Internet DRAFT - draft-gandhi-spring-rfc6374-srpm-udp
draft-gandhi-spring-rfc6374-srpm-udp
SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended status: Standards Track Cisco Systems, Inc.
Expires: February 7, 2021 D. Voyer
Bell Canada
S. Salsano
Universita di Roma "Tor Vergata"
M. Chen
Huawei
August 6, 2020
Performance Measurement Using RFC 6374 with UDP Path for Segment Routing
Networks
draft-gandhi-spring-rfc6374-srpm-udp-05
Abstract
Segment Routing (SR) leverages the source routing paradigm. Segment
Routing (SR) is applicable to both Multiprotocol Label Switching (SR-
MPLS) and IPv6 (SRv6) data planes. This document specifies
procedures for using UDP path for sending and processing probe query
and response messages for Performance Measurement (PM). The
procedure uses the mechanisms defined in RFC 6374 for Performance
Delay and Loss Measurement. The procedure specified is applicable to
SR-MPLS and SRv6 data planes for both Links and end-to-end SR Paths
including SR Policies measurements.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 7, 2021.
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Copyright Notice
Copyright (c) 2020 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Reference Topology . . . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Example Provisioning Model . . . . . . . . . . . . . . . 6
4. Probe Query Message . . . . . . . . . . . . . . . . . . . . . 7
4.1. Delay Measurement Probe Query Message . . . . . . . . . . 7
4.2. Loss Measurement Probe Query Message . . . . . . . . . . 7
4.3. Combined Loss/Delay Measurement Probe Query Message . . . 8
4.4. Probe Query Message for Links . . . . . . . . . . . . . . 9
4.5. Probe Query Message for SR Policies . . . . . . . . . . . 9
4.5.1. Probe Query Message for SR-MPLS Policy . . . . . . . 9
4.5.2. Probe Query Message for SRv6 Policy . . . . . . . . . 10
5. Probe Response Message . . . . . . . . . . . . . . . . . . . 11
5.1. One-way Measurement Mode . . . . . . . . . . . . . . . . 13
5.1.1. Links and SR Policies . . . . . . . . . . . . . . . . 13
5.1.2. Probe Response Message to Controller . . . . . . . . 13
5.2. Two-way Measurement Mode . . . . . . . . . . . . . . . . 13
5.2.1. Links . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2.2. SR Policies . . . . . . . . . . . . . . . . . . . . . 13
5.2.3. Return Path TLV Extensions . . . . . . . . . . . . . 14
5.2.4. Probe Response Message for SR-MPLS Policy . . . . . . 14
5.2.5. Probe Response Message for SRv6 Policy . . . . . . . 15
5.3. Loopback Measurement Mode . . . . . . . . . . . . . . . . 15
6. Performance Measurement for P2MP SR Policies . . . . . . . . 16
7. ECMP Support for SR Policies . . . . . . . . . . . . . . . . 16
8. Additional Probe Message Processing Rules . . . . . . . . . . 16
9. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Sequence Number TLV Extension in Unauthenticated Mode . . 16
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9.2. Sequence Number TLV Extension in Authenticated Mode . . . 17
10. Performance Delay and Liveness Monitoring . . . . . . . . . . 18
11. Security Considerations . . . . . . . . . . . . . . . . . . . 19
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
13.1. Normative References . . . . . . . . . . . . . . . . . . 20
13.2. Informative References . . . . . . . . . . . . . . . . . 20
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 22
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
Segment Routing (SR) leverages the source routing paradigm and
greatly simplifies network operations for Software Defined Networks
(SDNs). SR is applicable to both Multiprotocol Label Switching (SR-
MPLS) and IPv6 (SRv6) data planes. SR takes advantage of the Equal-
Cost Multipaths (ECMPs) between source and transit nodes, between
transit nodes and between transit and destination nodes. SR Policies
as defined in [I-D.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).
[RFC6374] specifies protocol mechanisms to enable the efficient and
accurate measurement of performance metrics and can be used in SR
networks with MPLS data plane [I-D.ietf-mpls-rfc6374-sr]. [RFC6374]
addresses the limitations of the IP based performance measurement
protocols as specified in Section 1 of [RFC6374]. [RFC6374] requires
data plane to support MPLS Generic Associated Channel Label (GAL) and
Generic Associated Channel (G-ACh), which may not be supported on all
nodes in the segment routing network.
[RFC7876] specifies the procedures to be used when sending and
processing out-of-band performance measurement probe response
messages over an UDP return path for RFC 6374 based probe queries.
[RFC7876] can be used to send out-of-band probe response messages in
both SR-MPLS and SRv6 networks for one-way performance measurement.
For SR Policies, there are ECMPs between the source and transit
nodes, between transit nodes and between transit and destination
nodes. RFC 6374 does not define handling for ECMP forwarding paths
when used in SR networks.
For two-way measurements for SR Policies, there is a requirement to
specify a return path in the form of a Segment List in probe query
messages that does not require on any SR Policy state information on
the destination node.
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This document specifies a procedure for sending and processing probe
query and response messages using UDP paths for Performance
Measurement in SR networks. The procedure uses RFC 6374 defined
mechanisms for Performance Delay and Loss Measurement and unless
otherwise specified, the procedures from RFC 6374 are not modified.
The procedure specified is applicable to both SR-MPLS and SRv6 data
planes. The procedure can be used for both Links and end-to-end SR
Paths including SR Policies and Flex-Algo IGP Paths.
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.
ECMP: Equal Cost Multi-Path.
G-ACh: Generic Associated Channel (G-ACh).
GAL: Generic Associated Channel (G-ACh) Label.
LM: Loss Measurement.
MPLS: Multiprotocol Label Switching.
NTP: Network Time Protocol.
PM: Performance Measurement.
PSID: Path Segment Identifier.
PTP: Precision Time Protocol.
SID: Segment ID.
SL: Segment List.
SR: Segment Routing.
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SRH: Segment Routing Header.
SR-MPLS: Segment Routing with MPLS data plane.
SRv6: Segment Routing with IPv6 data plane.
TC: Traffic Class.
URO: UDP Return Object.
2.3. Reference Topology
In the reference topology shown below, the querier node R1 initiates
a probe query for performance measurement and the responder node R5
sends a probe response message for the probe query message received.
The probe response message may be sent to the querier node R1 or to a
controller node R100.
SR is enabled on nodes R1 and R5. 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 Path e.g. SR Policy
[I-D.ietf-spring-segment-routing-policy] on node R1 (called head-end)
with destination to node R5 (called head-end).
------
|R100|
------
^
| Response
|
t1 t2 |
/ \ |
+-------+ Query +-------+
| | - - - - - - - - - ->| |
| R1 |=====================| R5 |
| |<- - - - - - - - - - | |
+-------+ Response +-------+
\ /
t4 t3
Querier Responder
Reference Topology
3. Overview
For one-way, two-way and round-trip delay measurements in Segment
Routing networks, the procedures defined in Section 2.4 and
Section 2.6 of [RFC6374] are used. For transmit and receive packet
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loss measurements, the procedures defined in Section 2.2 and
Section 2.6 of [RFC6374] are used. The procedures use probe messages
with IP/UDP path and do not use MPLS GAL. For both Links and end-to-
end SR Paths including SR Policies and Flex-Algo IGP Paths, no PM
state for delay or loss measurement is created on the responder node
R5 [RFC6374].
Separate UDP destination port numbers are user-configured for delay
and loss measurements from the range specified in [RFC8762]. The
querier and responder nodes use the destination UDP port number
following the guidelines specified in Section 6 in [RFC6335]. The
same destination UDP port is used for Links and SR Paths and the
responder is unaware if the query is for the Links or SR Paths. The
number of UDP ports with PM functionality needs to be minimized due
to limited hardware resoucres.
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 querier 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 querier node, and are used to
collect the receive traffic counters for the incoming link or
incoming SID where the probe query messages are received at the
responder node (incoming link or incoming SID needed since the
responder node does not have PM state present).
The In-Situ Operations, Administration, and Maintenance (IOAM)
mechanisms for SR-MPLS defined in [I-D.gandhi-mpls-ioam-sr] and for
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 provisioning model described in
[I-D.gandhi-spring-stamp-srpm] is also applicable to the procedures
defined in this document, albeit using the Measurrement Protocol as
[RFC6374]. The querier node is the sender node and the responder
node is the reflector node when using [RFC6374]. The provisioning
model is not used for signaling PM parameters between the responder
and querier nodes in SR networks.
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4. Probe Query Message
In this document, UDP path is used for delay and loss measurements
for Links and end-to-end SR Policies for the probe messages defined
in [RFC6374]. The user-configured destination UDP ports (separate
UDP ports for different delay and loss message formats) are used for
identifying the probe messages.
4.1. Delay Measurement Probe Query Message
The message content for delay measurement for probe query message
using UDP header [RFC0768] is shown in Figure 1. The DM probe query
message is sent with user-configured Destination UDP port number for
DM. The Destination UDP port can also be used as Source port for
two-way delay measurement, since the message has a flag to
distinguish between query and response. The DM probe query message
contains the payload format for delay measurement defined in
Section 3.2 of [RFC6374].
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for Delay Measurement.
. .
+---------------------------------------------------------------+
| Payload = Message as specified in Section 3.2 of RFC 6374 |
. .
+---------------------------------------------------------------+
Figure 1: DM Probe Query Message
It is recommended to use the IEEE 1588v2 Precision Time Protocol
(PTP) truncated 64-bit timestamp format as a default format as
specified in Appendix A of [RFC6374], with hardware support. As an
alternative, Network Time Protocol (NTP) timestamp format can also be
used [RFC6374].
4.2. Loss Measurement Probe Query Message
The message content for loss measurement probe query message using
UDP header [RFC0768] is shown in Figure 2. As shown, the LM probe
query message is sent with user-configured Destination UDP port
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number for LM. Separate Destination UDP ports are used for direct-
mode and inferred-mode loss measurements. The Destination UDP port
can also be used as Source port for two-way loss measurement, since
the message has a flag to distinguish between query and response.
The LM probe query message contains the payload format for loss
measurement defined in Section 3.1 of [RFC6374].
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for Loss Measurement .
. .
+---------------------------------------------------------------+
| Payload = Message as specified in Section 3.1 of RFC 6374 |
. .
+---------------------------------------------------------------+
Figure 2: LM Probe Query Message
4.3. Combined Loss/Delay Measurement Probe Query Message
The message content for combined Loss/Delay measurement probe query
message using UDP header [RFC0768] is shown in Figure 3. As shown,
the probe query message is sent with user-configured Destination UDP
port number for combined LM/DM message format. Separate Destination
UDP ports are used for direct-mode and inferred-mode loss
measurements. The Destination UDP port can also be used as Source
port for two-way loss/delay measurement, since the message has a flag
to distinguish between query and response. The probe query message
contains the payload format for combined loss/delay measurement
defined in Section 3.3 of [RFC6374].
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+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for .
. Loss/Delay Measurement .
. .
+---------------------------------------------------------------+
| Payload = Message as specified in Section 3.3 of RFC 6374 |
. .
+---------------------------------------------------------------+
Figure 3: LM/DM Probe Query Message
4.4. Probe Query Message for Links
The probe query message as defined in Figure 1 for delay measurement
and Figure 2 for loss measurement are used for Links which may be
physical, virtual or LAG (bundle), LAG (bundle) member, numbered/
unnumbered Links. The probe messages are pre-routed over the Link
for both delay and loss measurement.
4.5. Probe Query Message for SR Policies
The performance delay and loss measurement for segment routing is
applicable to both end-to-end SR-MPLS and SRv6 Policies.
4.5.1. Probe Query Message for SR-MPLS Policy
The probe query message for performance measurement of end-to-end SR-
MPLS Policy is sent using its SR-MPLS header containing the MPLS
segment list as shown in Figure 4.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload = DM Message as specified in Figure 1 |
. Payload = LM Message as specified in Figure 2 .
. Payload = LM/DM Message as specified in Figure 3 .
. .
+---------------------------------------------------------------+
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.
4.5.2. Probe Query Message for SRv6 Policy
An SRv6 Policy setup using the SRv6 Segment Routing Header (SRH) and
a Segment List is defined in [RFC8754]. The SRv6 network programming
is defined in [I-D.ietf-spring-srv6-network-programming]. The probe
query messages using UDP header for performance measurement of end-
to-end SRv6 Policy is sent using its SRv6 Segment Routing Header
(SRH) with Segment List as shown in Figure 5. The procedure defined
for upper-layer header processing for SRv6 SIDs in
[I-D.ietf-spring-srv6-network-programming] is used to process the UDP
header in the received probe query messages.
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+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Querier IPv6 Address .
. Destination IP Address = Destination IPv6 Address .
. .
+---------------------------------------------------------------+
| SRH as specified in RFC 8754 |
. <Segment List> .
. .
+---------------------------------------------------------------+
| IP Header (as needed) |
. Source IP Address = Querier IPv6 Address .
. Destination IP Address = Responder IPv6 Address .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port .
. .
+---------------------------------------------------------------+
| Payload = DM Message as specified in Figure 1 |
. Payload = LM Message as specified in Figure 2 .
. Payload = LM/DM Message as specified in Figure 3 .
. .
+---------------------------------------------------------------+
Figure 5: Example Probe Query Message for SRv6 Policy
5. Probe Response Message
When the received probe query message does not contain any UDP Return
Object (URO) TLV [RFC7876], the probe response message is sent using
the IP/UDP information from the received probe query message. The
content of the probe response message is shown in Figure 6.
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+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Responder IPv4 or IPv6 Address .
. Destination IP Address = Source IP Address from Query .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Responder .
. Destination Port = Source Port from Query .
. .
+---------------------------------------------------------------+
| Message as specified in Section 3.2 of RFC 6374 for DM, or |
. Message as specified in Section 3.1 of RFC 6374 for LM, or .
. Message as specified in Section 3.3 of RFC 6374 for LM/DM .
. .
+---------------------------------------------------------------+
Figure 6: Probe Response Message
When the received probe query message contains UDP Return Object
(URO) TLV [RFC7876], the probe response message uses the IP/UDP
information from the URO in the probe query message. The content of
the probe response message is shown in Figure 7.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Responder IPv4 or IPv6 Address .
. Destination IP Address = URO.Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Responder .
. Destination Port = URO.UDP-Destination-Port .
. .
+---------------------------------------------------------------+
| Message as specified in Section 3.2 of RFC 6374 for DM, or |
. Message as specified in Section 3.1 of RFC 6374 for LM, or .
. Message as specified in Section 3.3 of RFC 6374 for LM/DM .
. .
+---------------------------------------------------------------+
Figure 7: Probe Response Message Using URO from Probe Query
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5.1. One-way Measurement Mode
5.1.1. Links and SR Policies
In one-way measurement mode, the probe response message as defined in
Figure 6 or Figure 7 is sent out-of-band to the querier node, for
both Links and SR Policies.
The querier node can receive probe response message back by setting
its own IP address as Source Address of the header or by adding URO
TLV in the probe query message and setting its own IP address in the
IP Address in the URO TLV (Type=131) [RFC7876]. The "control code"
in the probe query message is set to "out-of-band response
requested". The "Source Address" TLV (Type 130), and "Return
Address" TLV (Type 1), if present in the probe query message, are not
used to send probe response message. In this delay measurement mode,
as per Reference Topology, timestamps t1 and t2 are collected by the
probes to measure one-way delay as (t2 - t1).
5.1.2. Probe Response Message to Controller
As shown in the Reference Topology, if the querier node requires the
probe response message to be sent to the controller R100, it adds URO
TLV in the probe query message and sets the IP address of R100 in the
IP Address field and user-configured UDP port for DM and for LM in
the UDP-Destination-Port field of the URO TLV (Type=131) [RFC7876].
5.2. Two-way Measurement Mode
5.2.1. Links
In two-way measurement mode, when using a bidirectional link, the
probe response message as defined in Figure 6 or Figure 7 is sent
back on the congruent path of the data traffic to the querier node
for Links. In this case, the "control code" in the probe query
message is set to "in-band response requested" [RFC6374]. In this
delay measurement mode, as per Reference Topology, timestamps t1, t2,
t3 and t4 are collected by the probes to measure two-way delay as
((t4 - t1) - (t3 - t2)).
5.2.2. SR Policies
In two-way measurement mode, when using a bidirectional path, the
probe response message is sent back on the congruent path of the data
traffic to the querier node for end-to-end SR Policies measurements.
In this case, the "control code" in the probe query message is set to
"in-band response requested" [RFC6374].
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5.2.3. Return Path TLV Extensions
For two-way measurement, the querier node can request the responder
node to send a response message back on a given reverse path (e.g.
co-routed path for two-way measurement). Return Path TLV defined in
[I-D.ietf-mpls-rfc6374-sr] is used to carry reverse SR path
information as part of the payload of the probe query message. This
way the responder node does not require any additional SR state for
PM (recall that in SR networks, the state is in the probe packet and
signaling of the parameters is avoided).
Additional Sub-TLVs are defined in this document for the Return Path
TLV for the following Types:
o Type (value TBA1): SRv6 Segment List of the Reverse Path
o Type (value TBA2): SRv6 Binding SID
[I-D.ietf-pce-binding-label-sid] of the Reverse SR Policy
5.2.4. Probe Response Message for SR-MPLS Policy
The message content for sending probe response message on the
congruent path of the data traffic for two-way end-to-end SR-MPLS
Policy performance measurement is shown in Figure 8. The SR-MPLS
label stack in the probe packet header is built using the Segment
List received in the Return Path TLV in the probe query message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 6 or Figure 7 |
. .
+---------------------------------------------------------------+
Figure 8: Example Probe Response Message for SR-MPLS Policy
The Path Segment Identifier (PSID)
[I-D.ietf-spring-mpls-path-segment] of the forward SR-MPLS Policy can
be used to find the reverse SR-MPLS Policy to send the probe response
message for two-way measurement in the absence of Return Path TLV.
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5.2.5. Probe Response Message for SRv6 Policy
The message content for sending probe response message on the
congruent path of the data traffic for two-way end-to-end SRv6 Policy
performance measurement is shown in Figure 9. For SRv6 Policy using
SRH, the SRv6 SID list in the SRH of the probe response message is
built using the SRv6 Segment List received in the Return Path TLV in
the probe query message. The procedure defined for upper-layer
header processing for SRv6 SIDs in
[I-D.ietf-spring-srv6-network-programming] is used to process the UDP
header in the received probe response messages.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Responder IPv6 Address .
. Destination IP Address = Destination IPv6 Address .
. .
+---------------------------------------------------------------+
| SRH as specified in RFC 8754 |
. <Segment List> .
. .
+---------------------------------------------------------------+
| IP Header (as needed) |
. Source IP Address = Responder IPv6 Address .
. Destination IP Address = Querier IPv6 Address .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Responder .
. Destination Port = Source Port from Query .
. .
+---------------------------------------------------------------+
| Message as specified in Section 3.2 of RFC 6374 for DM, or |
. Message as specified in Section 3.1 of RFC 6374 for LM, or .
. Message as specified in Section 3.3 of RFC 6374 for LM/DM .
. .
+---------------------------------------------------------------+
Figure 9: Example Probe Response Message for SRv6 Policy
5.3. Loopback Measurement Mode
The Loopback measurement mode defined in Section 2.8 of [RFC6374] can
be used to measure round-trip delay of a bidirectional SR Path. The
IP header of the probe query message contains the destination address
equals to the querier node address and the source address equals to
the responder address. Optionally, the probe query message can carry
the reverse path information (e.g. reverse path label stack for SR-
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MPLS) as part of the SR header. The responder node does not process
the probe messages and generate response messages, and hence Loopback
Request object (Type 3) is not required for SR. In this delay
measurement mode, as per Reference Topology, timestamps t1 and t4 are
collected by the probes to measure round-trip delay.
6. Performance Measurement for P2MP SR Policies
The procedure defined for P2MP SR Policies
[I-D.ietf-pim-sr-p2mp-policy] in [I-D.gandhi-spring-stamp-srpm] is
also applicable using the RFC 6374 defined messages in the payload.
7. ECMP Support for SR Policies
The procedure defined for handling ECMP for SR Policies in
[I-D.gandhi-spring-stamp-srpm] is also applicable to the procedure
defined in this document.
8. Additional Probe Message Processing Rules
The additional probe message processing rules defined in
[I-D.gandhi-spring-stamp-srpm] are also applicable to the procedures
defined in this document.
9. Sequence Numbers
The message formats for DM and LM [RFC6374] can carry either
timestamp or sequence number but not both. There are case where both
timestamp and sequence number are desired for both DM and LM.
Sequence numbers can be useful when some probe query messages are
lost or they arrive out of order. In addition, the sequence numbers
can be useful for detecting denial-of-service (DoS) attacks on UDP
ports.
9.1. Sequence Number TLV Extension in Unauthenticated Mode
[RFC6374] defines DM and LM probe query and response messages that
can include one or more optional TLVs. New TLV Type (value TBA3) is
defined in this document to carry sequence number for probe query and
response messages for delay and loss measurement. The format of the
Sequence Number TLV in unauthenticated mode is shown in Figure 10.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type TBA3 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Sequence Number TLV - Unauthenticated Mode
o The sequence numbers start with 0 and are incremented by one for
each subsequent probe query message.
o The sequence number are independent for DM and LM messages.
o The sequence number can be of any length determined by the querier
node.
o The Sequence Number TLV is optional.
o The querier node SHOULD only insert one Sequence Number TLV in the
probe query message and the responder node in the probe response
message SHOULD return the first Sequence Number TLV from the probe
query message and ignore the other Sequence Number TLVs if
present.
o When Sequence Number TLV is added, the DM and LM messages SHOULD
NOT carry sequence number in the timestamp field of the message.
9.2. Sequence Number TLV Extension in Authenticated Mode
The probe query and response message format in authenticated mode
includes a key Hashed Message Authentication Code (HMAC) ([RFC2104])
hash. Each probe query and response messages are authenticated by
adding Sequence Number with Hashed Message Authentication Code (HMAC)
TLV. It can use HMAC-SHA-256 truncated to 128 bits (similarly to the
use of it in IPSec defined in [RFC4868]); hence the length of the
HMAC field is 16 octets.
In authenticated mode, only the sequence number is encrypted, and the
other payload fields are sent in clear text. The probe message MAY
include Comp.MBZ (Must Be Zero) variable length field to align the
message on 16 octets boundary.
The computation of HMAC field using HMAC-SHA1 can be used with the
procedure defined in this document. HMAC uses own key and the
definition of the mechanism to distribute the HMAC key is outside the
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scope of this document. Both the authentication type and key can be
user-configured on both the querier and responder nodes.
The format of the Sequence Number TLV in authentication mode is shown
in Figure 11.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type TBA4 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Comp.MBZ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HMAC (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Sequence Number TLV - Authenticated Mode
o This TLV is mandatory in the authenticated mode.
o The node MUST discard the probe message if HMAC is invalid.
o The Sequence Number follows the same processing rule as defined in
the unauthenticated mode.
10. Performance Delay and Liveness Monitoring
Liveness monitoring is required for connectivity verification and
continuity check in an SR network. The procedure defined in this
document for one-way, two-way and loopback mode for delay measurement
can also be applied to liveness monitoring of Links and SR Paths.
Liveness failure is notified when consecutive N number of probe
response messages are not received back at the querier node, where N
is locally provisioned value. Note that for one-way and two-way
modes, the failure detection interval and scale for number of probe
messages need to account for the processing of the probe query
messages which need to be punted from the forwarding fast path (to
slow path or control plane), and response messages need to be
injected on the responder node. Hence, loopback mode is more
suitbale for liveness monitoring.
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11. Security Considerations
The performance measurement is intended for deployment in well-
managed private and service provider networks. As such, it assumes
that a node involved in a measurement operation has previously
verified the integrity of the path and the identity of the far end
responder node. The security considerations described in Section 8
of [RFC6374] are applicable to this specification, and particular
attention should be paid to the last three paragraphs.
If desired, attacks can be mitigated by performing basic validation
and sanity checks, at the querier node, 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 [RFC8754]. Hence,
probe messages for SRv6 may not need authentication mode.
Cryptographic measures may be enhanced by the correct configuration
of access-control lists and firewalls.
12. IANA Considerations
IANA is requested to allocate the values for the following Sub-TLV
Types for the Return Path TLV for RFC 6374 from the sub-registry
"Return Path Sub-TLV Type" of the "MPLS Loss/Delay Measurement TLV
Object" registry contained within the "Generic Associated Channel
(G-ACh) Parameters" registry set:
o Type TBA1: SRv6 Segment List of the Reverse Path
o Type TBA2: SRv6 Binding SID of the Reverse SR Policy
IANA is also requested to allocate the values for the following
Sequence Number TLV Types for RFC 6374 to be carried in the probe
query and response messages for delay and loss measurement from the
"MPLS Loss/Delay Measurement TLV Object" registry contained within
the "Generic Associated Channel (G-ACh) Parameters" registry set:
o Type TBA3: Sequence Number TLV in Unauthenticated Mode
o Type TBA4: Sequence Number TLV in Authenticated Mode
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13. References
13.1. 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>.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374,
DOI 10.17487/RFC6374, September 2011,
<https://www.rfc-editor.org/info/rfc6374>.
[RFC7876] Bryant, S., Sivabalan, S., and S. Soni, "UDP Return Path
for Packet Loss and Delay Measurement for MPLS Networks",
RFC 7876, DOI 10.17487/RFC7876, July 2016,
<https://www.rfc-editor.org/info/rfc7876>.
[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>.
[I-D.ietf-mpls-rfc6374-sr]
Gandhi, R., Filsfils, C., Voyer, D., Salsano, S., and M.
Chen, "Performance Measurement Using RFC 6374 for Segment
Routing Networks with MPLS Data Plane", draft-ietf-mpls-
rfc6374-sr-00 (work in progress), July 2020.
[I-D.gandhi-spring-stamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B.
Janssens, "Performance Measurement Using STAMP for Segment
Routing Networks", draft-gandhi-spring-stamp-srpm-02 (work
in progress), August 2020.
13.2. Informative References
[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>.
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[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>.
[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>.
[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>.
[RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
Two-Way Active Measurement Protocol", RFC 8762,
DOI 10.17487/RFC8762, March 2020,
<https://www.rfc-editor.org/info/rfc8762>.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-08 (work in progress),
July 2020.
[I-D.ietf-pim-sr-p2mp-policy]
Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z.
Zhang, "Segment Routing Point-to-Multipoint Policy",
draft-ietf-pim-sr-p2mp-policy-00 (work in progress), July
2020.
[I-D.ietf-pce-binding-label-sid]
Filsfils, C., Sivabalan, S., Tantsura, J., Hardwick, J.,
Previdi, S., and C. Li, "Carrying Binding Label/Segment-ID
in PCE-based Networks.", draft-ietf-pce-binding-label-
sid-03 (work in progress), June 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-16 (work in
progress), June 2020.
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[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.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.
Acknowledgments
The authors would like to thank Patrick Khordoc for the discussions
on RFC 6374; Nagendra Kumar and Carlos Pignataro for the discussion
on SRv6 Performance Measurement. The authors would like to thank
Thierry Couture for the discussions on the use-cases for the
performance measurement in segment routing networks. The authors
would also like to thank Stewart Bryant for the discussion on UDP
port allocation for Performance Measurement and Greg Mirsky for
providing useful comments and suggestions.
Contributors
Sagar Soni
Cisco Systems, Inc.
Email: sagsoni@cisco.com
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
Pier Luigi Ventre
CNIT
Italy
Email: pierluigi.ventre@cnit.it
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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
Stefano Salsano
Universita di Roma "Tor Vergata"
Italy
Email: stefano.salsano@uniroma2.it
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
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