR links are used to compute extended Traffic
metrics for delay and loss and are advertised in the network using Engineering (TE) metrics for delay and loss and can be advertised in
the routing protocol extensions. the network using the routing protocol extensions.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
skipping to change at page 2, line 26 skipping to change at page 2, line 26
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Reference Topology . . . . . . . . . . . . . . . . . . . . 4 2.2. Reference Topology . . . . . . . . . . . . . . . . . . . . 4
2.3. In-band Probe Messages . . . . . . . . . . . . . . . . . . 5
3. Probe Query and Response Packets . . . . . . . . . . . . . . . 5 3. Probe Query and Response Packets . . . . . . . . . . . . . . . 5
3.1. Probe Packet Header for SR-MPLS Policies . . . . . . . . . 5 3.1. Probe Packet Header for SR-MPLS Policies . . . . . . . . . 5
3.2. Probe Packet Header for SR-MPLS Links . . . . . . . . . . 6 3.2. Probe Packet Header for SR-MPLS Links . . . . . . . . . . 6
3.3. Probe Response Message for SR-MPLS Links and Policies . . 6 3.3. Probe Response Message for SR-MPLS Links and Policies . . 6
3.3.1. One-way Measurement Probe Response Message . . . . . . 6 3.3.1. One-way Measurement Mode . . . . . . . . . . . . . . . 6
3.3.2. Two-way Measurement Probe Response Message . . . . . . 6 3.3.2. Two-way Measurement Mode . . . . . . . . . . . . . . . 7
3.3.2.1. Return Path TLV . . . . . . . . . . . . . . . . . 7
3.3.3. Loopback Measurement Mode . . . . . . . . . . . . . . 7
4. Performance Delay Measurement . . . . . . . . . . . . . . . . 7 4. Performance Delay Measurement . . . . . . . . . . . . . . . . 7
4.1. Delay Measurement Message Format . . . . . . . . . . . . . 7 4.1. Delay Measurement Message Format . . . . . . . . . . . . . 7
4.2. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Timestamps . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Performance Loss Measurement . . . . . . . . . . . . . . . . . 7 5. Performance Loss Measurement . . . . . . . . . . . . . . . . . 8
5.1. Loss Measurement Message Format . . . . . . . . . . . . . 8 5.1. Loss Measurement Message Format . . . . . . . . . . . . . 9
6. Performance Measurement for P2MP SR Policies . . . . . . . . . 8 5.1.1. Block Number TLV . . . . . . . . . . . . . . . . . . . 9
7. ECMP for SR-MPLS Policies . . . . . . . . . . . . . . . . . . 8 6. Performance Measurement for P2MP SR Policies . . . . . . . . . 9
8. SR Link Extended TE Metrics Advertisements . . . . . . . . . . 8 7. ECMP for SR-MPLS Policies . . . . . . . . . . . . . . . . . . 10
9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. SR Link Extended TE Metrics Advertisements . . . . . . . . . . 10
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . 9 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . 9 11.1. Normative References . . . . . . . . . . . . . . . . . . 11
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11 11.2. Informative References . . . . . . . . . . . . . . . . . 11
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
Service provider's ability to satisfy Service Level Agreements (SLAs) Service provider's ability to satisfy Service Level Agreements (SLAs)
depend on the ability to measure and monitor performance metrics for 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 packet loss and one-way and two-way delay, as well as related metrics
such as delay variation. The ability to monitor these performance such as delay variation. The ability to monitor these performance
metrics also provides operators with greater visibility into the metrics also provides operators with greater visibility into the
performance characteristics of their networks, thereby facilitating performance characteristics of their networks, thereby facilitating
planning, troubleshooting, and network performance evaluation. planning, troubleshooting, and network performance evaluation.
[RFC6374] specifies protocol mechanisms to enable the efficient and [RFC6374] specifies protocol mechanisms to enable the efficient and
accurate measurement of performance metrics in MPLS networks using accurate measurement of performance metrics in MPLS networks using
probe messages. The One-Way Active Measurement Protocol (OWAMP) probe messages. The One-Way Active Measurement Protocol (OWAMP)
defined in [RFC4656] and Two-Way Active Measurement Protocol (TWAMP) defined in [RFC4656] and Two-Way Active Measurement Protocol (TWAMP)
defined in [RFC5357] provide capabilities for the measurement of defined in [RFC5357] provide capabilities for the measurement of
various performance metrics in IP networks. However, mechanisms various performance metrics in IP networks. However, mechanisms
defined in [RFC6374] are more suitable for Segment Routing (SR) when defined in [RFC6374] are more suitable for Segment Routing (SR) when
using MPLS data plane (SR-MPLS). The [RFC6374] also supports IEEE using MPLS data plane (SR-MPLS). [RFC6374] also supports IEEE 1588
1588 timestamps [IEEE1588] and "direct mode" Loss Measurement (LM), timestamps [IEEE1588] and "direct mode" Loss Measurement (LM), which
which are required in SR networks. are required in SR networks.
[RFC7876] specifies the procedures to be used when sending and [RFC7876] specifies the procedures to be used when sending and
processing out-of-band performance measurement probe replies over an processing out-of-band performance measurement probe replies over an
UDP return path when receiving RFC 6374 based probe queries. These 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 procedures can be used to send out-of-band PM replies for both
links and SR Policies [I-D.spring-segment-routing-policy] for one-way SR-MPLS links and Policies [I-D.spring-segment-routing-policy] for
measurement. one-way measurement.
This document reviews how probe based mechanisms defined in [RFC6374] This document reviews how synthetic probe-based mechanisms defined in
can be used for Delay and Loss Performance Measurements (PM) in SR [RFC6374] can be used for Performance Delay and Loss Measurements in
networks with MPLS data plane, for both SR links and end-to-end SR 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 Policies. The Performance Measurements (PM) for SR links are used to
compute extended Traffic Engineering (TE) metrics for delay and loss compute extended Traffic Engineering (TE) metrics for delay and loss
and are advertised in the network using routing protocol extensions. and can be advertised in the network using the routing protocol
extensions.
2. Conventions Used in This Document 2. Conventions Used in This Document
2.1. Abbreviations 2.1. Abbreviations
ACH: Associated Channel Header. ACH: Associated Channel Header.
DM: Delay Measurement. DM: Delay Measurement.
ECMP: Equal Cost Multi-Path. ECMP: Equal Cost Multi-Path.
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TE: Traffic Engineering. TE: Traffic Engineering.
URO: UDP Return Object. URO: UDP Return Object.
2.2. Reference Topology 2.2. Reference Topology
In the reference topology shown in Figure 1, the querier node R1 In the reference topology shown in Figure 1, the querier node R1
initiates a performance measurement probe query and the responder initiates a performance measurement probe query and the responder
node R5 sends a probe response for the query message received. The node R5 sends a probe response for the query message received. The
probe response is typically sent to the querier node R1. The nodes probe response is typically sent back to the querier node R1. The
R1 and R5 may be directly connected via a link enabled with Segment nodes R1 and R5 may be directly connected via a link enabled with
Routing or there exists a Point-to-Point (P2P) SR Policy Segment Routing or there exists a Point-to-Point (P2P) SR Policy
[I-D.spring-segment-routing-policy] on node R1 with destination to [I-D.spring-segment-routing-policy] on node R1 with destination to
node R5. In case of Point-to-Multipoint (P2MP), SR Policy node R5. In case of Point-to-Multipoint (P2MP), SR Policy
originating from source node R1 may terminate on multiple destination originating from source node R1 may terminate on multiple destination
leaf nodes [I-D.spring-sr-p2mp-policy]. leaf nodes [I-D.spring-sr-p2mp-policy].
+-------+ Query +-------+ +-------+ Query +-------+
| | - - - - - - - - - ->| | | | - - - - - - - - - ->| |
| R1 |---------------------| R5 | | R1 |---------------------| R5 |
| |<- - - - - - - - - - | | | |<- - - - - - - - - - | |
+-------+ Response +-------+ +-------+ Response +-------+
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[I-D.spring-segment-routing-policy] on node R1 with destination to [I-D.spring-segment-routing-policy] on node R1 with destination to
node R5. In case of Point-to-Multipoint (P2MP), SR Policy node R5. In case of Point-to-Multipoint (P2MP), SR Policy
originating from source node R1 may terminate on multiple destination originating from source node R1 may terminate on multiple destination
leaf nodes [I-D.spring-sr-p2mp-policy]. leaf nodes [I-D.spring-sr-p2mp-policy].
+-------+ Query +-------+ +-------+ Query +-------+
| | - - - - - - - - - ->| | | | - - - - - - - - - ->| |
| R1 |---------------------| R5 | | R1 |---------------------| R5 |
| |<- - - - - - - - - - | | | |<- - - - - - - - - - | |
+-------+ Response +-------+ +-------+ Response +-------+
Figure 1: Reference Topology Figure 1: Reference Topology
Both delay and loss performance measurement is performed in-band for For delay and loss measurements, for both links and end-to-end SR
the traffic traversing between node R1 and node R5. One-way delay Policies, no PM session is created on the responder node R5. One-way
and two-way delay measurements are defined in Section 2.4 of delay and two-way delay measurements are defined in Section 2.4 of
[RFC6374]. Transmit and Receive packet loss measurements are defined [RFC6374]. Transmit and Receive packet loss measurements are defined
in Section 2.2 and Section 2.6 of [RFC6374]. One-way loss in Section 2.2 and Section 2.6 of [RFC6374]. One-way loss
measurement provides receive packet loss whereas two-way loss measurement provides receive packet loss whereas two-way loss
measurement provides both transmit and receive packet loss. measurement provides both transmit and receive packet loss.
2.3. In-band Probe Messages For Performance Measurement, synthetic probe query and response
messages are used as following:
For both Delay and Loss measurements for links and SR Policies, no PM o For Delay Measurement, the probe messages are sent on the
session is created on the responder node. The probe messages for congruent path of the data traffic by the querier node, and are
Delay measurement are sent in-band by the querier node to measure the used to measure the delay experienced by the actual data traffic
delay experienced by the actual traffic flowing on the links and SR flowing on the links and SR Policies.
Policies. For Loss measurement, in-band probe messages are used to
collect the traffic counter for the incoming link or incoming SID on o For Loss Measurement, the probe messages are sent on the congruent
which the probe query message is received at the responder node R5 path of the data traffic by the querier node, and are used to
(as it has no PM session state present on the node). 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 used as the
responder node has no PM session state present).
The In-Situ Operations, Administration, and Maintenance (IOAM)
mechanisms for SR-MPLS defined in [I-D.spring-ioam-sr-mpls] are used
to carry PM information in-band as part of the data traffic, and are
outside the scope of this document.
3. Probe Query and Response Packets 3. Probe Query and Response Packets
3.1. Probe Packet Header for SR-MPLS Policies 3.1. Probe Packet Header for SR-MPLS Policies
As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and
response messages flow over the MPLS Generic Associated Channel (G- response messages flow over the MPLS Generic Associated Channel
ACh). A probe packet for an end-to-end measurement for SR Policy (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], 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 with the G-ACh Label (GAL) at the bottom of the stack (with S=1).
followed by an Associated Channel Header (ACH), which identifies the The GAL is followed by an Associated Channel Header (ACH), which
message type and the message payload following the ACH as shown in identifies the message type, and the message payload following the
Figure 2. ACH as shown in Figure 2.
0 1 2 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 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(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label(n) | TC |S| TTL | | Label(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GAL (value 13) | TC |S| TTL | | GAL (value 13) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | GAL Channel Type | |0 0 0 1|Version| Reserved | GAL Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Probe Packet Header for an End-to-end SR-MPLS Policy 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 The SR-MPLS label stack can be empty (as shown in Figure 3) to
case. indicate Implicit NULL label case.
3.2. Probe Packet Header for SR-MPLS Links 3.2. Probe Packet Header for SR-MPLS Links
As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and As described in Section 2.9.1 of [RFC6374], MPLS PM probe query and
response messages flow over the MPLS Generic Associated Channel response messages flow over the MPLS Generic Associated Channel
(G-ACh). A probe packet for SR-MPLS links contains G-ACh Label (G-ACh). A probe packet for SR-MPLS links contains G-ACh Label (GAL)
(GAL). The GAL is followed by an Associated Channel Header (ACH), (with S=1). The GAL is followed by an Associated Channel Header
which identifies the message type, and the message payload following (ACH), which identifies the message type, and the message payload
the ACH as shown in Figure 3. following the ACH as shown in Figure 3.
0 1 2 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 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 | | GAL (value 13) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | GAL Channel Type | |0 0 0 1|Version| Reserved | GAL Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Probe Packet Header for an SR-MPLS Link Figure 3: Probe Packet Header for an SR-MPLS Link
3.3. Probe Response Message for SR-MPLS Links and Policies 3.3. Probe Response Message for SR-MPLS Links and Policies
3.3.1. One-way Measurement Probe Response Message 3.3.1. One-way Measurement Mode
For one-way performance measurement [RFC7679], the PM querier node In one-way performance measurement mode [RFC7679], the PM querier
can receive "out-of-band" probe replies by properly setting the UDP node can receive "out-of-band" probe replies by properly setting the
Return Object (URO) TLV in the probe query message. The URO TLV UDP Return Object (URO) TLV in the probe query message. The URO TLV
(Type=131) is defined in [RFC7876] and includes the (Type=131) is defined in [RFC7876] and includes the
UDP-Destination-Port and IP Address. In particular, if the querier 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 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 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 "control code" in the probe query message is set to "out-of-band
response requested". The "Source Address" TLV (Type 130), and response requested". The "Source Address" TLV (Type 130), and
"Return Address" TLV (Type 1), if present in the probe query message, "Return Address" TLV (Type 1), if present in the probe query message,
are not used to send probe response message. are not used to send probe response message.
3.3.2. Two-way Measurement Probe Response Message 3.3.2. Two-way Measurement Mode
For two-way performance measurement [RFC6374], when using a In two-way performance measurement mode [RFC6374], when using a
bidirectional channel, the probe response message is sent back to the bidirectional path, the probe response message is sent back to the
querier node in-band on the reverse direction SR Link or SR Policy querier node on the congruent path of the data traffic on the reverse
using a message with format similar to their probe query message. In direction SR Link or SR Policy using a message with format similar to
this case, the "control code" in the probe query message is set to their probe query message. In this case, the "control code" in the
"in-band response requested". probe query message is set to "in-band response requested".
A Path Segment Identifier [I-D.spring-mpls-path-segment] of the A Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of
forward SR Policy can be used to find the reverse SR Policy and to the forward SR-MPLS Policy can be used to find the reverse SR-MPLS
send back the probe response message. Policy and to send back the probe response message for two-way
measurement.
3.3.2.1. Return Path TLV
For two-way performance measurement, the querier node can request the
responder node to send a response message back on a given reverse
path (typically co-routed path for two-way measurement). Return Path
TLV defined in [I-D.spring-rfc6374-srpm-udp] can be used to carry
reverse SR path information as part of the payload of the probe query
message.
3.3.3. Loopback Measurement Mode
The Loopback measurement mode defined in Section 2.8 of [RFC6374] can
be used to measure round-trip delay for a bidirectional SR Path. The
probe query messages in this case carries the reverse SR Path label
stack as part of the MPLS header. The GAL is still carried at the
bottom of the label stack (with S=1). The responder node does not
process the PM probe messages and generate response messages.
4. Performance Delay Measurement 4. Performance Delay Measurement
4.1. Delay Measurement Message Format 4.1. Delay Measurement Message Format
As defined in [RFC6374], MPLS DM probe query and response messages As defined in [RFC6374], MPLS DM probe query and response messages
use Associated Channel Header (ACH) (value 0x000C for delay use Associated Channel Header (ACH) (value 0x000C for delay
measurement) [RFC6374], which identifies the message type, and the measurement) [RFC6374], which identifies the message type, and the
message payload following the ACH. For both SR links and end-to-end 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. measurement for SR-MPLS Policies, the same MPLS DM ACH value is used.
The DM message payload as defined in Section 3.2 of [RFC6374] 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 for SR-MPLS delay measurement, for both SR links and end-to-end SR
Policies. Policies.
4.2. Timestamps 4.2. Timestamps
The Section 3.4 of [RFC6374] defines timestamp format that can be The Section 3.4 of [RFC6374] defines timestamp format that can be
used for delay measurement. The IEEE 1588 Precision Time Protocol used for delay measurement. The IEEE 1588 Precision Time Protocol
(PTP) timestamp format [IEEE1588] is used by default as described in (PTP) timestamp format [IEEE1588] is used by default as described in
Appendix A of [RFC6374], but it may require hardware support. As an Appendix A of [RFC6374], preferred with hardware support. As an
alternative, Network Time Protocol (NTP) timestamp format can also be alternative, Network Time Protocol (NTP) timestamp format can also be
used [RFC6374]. used [RFC6374].
Note that for one-way delay measurement, clock synchronization Note that for one-way delay measurement mode, clock synchronization
between the querier and responder nodes using the methods detailed in between the querier and responder nodes using the methods detailed in
[RFC6374] is required. The two-way delay measurement does not [RFC6374] is required. The two-way delay measurement mode and
require clock synchronization between the querier and responder loopback measurement mode do not require clock synchronization
nodes. between the querier and responder nodes.
5. Performance Loss Measurement 5. Performance Loss Measurement
The LM protocol can perform two distinct kinds of loss measurement as The LM protocol can perform two distinct kinds of loss measurement as
described in Section 2.9.8 of [RFC6374]. described in Section 2.9.8 of [RFC6374].
o In inferred mode, LM will measure the loss of specially generated o In inferred mode, LM will measure the loss of specially generated
test messages in order to infer the approximate data plane loss test messages in order to infer the approximate data plane loss
level. Inferred mode LM provides only approximate loss level. Inferred mode LM provides only approximate loss
accounting. accounting.
o In direct mode, LM will directly measure data plane packet loss. o In direct mode, LM will directly measure data plane packet loss.
Direct mode LM provides perfect loss accounting, but may require Direct mode LM provides perfect loss accounting, but may require
hardware support. hardware support.
For both of these modes of LM, Path Segment Identifier (PSID) For both of these modes of LM, Path Segment Identifier (PSID)
[I-D.spring-mpls-path-segment] is used for accounting received [I-D.spring-mpls-path-segment] is used for accounting received
traffic on the egress node of the SR-MPLS Policy. traffic on the egress node of the SR-MPLS Policy as shown in Figure
4. Different values of PSID can be used to measure packet loss per
SR-MPLS Policy, per Candidate Path or per Segment List of the SR
Policy.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GAL (value 13) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | GAL Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: With Path Segment Identifier for SR-MPLS Policy
5.1. Loss Measurement Message Format 5.1. Loss Measurement Message Format
As defined in [RFC6374], MPLS LM probe query and response messages As defined in [RFC6374], MPLS LM probe query and response messages
use Associated Channel Header (ACH) (value 0x000A for direct loss use Associated Channel Header (ACH) (value 0x000A for direct loss
measurement or value 0x000B for inferred loss measurement), which measurement or value 0x000B for inferred loss measurement), which
identifies the message type, and the message payload following the identifies the message type, and the message payload following the
ACH. For both SR links and end-to-end measurement for SR Policies, ACH. For both SR links and end-to-end measurement for SR-MPLS
the same MPLS LM ACH value is used. Policies, the same MPLS LM ACH value is used.
The LM message payload as defined in Section 3.1 of [RFC6374] 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 for SR-MPLS loss measurement, for both SR links and end-to-end SR
Policies. Policies.
5.1.1. Block Number TLV
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-udp] is used to
carry Block Number for the traffic counters in the probe query and
response messages for loss measurement.
6. Performance Measurement for P2MP SR Policies 6. Performance Measurement for P2MP SR Policies
The procedures for delay and loss measurement reviewed in this The procedures for delay and loss measurement reviewed in this
document for Point-to-Point (P2P) SR-MPLS Policies are also equally document for Point-to-Point (P2P) SR-MPLS Policies
applicable to the Point-to-Multipoint (P2MP) SR Policies. [I-D.spring-segment-routing-policy] are also equally applicable to
the Point-to-Multipoint (P2MP) SR-MPLS Policies
[I-D.spring-sr-p2mp-policy] as following:
The responder node adds the "Source Address" TLV (Type 130) [RFC6374] o The querier root node sends probe query messages using the either
in the probe response message. This TLV allows the querier node to Spray P2MP segment or TreeSID P2MP segment defined in
identify the responder nodes of the P2MP SR Policy. [I-D.spring-sr-p2mp-policy] over the P2MP SR Policy as shown in
Figure 5.
o Each responder leaf node adds the "Source Address" TLV (Type 130)
[RFC6374] with its IP address in the probe response messages.
This TLV allows the querier 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.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TreeSID OR Spray SID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GAL (value 13) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | GAL Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: With P2MP Segment Identifier for SR-MPLS Policy
7. ECMP for SR-MPLS Policies 7. ECMP for SR-MPLS Policies
An SR Policy can have ECMPs between the source and transit nodes, An SR Policy can have ECMPs between the source and transit nodes,
between transit nodes and between transit and destination nodes. between transit nodes and between transit and destination nodes.
Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP 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 paths via transit nodes part of that Anycast group. The PM probe
using [RFC6374] can not traverse all ECMP paths to measure messages need to be sent to traverse different ECMP paths to measure
performance delay of all paths of an SR Policy. performance delay of an SR Policy.
Forwarding plane has various hashing functions available to forward
packets on specific ECMP paths. For SR-MPLS Policy, entropy label
[RFC6790] can be used in PM probe messages to take advantage of the
hashing function in forwarding plane to influence the ECMP path taken
by them.
8. SR Link Extended TE Metrics Advertisements 8. SR Link Extended TE Metrics Advertisements
The extended TE metrics for SR link delay and loss computed using the The extended TE metrics for SR link delay and loss computed using the
performance measurement procedures reviewed in this document can be performance measurement procedures reviewed in this document can be
advertised in the routing domain as follows: advertised in the routing domain as follows:
o For OSPF, ISIS, and BGP-LS, protocol extensions defined in o For OSPF, ISIS, and BGP-LS, protocol extensions defined in
[RFC7471], [RFC7810] [I-D.lsr-isis-rfc7810bis], and [RFC7471], [RFC8570], and [RFC8571] are used, respectively for
[I-D.idr-te-pm-bgp] are used, respectively for advertising the advertising the extended TE link metrics in the network.
extended TE link metrics in the network.
o The extended TE link delay metrics advertised are minimum-delay, o The extended TE link delay metrics advertised are minimum-delay,
maximum-delay, average-delay, and delay-variance for one-way. maximum-delay, average-delay, and delay-variance for one-way.
o The delay-variance metric is computed as specified in Section 4.2 o The delay-variance metric is computed as specified in Section 4.2
of [RFC5481]. of [RFC5481].
o The one-way delay metrics can be computed using two-way o The one-way delay metrics can be computed using two-way delay
measurement by dividing the measured delay values by 2. measurement or round-trip delay measurement from loopback mode by
dividing the measured delay values by 2.
o The extended TE link loss metric advertised is one-way percentage o The extended TE link loss metric advertised is one-way percentage
packet loss. packet loss.
9. Security Considerations 9. Security Considerations
This document reviews the procedures for performance delay and loss This document reviews the procedures for performance delay and loss
measurement for SR-MPLS networks, for both links and end-to-end SR measurement for SR-MPLS networks, for both links and end-to-end SR
Policies using the mechanisms defined in [RFC6374]. This document Policies using the mechanisms defined in [RFC6374] and [RFC7876].
does not introduce any additional security considerations other than This document does not introduce any additional security
those covered in [RFC6374], [RFC7471], [RFC7810], and [RFC7876]. considerations other than those covered in [RFC6374], [RFC7471],
[RFC8570], [RFC8571], and [RFC7876].
10. IANA Considerations 10. IANA Considerations
This document does not require any IANA actions. This document does not require any IANA actions.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
skipping to change at page 10, line 16 skipping to change at page 12, line 12
Zekauskas, "A One-way Active Measurement Protocol Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006. (OWAMP)", RFC 4656, September 2006.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008. RFC 5357, October 2008.
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", RFC 5481, March 2009. Applicability Statement", RFC 5481, March 2009.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, November 2012.
[RFC7679] Almes, G., et al., "A One-Way Delay Metric for IP [RFC7679] Almes, G., et al., "A One-Way Delay Metric for IP
Performance Metrics (IPPM)', RFC 7679, January 2016. Performance Metrics (IPPM)', RFC 7679, January 2016.
[RFC7471] Giacalone, S., et al., "OSPF Traffic Engineering (TE) [RFC7471] Giacalone, S., et al., "OSPF Traffic Engineering (TE)
Metric Extensions", RFC 7471, March 2015. Metric Extensions", RFC 7471, March 2015.
[RFC7810] Previdi, S., et al., "IS-IS Traffic Engineering (TE) [RFC8321] Fioccola, G. Ed., "Alternate-Marking Method for Passive
Metric Extensions", RFC 7810, May 2016. and Hybrid Performance Monitoring", RFC 8321, January
2018.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, July 2018.
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[I-D.lsr-isis-rfc7810bis] Ginsberg, L., et al., "IS-IS Traffic [RFC8570] Ginsberg, L. Ed., et al., "IS-IS Traffic Engineering (TE)
Engineering (TE) Metric Extensions", Metric Extensions", RFC 8570, March 2019.
draft-ietf-lsr-isis-rfc7810bis, work in progress.
[I-D.idr-te-pm-bgp] Ginsberg, L. Ed., et al., "BGP-LS Advertisement [RFC8571] Ginsberg, L. Ed., et al., "BGP - Link State (BGP-LS)
of IGP Traffic Engineering Performance Metric Extensions", Advertisement of IGP Traffic Engineering Performance
draft-ietf-idr-te-pm-bgp, work in progress. Metric Extensions", RFC 8571, March 2019.
[I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment [I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment
Routing Policy Architecture", Routing Policy Architecture",
draft-ietf-spring-segment-routing-policy, work in draft-ietf-spring-segment-routing-policy, work in
progress. progress.
[I-D.spring-sr-p2mp-policy] Voyer, D. Ed., et al., "SR Replication [I-D.spring-sr-p2mp-policy] Voyer, D. Ed., et al., "SR Replication
Policy for P2MP Service Delivery", Policy for P2MP Service Delivery",
draft-voyer-spring-sr-p2mp-policy, work in progress. draft-voyer-spring-sr-p2mp-policy, work in progress.
[I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in [I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in
MPLS Based Segment Routing Network", MPLS Based Segment Routing Network",
draft-cheng-spring-mpls-path-segment, work in progress. draft-ietf-spring-mpls-path-segment, work in progress.
[I-D.spring-rfc6374-srpm-udp] Gandhi, R. Ed., et al., "Performance
Measurement Using UDP Path for Segment Routing Networks",
draft-gandhi-spring-rfc6374-srpm-udp, work in progress.
[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.
Acknowledgments Acknowledgments
The authors would like to thank Greg Mirsky for providing many useful The authors would like to thank Thierry Couture for various
comments and suggestions. discussions on the use-cases for the performance measurement in
segment routing networks. The authors would like to thank Greg
Mirsky for providing many useful comments and suggestions. The
authors would also like to thank Stewart Bryant and Rajiv Asati for
their review comments.
Contributors Contributors
Sagar Soni Sagar Soni
Cisco Systems, Inc. Cisco Systems, Inc.
Email: sagsoni@cisco.com Email: sagsoni@cisco.com
Patrick Khordoc Patrick Khordoc
Cisco Systems, Inc. Cisco Systems, Inc.
Email: pkhordoc@cisco.com Email: pkhordoc@cisco.com
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