Internet DRAFT - draft-gandhi-ippm-stamp-srpm
draft-gandhi-ippm-stamp-srpm
IPPM Working Group R. Gandhi, Ed.
Internet-Draft C. Filsfils
Intended status: Standards Track Cisco Systems, Inc.
Expires: October 31, 2021 D. Voyer
Bell Canada
M. Chen
Huawei
B. Janssens
Colt
R. Foote
Nokia
April 29, 2021
Simple TWAMP (STAMP) Extensions for Segment Routing Networks
draft-gandhi-ippm-stamp-srpm-03
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 specifies RFC 8762 (Simple Two-Way
Active Measurement Protocol (STAMP)) extensions for SR networks, for
both SR-MPLS and SRv6 data planes by augmenting the optional
extensions defined in RFC 8972.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 31, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Reference Topology . . . . . . . . . . . . . . . . . . . 3
3. Destination Node Address TLV . . . . . . . . . . . . . . . . 4
4. Return Path TLV . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Return Path Sub-TLVs . . . . . . . . . . . . . . . . . . 6
4.1.1. Return Path Control Code Sub-TLV . . . . . . . . . . 6
4.1.2. Return Address Sub-TLV . . . . . . . . . . . . . . . 7
4.1.3. Return Segment List Sub-TLVs . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . 10
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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 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] without the use of a control channel to pre-signal
session parameters. [RFC8972] defines optional extensions for STAMP.
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The STAMP test packets are transmitted along an IP path between a
Session-Sender and a Session-Reflector to measure performance delay
and packet loss along that IP path. It may be desired in SR networks
that the same path (same set of links and nodes) between the Session-
Sender and Session-Reflector is used for the STAMP test packets in
both directions. This is achieved by using the STAMP [RFC8762]
extensions for SR-MPLS and SRv6 networks specified in this document
by augmenting the optional extensions defined in [RFC8972].
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
MPLS: Multiprotocol Label Switching.
PM: Performance Measurement.
SID: Segment ID.
SL: Segment List.
SR: Segment Routing.
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.
2.3. 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 may be
transmitted to the STAMP Session-Sender R1 on the same path (same set
of links and nodes) or a different path in the reverse direction from
the path taken towards the Session-Reflector.
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The nodes R1 and R3 may be connected via a link or 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 [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. Destination Node Address TLV
The STAMP Session-Sender may need to transmit test packets to the
STAMP Session-Reflector with a different destination address not
matching an address on the Session-Reflector e.g. when the STAMP test
packet is encapsulated by a tunneling protocol or an MPLS Segment
List with IPv4 address from 127/8 range. In an error condition, the
STAMP test packet may not reach the intended STAMP Session-Reflector,
an un-intended node may transmit reply test packets resulting in
reporting of invalid measurement metrics.
[RFC8972] defines STAMP test packets that can include one or more
optional TLVs. In this document, Destination Node Address TLV (Type
TBA1) is defined for STAMP test packet [RFC8972] and has the
following format shown in Figure 1:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|STAMP TLV Flags| Type=TBA1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Address Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Address .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Destination Node Address TLV Format
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The Address Family field indicates the type of the address, and it
SHALL be set to one of the assigned values in the "IANA Address
Family Numbers" registry.
The STAMP TLV Flags are set using the procedures described in
[RFC8972].
The Destination Node Address TLV is optional. The Destination Node
Address TLV indicates the address of the intended Session-Reflector
node of the test packet. The STAMP Session-Reflector that supports
this TLV, MUST NOT transmit reply test packet if it is not the
intended destination node of the received Session-Sender test packet.
4. Return Path TLV
For end-to-end SR paths, the STAMP Session-Reflector may need to
transmit the reply test packet on a specific return path. The STAMP
Session-Sender can request this in the test packet to the STAMP
Session-Reflector using a Return Path TLV. With this TLV carried in
the STAMP Session-Sender test packet, signaling and maintaining
dynamic SR network state for the STAMP sessions on the Session-
Reflector are avoided.
For links, the STAMP Session-Reflector may need to transmit the reply
test packet on the same incoming link in the reverse direction. The
STAMP Session-Sender can request this in the test packet to the STAMP
Session-Reflector using a Return Path TLV.
[RFC8972] defines STAMP test packets that can include one or more
optional TLVs. In this document, the TLV Type (value TBA2) is
defined for the Return Path TLV that carries the return path for the
STAMP Session-Sender test packet. The format of the Return Path TLV
is shown in Figure 2:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|STAMP TLV Flags| Type=TBA2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Return Path Sub-TLVs |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Return Path TLV
The STAMP TLV Flags are set using the procedures described in
[RFC8972].
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The Return Path TLV is optional. The STAMP Session-Sender MUST only
insert one Return Path TLV in the STAMP test packet. The STAMP
Session-Reflector that supports this TLV, MUST only process the first
Return Path TLV in the test packet and ignore other Return Path TLVs
if present, and it MUST NOT add Return Path TLV in the reply test
packet.
4.1. Return Path Sub-TLVs
The Return Path TLV contains one or more Sub-TLVs to carry the
information for the requested return path. A Return Path Sub-TLV can
carry Return Path Control Code, Return Path IP Address or Return Path
Segment List.
The STAMP Sub-TLV Flags are set using the procedures described in
[RFC8972].
When Return Path Sub-TLV is present in the Session-Sender test
packet, the STAMP Session-Reflector that supports this TLV, MUST
transmit reply test packet using the return path information
specified in the Return Path Sub-TLV.
A Return Path TLV MUST NOT contain both Control Code Sub-TLV as well
as Return Address or Return Segment List Sub-TLV.
4.1.1. Return Path Control Code Sub-TLV
The format of the Return Path Control Code Sub-TLV is shown in
Figure 3. The Type of the Return Path Control Code Sub-TLV is
defined as following:
o Type (value 1): Return Path Control Code. The STAMP Session-
Sender can request the STAMP Session-Reflector to transmit the
reply test packet based on the flags defined in the Control Code
field.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|STAMP TLV Flags| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Control Code Sub-TLV in Return Path TLV
Control Code Flags (32-bit): Defined as follows.
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0x0: No Reply Requested.
0x1: Reply Requested on the Same Link.
When Control Code flag is set to 0x0 in the STAMP Session-Sender test
packet, the Session-Reflector does not transmit reply test packet to
the Session-Sender and terminates the STAMP test packet. Optionally,
the Session-Reflector may locally stream performance metrics via
telemetry using the information from the received test packet. All
other Return Path Sub-TLVs are ignored in this case.
When Control Code flag is set to 0x1 in the STAMP Session-Sender test
packet, the Session-Reflector transmits the reply test packet over
the same incoming link where the test packet is received in the
reverse direction towards the Session-Sender.
4.1.2. Return Address Sub-TLV
The STAMP reply test packet may be transmitted to a different node
than the Session-Sender (e.g. to a controller for telemetry use-
cases). For this, the Session-Sender can specify in the test packet
the receiving destination node address for the Session-Reflector
reply test packet.
The format of the Return Address Sub-TLV is shown in Figure 4. The
Address Family field indicates the type of the address, and it SHALL
be set to one of the assigned values in the "IANA Address Family
Numbers" registry. The Type of the Return Address Sub-TLV is defined
as following:
o Type (value 2): Return Address. Destination node address of the
STAMP Session-Reflector reply test packet different than the
Source Address in the Session-Sender test packet.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|STAMP TLV Flags| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Address Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Address .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Return Address Sub-TLV in Return Path TLV
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4.1.3. Return Segment List Sub-TLVs
The format of the Segment List Sub-TLVs in the Return Path TLV is
shown in Figure 5. The segment entries MUST be in network order.
The Segment List Sub-TLV can be one of the following Types:
o Type (value 3): SR-MPLS Label Stack of the Return Path
o Type (value 4): SRv6 Segment List of the Return Path
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|STAMP TLV Flags| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(1) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Segment(n) (bottom of stack) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Segment List Sub-TLV in Return Path TLV
An SR-MPLS Label Stack Sub-TLV may carry only Binding SID
[I-D.ietf-pce-binding-label-sid] of the Return SR-MPLS Policy.
An SRv6 Segment List Sub-TLV may carry only Binding SID
[I-D.ietf-pce-binding-label-sid] of the Return SRv6 Policy.
The STAMP Session-Sender MUST only insert one Segment List Return
Path Sub-TLV in the test packet. The STAMP Session-Reflector MUST
only process the first Segment List Return Path Sub-TLV in the test
packet and ignore other Segment List Return Path Sub-TLVs if present.
5. 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 STAMP
Session-Reflector.
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If desired, attacks can be mitigated by performing basic validation
and sanity checks, at the STAMP Session-Sender, of the timestamp
fields in received 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 test packet to a single
test cycle.
The security considerations specified in [RFC8762] and [RFC8972] also
apply to the extensions defined in this document.
6. IANA Considerations
IANA will create a "STAMP TLV Type" registry for [RFC8972]. IANA is
requested to allocate a value for the following Destination Address
TLV Type from the IETF Review TLV range of this registry. This TLV
is to be carried in the STAMP test packets.
o Type TBA1: Destination Node Address TLV
IANA is also requested to allocate a value for the following Return
Path TLV Type from the IETF Review TLV range of the same registry.
This TLV is to be carried in the STAMP test packets.
o Type TBA2: Return Path TLV
IANA is requested to create a sub-registry for "Return Path Sub-TLV
Type". All code points in the range 1 through 175 in this registry
shall be allocated according to the "IETF Review" procedure as
specified in [RFC8126]. Code points in the range 176 through 239 in
this registry shall be allocated according to the "First Come First
Served" procedure as specified in [RFC8126]. Remaining code points
are allocated according to Table 1:
+-----------+--------------+---------------+
| Value | Description | Reference |
+-----------+--------------+---------------+
| 0 | Reserved | This document |
| 1 - 175 | Unassigned | This document |
| 176 - 239 | Unassigned | This document |
| 240 - 251 | Experimental | This document |
| 252 - 254 | Private Use | This document |
| 255 | Reserved | This document |
+-----------+--------------+---------------+
Table 1: Return Path Sub-TLV Type Registry
IANA is requested to allocate the values for the following Sub-TLV
Types from this registry.
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o Type (value 1): Return Path Control Code
o Type (value 2): Return Address
o Type (value 3): SR-MPLS Label Stack of the Return Path
o Type (value 4): SRv6 Segment List of the Return Path
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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>.
7.2. Informative References
[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>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
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[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-pce-binding-label-sid]
Sivabalan, S., Filsfils, C., Tantsura, J., Previdi, S.,
and C. Li, "Carrying Binding Label/Segment Identifier in
PCE-based Networks.", draft-ietf-pce-binding-label-sid-08
(work in progress), April 2021.
[IEEE802.1AX]
IEEE Std. 802.1AX, "IEEE Standard for Local and
metropolitan area networks - Link Aggregation", November
2008.
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, Mike Koldychev, Gyan
Mishra, Tianran Zhou, and Cheng Li for providing comments and
suggestions.
Authors' Addresses
Rakesh Gandhi (editor)
Cisco Systems, Inc.
Canada
Email: rgandhi@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
Email: cfilsfil@cisco.com
Daniel Voyer
Bell Canada
Email: daniel.voyer@bell.ca
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Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
Bart Janssens
Colt
Email: Bart.Janssens@colt.net
Richard Foote
Nokia
Email: footer.foote@nokia.com
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