Performance Measurement Using UDP Path for Segment Routing Networks
draft-gandhi-spring-rfc6374-srpm-udp-02
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 , Stefano Salsano , Mach Chen | ||
| Last updated | 2019-10-04 (Latest revision 2019-05-15) | ||
| Replaces | draft-gandhi-spring-udp-pm | ||
| Replaced by | draft-gandhi-spring-stamp-srpm | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-gandhi-spring-rfc6374-srpm-udp-02
SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended Status: Standards Track Cisco Systems, Inc.
Expires: April 6, 2020 D. Voyer
Bell Canada
S. Salsano
Universita di Roma "Tor Vergata"
M. Chen
Huawei
October 4, 2019
Performance Measurement Using UDP Path
for Segment Routing Networks
draft-gandhi-spring-rfc6374-srpm-udp-02
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
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://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."
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(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
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 . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Reference Topology . . . . . . . . . . . . . . . . . . . . 5
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Example Provisioning Model . . . . . . . . . . . . . . . . 7
4. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 7
4.1.1. Delay Measurement Probe Query Message . . . . . . . . 8
4.1.2. Loss Measurement Probe Query Message . . . . . . . . . 8
4.1.3. Probe Query for SR Links . . . . . . . . . . . . . . . 9
4.1.4. Probe Query for End-to-end Measurement for SR Policy . 9
4.1.4.1. Probe Query Message for SR-MPLS Policy . . . . . . 9
4.1.4.2. Probe Query Message for SRv6 Policy . . . . . . . 10
4.2. Probe Response Message . . . . . . . . . . . . . . . . . . 11
4.2.1. One-way Measurement Mode . . . . . . . . . . . . . . . 12
4.2.1.1. SR Links and End-to-end Measurement for SR
Policy . . . . . . . . . . . . . . . . . . . . . . 12
4.2.1.2. Probe Response Message to Controller . . . . . . . 12
4.2.2. Two-way Measurement Mode . . . . . . . . . . . . . . . 12
4.2.2.1. SR Links . . . . . . . . . . . . . . . . . . . . . 12
4.2.2.2. End-to-end Measurement for SR Policy . . . . . . . 12
4.2.2.3. Return Path TLV . . . . . . . . . . . . . . . . . 13
4.2.2.4. Probe Response Message for SR-MPLS Policy . . . . 13
4.2.2.5. Probe Response Message for SRv6 Policy . . . . . . 14
4.2.3. Loopback Measurement Mode . . . . . . . . . . . . . . 14
5. Performance Measurement for P2MP SR Policies . . . . . . . . . 14
6. ECMP Support for SR Policies . . . . . . . . . . . . . . . . . 15
7. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . . 15
7.1. Sequence Number TLV in Unauthenticated Mode . . . . . . . 16
7.2. Sequence Number TLV in Authenticated Mode . . . . . . . . 16
8. Additional Message Processing Rules . . . . . . . . . . . . . 18
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8.1. TTL Value . . . . . . . . . . . . . . . . . . . . . . . . 18
8.2. Router Alert Option . . . . . . . . . . . . . . . . . . . 18
8.3. UDP Checksum . . . . . . . . . . . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 18
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . 20
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 23
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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.spring-segment-routing-policy] are used
to steer traffic through a specific, user-defined paths using a stack
of Segments. Built-in SR Performance Measurement (PM) is one of the
essential requirements to provide Service Level Agreements (SLAs).
The One-Way Active Measurement Protocol (OWAMP) defined in [RFC4656]
and Two-Way Active Measurement Protocol (TWAMP) defined in [RFC5357]
provide capabilities for the measurement of various performance
metrics in IP networks. These protocols rely on control-channel
signaling to establish a test-channel over an UDP path. These
protocols lack support for IEEE 1588 timestamp [IEEE1588] format and
direct-mode Loss Measurement (LM), which are required in SR networks
[RFC6374]. The Simple Two-way Active Measurement Protocol (STAMP)
[I-D.ippm-stamp] alleviates the control-channel signaling by using
configuration data model to provision a test-channel. In addition,
the STAMP supports IEEE 1588 timestamp format for Delay Measurement
(DM). The TWAMP Light [Appendix I in RFC5357] [BBF.TR-390] provides
simplified mechanisms for active performance measurement in Customer
IP networks by provisioning UDP paths and eliminates the
control-channel signaling. [Y1731] specifies the mechanisms to carry
OAM messages specifically for Ethernet networks that include Ethernet
Frame Delay and Loss measurements.
[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.spring-rfc6374-srpm-mpls].
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[RFC6374] addresses the limitations of the IP based performance
measurement protocols as specified in Section 1 of [RFC6374]. The
[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 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 PM probe responses 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. Existing PM protocols (e.g. RFC 6374) do not define handling
for ECMP forwarding paths in SR networks.
For two-way measurements for SR Policies, there is a need to specify
a return path in the form of a Segment List in PM probe query
messages without requiring any SR Policy state on the destination
node. Existing protocols do not have such mechanisms to specify
return path in the PM probe query messages.
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 SR links and end-to-end
performance measurement for SR Policies and it does not require to
bootstrap PM sessions.
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
ACH: Associated Channel Header.
BSID: Binding Segment ID.
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DFLag: Data Format Flag.
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.
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.
URO: UDP Return Object.
2.3. Reference Topology
In the reference topology shown below, the sender 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
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response may be sent to the sender node R1 or to a controller node
R100. 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].
------
|R100|
------
^
| Response
|
+-------+ Query +-------+
| | - - - - - - - - - ->| |
| R1 |---------------------| R5 |
| |<- - - - - - - - - - | |
+-------+ Response +-------+
Sender Responder
Reference Topology
3. Overview
One-way delay and two-way delay measurement procedure defined in
Section 2.4 of [RFC6374] are used. Transmit and Receive packet loss
measurement procedures defined in Section 2.2 and Section 2.6 of
[RFC6374] are used. One-way loss measurement provides receive packet
loss whereas two-way loss measurement provides both transmit and
receive packet loss. Separate UDP destination port numbers are
user-configured for delay and loss measurements from the range
specified in [I-D.ippm-stamp]. The sender uses the destination UDP
port number following the guidelines specified in Section 6 in
[RFC6335]. For both links and end-to-end SR Policies, no PM session
for delay or loss measurement is created on the responder node R5
[RFC6374].
For Performance Measurement, probe query and response messages are
sent as following:
o For Delay Measurement, the probe messages are sent on the
congruent path of the data traffic by the sender node, and are
used to measure the delay experienced by the actual data traffic
flowing on the links and SR Policies.
o For Loss Measurement, the probe messages are sent on the congruent
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path of the data traffic by the sender node, and are used to
collect the receive traffic counters for the incoming link or
incoming SID where the probe query messages are received at the
responder node (incoming link or incoming SID needed since the
responder node does not have PM session state present).
The In-Situ Operations, Administration, and Maintenance (IOAM)
mechanisms for SR-MPLS defined in [I-D.spring-ioam-sr-mpls] and for
SRv6 defined in [I-D.spring-ioam-srv6] are used to carry PM
information such as timestamp in-band as part of the data packets,
and are outside the scope of this document.
3.1. Example Provisioning Model
An example of a provisioning model and typical measurement parameters
for performance delay and loss measurements is shown in the following
Figure:
+------------+
| Controller |
+------------+
Measurement Protocol / \ Measurement Protocol
Destination UDP Port / \ Destination UDP port
Measurement Type / \ Measurement Type
Delay/Loss / \ Delay/Loss
Authentication Mode & Key / \ Authentication Mode & Key
Timestamp Format / \
Delay Measurement Mode / \
Loss Measurement Mode / \
v v
+-------+ +-------+
| | | |
| R1 |-----------| R5 |
| | | |
+-------+ +-------+
Sender Responder
Provisioning Model
The mechanisms used to provision the sender and responder nodes are
outside the scope of this document.
4. Probe Messages
4.1. Probe Query Message
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In this document, UDP path is used for Delay and Loss measurements
for SR 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 PM probe packets.
4.1.1. Delay Measurement Probe Query Message
The message content for Delay Measurement for 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 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 = Sender IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Sender .
. 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 [IEEE1588] as a default
format as specified in Appendix A of [RFC6374], preferred with
hardware support. As an alternative, Network Time Protocol (NTP)
timestamp format can also be used [RFC6374].
4.1.2. Loss Measurement Probe Query Message
The message content for Loss measurement probe query message using
UDP header [RFC768] is shown in Figure 2. As shown, the LM probe
query message is sent with user-configured Destination UDP port
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,
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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 = Sender IPv4 or IPv6 Address .
. Destination IP Address = Responder IPv4 or IPv6 Address .
. Protocol = UDP .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Sender .
. 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
The Loss Measurement using Alternate-Marking method defined in
[RFC8321] requires to identify the Block Number (or color) of the
traffic counters carried by the probe query and response messages.
Block Number TLV defined in [I-D.spring-rfc6374-srpm-mpls] is used to
carry Block Number for the counters in the probe query and response
messages for loss measurement.
4.1.3. Probe Query for SR Links
The probe query message as defined in Figure 1 is sent on the
congruent path of the data traffic for performance Delay measurement.
Similarly, the probe query message as defined in Figure 2 is sent on
the congruent path of the data traffic for performance Loss
measurement.
4.1.4. Probe Query for End-to-end Measurement for SR Policy
The performance delay and loss measurement for segment routing is
applicable to both SR-MPLS and SRv6 Policies.
4.1.4.1. Probe Query Message for SR-MPLS Policy
The probe query message for end-to-end performance measurement of an
SR-MPLS Policy is sent using its SR-MPLS header containing the MPLS
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segment list as 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(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PSID | 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 for a single-hop SR Policy.
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. The PSID is not added for end-to-
end SR Policy delay measurement.
4.1.4.2. Probe Query Message for SRv6 Policy
An SRv6 Policy is setup using the SRv6 Segment Routing Header (SRH)
and a Segment List as defined in [I-D.6man-segment-routing-header].
The probe query messages using UDP header for end-to-end performance
measurement of an SRv6 Policy is sent using its SRv6 Segment Routing
Header (SRH) and Segment List as shown in Figure 4.
+---------------------------------------------------------------+
| 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 Source and Destination Addresses) .
. .
+---------------------------------------------------------------+
Figure 4: Probe Query Message for SRv6 Policy
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For delay measurement of SRv6 Policy using SRH, END function END.OTP
[I-D.6man-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.6man-srv6-oam] is used with target SRv6 SID to punt probe
messages on the target node.
4.2. 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 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 .
. .
+---------------------------------------------------------------+
| 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 .
. .
+---------------------------------------------------------------+
Figure 5: 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 6.
+---------------------------------------------------------------+
| IP Header |
. Source IP Address = Responder IPv4 or IPv6 Address .
. Destination IP Address = URO.Address .
. Protocol = UDP .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
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. 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 .
. .
+---------------------------------------------------------------+
Figure 6: Probe Response Message Using URO from Probe Query
4.2.1. One-way Measurement Mode
4.2.1.1. SR Links and End-to-end Measurement for SR Policy
In one-way performance measurement mode, the probe response message
as defined in Figure 5 or Figure 6 is sent out-of-band to the sender
node, for both SR links and SR Policies.
The PM sender 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.
4.2.1.2. Probe Response Message to Controller
As shown in the Reference Topology, if the sender 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].
4.2.2. Two-way Measurement Mode
4.2.2.1. SR Links
In two-way performance measurement mode, when using a bidirectional
link, the probe response message as defined in Figure 5 or Figure 6
is sent back on the congruent path of the data traffic to the sender
node for SR links. In this case, the "control code" in the probe
query message is set to "in-band response requested" [RFC6374].
4.2.2.2. End-to-end Measurement for SR Policy
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In two-way performance measurement mode, when using a bidirectional
path, the probe response message is sent back on the congruent path
of the data traffic to the sender node for end-to-end measurement of
SR Policies. In this case, the "control code" in the probe query
message is set to "in-band response requested" [RFC6374].
4.2.2.3. Return Path TLV
For two-way performance measurement, the sender 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.spring-rfc6374-srpm-mpls] is used to carry reverse SR
path information as part of the payload of the probe query message.
Additional Segment List Sub-TLVs are defined in this document for the
Return Path TLV for the following Types:
o Type (value TBD4): SRv6 Segment List of the Reverse SR Path
o Type (value TBD5): SRv6 Binding SID [I-D.pce-binding-label-sid] of
the Reverse SR Policy
4.2.2.4. 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 performance
measurement of an SR-MPLS Policy is shown in Figure 8. The SR-MPLS
label stack in the 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 List(1) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(n) | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 5 or 6 |
. .
+---------------------------------------------------------------+
Figure 8: Probe Response Message for SR-MPLS Policy
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The Path Segment Identifier (PSID) [I-D.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 defined in the following Section.
4.2.2.5. 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 performance
measurement of an SRv6 Policy 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.
+---------------------------------------------------------------+
| SRH |
. END.OTP (DM) or END.OP (LM) with Target SRv6 SID .
. .
+---------------------------------------------------------------+
| Message as shown in Figure 5 or 6 |
. (Using IPv6 Source and Destination Addresses) .
. .
+---------------------------------------------------------------+
Figure 9: Probe Response Message for SRv6 Policy
4.2.3. 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 sender 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-MPLS)
as part of the SR header. The responder node does not process the PM
probe messages and generate response messages.
5. Performance Measurement for P2MP SR Policies
The procedures for delay and loss measurement described in this
document for Point-to-Point (P2P) SR Policies
[I-D.spring-segment-routing-policy] are also equally applicable to
the Point-to-Multipoint (P2MP) SR Policies
[I-D.spring-sr-p2mp-policy] as following:
o The sender root node sends probe query messages using the either
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Spray P2MP segment or TreeSID P2MP segment defined in
[I-D.spring-sr-p2mp-policy] over the P2MP SR Policy.
o The sender root node sets the PM probe query message Destination
IPv4 Address from the 127/8 range for SR-MPLS Policy.
o Each responder leaf node sends its IP address in the Source
Address of the probe response messages. This allows the sender
root node to identify the responder leaf nodes of the P2MP SR
Policy.
o The P2MP root node measures the end-to-end delay and loss
performance for each P2MP leaf node.
6. ECMP Support for SR Policies
An SR Policy can have ECMPs between the source and transit nodes,
between transit nodes and between transit and destination nodes.
Usage of Anycast SID [RFC8402] by an SR Policy can result in ECMP
paths via transit nodes part of that Anycast group. The PM probe
messages need to be sent to traverse different ECMP paths to measure
performance delay of an SR Policy.
Forwarding plane has various hashing functions available to forward
packets on specific ECMP paths. 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] and [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 Policy, entropy label [RFC6790] can be used in the PM
probe messages.
o For SRv6 Policy using SRH, Flow Label in the SRH
[I-D.6man-segment-routing-header] of the PM probe messages can be
used.
7. Sequence Numbers
The message formats for DM and LM [RFC6374] can carry either
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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.
7.1. Sequence Number TLV 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 TBA1) 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.
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 TBA1 | 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 packet.
o The sequence number are independent for DM and LM messages.
o The sequence number can be of any length determined by the sender
node.
o The Sequence Number TLV is optional.
o The PM sender 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.
7.2. Sequence Number TLV in Authenticated Mode
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The PM probe query and response packet 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 packet MAY
include Comp.MBZ (Must Be Zero) variable length field to align the
packet on 16 octets boundary.
The computation of HMAC field using HMAC-SHA1 [RFC5357] 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 scope of this document. Both the authentication type and key can
be user-configured on both the sender 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 TBA2 | 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.
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8. Additional Message Processing Rules
8.1. TTL Value
The TTL or the Hop Limit field in the IP, MPLS and SRH headers of the
probe query messages are set to 255.
When using the Destination IPv4 Address from the 127/8 range, the TTL
in the IPv4 header is set to 1 [RFC8029]. Similarly, when using the
Destination IPv6 Address from the 0:0:0:0:0:FFFF:7F00/104 range, the
Hop Limit field in the inner IPv6 header is set to 1 whereas in the
outer IPv6 header is set to 255.
8.2. Router Alert Option
The Router Alert IP option is not set when using the routable
Destination IP Address in the probe messages.
When using the Destination IPv4 Address from the 127/8 range, the
Router Alert IP Option of value 0x0 [RFC2113] for IPv4 is set in the
IP header [RFC8029]. Similarly, when using the Destination IPv6
Address from the 0:0:0:0:0:FFFF:7F00/104 range, the Router Alert IP
Option of value 69 [RFC7506] for IPv6 is set in the IP header.
8.3. UDP Checksum
The Checksum Complement for delay and loss measurement messages
follows the procedure defined in [RFC7820] and can be optionally used
with the procedures defined in this document.
For IPv4 and IPv6 probe messages, where the hardware is not capable
of re-computing the UDP checksum or adding checksum complement
[RFC7820], the sender node sets the UDP checksum to 0 [RFC6936]
[RFC8085]. The receiving node bypasses the checksum validation and
accepts the packets with UDP checksum of 0 for the UDP port being
used for PM.
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 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.
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If desired, attacks can be mitigated by performing basic validation
and sanity checks, at the sender, of the counter or timestamp fields
in received measurement response messages. The minimal state
associated with these protocols also limits the extent of measurement
disruption that can be caused by a corrupt or invalid message to a
single query/response cycle.
Use of HMAC-SHA-256 in the authenticated mode 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.
10. IANA Considerations
IANA is requested to allocate the values for the following Sub-TLV
Types for the Return Path TLV for RFC 6374.
o Type TBD4: SRv6 Segment List of the Reverse SR Path
o Type TBD5: 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 PM probe
query and response messages for delay and loss measurement:
o Type TBA1: Sequence Number TLV in Unauthenticated Mode
o Type TBA2: Sequence Number TLV in Authenticated Mode
11. References
11.1. 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.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS networks', RFC 6374, September 2011.
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[RFC7876] Bryant, S., Sivabalan, S., and Soni, S., "UDP Return Path
for Packet Loss and Delay Measurement for MPLS Networks",
RFC 7876, July 2016.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", RFC 8174, May 2017.
[I-D.spring-rfc6374-srpm-mpls] Gandhi, R. Ed., et al. "Performance
Measurement in Segment Routing Networks with MPLS Data
Plane", draft-gandhi-spring-rfc6374-srpm-mpls, work in
progress.
[I-D.6man-srv6-oam] Ali, Z., et al., "Operations, Administration,
and Maintenance (OAM) in Segment Routing Networks with
IPv6 Data plane (SRv6)", draft-ietf-6man-spring-srv6-oam,
work in progress.
11.2. Informative References
[IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", March 2008.
[Y1731] ITU-T Recommendation Y.1731 (02/08), "OAM functions and
mechanisms for Ethernet based networks", February 2008.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, DOI
10.17487/RFC2104, February 1997, <https://www.rfc-
editor.org/info/rfc2104>.
[RFC2113] Katz, D., "IP Router Alert Option", RFC 2113, February
1997.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, September 2006.
[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>.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008.
[RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
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"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
June 2010.
[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, August 2011.
[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.
[RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement
for the Use of IPv6 UDP Datagrams with Zero Checksums",
RFC 6936, April 2013.
[RFC7506] Raza, K., Akiya, N., and C. Pignataro, "IPv6 Router Alert
Option for MPLS Operations, Administration, and
Maintenance (OAM)", RFC 7506, DOI 10.17487/RFC7506, April
2015, <http://www.rfc-editor.org/info/rfc7506>.
[RFC7820] Mizrahi, T., "UDP Checksum Complement in the One-Way
Active Measurement Protocol (OWAMP) and Two-Way Active
Measurement Protocol (TWAMP)", RFC 7820, March 2016.
[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.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <http://www.rfc-editor.org/info/rfc8085>.
[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>.
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[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.6man-segment-routing-header] Filsfils, C., et al., "IPv6
Segment Routing Header (SRH)",
draft-ietf-6man-segment-routing-header, work in progress.
[I-D.pce-binding-label-sid] Filsfils, C., et al., "Carrying Binding
Label/Segment-ID in PCE-based Networks",
draft-ietf-pce-binding-label-sid, work in progress.
[I-D.spring-mpls-path-segment] Cheng, W., et al., "Path Segment in
MPLS Based Segment Routing Network",
draft-ietf-spring-mpls-path-segment, work in progress.
[I-D.ippm-stamp] Mirsky, G. et al. "Simple Two-way Active
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.
[I-D.spring-ioam-sr-mpls] Gandhi, R. Ed., et al., "Segment Routing
with MPLS Data Plane Encapsulation for In-situ OAM Data",
draft-gandhi-spring-ioam-sr-mpls, work in progress.
[I-D.spring-ioam-srv6]. Ali, Z., et al., "Segment Routing Header
encapsulation for In-situ OAM Data",
draft-ali-spring-ioam-srv6, work in progress.
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Acknowledgments
The authors would like to thank 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
Patrick Khordoc
Cisco Systems, Inc.
Email: pkhordoc@cisco.com
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
Pier Luigi Ventre
CNIT
Italy
Email: pierluigi.ventre@cnit.it
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
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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