Performance Measurement Using UDP Path for Segment Routing Networks
draft-gandhi-spring-rfc6374-srpm-udp-01
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 , Pier Luigi Ventre , Mach Chen | ||
| Last updated | 2019-05-15 | ||
| Replaces | draft-gandhi-spring-udp-pm | ||
| Replaced by | draft-gandhi-spring-stamp-srpm | ||
| RFC stream | (None) | ||
| Formats | |||
| 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-01
SPRING Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended Status: Standards Track Cisco Systems, Inc.
Expires: November 16, 2019 D. Voyer
Bell Canada
S. Salsano
Universita di Roma "Tor Vergata"
P. L. Ventre
CNIT
M. Chen
Huawei
May 15, 2019
Performance Measurement Using UDP Path
for Segment Routing Networks
draft-gandhi-spring-rfc6374-srpm-udp-01
Abstract
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
synthetic probe query and response messages for Performance
Measurement (PM). The procedure uses the RFC 6374 defined mechanisms
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. In addition, this document
defines Return Path TLV for two-way performance measurement and Block
Number TLV for loss measurement.
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."
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Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(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
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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 . . . . . . . . . . . . . . 4
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Reference Topology . . . . . . . . . . . . . . . . . . . . 5
3. Probe Messages . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Probe Query Message . . . . . . . . . . . . . . . . . . . 7
3.1.1. Delay Measurement Probe Query Message . . . . . . . . 7
3.1.2. Loss Measurement Probe Query Message . . . . . . . . . 7
3.1.2.1. Block Number TLV . . . . . . . . . . . . . . . . . 8
3.1.3. Probe Query for SR Links . . . . . . . . . . . . . . . 9
3.1.4. Probe Query for End-to-end Measurement for SR Policy . 9
3.1.4.1. Probe Query Message for SR-MPLS Policy . . . . . . 9
3.1.4.2. Probe Query Message for SRv6 Policy . . . . . . . 10
3.2. Probe Response Message . . . . . . . . . . . . . . . . . . 10
3.2.1. One-way Measurement Mode . . . . . . . . . . . . . . . 11
3.2.1.1. SR Links and End-to-end Measurement for SR
Policy . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1.2. Probe Response Message to Controller . . . . . . . 12
3.2.2. Two-way Measurement Mode . . . . . . . . . . . . . . . 12
3.2.2.1. SR Links . . . . . . . . . . . . . . . . . . . . . 12
3.2.2.2. End-to-end Measurement for SR Policy . . . . . . . 12
3.2.2.3. Return Path TLV . . . . . . . . . . . . . . . . . 12
3.2.2.4. Probe Response Message for SR-MPLS Policy . . . . 14
3.2.2.5. Probe Response Message for SRv6 Policy . . . . . . 14
3.2.3. Loopback Measurement Mode . . . . . . . . . . . . . . 15
3.3. Checksum Complement . . . . . . . . . . . . . . . . . . . 15
4. Performance Measurement for P2MP SR Policies . . . . . . . . . 15
5. ECMP Support for SR Policies . . . . . . . . . . . . . . . . . 16
6. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . . 16
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6.1. Sequence Number TLV in Unauthenticated Mode . . . . . . . 17
6.2. Sequence Number TLV in Authenticated Mode . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . . 20
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 23
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
Segment Routing (SR) technology greatly simplifies network operations
for Software Defined Networks (SDNs). SR is applicable to both
Multiprotocol Label Switching (SR-MPLS) and IPv6 (SRv6) data planes.
SR takes advantage of the Equal-Cost Multipaths (ECMPs) between
source, transit and destination nodes. SR Policies as defined in
[I-D.spring-segment-routing-policy] are used to steer traffic through
a specific, user-defined path using a stack of Segments. Built-in SR
Performance Measurement (PM) is one of the essential requirements to
provide Service Level Agreements (SLAs).
The One-Way Active Measurement Protocol (OWAMP) defined in [RFC4656]
and Two-Way Active Measurement Protocol (TWAMP) defined in [RFC5357]
provide capabilities for the measurement of various performance
metrics in IP networks. These protocols rely on control channel
signaling to establish a test channel over an UDP path. These
protocols lack support for 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 test channels. In addition,
the STAMP supports IEEE 1588 timestamp format for Delay Measurement
(DM). The TWAMP Light from broadband forum [BBF.TR-390] provides
simplified mechanisms for active performance measurement in Customer
Edge IP networks. [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].
[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
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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 using UDP path for sending
and processing synthetic probe query and response messages for
Performance Measurement that does not require to bootstrap PM
sessions. 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. This document also defines
mechanisms for handling Equal Cost Multi-Paths (ECMPs) of SR Policies
for performance delay measurement. In addition, this document
defines Return Path TLV for two-way performance measurement, Block
Number TLV for loss measurement and Sequence Number TLV.
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.
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BSID: Binding Segment ID.
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, the querier node R1 initiates a probe
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query for performance measurement and the responder node R5 sends a
probe response for the query message received. The probe response
may be sent to the querier node R1 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 +-------+
Reference Topology
For delay and loss measurements, for both links and end-to-end SR
Policies, no PM session is created on the responder node R5. One-way
delay and two-way delay measurements are defined in Section 2.4 of
[RFC6374]. Transmit and Receive packet loss measurements are defined
in Section 2.2 and Section 2.6 of [RFC6374]. One-way loss
measurement provides receive packet loss whereas two-way loss
measurement provides both transmit and receive packet loss.
For Performance Measurement, synthetic probe query and response
messages are used 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 used as the
responder node has no PM session state present).
The In-Situ Operations, Administration, and Maintenance (IOAM)
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mechanisms for SR-MPLS defined in [I-D.spring-ioam-sr-mpls] and for
SRv6 defined in [I-D.spring-srv6-oam] are used to carry PM
information in-band as part of the data traffic, and are outside the
scope of this document.
3. Probe Messages
3.1. Probe Query Message
In this document, UDP path is used for Delay and Loss measurements
for SR links and end-to-end SR Policies. The user-configured UDP
ports are used for identifying PM probe packets and to avoid
signaling to bootstrap PM sessions. This approach is similar to the
one defined in STAMP protocol [I-D.ippm-stamp]. The IPv4 TTL or IPv6
Hop Limit field of the IP header MUST be set to 255.
3.1.1. Delay Measurement Probe Query Message
The message content for Delay Measurement 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 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 .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| UDP Header |
. Source Port = As chosen by Querier .
. Destination Port = User-configured Port for Delay Measurement.
. .
+---------------------------------------------------------------+
| Payload = Message as specified in Section 3.2 of RFC 6374 |
. .
+---------------------------------------------------------------+
Figure 1: DM Probe Query Message
3.1.2. Loss Measurement Probe Query Message
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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. Different 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 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 .
. Router Alert Option Not Set .
. .
+---------------------------------------------------------------+
| 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
3.1.2.1. Block Number TLV
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.
Probe query and response messages specified in [RFC6374] for Loss
Measurement do not define any means to carry the Block Number.
[RFC6374] defines probe query and response messages that can include
one or more optional TLVs. New TLV Type (value TBA2) is defined in
this document to carry Block Number (16-bit) for the traffic counters
in the probe query and response messages for loss measurement. The
format of the Block Number TLV 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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type TBA2 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Block Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Block Number TLV
The Block Number TLV is optional. The PM querier node SHOULD only
insert one Block Number TLV in the probe query message and the
responder node in the probe response message SHOULD return the first
Block Number TLV from the probe query messages and ignore other Block
Number TLVs if present. In both probe query and response messages,
the counters MUST belong to the same Block Number.
3.1.3. 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.
3.1.4. Probe Query for End-to-end Measurement for SR Policy
3.1.4.1. Probe Query Message for SR-MPLS Policy
The message content for the probe query message using UDP header for
end-to-end performance measurement of SR-MPLS Policy is shown in
Figure 3.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(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 |
. .
+---------------------------------------------------------------+
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Figure 3: Probe Query Message for SR-MPLS Policy
The Segment List (SL) can be empty to indicate Implicit NULL label
case.
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 required for delay
measurement.
3.1.4.2. 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.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRH |
. END.OTP (DM) or END.OP (LM) with Target SRv6 SID .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 1 for DM or Figure 2 for LM |
. (Using IPv6 Addresses) .
. .
+---------------------------------------------------------------+
Figure 4: Probe Query Message for SRv6 Policy
For delay measurement of SRv6 Policy using SRH, END function END.OTP
[I-D.spring-srv6-oam] is used with the target SRv6 SID to punt probe
messages on the target node, as shown in Figure 4. Similarly, for
loss measurement of SRv6 Policy, END function END.OP
[I-D.spring-srv6-oam] is used with target SRv6 SID to punt probe
messages on the target node.
3.2. Probe Response Message
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 probe query message. The content of
the probe response message is shown in Figure 5.
+---------------------------------------------------------------+
| IP Header |
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. 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 |
. 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
3.2.1. One-way Measurement Mode
3.2.1.1. SR Links and End-to-end Measurement for SR Policy
In one-way performance measurement mode, the probe response message
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as defined in Figure 5 or Figure 6 is sent out-of-band for both SR
links and SR Policies.
The PM 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.
3.2.1.2. 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].
3.2.2. Two-way Measurement Mode
3.2.2.1. 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 querier
node for SR links. In this case, the "control code" in the probe
query message is set to "in-band response requested" [RFC6374].
3.2.2.2. End-to-end Measurement for SR Policy
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 querier 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].
3.2.2.3. Return Path TLV
For two-way performance measurement, the responder node needs to send
the probe response message on a specific reverse SR path. This way
the destination node does not require any additional SR Policy state.
The querier node can request in the probe query message to the
responder node to send a response back on a given reverse path
(typically co-routed path for two-way measurement).
[RFC6374] defines DM and LM probe query messages that can include one
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or more optional TLVs. New TLV Type (TBA1) is defined in this
document for Return Path to carry reverse SR path for probe response
messages (in the payload of the message). The format of the Return
Path TLV is shown in Figure 7A and 7B:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Return Path Sub-TLVs |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7A: Return Path TLV
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 | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(1) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment List(n) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7B: Segment List Sub-TLV in Return Path TLV
The Sub-TLV in the Return Path TLV can be one of the following Types:
o Type (value 1): SR-MPLS Label Stack of the Reverse SR Policy
o Type (value 2): SR-MPLS Binding SID [I-D.pce-binding-label-sid] of
the Reverse SR Policy
o Type (value 3): SRv6 Segment List of the Reverse SR Policy
o Type (value 4): SRv6 Binding SID [I-D.pce-binding-label-sid] of
the Reverse SR Policy
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With sub-TLV Type 1, the Segment List(1) can be used by the responder
node to compute the next-hop IP address and outgoing interface to
send the probe response messages.
The Return Path TLV is optional. The PM querier node MUST only
insert one Return Path TLV in the probe query message and the
responder node MUST only process the first Return Path TLV in the
probe query message and ignore other Return Path TLVs if present.
The responder node MUST send probe response message back on the
reverse path specified in the Return Path TLV and MUST NOT add Return
Path TLV in the probe response message.
3.2.2.4. Probe Response Message for SR-MPLS Policy
The message content for sending probe response message on the
congruent path of the data traffic using UDP header 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
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.
3.2.2.5. Probe Response Message for SRv6 Policy
The message content for sending probe response message on the
congruent path of the data traffic using UDP header for two-way
end-to-end performance measurement of an SRv6 Policy is shown in
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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.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRH |
. END.OTP (DM) or END.OP (LM) with Target SRv6 SID .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message as shown in Figure 5 or 6 (with IPv6 Addresses) |
. .
+---------------------------------------------------------------+
Figure 9: Probe Response Message for SRv6 Policy
3.2.3. 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 Path. The
probe query messages in this case either carry the reverse Path
information as part of the SR header or set the querier address in
the destination address in the IP header. The responder node does
not process the PM probe messages and generate response messages.
3.3. Checksum Complement
For both delay and loss measurement, when the probe packets are
updated with timestamp or counter, UDP Checksum field also need
updating since these packets are transported over UDP. As an
alternative, the Checksum Complement field (2 Bytes) can be
optionally updated using the procedure defined in [RFC7820]. The
Checksum Complement field can be any unused field in the probe
message and is a local behavior.
4. 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 querier root node sends probe query messages using the either
Spray P2MP segment or TreeSID P2MP segment defined in
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[I-D.spring-sr-p2mp-policy] over the P2MP SR Policy.
o Each responder leaf node sends its IP address in the Source
Address of the probe response messages. This allows the querier
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.
5. 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.
6. 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
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can be useful for detecting denial-of-service (DoS) attacks on UDP
ports.
6.1. 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 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 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 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 packet.
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 PM 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.
6.2. Sequence Number TLV in Authenticated Mode
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)
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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 OWAMP and TWAMP compute HMAC field using HMAC-SHA1 and can also
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
querier and responder nodes.
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.
7. Security Considerations
The performance measurement is intended for deployment in
well-managed private and service provider networks. As such, it
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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.
Use of HMAC-SHA-256 in the authenticated mode defined in this
document protects the data integrity of the probe messages. SRv6 has
HMAC protection authentication defined for SRH
[I-D.6man-segment-routing-header]. Hence, PM probe messages for SRv6
may not need authentication mode. Cryptographic measures may be
enhanced by the correct configuration of access-control lists and
firewalls.
8. IANA Considerations
IANA is requested to allocate values for the following Return Path
TLV Type for RFC 6374 to be carried in PM probe query messages:
o Type TBA1: Return Path TLV
IANA is requested to allocate the values for the following Sub-TLV
Types for the Return Path TLV.
o Type 1: SR-MPLS Label Stack of the Reverse SR Policy
o Type 2: SR-MPLS Binding SID of the Reverse SR Policy
o Type 3: SRv6 Segment List of the Reverse SR Policy
o Type 4: SRv6 Binding SID of the Reverse SR Policy
IANA is also requested to allocate a value for the following Block
Number TLV Type for RFC 6374 to be carried in the PM probe query and
response messages for loss measurement:
o Type TBA2: Block Number TLV
IANA is also requested to allocate a value 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 TBA3: Sequence Number TLV in Unauthenticated Mode
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o Type TBA4: Sequence Number TLV in Authenticated Mode
9. References
9.1. Normative References
[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS networks', RFC 6374, September 2011.
[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-srv6-oam] Ali, Z., et al., "Operations, Administration,
and Maintenance (OAM) in Segment Routing Networks with
IPv6 Data plane (SRv6)", draft-ali-spring-srv6-oam.
9.2. Informative References
[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>.
[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-
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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,
"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
June 2010.
[RFC6437] Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
"IPv6 Flow Label Specification", RFC 6437, November 2011.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, November 2012.
[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.
[RFC8321] Fioccola, G. Ed., "Alternate-Marking Method for Passive
and Hybrid Performance Monitoring", RFC 8321, January
2018.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[I-D.spring-segment-routing-policy] Filsfils, C., et al., "Segment
Routing Policy Architecture",
draft-ietf-spring-segment-routing-policy, work in
progress.
[I-D.spring-sr-p2mp-policy] Voyer, D. Ed., et al., "SR Replication
Policy for P2MP Service Delivery",
draft-voyer-spring-sr-p2mp-policy, work in progress.
[I-D.6man-segment-routing-header] Filsfils, C., et al., "IPv6
Segment Routing Header (SRH)",
draft-ietf-6man-segment-routing-header, work in progress.
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[I-D.spring-rfc6374-srpm-mpls] Filsfils, C., 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.pce-binding-label-sid] Filsfils, C., et al., "Carrying Binding
Label Segment-ID in PCE-based Networks",
draft-sivabalan-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.
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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 various 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
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
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Universita di Roma "Tor Vergata"
Italy
Email: stefano.salsano@uniroma2.it
Pier Luigi Ventre
CNIT
Italy
Email: pierluigi.ventre@cnit.it
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
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