Performance Measurement Using Simple TWAMP (STAMP) for Segment Routing Networks
draft-gandhi-spring-stamp-srpm-05
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Rakesh Gandhi , Clarence Filsfils , Daniel Voyer , Mach Chen , Bart Janssens | ||
| Last updated | 2021-02-10 (Latest revision 2021-01-12) | ||
| Replaces | draft-gandhi-spring-rfc6374-srpm-udp, draft-gandhi-spring-twamp-srpm | ||
| Replaced by | draft-ietf-spring-stamp-srpm, draft-ietf-spring-stamp-srpm | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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| Additional resources | Mailing list discussion | ||
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draft-gandhi-spring-stamp-srpm-05
SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended status: Informational Cisco Systems, Inc.
Expires: August 14, 2021 D. Voyer
Bell Canada
M. Chen
Huawei
B. Janssens
Colt
February 10, 2021
Performance Measurement Using Simple TWAMP (STAMP) for Segment Routing
Networks
draft-gandhi-spring-stamp-srpm-05
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 procedures for
Performance Measurement in SR networks using the mechanisms defined
in RFC 8762 (Simple Two-Way Active Measurement Protocol (STAMP)) and
its optional extensions defined in RFC 8972 and draft-gandhi-ippm-
stamp-srpm. 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
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 August 14, 2021.
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Copyright Notice
Copyright (c) 2021 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
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Reference Topology . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Example STAMP Reference Model . . . . . . . . . . . . . . 5
4. Delay Measurement for Links and SR Paths . . . . . . . . . . 7
4.1. Session-Sender Test Packet . . . . . . . . . . . . . . . 7
4.1.1. Session-Sender Test Packet for Links . . . . . . . . 7
4.1.2. Session-Sender Test Packet for SR Paths . . . . . . . 7
4.2. Session-Reflector Test Packet . . . . . . . . . . . . . . 9
4.2.1. One-way Delay Measurement Mode . . . . . . . . . . . 10
4.2.2. Two-way Delay Measurement Mode . . . . . . . . . . . 10
4.2.3. Round-trip Delay Measurement Mode . . . . . . . . . . 12
4.3. Delay Measurement for P2MP SR Policies . . . . . . . . . 13
4.4. Additional STAMP Test Packet Processing Rules . . . . . . 14
4.4.1. TTL . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.4.2. IPv6 Hop Limit . . . . . . . . . . . . . . . . . . . 14
4.4.3. Router Alert Option . . . . . . . . . . . . . . . . . 15
5. Packet Loss Measurement for Links and SR Paths . . . . . . . 15
6. Direct Measurement for Links and SR Paths . . . . . . . . . . 15
7. Session Status for Links and SR Paths . . . . . . . . . . . . 15
8. ECMP Support for SR Policies . . . . . . . . . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
11.1. Normative References . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . 17
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
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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 [RFC8402]. 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 Simple Two-way Active Measurement Protocol (STAMP) provides
capabilities for the measurement of various performance metrics in IP
networks [RFC8762]. It eliminates the need for control protocol by
using configuration and management model to provision and manage test
sessions. [RFC8972] defines optional extensions for STAMP.
[I-D.gandhi-ippm-stamp-srpm] defines STAMP extensions for SR
networks.
The STAMP supports two modes of STAMP Session-Reflector: Stateless
and Stateful as described in Section 4 of [RFC8762]. In Stateless
mode, maintenance of each STAMP test session on Session-Reflector is
avoided. In SR networks, as the state is in the packet, the
signaling of the parameters and creating extra states in the network
are undesired. Hence, Stateless mode of Session-Reflector is
preferred in SR networks.
This document describes procedures for Performance Measurement in SR
networks using the mechanisms defined in STAMP [RFC8762] and its
optional extensions defined in [RFC8972] and
[I-D.gandhi-ippm-stamp-srpm]. 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 [RFC8402].
2. Conventions Used in This Document
2.1. Abbreviations
BSID: Binding Segment ID.
DM: Delay Measurement.
ECMP: Equal Cost Multi-Path.
HMAC: Hashed Message Authentication Code.
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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.
SHA: Secure Hash Algorithm.
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.
SSID: STAMP Session Identifier.
STAMP: Simple Two-way Active Measurement Protocol.
TC: Traffic Class.
TTL: Time To Live.
2.2. Reference Topology
In the reference topology shown below, the STAMP Session-Sender R1
initiates a STAMP test packet and the STAMP Session-Reflector R3
transmits a reply test packet. The reply test packet is transmitted
back to the STAMP Session-Sender R1 on the same path or a different
path in the reverse direction.
The nodes R1 and R3 may be connected via a link or there exists an SR
path [RFC8402]. The link may be a physical interface, virtual link,
or Link Aggregation Group (LAG) [IEEE802.1AX], or LAG member link.
The SR path may be an SR Policy
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[I-D.ietf-spring-segment-routing-policy] on node R1 (called head-end)
with destination to node R3 (called tail-end).
T1 T2
/ \
+-------+ Test Packet +-------+
| | - - - - - - - - - ->| |
| R1 |=====================| R3 |
| |<- - - - - - - - - - | |
+-------+ Reply Test Packet +-------+
\ /
T4 T3
STAMP Session-Sender STAMP Session-Reflector
Reference Topology
3. Overview
For performance measurement in SR networks, the STAMP test packets
defined in [RFC8762] and its optional extensions defined in [RFC8972]
and [I-D.gandhi-ippm-stamp-srpm] are used as described in this
document. The procedures are used to measure one-way, two-way and
round-trip delay as well as packet loss metrics in an SR network.
For performance delay and packet loss measurement, STAMP Session-
Sender test packets are transmitted in-band on the same path as the
data traffic flow under measurement to measure the delay and packet
loss experienced by the data traffic flow. It is also desired that
Session-Reflector reply test packets are transmitted in-band on the
same path in the reverse direction. This is achieved in SR networks
by using the STAMP extensions defined in
[I-D.gandhi-ippm-stamp-srpm].
A destination UDP port number is selected as described in [RFC8762].
The same destination UDP port is used for link and end-to-end SR path
STAMP test sessions.
3.1. Example STAMP Reference Model
An example of a STAMP reference model and typical measurement
parameters including the destination UDP port for STAMP test session
is shown in the following Figure 1:
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+------------+
| Controller |
+------------+
/ \
Destination UDP Port / \ Destination UDP port
Authentication Mode & Key / \ Authentication Mode & Key
Delay Measurement Mode / \
Timestamp Format / \
Packet Loss Type / \
/ \
v v
+-------+ +-------+
| | | |
| R1 |==========| R3 |
| | | |
+-------+ +-------+
STAMP Session-Sender STAMP Session-Reflector
Figure 1: Example STAMP Reference Model
Example of the Timestamp Format is PTPv2 [IEEE1588] and NTP. Example
of Delay Measurement Mode is one-way, two-way and round-trip mode as
described in this document. Example of Packet Loss Type is round-
trip packet loss [RFC8762].
When using the authenticated mode for delay measurement, the matching
Authentication Type (e.g. HMAC-SHA-256) and Key are user-configured
on STAMP Session-Sender and STAMP Session-Reflector [RFC8762].
The STAMP Session-Reflector R3 uses the timestamp format from the
received STAMP test packet. In addition, the STAMP Session-Reflector
R3 uses the parameters of the return path for the reply test packet
from the received STAMP test packet, as described in this document.
Note that the controller in the reference model is not intended for
signaling the SR parameters for STAMP test sessions between the STAMP
Session-Sender and STAMP Session-Reflector. In addition, maintenance
of each STAMP test session on Session-Reflector and creating extra
state are avoided in an SR network.
The YANG data model defined in [I-D.ietf-ippm-stamp-yang] can be used
to provision the STAMP Session-Sender and STAMP Session-Reflector.
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4. Delay Measurement for Links and SR Paths
4.1. Session-Sender Test Packet
The content of an example STAMP Session-Sender test packet using an
UDP header [RFC0768] is shown in Figure 2. The payload contains the
STAMP Session-Sender test packet defined in [RFC8762].
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Session-Sender IPv4 or IPv6 Address .
. Destination IP Address=Session-Reflector IPv4 or IPv6 Address.
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Session-Sender .
. Destination Port = User-configured Port | 862 .
. .
+---------------------------------------------------------------+
| Payload = Test Packet as specified in Section 4.2 of RFC 8762 |
. .
+---------------------------------------------------------------+
Figure 2: Example Session-Sender Test Packet
4.1.1. Session-Sender Test Packet for Links
The STAMP Session-Sender test packet as shown in Figure 2 is
transmitted over the link for delay measurement. The local and
remote IP addresses of the link are used as Source and Destination
Addresses.
4.1.2. Session-Sender Test Packet for SR Paths
The delay measurement for end-to-end SR path in SR network is
applicable to both end-to-end SR-MPLS and SRv6 paths including SR
Policies.
The STAMP Session-Sender IPv4 or IPv6 address is used as the Source
Address. The SR Policy endpoint IPv4 or IPv6 address is used as the
Destination Address.
In the case of Color-Only Destination Steering, with IPv4 endpoint of
0.0.0.0 or IPv6 endpoint of ::0
[I-D.ietf-spring-segment-routing-policy], the loopback address from
the range 127/8 for IPv4, or the loopback address ::1/128 for IPv6 is
used as the Destination Address, respectively.
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4.1.2.1. Session-Sender Test Packet for SR-MPLS Policies
An SR-MPLS Policy may contain a number of Segment Lists. A STAMP
Session-Sender test packet is transmitted for each Segment List of
the SR-MPLS Policy. The content of an example STAMP Session-Sender
test packet for an end-to-end 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(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Test Packet as shown in Figure 2 |
. .
+---------------------------------------------------------------+
Figure 3: Example Session-Sender Test Packet for SR-MPLS Policy
The Segment List (SL) can be empty in case of a single-hop SR-MPLS
Policy with Implicit NULL label.
The Path Segment Identifier (PSID)
[I-D.ietf-spring-mpls-path-segment] of an SR-MPLS Policy can be
carried in the MPLS header as shown in Figure 3, and can be used for
direct measurement as described in Section 7.
4.1.2.2. Session-Sender Test Packet for SRv6 Policies
An SRv6 Policy may contain a number of Segment Lists. A STAMP
Session-Sender test packet is transmitted for each Segment List of
the SRv6 Policy. An SRv6 Policy can contain an SRv6 Segment Routing
Header (SRH) carrying a Segment List as described in [RFC8754]. The
content of an example STAMP Session-Sender test packet for an end-to-
end SRv6 Policy is shown in Figure 4.
The SRv6 network programming is described in
[I-D.ietf-spring-srv6-network-programming]. The procedure defined
for upper-layer header processing for SRv6 SIDs in
[I-D.ietf-spring-srv6-network-programming] is used to process the
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IPv6/UDP header in the received test packets on the Session-
Reflector.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Session-Sender IPv6 Address .
. Destination IP Address = Destination IPv6 Address .
. .
+---------------------------------------------------------------+
| SRH as specified in RFC 8754 |
. <PSID, Segment List> .
. .
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Session-Sender IPv6 Address .
. Destination IP Address = Session-Reflector IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Session-Sender .
. Destination Port = User-configured Port | 862 .
. .
+---------------------------------------------------------------+
| Payload = Test Packet as specified in Section 4.2 of RFC 8762 |
. .
+---------------------------------------------------------------+
Figure 4: Example Session-Sender Test Packet for SRv6 Policy
The Segment List (SL) may be empty and no SRH may be carried.
The Path Segment Identifier (PSID)
[I-D.ietf-spring-srv6-path-segment] of the SRV6 Policy can be carried
in the SRH as shown in Figure 4 and can be used for direct
measurement as described in Section 7.
4.2. Session-Reflector Test Packet
The STAMP Session-Reflector reply test packet is transmitted using
the IP/UDP information from the received test packet. The content of
an example STAMP Session-Reflector reply test packet is shown in
Figure 5.
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+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Session-Reflector IPv4 or IPv6 Address .
. Destination IP Address .
. = Source IP Address from Received Test Packet .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Session-Reflector .
. Destination Port = Source Port from Received Test Packet .
. .
+---------------------------------------------------------------+
| Payload = Test Packet as specified in Section 4.3 of RFC 8762 |
. .
+---------------------------------------------------------------+
Figure 5: Example Session-Reflector Test Packet
4.2.1. One-way Delay Measurement Mode
In one-way delay measurement mode, a reply test packet as shown in
Figure 5 is transmitted by the STAMP Session-Reflector, for both
links and SR Policies. The reply test packet may be transmitted on
the same path or a different path in the reverse direction.
The STAMP Session-Sender address may not be reachable via IP route
from the STAMP Session-Reflector. The STAMP Session-Sender in this
case can send its reachability path information to the STAMP Session-
Reflector using the Return Path TLV defined in
[I-D.gandhi-ippm-stamp-srpm].
In this mode, as per Reference Topology, all timestamps T1, T2, T3,
and T4 are collected by the test packets. However, only timestamps
T1 and T2 are used to measure one-way delay as (T2 - T1).
4.2.2. Two-way Delay Measurement Mode
In two-way delay measurement mode, a reply test packet as shown in
Figure 5 is transmitted by the STAMP Session-Reflector in-band on the
same path in the reverse direction, e.g. on the reverse direction
link or associated reverse SR path [I-D.ietf-pce-sr-bidir-path].
For two-way delay measurement mode for links, the STAMP Session-
Reflector needs to transmit the reply test packet in-band on the same
link where the test packet is received. The STAMP Session-Sender can
request in the test packet to the STAMP Session-Reflector to transmit
the reply test packet back on the same link using the Control Code
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Sub-TLV in the Return Path TLV defined in
[I-D.gandhi-ippm-stamp-srpm].
For two-way delay measurement mode for end-to-end SR paths, the STAMP
Session-Reflector needs to transmit the reply test packet in-band on
a specific reverse path. The STAMP Session-Sender can request in the
test packet to the STAMP Session-Reflector to transmit the reply test
packet back on a given reverse path using a Segment List sub-TLV in
the Return Path TLV defined in [I-D.gandhi-ippm-stamp-srpm].
In this mode, as per Reference Topology, all timestamps T1, T2, T3,
and T4 are collected by the test packets. All four timestamps are
used to measure two-way delay as ((T4 - T1) - (T3 - T2)).
4.2.2.1. Session-Reflector Test Packet for SR-MPLS Policies
The content of an example STAMP Session-Reflector reply test packet
transmitted in-band on the same path as the data traffic flow under
measurement for two-way delay measurement of an end-to-end 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(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Test Packet as shown in Figure 5 |
. .
+---------------------------------------------------------------+
Figure 6: Example Session-Reflector Test Packet for SR-MPLS Policy
4.2.2.2. Session-Reflector Test Packet for SRv6 Policies
The content of an example STAMP Session-Reflector reply test packet
transmitted in-band on the same path as the data traffic flow under
measurement for two-way delay measurement of an end-to-end SRv6
Policy with SRH is shown in Figure 7.
The procedure defined for upper-layer header processing for SRv6 SIDs
in [I-D.ietf-spring-srv6-network-programming] is also used to process
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the IPv6/UDP header in the received reply test packets on the
Session-Sender.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Session-Reflector IPv6 Address .
. Destination IP Address = Destination IPv6 Address .
. .
+---------------------------------------------------------------+
| SRH as specified in RFC 8754 |
. <Segment List> .
. .
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Session-Reflector IPv6 Address .
. Destination IP Address .
. = Source IPv6 Address from Received Test Packet .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Session-Reflector .
. Destination Port = Source Port from Received Test Packet .
. .
+---------------------------------------------------------------+
| Payload = Test Packet as specified in Section 4.3 of RFC 8762 |
. .
+---------------------------------------------------------------+
Figure 7: Example Session-Reflector Test Packet for SRv6 Policy
4.2.3. Round-trip Delay Measurement Mode
The STAMP Session-Sender test packets are sent in loopback mode to
measure round-trip delay of a bidirectional path. The IP header of
the STAMP Session-Sender test packet contains the Destination Address
equals to the STAMP Session-Sender address and the Source Address
equals to the STAMP Session-Reflector address. Optionally, the STAMP
Session-Sender test packet can carry the return path information
(e.g. return path label stack for SR-MPLS) as part of the SR header.
This way, the received Session-Sender test packets are not punted out
of the fast path in forwarding (to slow path or control-plane) at the
STAMP Session-Reflector. Also, the Session-Reflector does not
process them and generate reply test packets.
As the reply test packet is not generated by the STAMP Session-
Reflector, the STAMP Session-Sender ignores the 'Session-Sender
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Sequence Number', 'Session-Sender Timestamp', 'Session-Sender Error
Estimate', and 'Session-Sender TTL' in the received test packet.
In this mode, as per Reference Topology, the timestamps T1 and T4 are
collected by the test packets. Both these timestamps are used to
measure round-trip delay as (T4 - T1).
4.3. Delay Measurement for P2MP SR Policies
The Point-to-Multipoint (P2MP) SR path that originates from a root
node terminates on multiple destinations called leaf nodes (e.g.
P2MP SR Policy [I-D.ietf-pim-sr-p2mp-policy]).
The procedures for performance measurement described in this document
for P2P SR Policies are used for the P2MP SR Policies as listed
below.
o The STAMP Session-Sender root node transmits test packets using
the Tree-SID defined in [I-D.ietf-pim-sr-p2mp-policy] for the P2MP
SR-MPLS Policy as shown in Figure 8. The STAMP Session-Sender
test packets may contain the replication SID as defined in
[I-D.ietf-spring-sr-replication-segment].
o The Destination Address is set to the loopback address from the
range 127/8 for IPv4, or the loopback address ::1/128 for IPv6.
o Each STAMP Session-Reflector leaf node transmits its node address
in the Source Address of the reply test packets shown in Figure 5.
This allows the STAMP Session-Sender root node to identify the
STAMP Session-Reflector leaf nodes of the P2MP SR Policy.
o The P2MP root node measures the delay for each P2MP leaf node
individually.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tree-SID | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Test Packet as shown in Figure 2 |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Example Session-Sender Test Packet with Tree-SID for SR-
MPLS Policy
The round-trip delay measurement for a P2MP SR-MPLS Policy can use
the Node SID of the Session-Sender in the MPLS header of the Session-
Sender test packet.
4.4. Additional STAMP Test Packet Processing Rules
The processing rules described in this section are applicable to the
STAMP test packets for links and end-to-end SR paths including SR
Policies.
4.4.1. TTL
The TTL field in the IPv4 and MPLS headers of the STAMP Session-
Sender and STAMP Session-Reflector reply test packets is set to 255,
except in the following cases.
When using the Destination IPv4 Address from the range 127/8, the TTL
field in the IPv4 header is set to 1.
For link delay, the TTL field in the STAMP test packet is set to 1 in
one-way and two-way delay measurement modes.
4.4.2. IPv6 Hop Limit
The Hop Limit field in the IPv6 and SRH headers of the STAMP Session-
Sender and STAMP Session-Reflector reply test packets is set to 255,
except in the following cases.
When using the Destination IPv6 Address of loopback address ::1/128,
the Hop Limit field in the IPv6 header is set to 1.
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For link delay, the Hop Limit field in the STAMP test packet is set
to 1 in one-way and two-way delay measurement modes.
4.4.3. Router Alert Option
The Router Alert IP option (RAO) [RFC2113] is not set in the STAMP
test packets for links and end-to-end SR paths.
5. Packet Loss Measurement for Links and SR Paths
The procedure described in Section 4 for delay measurement using
STAMP test packets can be used to detect (test) packet loss for links
and end-to-end SR paths. The Sequence Number field in the STAMP test
packet is used as described in Section 4 "Theory of Operation" of
[RFC8762], to detect forward, reverse and round-trip packet loss.
6. Direct Measurement for Links and SR Paths
The STAMP "Direct Measurement" TLV (Type 5) defined in [RFC8972] can
be used in SR networks. The STAMP test packets with this TLV are
transmitted using the procedures described in Section 4 to collect
the transmit and receive counters of the data flow for the links and
end-to-end SR paths. Note that in this case, the STAMP test packets
may follow the same or a different path than the data flow under
direct measurement.
The PSID carried in the received data packet for the traffic flow
under measurement can be used to measure receive data packets for
end-to-end SR path on the STAMP Session-Reflector. The PSID in the
received Session-Sender test packet header can be used to associate
the receive traffic counter on the Session-Reflector for the end-to-
end SR path.
7. Session Status for Links and SR Paths
The STAMP test session status allows to know if the performance
measurement is active on the links and end-to-end SR paths. The
STAMP test session status initially is declared succeeded when one or
more reply test packets are received at the STAMP Session-Sender.
The STAMP test session status is declared failed when consecutive N
number of reply test packets are not received at the STAMP Session-
Sender, where N is locally provisioned value.
8. 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
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paths via transit nodes part of that Anycast group. The test packets
need to be transmitted to traverse different ECMP paths to measure
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
delay measurement.
In IPv4 header of the STAMP Session-Sender test packets, sweeping of
Destination Address from the range 127/8 can be used to exercise
particular ECMP paths. Note that in the loopback mode for round-trip
delay measurement, both the forward and the return paths must be SR-
MPLS paths in this case.
As specified in [RFC6437], Flow Label field in the outer IPv6 header
can also be used for sweeping to exercise different IPv6 ECMP paths.
The "Destination Node Address" TLV [I-D.gandhi-ippm-stamp-srpm] can
be carried in the STAMP Session-Sender test packet to identify the
intended destination node, for example, when using IPv4 Destination
Address from the range 127/8. The STAMP Session-Reflector must not
transmit reply test packet if it is not the intended destination node
in the "Destination Node Address" TLV [I-D.gandhi-ippm-stamp-srpm].
9. Security Considerations
The performance measurement is intended for deployment in well-
managed private and service provider networks. As such, it assumes
that a node involved in a measurement operation has previously
verified the integrity of the path and the identity of the far-end
STAMP Session-Reflector.
If desired, attacks can be mitigated by performing basic validation
and sanity checks, at the STAMP Session-Sender, of the counter or
timestamp fields in received measurement reply test packets. The
minimal state associated with these protocols also limits the extent
of measurement disruption that can be caused by a corrupt or invalid
packet to a single test cycle.
Use of HMAC-SHA-256 in the authenticated mode protects the data
integrity of the test packets. SRv6 has HMAC protection
authentication defined for SRH [RFC8754]. Hence, test packets for
SRv6 may not need authentication mode. Cryptographic measures may be
enhanced by the correct configuration of access-control lists and
firewalls.
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The security considerations specified in [RFC8762] and [RFC8972] also
apply to the procedures described in this document.
10. IANA Considerations
This document does not require any IANA action.
11. References
11.1. 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>.
[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>.
[RFC8972] Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A.,
and E. Ruffini, "Simple Two-Way Active Measurement
Protocol Optional Extensions", RFC 8972,
DOI 10.17487/RFC8972, January 2021,
<https://www.rfc-editor.org/info/rfc8972>.
[I-D.gandhi-ippm-stamp-srpm]
Gandhi, R., Filsfils, C., Voyer, D., Chen, M., and B.
Janssens, "Simple TWAMP (STAMP) Extensions for Segment
Routing Networks", draft-gandhi-ippm-stamp-srpm-02 (work
in progress), February 2021.
[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-28 (work in
progress), December 2020.
11.2. Informative References
[IEEE1588]
IEEE, "1588-2008 IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", March 2008.
[RFC2113] Katz, D., "IP Router Alert Option", RFC 2113,
DOI 10.17487/RFC2113, February 1997,
<https://www.rfc-editor.org/info/rfc2113>.
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[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>.
[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>.
[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>.
[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>.
[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., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-09 (work in progress),
November 2020.
[I-D.ietf-spring-sr-replication-segment]
Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z.
Zhang, "SR Replication Segment for Multi-point Service
Delivery", draft-ietf-spring-sr-replication-segment-02
(work in progress), October 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-01 (work in progress),
October 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-03 (work in progress),
September 2020.
[I-D.ietf-spring-srv6-path-segment]
Li, C., Cheng, W., Chen, M., Dhody, D., and R. Gandhi,
"Path Segment for SRv6 (Segment Routing in IPv6)", draft-
ietf-spring-srv6-path-segment-00 (work in progress),
November 2020.
[I-D.ietf-pce-sr-bidir-path]
Li, C., Chen, M., Cheng, W., Gandhi, R., and Q. Xiong,
"Path Computation Element Communication Protocol (PCEP)
Extensions for Associated Bidirectional Segment Routing
(SR) Paths", draft-ietf-pce-sr-bidir-path-05 (work in
progress), January 2021.
[I-D.ietf-ippm-stamp-yang]
Mirsky, G., Min, X., and W. Luo, "Simple Two-way Active
Measurement Protocol (STAMP) Data Model", draft-ietf-ippm-
stamp-yang-06 (work in progress), October 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, Gyan Mishra, Xie
Jingrong, and Mike Koldychev for reviewing this document and
providing useful comments and suggestions. Patrick Khordoc and Radu
Valceanu have helped improve the mechanisms described in this
document.
Authors' Addresses
Rakesh Gandhi (editor)
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
Email: cfilsfil@cisco.com
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Daniel Voyer
Bell Canada
Email: daniel.voyer@bell.ca
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
Bart Janssens
Colt
Email: Bart.Janssens@colt.net
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