BMWG G. Fioccola
Internet-Draft E. Vasilenko
Intended status: Informational P. Volpato
Expires: September 3, 2022 Huawei Technologies
March 2, 2022
Benchmarking Methodology for MPLS Segment Routing
draft-vfv-bmwg-srmpls-bench-meth-00
Abstract
This document defines a methodology for benchmarking Segment Routing
(SR) performance for Segment Routing over MPLS (SR-MPLS).
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 RFC 2119 [RFC2119].
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 3, 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. SR-MPLS Forwarding . . . . . . . . . . . . . . . . . . . . . 3
3. Test Methodology . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Test Setup . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. IGP and BGP Support . . . . . . . . . . . . . . . . . . . 5
3.3. Frame Formats and Sizes . . . . . . . . . . . . . . . . . 5
4. Reporting Format . . . . . . . . . . . . . . . . . . . . . . 6
5. SR-MPLS Forwarding Benchmarking Tests . . . . . . . . . . . . 6
5.1. Throughput . . . . . . . . . . . . . . . . . . . . . . . 6
5.1.1. Throughput for SR-MPLS PUSH . . . . . . . . . . . . . 6
5.1.2. Throughput for SR-MPLS NEXT . . . . . . . . . . . . . 6
5.1.3. Throughput for SR-MPLS CONTINUE . . . . . . . . . . . 7
5.2. Latency . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.3. Frame Loss . . . . . . . . . . . . . . . . . . . . . . . 7
5.4. System Recovery . . . . . . . . . . . . . . . . . . . . . 7
5.5. Reset . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6. SR Policy: protection performance . . . . . . . . . . . . . . 8
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Segment Routing (SR), defined in [RFC8402], leverages the source
routing paradigm. The headend node steers a packet through an SR
Policy [I-D.ietf-spring-segment-routing-policy], instantiated as an
ordered list of segments. A segment, referred to by its Segment
Identifier (SID), can have a semantic local to an SR node or global
within an SR domain.
However, there is no standard method defined to compare and contrast
the foundational SR packet forwarding capabilities of network
devices. This document aims to extend the efforts of [RFC1242] and
[RFC2544] to SR network.
The SR architecture can be instantiated on two data-plane: SR over
MPLS (SR-MPLS) and SR over IPv6 (SRv6).
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SR can be directly applied to the Multiprotocol Label Switching
(MPLS) architecture with no change to the forwarding plane [RFC8660].
A segment is encoded as an MPLS label. An SR Policy is instantiated
as a stack of labels.
For Segment Routing, PUSH, NEXT, and CONTINUE are operations applied
by the forwarding plane.
PUSH consists of the insertion of a segment at the top of the segment
list. In SR-MPLS, the top of the segment list is the outer label of
the label stack. In SRv6, the top of the segment list is represented
by the first segment in the SRH.
NEXT consists of the inspection of the next segment. The active
segment is completed and the next segment becomes active. In SR-
MPLS, NEXT is implemented as a POP of the top label.
CONTINUE happens when the active segment is not completed; hence, it
remains active. In SR-MPLS, the CONTINUE operation is implemented as
a SWAP of the top label.
[RFC5695] describes a methodology specific to the benchmarking of
MPLS forwarding devices, by considering the most common MPLS packet
forwarding scenarios and corresponding performance measurements.
The purpose of this document is to describe a methodology specific to
the benchmarking of Segment Routing. The methodology described is a
complement for [RFC5695].
2. SR-MPLS Forwarding
In MPLS, a Prefix-SID is allocated in the form of an MPLS label. For
SR-MPLS, Segment Routing does not require any change to the MPLS
forwarding plane. An SR Policy is instantiated through the MPLS
Label Stack: the Segment IDs (SIDs) of a Segment List are inserted as
MPLS Labels. The classical forwarding functions available for MPLS
networks allow implementing the SR operations.
The operations applied by the SR-MPLS forwarding plane are PUSH,
NEXT, and CONTINUE.
The PUSH operation corresponds to the Label Push function, according
to the MPLS label pushing rules specified in [RFC3032]. It consists
of pushing one or more MPLS labels on top of an incoming packet then
sending it out of a particular physical interface or virtual
interface towards a particular next hop.
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The NEXT operation corresponds to the Label Pop function, that
consists of removing the topmost label. The action before and/or
after the popping depends on the instruction associated with the
active SID on the received packet prior to the popping. It is
equivalent to Penultimate Hop Popping (PHP).
The CONTINUE operation corresponds to the Label Swap function,
according to the MPLS label-swapping rules in [RFC3031]. It consists
of associating an incoming label with an outgoing interface and
outgoing label and forwarding the packet on the outgoing interface.
It is equivalent to Ultimate Hop Popping (UHP).
The encapsulation of an IP packet into an SR-MPLS packet is performed
at the edge of an SR-MPLS domain, reusing the MPLS Forwarding
Equivalent Class (FEC) concept. A Forwarding Equivalent Class (FEC)
can be associated with an SR Policy ([RFC8660]). When pushing labels
onto a packet's label stack, the Time-to-Live (TTL) field and the
Traffic Class (TC) field of each label stack entry must also be set.
All SR nodes in the SR domain use an IGP signaling extension to
advertise their own prefix SIDs. After receiving advertised prefix
SIDs, each SR node calculates the prefix SIDs to the advertisers.
The prefix SID advertisement can be an absolute value advertisement
or an index value advertisement. In this regard, the mapping of
Segments to MPLS Labels (SIDs) is an important process in the SR-MPLS
data plane. Each router can advertise its own available label space
to be used for Global Segments called Segment Routing Global Block
(SRGB) and an identical range of labels (SRGB) should be used in all
routers in order to simplify services and operations. In the SR
domain Global Segments can be identified by an index, which has to be
re-mapped into a label, or by an absolute value. This is relevant
for the nodes that perform the NEXT operation to the segments,
because the label for the next segments needs to be crafted
accordingly.
[I-D.ietf-spring-segment-routing-policy] specifies the concepts of SR
Policy and steering into an SR Policy. The header of a packet
steered in an SR Policy is augmented with the ordered list of
segments associated with that SR Policy. SR Policy state is
instantiated only on the headend node, that steers a flow into an SR
Policy. Indeed intermediate and endpoint nodes do not require any
state to be maintained. SR Policies can be be instantiated on the
headend dynamically and on demand basis. Moreover, signaling can be
used in the case of a controller based deployment. For all these
reasons, SR Policies scale better than traditional TE mechanisms.
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3. Test Methodology
3.1. Test Setup
The Device Under Test (DUT) is connected to the test ports on the
test tool according to [RFC2544].
The recommended topology for SR-MPLS Forwarding Benchmarking should
be the same as MPLS and it is described in [RFC5695] for both single-
port and multi-port scenarios. Indeed, the number of ports is a
parameter that MUST be reported.
3.2. IGP and BGP Support
It is RECOMMENDED that all of the ports on the DUT and test tool
support a dynamic Interior Gateway Protocol (IGP) for routing such as
IS-IS and OSPF as well as Border Gateway Protocol (BGP).
As specified in [RFC8402], in the context of an IGP-based distributed
control plane, two topological segments are defined: the IGP-
Adjacency segment and the IGP-Prefix segment; while, in the context
of a BGP-based distributed control plane, two topological segments
are defined: the BGP peering segment and the BGP-Prefix segment.
The distribution method that is used (e.g. OSPF, IS-IS, BGP) MUST be
reported.
3.3. Frame Formats and Sizes
The tests for SR-MPLS will use the Frame characteristics as described
in [RFC5695].
Note that [RFC5695] requires exactly a single entry in the MPLS label
stack in an MPLS packet. In other words, the depth of the label
stack is set to one.
To ensure successful delivery of Layer 2 frames carrying SR-MPLS
packets and realistic benchmarking, it is RECOMMENDED to set the
media MTU value to the effective maximum frame payload size (payload
of 1500 octets for Ethernet).
The number of entries in the label stack MUST be reported. In
addition, it MUST be chosen taking into account this condition.
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4. Reporting Format
There are new parameters that MUST be replaced or added to the
parameters specified in [RFC5695]:
o SR-MPLS Forwarding Operations (PUSH/ NEXT/ CONTINUE).
o Number of Segments considered in the MPLS Label Stack.
o Global SIDs or Local SID forwarding behavior.
o SR Policy headend or endpoint behavior.
5. SR-MPLS Forwarding Benchmarking Tests
This document recommends the same benchmarking tests described in
[RFC2544] and [RFC5695] while observing the DUT setup and the traffic
setup considerations specific for SR-MPLS as described above. It may
require additional benchmarking steps.
5.1. Throughput
This section contains the description of the tests that are related
to the characterization of a DUT's SR-MPLS traffic forwarding
throughput.
The list of segments for SR-MPLS is represented as a stack of MPLS
labels. There are three distinct operations to be tested: PUSH, NEXT
and CONTINUE. These correspond to the three forwarding operations of
an MPLS packet: PUSH (or LSP Ingress), SWAP, or POP (or LSP Egress).
5.1.1. Throughput for SR-MPLS PUSH
Objective: To obtain the DUT's Throughput during PUSH forwarding
operation. It is similar to label Push or LSP Ingress forwarding
operation, as per [RFC5695]. Non-reserved MPLS label values MUST be
used.
Procedure: Same as [RFC5695].
Reporting Format: Same as [RFC5695] but adding the additional
parameters specified in Section 4.
5.1.2. Throughput for SR-MPLS NEXT
Objective: To obtain the DUT's Throughput during NEXT forwarding
operation. It is equivalent to MPLS Label Pop or Penultimate Hop
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Popping (PHP), as per [RFC5695]. Non-reserved MPLS label values MUST
be used.
Procedure: Same as [RFC5695].
Reporting Format: Same as [RFC5695] but adding the additional
parameters specified in Section 4.
5.1.3. Throughput for SR-MPLS CONTINUE
Objective: To obtain the DUT's Throughput during CONTINUE forwarding
operation. It is equivalent to MPLS Label Swap or Ultimate Hop
Popping (UHP), as per [RFC5695]. Non-reserved MPLS label values MUST
be used.
Procedure: Same as [RFC5695].
Reporting Format: Same as [RFC5695] but adding the additional
parameters specified in Section 4.
5.2. Latency
Objective: To determine the latency as defined in [RFC5695] for each
of the SR-MPLS forwarding operations.
Procedure: Same as [RFC5695].
Reporting Format: Same as [RFC5695] but adding the additional
parameters specified in Section 4.
5.3. Frame Loss
Objective: To determine the frame-loss rate (as defined in [RFC5695])
for each of the SR-MPLS forwarding operations of a DUT throughout the
entire range of input data rates and frame sizes.
Procedure: Same as [RFC5695].
Reporting Format: Same as [RFC5695] but adding the additional
parameters specified in Section 4.
5.4. System Recovery
Objective: To characterize the speed at which a DUT recovers from an
overload condition for each of the SR-MPLS forwarding operations.
Procedure: Same as [RFC5695].
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Reporting Format: Same as [RFC5695]. but adding the additional
parameters specified in Section 4.
5.5. Reset
Objective: To characterize the speed at which a DUT recovers from a
device or software reset for each of the SR-MPLS forwarding
operations.
Procedure: Same as [RFC5695].
Reporting Format: Same as [RFC5695] but adding the additional
parameters specified in Section 4.
6. SR Policy: protection performance
[RFC6414] provides common terminology and metrics for benchmarking
the performance of protection mechanisms. [RFC6894] provides
detailed test cases with different topologies and scenarios that
should be considered to effectively benchmark MPLS-FRR protection
mechanisms and failover times on the data plane. The same approach
can be considered also for Segment Routing protection mechanisms.
An SR Policy can be used for Traffic Engineering (TE), Operations,
Administration, and Maintenance (OAM), or Fast Reroute (FRR) reasons.
Protection allows that, in the event the interface associated with
the Adj-SID is down, the packet can still be forwarded via an
alternate path. The use of protection is clearly a policy-based
decision that determines, for example, that a PUSH operation is done
to forward a packet over a backup path calculated using TI-LFA.
7. Security Considerations
Benchmarking methodologies are limited to technology characterization
in a laboratory environment, with dedicated address space and
constraints. Special capabilities SHOULD NOT exist in the DUT/SUT
specifically for benchmarking purposes. Any implications for network
security arising from the DUT/SUT SHOULD be identical in the lab and
in production networks. The benchmarking network topology is an
independent test setup and MUST NOT be connected to devices that may
forward the test traffic into a production network or misroute
traffic to the test management network.
There are no specific security considerations within the scope of
this document.
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8. IANA Considerations
This document has no IANA actions.
9. Acknowledgements
TBD
10. References
10.1. Normative References
[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-18 (work in progress),
February 2022.
[RFC1242] Bradner, S., "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, DOI 10.17487/RFC1242,
July 1991, <https://www.rfc-editor.org/info/rfc1242>.
[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>.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
Network Interconnect Devices", RFC 2544,
DOI 10.17487/RFC2544, March 1999,
<https://www.rfc-editor.org/info/rfc2544>.
[RFC5695] Akhter, A., Asati, R., and C. Pignataro, "MPLS Forwarding
Benchmarking Methodology for IP Flows", RFC 5695,
DOI 10.17487/RFC5695, November 2009,
<https://www.rfc-editor.org/info/rfc5695>.
[RFC6414] Poretsky, S., Papneja, R., Karthik, J., and S. Vapiwala,
"Benchmarking Terminology for Protection Performance",
RFC 6414, DOI 10.17487/RFC6414, November 2011,
<https://www.rfc-editor.org/info/rfc6414>.
[RFC6894] Papneja, R., Vapiwala, S., Karthik, J., Poretsky, S., Rao,
S., and JL. Le Roux, "Methodology for Benchmarking MPLS
Traffic Engineered (MPLS-TE) Fast Reroute Protection",
RFC 6894, DOI 10.17487/RFC6894, March 2013,
<https://www.rfc-editor.org/info/rfc6894>.
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[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>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
10.2. Informative References
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
Authors' Addresses
Giuseppe Fioccola
Huawei Technologies
Riesstrasse, 25
Munich 80992
Germany
Email: giuseppe.fioccola@huawei.com
Eduard Vasilenko
Huawei Technologies
17/4 Krylatskaya str.
Moscow 121614
Russia
Email: vasilenko.eduard@huawei.com
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Paolo Volpato
Huawei Technologies
Via Lorenteggio, 240
Milan 20147
Italy
Email: paolo.volpato@huawei.com
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