In-band Performance Measurement Using TWAMP for Segment Routing Networks
draft-gandhi-spring-twamp-srpm-00
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|---|---|---|---|
| Authors | Rakesh Gandhi , Clarence Filsfils , Daniel Voyer | ||
| Last updated | 2019-02-09 | ||
| Replaced by | draft-gandhi-spring-stamp-srpm | ||
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draft-gandhi-spring-twamp-srpm-00
SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended Status: Standards Track Cisco Systems, Inc.
Expires: August 13, 2019 D. Voyer
Bell Canada
February 9, 2019
In-band Performance Measurement Using TWAMP
for Segment Routing Networks
draft-gandhi-spring-twamp-srpm-00
Abstract
Segment Routing (SR) is applicable to both Multiprotocol Label
Switching (SR-MPLS) and IPv6 (SRv6) data planes. This document
specifies procedures for sending and processing in-band probe query
and response messages for Performance Measurement. The procedure
uses the mechanisms defined in RFC 5357 (Two-Way Active Measurement
Protocol (TWAMP)) for Delay Measurement, and also uses the mechanisms
for direct-mode loss measurement defined in this document. 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
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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
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Reference Topology . . . . . . . . . . . . . . . . . . . . 4
2.4. In-band Probe Messages . . . . . . . . . . . . . . . . . . 5
3. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 5
3.1.1. Delay Measurement Probe Query Message . . . . . . . . 5
3.1.2. Loss Measurement Probe Query Message . . . . . . . . . 6
3.1.3. Probe Query for SR Links . . . . . . . . . . . . . . . 10
3.1.4. Probe Query for End-to-end Measurement for SR Policy . 11
3.1.4.1. Probe Query Message for SR-MPLS Policy . . . . . . 11
3.1.4.2. Probe Query Message for SRv6 Policy . . . . . . . 11
3.2. Probe Response Message . . . . . . . . . . . . . . . . . . 12
3.2.1. One-way Measurement . . . . . . . . . . . . . . . . . 12
3.2.2. Two-way Measurement . . . . . . . . . . . . . . . . . 12
3.2.2.1. Probe Response Message for SR-MPLS Policy . . . . 13
3.2.2.2. Probe Response Message for SRv6 Policy . . . . . . 13
4. Packet Loss Calculation . . . . . . . . . . . . . . . . . . . 13
5. Performance Measurement for P2MP SR Policies . . . . . . . . . 14
6. ECMP Support . . . . . . . . . . . . . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 15
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
Segment Routing (SR) technology greatly simplifies network operations
for Software Defined Networks (SDNs). SR is applicable to both
Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) data planes.
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SR takes advantage of the Equal-Cost Multipaths (ECMPs) between
source, 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 path 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 direct-mode Loss Measurement (LM) to
detect actual data traffic loss which is required in SR networks.
The Simple Two-way Active Measurement Protocol (STAMP)
[I-D.ippm-stamp] alleviates the control channel signaling by using
configuration data model to provision test channels and required UDP
ports. The TWAMP Light from broadband forum [BBF.TR-390] provides
simplified mechanisms for active performance measurement in Customer
Edge IP networks.
This document specifies procedures for sending and processing in-band
probe query and response messages for Performance Measurement. The
procedure uses the mechanisms defined in RFC 5357 (Two-Way Active
Measurement Protocol (TWAMP)) for Delay Measurement, and also uses
the mechanisms for direct-mode loss measurement defined in this
document. The procedure specified is applicable to SR-MPLS and SRv6
data planes for both links and end-to-end measurement for SR
Policies. For SR Policies, there are ECMPs between the source and
transit nodes, between transit nodes and between transit and
destination nodes. This document also defines mechanisms for
handling ECMPs of SR Policies for performance delay measurement.
2. Conventions Used in This Document
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119] [RFC8174]
when, and only when, they appear in all capitals, as shown here.
2.2. Abbreviations
BSID: Binding Segment ID.
DM: Delay Measurement.
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ECMP: Equal Cost Multi-Path.
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.
2.3. Reference Topology
In the reference topology, the querier 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 response
may be sent to the querier node R1. The nodes R1 and R5 may be
directly connected via a link enabled with Segment Routing or there
exists a Point-to-Point (P2P) SR Policy
[I-D.spring-segment-routing-policy] on node R1 with destination to
node R5. In case of Point-to-Multipoint (P2MP), SR Policy
originating from source node R1 may terminate on multiple destination
leaf nodes [I-D.spring-sr-p2mp-policy].
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+-------+ Query +-------+
| | - - - - - - - - - ->| |
| R1 |---------------------| R5 |
| |<- - - - - - - - - - | |
+-------+ Response +-------+
Reference Topology
Both Delay and Loss performance measurement is performed in-band for
the traffic traversing between node R1 and node R5. One-way delay
and two-way delay measurements are defined in [RFC4656] and
[RFC5357], respectively. One-way loss measurement provides receive
packet loss whereas two-way loss measurement provides both transmit
and receive packet loss.
2.4. In-band Probe Messages
For both Delay and Loss measurements for links and SR Policies, no PM
session is created on the responder node. The probe messages for
Delay measurement are sent in-band by the querier node to measure the
delay experienced by the actual traffic flowing on the links and SR
Policies. For Loss measurement, in-band probe messages are used to
collect the traffic counter for the incoming link or incoming SID on
which the probe query message is received at the responder node R5 as
it has no PM session state present on the node. The performance
measurement for Delay and Loss using out-of-band probe query messages
are outside the scope of this document.
3. Probe Messages
3.1. Probe Query Message
In this document, procedures using [RFC5357] is used for Delay and
Loss measurements for SR links and end-to-end SR Policies. A
user-configured UDP port is used for identifying PM probe packets
that does not require to bootstrap PM sessions. A UDP port number
from the Dynamic and/or Private Ports range 49152-65535 is used as
the destination UDP port. This approach is similar to the one
defined in STAMP protocol [I-D.ippm-stamp]. The IPv4 TTL or IPv6 Hop
Limit field of the IP header MUST be set to 255.
3.1.1. Delay Measurement Probe Query Message
The message content for Delay Measurement 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 [I-D.ippm-
stamp]. The Source UDP port is set to the same value for two-way
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delay measurement. The DM probe query message contains the payload
for delay measurement defined in Section 4.2.1 of [RFC5357] for TWAMP
or in Section 4.1.2 of [RFC4656] for OWAMP.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for Delay Measurement.
. .
+---------------------------------------------------------------+
| Payload = Message as specified in Section 4.2.1 of RFC 5357 |
| | Payload = Message as specified in Section 4.1.2 of RFC 4656 |
. .
+---------------------------------------------------------------+
Figure 1: DM Probe Query Message
Timestamp field is eight bytes and by default uses the IEEE 1588v2
Precision Time Protocol (PTP) truncated 64-bit timestamp format
[IEEE1588].
3.1.2. Loss Measurement Probe Query Message
The message content for Loss Measurement probe query message using
UDP header [RFC768] is shown in Figure 2. The LM probe query message
is sent with user-configured Destination UDP port number [I-D.ippm-
stamp]. The Source UDP port is set to the same value for two-way
loss measurement. The LM probe query message contains the payload
for loss measurement defined below.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
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. Destination Port = User-configured Port for Loss Measurement .
. .
+---------------------------------------------------------------+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | Block Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Padding |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2A: LM Probe Query Message for TWAMP
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for Loss Measurement .
. .
+---------------------------------------------------------------+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
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| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receive Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | Block Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Padding |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2B: LM Probe Query Message for TWAMP - Authenticated Mode
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
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. Destination Port = User-configured Port for Loss Measurement .
. .
+---------------------------------------------------------------+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | Block Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Padding |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2C: LM Probe Query Message for OWAMP
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for Loss Measurement .
. .
+---------------------------------------------------------------+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transmit Counter |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (8 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender TTL | Block Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ (12 octets) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| HMAC (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Padding |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2D: LM Probe Query Message for OWAMP - Authenticated Mode
Sequence Number (32-bit): As defined in [RFC5357].
Transmit Counter (64-bit): The number of packets sent by the querier
node in the query message and by the responder node in the response
message. The counter is always written at fixed location in the
probe query and response messages.
Receive Counter (64-bit): The number of packets received at the
responder node. It is written by the responder 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
responder node in the probe response message.
Sender Sequence Number (32-bit): As defined in [RFC5357].
Sender TTL: As defined in [RFC5357].
Block Number (24-bit): The Loss Measurement using Alternate-Marking
method defined in [RFC8321] requires to identify the Block Number (or
color) of the traffic counters. The probe query and response
messages carry Block Number for the traffic counters for loss
measurement. In both probe query and response messages, the counters
MUST belong to the same Block Number.
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.
3.1.3. Probe Query for SR Links
The probe query message as defined in Figure 1 is sent in-band for
Delay measurement. The probe query message as defined in Figure 2 is
sent in-band for Loss measurement.
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3.1.4. Probe Query for End-to-end Measurement for SR Policy
3.1.4.1. Probe Query Message for SR-MPLS Policy
The message content for in-band probe query message using UDP header
for end-to-end performance measurement of SR-MPLS Policy is 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(0) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(n) | 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.
3.1.4.2. Probe Query Message for SRv6 Policy
The in-band probe query messages using UDP header for end-to-end
performance measurement of an SRv6 Policy is sent using SRv6 Segment
Routing Header (SRH) and Segment List of the SRv6 Policy as defined
in [I-D.6man-segment-routing-header] and is shown in Figure 4.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRH |
. 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 Addresses) .
. .
+---------------------------------------------------------------+
Figure 4: Probe Query Message for SRv6 Policy
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For delay measurement of SRv6 Policy, END function END.OTP
[I-D.spring-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.spring-srv6-oam] is used with target SRv6 SID to punt probe
messages on the target node.
3.2. Probe Response Message
The probe response message is sent using the IP/UDP information from
the 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 .
. .
+---------------------------------------------------------------+
| Payload as specified in Section 4.2.1 of RFC 5357, or |
. Payload as specified in Figure 2 in this document .
. .
+---------------------------------------------------------------+
Figure 5: Probe Response Message
3.2.1. One-way Measurement
For one-way performance measurement, the probe response message as
defined in Figure 5 is sent for both SR links and SR Policies.
3.2.2. Two-way Measurement
For two-way performance measurement, when using a bidirectional
channel, the probe response message as defined in Figure 5 is sent
back in-band to the querier node.
The Path Segment Identifier (PSID) [I-D.spring-mpls-path-segment] of
the forward SR Policy can be used to find the reverse SR Policy to
send the probe response message for two-way measurement of SR Policy.
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3.2.2.1. Probe Response Message for SR-MPLS Policy
The message content for sending probe response message in-band using
UDP header for two-way end-to-end performance measurement of an
SR-MPLS Policy is shown in Figure 6.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(0) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 5 |
. .
+---------------------------------------------------------------+
Figure 6: Probe Response Message for SR-MPLS Policy
3.2.2.2. Probe Response Message for SRv6 Policy
The message content for sending probe response message in-band using
UDP header for two-way end-to-end performance measurement of an SRv6
Policy is shown in Figure 7.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRH |
. END.OTP (DM) or END.OP (LM) with Target SRv6 SID .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 5 (with IPv6 Addresses) |
. .
+---------------------------------------------------------------+
Figure 7: Probe Response Message for SRv6 Policy
4. Packet Loss Calculation
The formula for calculating the one-way packet loss using counters
for a given block number is as following:
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o One-way Packet_Loss[n-1, n] = (Sender_Counter[n] -
Sender_Counter[n-1]) - (Receive_Counter[n] - Receive_Counter[n-1])
5. Performance Measurement for P2MP SR Policies
The procedures for delay and loss measurement described in this
document for Point-to-Point (P2P) SR-MPLS Policies are also equally
applicable to the Point-to-Multipoint (P2MP) SR Policies.
6. ECMP Support
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] [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, entropy label [RFC6790] in the PM probe messages can
be used.
o For SRv6, Flow Label in SRH [I-D.6man-segment-routing-header] of
the PM probe messages can be used.
7. 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.
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If desired, attacks can be mitigated by performing basic validation
and sanity checks, at the querier, 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.
8. IANA Considerations
This document does not require any IANA actions.
9. References
9.1. 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.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", RFC 8174, May 2017.
[I-D.spring-srv6-oam] Ali, Z., et al., "Operations, Administration,
and Maintenance (OAM) in Segment Routing Networks with
IPv6 Data plane (SRv6)", draft-ali-spring-srv6-oam.
9.2. Informative References
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[IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", March 2008.
[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.
[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.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Kumar, N.,
Aldrin, S. and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029, March
2017.
[RFC8321] Fioccola, G. Ed., "Alternate-Marking Method for Passive
and Hybrid Performance Monitoring", RFC 8321, January
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, <https://www.rfc-editor.org/info/rfc8402>.
[I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment
Routing Policy Architecture",
draft-ietf-spring-segment-routing-policy, work in
progress.
[I-D.spring-sr-p2mp-policy] Voyer, D. Ed., et al., "SR Replication
Policy for P2MP Service Delivery",
draft-voyer-spring-sr-p2mp-policy, work in progress.
[I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in
MPLS Based Segment Routing Network", draft-cheng-spring-
mpls-path-segment, work in progress.
[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.ippm-stamp] Mirsky, G. et al. "Simple Two-way Active
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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.
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Acknowledgments
TBA
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
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