SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended status: Informational Cisco Systems, Inc.
Expires: December 7, 2020 D. Voyer
Bell Canada
M. Chen
Huawei
B. Janssens
Colt
June 5, 2020
Performance Measurement Using TWAMP Light for Segment Routing Networks
draft-gandhi-spring-twamp-srpm-09
Abstract
Segment Routing (SR) leverages the source routing paradigm. SR is
applicable to both Multiprotocol Label Switching (SR-MPLS) and IPv6
(SRv6) data planes. This document describes procedure for sending
and processing probe query and response messages for Performance
Measurement (PM) in Segment Routing networks. The procedure uses the
messages defined in RFC 5357 (Two-Way Active Measurement Protocol
(TWAMP) Light) for Delay Measurement, and uses the messages defined
in this document for Loss Measurement. The procedure described is
applicable to SR-MPLS and SRv6 data planes and is used for both Links
and end-to-end SR Paths including SR Policies.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 7, 2020.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Reference Topology . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Example Provisioning Model . . . . . . . . . . . . . . . 6
4. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 7
4.1.1. Delay Measurement Query Message . . . . . . . . . . . 7
4.1.2. Loss Measurement Query Message . . . . . . . . . . . 8
4.1.3. Probe Query for Links . . . . . . . . . . . . . . . . 9
4.1.4. Probe Query for End-to-end Measurement for SR Policy 9
4.1.5. Control Code Field for TWAMP Light Messages . . . . . 10
4.1.6. Loss Measurement Query Message Formats . . . . . . . 11
4.2. Probe Response Message . . . . . . . . . . . . . . . . . 14
4.2.1. One-way Measurement Mode . . . . . . . . . . . . . . 15
4.2.2. Two-way Measurement Mode . . . . . . . . . . . . . . 15
4.2.3. Loss Measurement Response Message Formats . . . . . . 17
4.3. Additional Probe Message Processing Rules . . . . . . . . 19
4.3.1. TTL and Hop Limit . . . . . . . . . . . . . . . . . . 20
4.3.2. Router Alert Option . . . . . . . . . . . . . . . . . 20
4.3.3. UDP Checksum . . . . . . . . . . . . . . . . . . . . 20
5. Performance Measurement for P2MP SR Policies . . . . . . . . 20
6. ECMP Support for SR Policies . . . . . . . . . . . . . . . . 21
7. Performance Delay and Liveness Monitoring . . . . . . . . . . 21
8. Security Considerations . . . . . . . . . . . . . . . . . . . 22
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
10.1. Normative References . . . . . . . . . . . . . . . . . . 22
10.2. Informative References . . . . . . . . . . . . . . . . . 23
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Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
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.ietf-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 using probe messages. These protocols rely on
control-channel signaling to establish a test-channel over an UDP
path. 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 need for
control-channel signaling. As described in Appendix A of [RFC8545],
TWAMP Light mechanism is informative only. These protocols lack
support for direct-mode Loss Measurement (LM) to detect actual
Customer data traffic loss which is required in SR networks.
This document describes procedures for sending and processing probe
query and response messages for Performance Measurement in SR
networks. The procedure uses the messages defined in [RFC5357]
(TWAMP Light) for Delay Measurement (DM), and uses the messages
defined in this document for Loss Measurement. The procedure
described is applicable to SR-MPLS and SRv6 data planes and is used
for both Links and end-to-end SR Paths including SR Policies. This
document also defines mechanisms for handling ECMPs of SR Paths for
performance delay measurement. Unless otherwise described, the
messages defined in [RFC5357] are not modified by this document.
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.
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2.2. Abbreviations
BSID: Binding Segment ID.
DM: Delay Measurement.
ECMP: Equal Cost Multi-Path.
HMAC: Hashed Message Authentication Code.
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.
SRH: Segment Routing Header.
SR-MPLS: Segment Routing with MPLS data plane.
SRv6: Segment Routing with IPv6 data plane.
TC: Traffic Class.
TWAMP: Two-Way Active Measurement Protocol.
2.3. Reference Topology
In the reference topology shown below, the sender node R1 initiates a
probe query for performance measurement and the reflector node R5
sends a probe response for the query message received. The probe
response is sent to the sender node R1. The nodes R1 and R5 may be
directly connected via a Link or there exists a Point-to-Point (P2P)
SR Paths e.g. SR Policy [I-D.ietf-spring-segment-routing-policy] on
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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.voyer-spring-sr-replication-segment].
+-------+ t1 Query t2 +-------+
| | - - - - - - - - - ->| |
| R1 |=====================| R5 |
| |<- - - - - - - - - - | |
+-------+ t4 Response t3 +-------+
Sender Reflector
Reference Topology
3. Overview
For one-way and two-way delay measurements in Segment Routing
networks, the probe messages defined in [RFC5357] are used. For
direct-mode and inferred-mode loss measurements in Segment Routing
networks, the messages defined in this document are used. Separate
UDP destination port numbers are user-configured for delay and loss
measurements. As specified in [RFC8545], the reflector supports the
destination UDP port 862 for delay measurement probe messages by
default. This UDP port however, is not used for loss measurement
probe messages defined in this document. The sender uses the UDP
port number following the guidelines specified in Section 6 in
[RFC6335]. For both Links and end-to-end SR Paths including SR
Policies, no PM session for delay or loss measurement is created on
the reflector node R5 [RFC5357].
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
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
reflector node (incoming link or incoming SID needed since the
reflector node does not have PM session state present).
The In-Situ Operations, Administration, and Maintenance (IOAM)
mechanisms for SR-MPLS defined in [I-D.gandhi-mpls-ioam-sr] and for
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SRv6 defined in [I-D.ali-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 each user-configured destination UDP port for performance delay
and loss measurements is shown in the following Figure 1:
+------------+
| Controller |
+------------+
Destination UDP Port / \ Destination UDP port
Measurement Protocol / \ Measurement Protocol
Measurement Type / \ Measurement Type
Delay/Loss / \ Delay/Loss
Authentication Mode & Key / \ Authentication Mode & Key
Timestamp Format / \ Loss Measurement Mode
Delay Measurement Mode / \
Loss Measurement Mode / \
v v
+-------+ +-------+
| | | |
| R1 |============| R5 |
| | SR Path | |
+-------+ Or Link +-------+
Sender Reflector
Figure 1: Example Provisioning Model
Example of Measurement Protocol is TWAMP Light, example of the
Timestamp Format is PTPv2 [IEEE1588] or NTP and example of the Loss
Measurement mode is inferred-mode or direct-mode.
The mechanisms to provision the sender and reflector nodes are
outside the scope of this document.
The reflector node R5 uses the parameters for the timestamp format
and delay measurement mode (i.e. one-way or two-way mode) from the
received probe query message.
4. Probe Messages
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4.1. Probe Query Message
The probe messages defined in [RFC5357] are used for Delay
Measurement for Links and end-to-end SR Paths including SR Policies.
For Loss Measurement, the probe messages defined in this document are
used.
The Sender IPv4 or IPv6 address is used as the source address. The
reflector IPv4 or IPv6 address is used as the destination address.
In the case of SR Policy with IPv4 endpoint of 0.0.0.0 or IPv6
endpoint of ::0 [I-D.ietf-spring-segment-routing-policy], the address
in the range of 127/8 for IPv4 or ::FFFF:127/104 for IPv6 is used as
the destination address, respectively.
4.1.1. Delay Measurement Query Message
The message content for Delay Measurement probe query message using
UDP header [RFC0768] is shown in Figure 2. The DM probe query
message is sent with user-configured Destination UDP port number for
DM. The Destination UDP port cannot be used as Source port for DM,
since the message does not have any indication to distinguish between
the query and response message. The payload of the DM probe query
message contains the delay measurement message defined in
Section 4.1.2 of [RFC5357]. For symmetrical size query and response
messages as defined in [RFC6038], the DM probe query message contains
the payload format defined in Section 4.2.1 of [RFC5357].
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Sender IPv4 or IPv6 Address .
. Destination IP Address = Reflector IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Sender .
. Destination Port = User-configured Port for Delay Measurement.
. .
+---------------------------------------------------------------+
| Payload = DM Message as specified in Section 4.2.1 of RFC 5357|
. Payload = DM Message as specified in Section 4.1.2 of RFC 5357.
. .
+---------------------------------------------------------------+
Figure 2: DM Probe Query Message
Timestamp field is eight bytes and use the format defined in
Section 4.2.1 of [RFC5357]. It is recommended to use the IEEE 1588v2
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Precision Time Protocol (PTP) truncated 64-bit timestamp format
[IEEE1588] as specified in [RFC8186], with hardware support in
Segment Routing networks.
4.1.1.1. Delay Measurement Authentication Mode
When using the authenticated mode for delay measurement, the matching
authentication type (e.g. HMAC-SHA-256) and key are user-configured
on both the sender and reflector nodes. A separate user-configured
destination UDP port is used for the delay measurement in
authentication mode due to the different probe message format.
4.1.2. Loss Measurement Query Message
The message content for Loss Measurement probe query message using
UDP header [RFC0768] is shown in Figure 3. The LM probe query
message is sent with user-configured Destination UDP port number for
LM, which is a different Destination UDP port number than DM.
Separate Destination UDP ports are used for direct-mode and inferred-
mode loss measurements. The Destination UDP port cannot be used as
Source port for LM, since the message does not have any indication to
distinguish between the query and response message. The LM probe
query message contains the payload for loss measurement as defined in
Figure 7 and Figure 8.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Sender IPv4 or IPv6 Address .
. Destination IP Address = Reflector IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Sender .
. Destination Port = User-configured Port for Loss Measurement .
. .
+---------------------------------------------------------------+
| Payload = LM Message as specified in Figure 7 or 8 |
. .
+---------------------------------------------------------------+
Figure 3: LM Probe Query Message
4.1.2.1. Loss Measurement Authentication Mode
When using the authenticated mode for loss measurement, the matching
authentication type (e.g. HMAC-SHA-256) and key are user-configured
on both the sender and reflector nodes. A separate user-configured
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destination UDP port is used for the loss measurement in
authentication mode due to the different message format.
4.1.3. Probe Query for Links
The probe query message as defined in Figure 2 for delay measurement
and Figure 3 for loss measurement is sent on the congruent path of
the data traffic. The probe messages are routed over the Link for
both delay and 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 messages for end-to-end performance measurement of an
SR-MPLS Policy is sent using its SR-MPLS header containing the MPLS
segment list 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 2 for DM or Figure 3 for LM |
. .
+---------------------------------------------------------------+
Figure 4: Example 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.ietf-spring-mpls-path-segment] of the SR-MPLS Policy is used for
accounting received traffic on the egress node for loss measurement.
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4.1.4.2. Probe Query Message for SRv6 Policy
An SRv6 Policy setup using the SRv6 Segment Routing Header (SRH) and
a Segment List as defined in [RFC8754]. For SRv6, network
programming is defined in [I-D.ietf-spring-srv6-network-programming].
The probe query messages for end-to-end performance measurement of an
SRv6 Policy is sent using its SRH with Segment List as shown in
Figure 5.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Sender IPv6 Address .
. Destination IP Address = Destination IPv6 Address .
. .
+---------------------------------------------------------------+
| SRH as specified in RFC 8754 |
. <Segment List> .
. .
+---------------------------------------------------------------+
| IP Header (Optional) |
. Source IP Address = Sender IPv6 Address .
. Destination IP Address = Reflector IPv6 Address .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Sender .
. Destination Port = User-configured Port .
. .
+---------------------------------------------------------------+
| Payload = DM Message as specified in Section 4.2.1 of RFC 5357|
. Payload = DM Message as specified in Section 4.1.2 of RFC 5357.
. Payload = LM Message as specified in Figure 7 or 8 .
. .
+---------------------------------------------------------------+
Figure 5: Example Probe Query Message for SRv6 Policy
4.1.5. Control Code Field for TWAMP Light Messages
The Control Code field is defined for delay and loss measurement
probe query messages for TWAMP Light in unauthenticated and
authenticated modes. The modified delay measurement probe query
message format is shown in Figure 6. This message format is
backwards compatible with the message format defined in [RFC5357] as
its reflectors ignore the received field (previously identified as
MBZ). The usage of the Control Code is not limited to the SR paths
and can be used for non-SR paths in a network.
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. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Estimate | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ |Se Control Code|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
Figure 6: Sender Control Code in TWAMP Light DM Message
Sender Control Code: Set as follows in TWAMP Light probe query
message.
In a Query:
0x0: Out-of-band Response Requested. Indicates that the probe
response is not required over the same path in the reverse
direction. This is also the default behavior.
0x1: In-band Response Requested. Indicates that this query has
been sent over a bidirectional path and the probe response is
required over the same path in the reverse direction.
0x2: No Response Requested.
4.1.6. Loss Measurement Query Message Formats
In this document, TWAMP Light probe query messages for loss
measurement are defined as shown in Figure 7 and Figure 8. The
message formats are hardware efficient due to well-known locations of
the counters and payload small in size. They are stand-alone and
similar to the delay measurement message formats (e.g. location of
the Counter and Timestamp). They also do not require backwards
compatibility and support for the existing DM message formats from
[RFC5357] as different user-configured destination UDP port is used
for loss measurement.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|B| Reserved | Block Number | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ |Se Control Code|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Packet Padding .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: TWAMP Light LM Probe Query Message - Unauthenticated Mode
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|B| Reserved | Block Number | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ |Se Control Code|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Packet Padding .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: TWAMP Light LM Probe Query Message - Authenticated Mode
Sequence Number (32-bit): As defined in [RFC5357].
Transmit Counter (64-bit): The number of packets or octets sent by
the sender node in the query message and by the reflector node in the
response message. The counter is always written at the well-known
location in the probe query and response messages.
Receive Counter (64-bit): The number of packets or octets received at
the reflector node. It is written by the reflector node in the probe
response message.
Sender Counter (64-bit): This is the exact copy of the transmit
counter from the received query message. It is written by the
reflector node in the probe response message.
Sender Sequence Number (32-bit): As defined in [RFC5357].
Sender TTL: As defined in Section 7.1.
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LM Flags: The meanings of the Flag bits are:
X: Extended counter format indicator. Indicates the use of
extended (64-bit) counter values. Initialized to 1 upon creation
(and prior to transmission) of an LM Query and copied from an LM
Query to an LM response. Set to 0 when the LM message is
transmitted or received over an interface that writes 32-bit
counter values.
B: Octet (byte) count. When set to 1, indicates that the Counter
1-4 fields represent octet counts. The octet count applies to all
packets within the LM scope, and the octet count of a packet sent
or received includes the total length of that packet (but excludes
headers, labels, or framing of the channel itself). When set to
0, indicates that the Counter fields represent packet counts.
Block Number (8-bit): The Loss Measurement using Alternate-Marking
method defined in [RFC8321] requires to color the data traffic. To
be able to compare the transmit and receive traffic counters of the
matching color, the Block Number (or color) of the traffic counters
is carried by the probe query and response messages for loss
measurement.
HMAC: The PM probe message 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.
HMAC uses its own key and the mechanism to distribute the HMAC key is
outside the scope of this document.
In authenticated mode, only the sequence number is encrypted, and the
other payload fields are sent in clear text. The probe message may
include Comp.MBZ (Must Be Zero) variable length field to align the
packet on 16 octets boundary.
4.2. Probe Response Message
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 9.
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+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Reflector IPv4 or IPv6 Address .
. Destination IP Address = Source IP Address from Query .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Reflector .
. Destination Port = Source Port from Query .
. .
+---------------------------------------------------------------+
| Payload = DM Message as specified in Section 4.2.1 of RFC 5357|
. Payload = LM Message as specified in Figure 12 or 13 .
. .
+---------------------------------------------------------------+
Figure 9: Probe Response Message
4.2.1. One-way Measurement Mode
In one-way performance measurement mode, the probe response message
as defined in Figure 9 is sent back out-of-band to the sender node,
for both Links and SR Policies. The Sender Control Code is set to
"Out-of-band Response Requested". In this delay measurement mode, as
per Reference Topology, all timestamps t1, t2, t3, and t4 are
collected by the probes. However, only timestamps t1 and t2 are used
to measure one-way delay.
4.2.2. Two-way Measurement Mode
In two-way performance measurement mode, when using a bidirectional
path, the probe response message as defined in Figure 9 is sent back
to the sender node on the congruent path of the data traffic on the
same reverse direction Link or associated reverse SR Policy
[I-D.ietf-pce-sr-bidir-path]. The Sender Control Code is set to "In-
band Response Requested". In this delay measurement mode, as per
Reference Topology, all timestamps t1, t2, t3, and t4 are collected
by the probes. All four timestamps are used to measure two-way
delay.
Specifically, the probe response message is sent back on the incoming
physical interface where the probe query message is received. This
is required for example, in case of two-way measurement mode for Link
delay.
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4.2.2.1. Probe Response Message for SR-MPLS Policy
The message content for sending probe response message for two-way
end-to-end performance measurement of an SR-MPLS Policy 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 9 |
. .
+---------------------------------------------------------------+
Figure 10: Example Probe Response Message for SR-MPLS Policy
The Path Segment Identifier (PSID)
[I-D.ietf-spring-mpls-path-segment] of the forward SR Policy in the
probe query can be used to find the associated reverse SR Policy
[I-D.ietf-pce-sr-bidir-path] to send the probe response message for
two-way measurement of SR Policy.
4.2.2.2. 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 with SRH is shown in Figure 11.
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+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Reflector IPv6 Address .
. Destination IP Address = Destination IPv6 Address .
. .
+---------------------------------------------------------------+
| SRH as specified in RFC 8754 |
. <Segment List> .
. .
+---------------------------------------------------------------+
| IP Header (Optional) |
. Source IP Address = Reflector IPv6 Address .
. Destination IP Address = Source IPv6 Address from Query .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Sender .
. Destination Port = User-configured Port .
. .
+---------------------------------------------------------------+
| Payload = DM Message as specified in Section 4.2.1 of RFC 5357|
. Payload = LM Message as specified in Figure 12 or 13 .
. .
+---------------------------------------------------------------+
Figure 11: Example Probe Response Message for SRv6 Policy
4.2.3. Loss Measurement Response Message Formats
In this document, TWAMP Light probe response message formats are
defined for loss measurement as shown in Figure 12 and Figure 13.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|B| Reserved | Block Number | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|B| Reserved |Sender Block Nu| MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | |
+-+-+-+-+-+-+-+-+ +
| |
. .
. Packet Padding .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: TWAMP Light LM Probe Response Message - Unauthenticated
Mode
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|B| Reserved | Block Number | MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Receive Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|B| Reserved |Sender Block Nu| MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | |
+-+-+-+-+-+-+-+-+ |
| MBZ (15 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Packet Padding .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: TWAMP Light LM Probe Response Message - Authenticated Mode
4.3. Additional Probe Message Processing Rules
The processing rules defined in this section are applicable to TWAMP
Light messages for delay and loss measurement for Links and end-to-
end SR Paths including SR Policies.
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4.3.1. TTL and Hop Limit
The TTL field in the IPv4 and MPLS headers of the probe query
messages is set to 255 [RFC5357]. Similarly, the Hop Limit field in
the IPv6 and SRH headers of the probe query messages is set to 255
[RFC5357].
When using the Destination IPv4 Address from the 127/8 range, the TTL
field in the IPv4 header is set to 1 [RFC8029]. Similarly, when
using the Destination IPv6 Address from the ::FFFF:127/104 range, the
Hop Limit field in the IPv6 header is set to 1.
For Link performance delay and loss measurements, the TTL or Hop
Limit field in the probe message is set to 1 in both one-way and two-
way measurement modes.
4.3.2. Router Alert Option
The Router Alert IP option (RAO) [RFC2113] is not set in the probe
messages.
4.3.3. UDP Checksum
The UDP 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 value 0 for the UDP port being
used for PM delay and loss measurements.
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.ietf-spring-segment-routing-policy] are also equally applicable
to the Point-to-Multipoint (P2MP) SR Policies as following:
o The sender root node sends probe query messages using the
Replication Segment defined in
[I-D.voyer-spring-sr-replication-segment] for the P2MP SR Policy
as shown in Figure 14.
o Each reflector leaf node sends its IP address in the Source
Address of the probe response messages as shown in Figure 9. This
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allows the sender root node to identify the reflector 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 of the P2MP 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replication SID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 2 for DM or Figure 3 for LM |
. .
+---------------------------------------------------------------+
Figure 14: Example Query with Replication Segment for SR-MPLS Policy
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. The mechanisms described in
[RFC8029] and [RFC5884] for handling ECMPs are also applicable to the
performance measurement. In IPv4 header of the PM probe messages,
sweeping of Destination Address in 127/8 range can be used to
exercise particular ECMP paths. As specified in [RFC6437], Flow
Label field in the outer IPv6 header can also be used for sweeping.
The considerations for performance loss measurement for different
ECMP paths of an SR Policy are outside the scope of this document.
7. Performance Delay and Liveness Monitoring
The procedure defined in this document for delay measurement using
the TWAMP Light probe messages can also be applied to liveness
monitoring of Links and SR Paths. The one-way or two-way measurement
mode can be used for liveness monitoring. Liveness failure is
notified when consecutive N number of probe response messages are not
received back at the sender node, where N is locally provisioned
value. Note that detection interval and scale for number of sessions
need to account for the processing of the probe messages which are
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punted out of fast path in forwarding (to slow path or control
plane), and re-injected back on the reflector node.
8. 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
reflector node.
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 protects the data
integrity of the probe messages. SRv6 has HMAC protection
authentication defined for SRH [RFC8754]. 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.
9. IANA Considerations
This document does not require any IANA action.
10. References
10.1. Normative References
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<https://www.rfc-editor.org/info/rfc4656>.
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[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<https://www.rfc-editor.org/info/rfc5357>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References
[IEEE1588]
IEEE, "1588-2008 IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", March 2008.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>.
[RFC2113] Katz, D., "IP Router Alert Option", RFC 2113,
DOI 10.17487/RFC2113, February 1997,
<https://www.rfc-editor.org/info/rfc2113>.
[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,
<https://www.rfc-editor.org/info/rfc4868>.
[RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
June 2010, <https://www.rfc-editor.org/info/rfc5884>.
[RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement
Protocol (TWAMP) Reflect Octets and Symmetrical Size
Features", RFC 6038, DOI 10.17487/RFC6038, October 2010,
<https://www.rfc-editor.org/info/rfc6038>.
[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, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
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[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
"IPv6 Flow Label Specification", RFC 6437,
DOI 10.17487/RFC6437, November 2011,
<https://www.rfc-editor.org/info/rfc6437>.
[RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement
for the Use of IPv6 UDP Datagrams with Zero Checksums",
RFC 6936, DOI 10.17487/RFC6936, April 2013,
<https://www.rfc-editor.org/info/rfc6936>.
[RFC7820] Mizrahi, T., "UDP Checksum Complement in the One-Way
Active Measurement Protocol (OWAMP) and Two-Way Active
Measurement Protocol (TWAMP)", RFC 7820,
DOI 10.17487/RFC7820, March 2016,
<https://www.rfc-editor.org/info/rfc7820>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>.
[RFC8186] Mirsky, G. and I. Meilik, "Support of the IEEE 1588
Timestamp Format in a Two-Way Active Measurement Protocol
(TWAMP)", RFC 8186, DOI 10.17487/RFC8186, June 2017,
<https://www.rfc-editor.org/info/rfc8186>.
[RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate-Marking Method for Passive and Hybrid
Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
January 2018, <https://www.rfc-editor.org/info/rfc8321>.
[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, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8545] Morton, A., Ed. and G. Mirsky, Ed., "Well-Known Port
Assignments for the One-Way Active Measurement Protocol
(OWAMP) and the Two-Way Active Measurement Protocol
(TWAMP)", RFC 8545, DOI 10.17487/RFC8545, March 2019,
<https://www.rfc-editor.org/info/rfc8545>.
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[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-07 (work in progress),
May 2020.
[I-D.voyer-spring-sr-replication-segment]
Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z.
Zhang, "SR Replication Segment for Multi-point Service
Delivery", draft-voyer-spring-sr-replication-segment-03
(work in progress), June 2020.
[I-D.ietf-spring-mpls-path-segment]
Cheng, W., Li, H., Chen, M., Gandhi, R., and R. Zigler,
"Path Segment in MPLS Based Segment Routing Network",
draft-ietf-spring-mpls-path-segment-02 (work in progress),
February 2020.
[I-D.ietf-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J., Voyer, D.,
Matsushima, S., and Z. Li, "SRv6 Network Programming",
draft-ietf-spring-srv6-network-programming-15 (work in
progress), March 2020.
[BBF.TR-390]
"Performance Measurement from IP Edge to Customer
Equipment using TWAMP Light", BBF TR-390, May 2017.
[I-D.gandhi-mpls-ioam-sr]
Gandhi, R., Ali, Z., Filsfils, C., Brockners, F., Wen, B.,
and V. Kozak, "MPLS Data Plane Encapsulation for In-situ
OAM Data", draft-gandhi-mpls-ioam-sr-02 (work in
progress), March 2020.
[I-D.ali-spring-ioam-srv6]
Ali, Z., Gandhi, R., Filsfils, C., Brockners, F., Kumar,
N., Pignataro, C., Li, C., Chen, M., and G. Dawra,
"Segment Routing Header encapsulation for In-situ OAM
Data", draft-ali-spring-ioam-srv6-02 (work in progress),
November 2019.
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[I-D.ietf-pce-sr-bidir-path]
Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
"PCEP Extensions for Associated Bidirectional Segment
Routing (SR) Paths", draft-ietf-pce-sr-bidir-path-02 (work
in progress), March 2020.
Acknowledgments
The authors would like to thank Thierry Couture for the discussions
on the use-cases for Performance Measurement in Segment Routing. The
authors would also like to thank Greg Mirsky for reviewing this
document and providing useful comments and suggestions. Patrick
Khordoc and Radu Valceanu, both from Cisco Systems have helped
significantly improve the mechanisms defined in this document. The
authors would like to acknowledge the earlier work on the loss
measurement using TWAMP described in draft-xiao-ippm-twamp-ext-
direct-loss.
Authors' Addresses
Rakesh Gandhi (editor)
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
Email: cfilsfil@cisco.com
Daniel Voyer
Bell Canada
Email: daniel.voyer@bell.ca
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
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Bart Janssens
Colt
Email: Bart.Janssens@colt.net
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