Internet DRAFT - draft-vfv-bmwg-srv6-bench-meth

draft-vfv-bmwg-srv6-bench-meth







BMWG                                                         G. Fioccola
Internet-Draft                                              E. Vasilenko
Intended status: Informational                                P. Volpato
Expires: 25 April 2024                               Huawei Technologies
                                                            L. Contreras
                                                              Telefonica
                                                             B. Decraene
                                                                  Orange
                                                         23 October 2023


           Benchmarking Methodology for IPv6 Segment Routing
                   draft-vfv-bmwg-srv6-bench-meth-08

Abstract

   This document defines a methodology for benchmarking Segment Routing
   (SR) performance for Segment Routing over IPv6 (SRv6).  It builds
   upon RFC 2544, RFC 5180, RFC 5695 and RFC 8402.

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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   This Internet-Draft will expire on 25 April 2024.

Copyright Notice

   Copyright (c) 2023 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 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  SRv6 Forwarding . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Test Methodology  . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Test Setup  . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Locator and Endpoint behaviors methods  . . . . . . . . .   7
     3.3.  Frame Formats and Sizes . . . . . . . . . . . . . . . . .   8
     3.4.  Protocol Addresses  . . . . . . . . . . . . . . . . . . .  10
     3.5.  Trial Duration  . . . . . . . . . . . . . . . . . . . . .  10
     3.6.  Traffic Verification  . . . . . . . . . . . . . . . . . .  10
     3.7.  Buffer tests  . . . . . . . . . . . . . . . . . . . . . .  11
   4.  Reporting Format  . . . . . . . . . . . . . . . . . . . . . .  12
   5.  SRv6 Forwarding Benchmarking Tests  . . . . . . . . . . . . .  13
     5.1.  Throughput  . . . . . . . . . . . . . . . . . . . . . . .  14
       5.1.1.  Throughput of a Source Node . . . . . . . . . . . . .  14
       5.1.2.  Throughput of a transit Segment Endpoint Node . . . .  15
       5.1.3.  Throughput of a Segment Endpoint Node with
               decapsulation . . . . . . . . . . . . . . . . . . . .  15
       5.1.4.  Throughput of a Transit Node  . . . . . . . . . . . .  16
     5.2.  Buffers size  . . . . . . . . . . . . . . . . . . . . . .  16
     5.3.  Latency . . . . . . . . . . . . . . . . . . . . . . . . .  17
     5.4.  Frame Loss  . . . . . . . . . . . . . . . . . . . . . . .  17
     5.5.  System Recovery . . . . . . . . . . . . . . . . . . . . .  17
     5.6.  Reset . . . . . . . . . . . . . . . . . . . . . . . . . .  18
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  19
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  19
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22









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1.  Introduction

   Segment Routing (SR), defined in [RFC8402], leverages the source
   routing paradigm.  The headend node steers a packet through an SR
   Policy [RFC9256], 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.  SR
   supports per-class explicit routing while maintaining per-class state
   only at the ingress nodes to the 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],
   [RFC2544], [RFC5180] and [RFC5695] to SR network.

   The SR architecture can be instantiated on two data-plane: SR over
   MPLS (SR-MPLS) and SR over IPv6 (SRv6).  This document is limited to
   SRv6.

   This document is limited to Headend encapsulations (H.Encaps.xxx) and
   segment Endpoints (End, End.X).  It is expected that future documents
   may cover the benchmarking of SRv6 applications with decapsulation
   (End.Dxxx), Binding (End.Bxxx), Fast ReRoute
   [I-D.ietf-rtgwg-segment-routing-ti-lfa], Compressed SID
   [I-D.ietf-spring-srv6-srh-compression], etc.

   SR can be applied to the IPv6 architecture with a new type of routing
   header called the SR Header (SRH) [RFC8754].  An instruction is
   associated with a segment and encoded as an IPv6 address.  An SRv6
   segment is also called an SRv6 SID.  An SR Policy is instantiated as
   an ordered list of SRv6 SIDs in the routing header.  The active
   segment is indicated by the Destination Address (DA) of the packet.

   SRv6 involves 3 types of forwarding plane operations (PUSH/ NEXT/
   CONTINUE) as further described in Section 2.  SR list for PUSH
   operation is typically constructed by the source node with a SR
   Policy, see [RFC9256].  NEXT operation is done by a SR segment
   endpoint node.  CONTINUE operation happens for a SR transit node.

   [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.

   [RFC5180] provides benchmarking methodology recommendations that
   address IPv6-specific aspects, such as evaluating the forwarding
   performance of traffic containing extension headers.





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   The purpose of this document is to describe a methodology specific to
   the benchmarking of Segment Routing over IPv6.  The methodology
   described is a complement for [RFC5180] and [RFC5695].

1.1.  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 RFC 2119 [RFC2119],
   RFC 8174 [RFC8174].

2.  SRv6 Forwarding

   SR leverages the source routing paradigm.  In SRv6, a SID is
   allocated as an IPv6 address.  For the IPv6 data plane, a new type of
   IPv6 Routing Extension Header, called Segment Routing Header (SRH)
   has been defined [RFC8754].  The SRH contains the Segment List as an
   ordered list of IPv6 addresses: each address in the list is a SID.
   Hence SRv6 Segment list typically contains more SIDs.  A dedicated
   field, referred to as Segments Left, is used to maintain the pointer
   to the active SID of the Segment List.

   There are three different categories of nodes that may be involved in
   segment routing networks.

   The SR source node is the headend node and steers a packet into an SR
   Policy.  It can be a host originating an IPv6 packet or an SR domain
   ingress router encapsulating a received packet into an outer IPv6
   packet and inserts the SRH in the outer IPv6 header.  It sets the
   first SID of the SR Policy as the IPv6 Destination Address of the
   packet.

   The SR transit node forwards packets destined for a remote segment as
   a normal IPv6 packet based on the IPv6 destination address, because
   the IPv6 destination address does not locally match with a segment.
   According to [RFC8200] the only node allowed to inspect the Routing
   Extension Header (and therefore the SRH) is the node corresponding to
   the destination address of the packet.

   The SR segment endpoint node receives packets whose IPv6 destination
   address is locally configured as a segment.  It creates Forwarding
   Information Base (FIB) entries for its local SIDs.  For each SR
   packet, it inspects the SRH, may prepare some actions (like
   forwarding through a particular interface), then replaces the IPv6
   destination address with the new active segment.

   The operations applied by the SRv6 packet processing are different at
   the SR source, transit, and SR segment endpoint nodes.



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   The processing of the SR source node corresponds to the sequence of
   insertion of the SRH, composed of SIDs stored in reverse order, and
   setting of the IPv6 Destination Address as the first SID of the SR
   Policy.  It can be performed by encapsulating a packet into an outer
   IPv6 packet with an SRH.

   The processing of the SR segment endpoint node corresponds to the
   detection of the new active segment, which is the next segment in the
   Segment List and the related modification of the IPv6 destination
   address of the outer IPv6 header.  Then packets are forwarded on the
   basis of the IPv6 forwarding table.

   The processing of the SR transit node corresponds to normal
   forwarding of the packets containing the SR header.  In SRv6, the
   transit nodes do not need to be SRv6 aware, as every IPv6 router can
   act as an SRv6 transit node since any IPv6 node will maintain a plain
   IPv6 FIB entry for any prefix, no matter if the prefix represents a
   segment or not.

   [RFC9256] 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, which steers a
   flow into an SR Policy.  Intermediate and endpoint nodes do not
   require any state to be maintained.  SR Policies can be instantiated
   on the headend dynamically and on demand basis.  SR policy may be
   installed by PCEP [RFC8664], BGP
   [I-D.ietf-idr-segment-routing-te-policy], or via manual configuration
   on the router.  PCEP and BGP signaling of SR Policies can be the case
   of a controller-based deployment.

   In addition to the basic SRv6 packet processing, the SRv6 Network
   Programming model [RFC8986] describes a set of functions that can be
   associated to segments and executed in a given SRv6 node.

   Examples of such functions are described in [RFC8986], but, in
   practice, any behavior and function can be associated with a local
   SID in a node, to apply any special processing on the packet.  The
   definition of a standardized set of segment routing functions
   facilitates the deployment of SR domains with interoperable equipment
   from multiple vendors.

   According to [RFC8986], 128 bit SID can be logically split into three
   fields and interpreted as LOCATOR:FUNCTION:ARGS (in short
   LOC:FUNCT:ARG) where LOC includes the L most significant bits, FUNCT
   the following F bits and ARG the remaining A bits, where L+F+A=128.
   The LOC corresponds to an IPv6 prefix (for example with a length of
   48, 56, or 64 bits) that can be distributed by the routing protocols



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   and provides the reachability of a node that hosts some functions.
   All the different functions residing in a node have a different FUNCT
   code, so that their SIDs will be different.  The ARG bits are used to
   provide information (arguments) to a function.  From the routing
   point of view, the solution is scalable, as a single prefix is
   distributed for a node, which implements a potentially large number
   of functions and related arguments.

3.  Test Methodology

3.1.  Test Setup

   The test setup in general is compliant with section 6 of [RFC2544]
   but augmented by the methodology specified in section 4 of [RFC5695]
   using many interfaces.  It is needed to test the packet forwarding
   engine that may have different performance based on the number of
   interfaces served.  The Device Under Test (DUT) may have
   oversubscribed interfaces, then traffic for such interfaces should be
   proportionally decreased according to the specific DUT
   oversubscription ratio.  All interfaces served by a particular packet
   forwarding engine should be loaded in reverse proportion to the
   claimed oversubscription ratio.  Tests SHOULD be done with
   bidirectional traffic that better reflects the real environment for
   SRv6 nodes.  It is OPTIONAL to choose a non-equal proportion for
   upstream and downstream traffic for some specific aggregation nodes.

   The RECOMMENDED topology for SRv6 Forwarding Benchmarking should be
   the same used for MPLS benchmarking, as described in section 4 of
   [RFC5695].  A simplified view is reported below for reference.

                               +----------+
                     +---------|          |<---------+
                     | +-------|  Tester  |<-------+ |
                     | | +-----|          |<-----+ | |
                     | | |     +----------+      | | |
                     | | |                       | | |
                     | | |      +--------+       | | |
                     | | +----->|        |-------+ | |
                     | +------->|  DUT   |---------+ |
                     +--------->|        |-----------+
                                +--------+

        Figure 1: Test environment for SRv6 Forwarding Benchmarking

   Differently from [RFC5695], this document prefers the use of the term
   "interface" instead of "port" as an interface may be either virtual
   or physical.




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   The RECOMMENDED topology for SRv6 Forwarding Benchmarking should be
   the same as MPLS and it is described in section 4 of [RFC5695].
   Interface numbers involved in the tests and their oversubscription
   ratio MUST be reported.  This document is benchmarking only "source
   routing".  Hence, SIDs represent only Headend encapsulation
   (H.Encaps.xxx) or segment Endpoint (End, End.X) that may be carried
   in IGP extensions.  In general, Functions of the last SID (called
   "behavior" in [RFC8986]) may be used to encode services (similar to
   L2/L3 VPNs and much more) but it is out of the scope of this
   document.

   It is OPTIONAL to test SRH in the combination with any other
   extension headers (fragmentation, hop-by-hop, destination options,
   etc.) but in all tests, the SRH header should be present for the test
   to be relevant for SRv6.  It is RECOMMENDED to follow section 5.3 of
   [RFC5180] to introduce other extension headers in proportion 1%, 10%,
   50% that may better reflect real use cases.

   Segment Routing may also be implemented as a software network
   function in an NFV Infrastructure and, in this case, additional
   considerations should be done.  [ETSI-GR-NFV-TST-007] describes test
   guidelines for NFV capabilities that require interactions between the
   components implementing NFV functionality.

   Special capabilities SHOULD NOT exist in the DUT/SUT specifically for
   benchmarking purposes.

3.2.  Locator and Endpoint behaviors methods

   As specified in [RFC8986], topological segments have the structure
   that consists of Locator and Endpoint behavior (H.Encaps, End, End.X,
   etc), the latter may have a few different flavors (PSP, USP, USD).
   Different combinations of behavior and flavor are recommended for
   every test.

   It is RECOMMENDED that the DUT and test tool support at least one
   option for SID stack construction:

   *  IS-IS Extensions to Support Segment Routing over IPv6 Dataplane
      [RFC9352]

   *  OSPFv3 Extensions for SRv6 [I-D.ietf-lsr-ospfv3-srv6-extensions]

   *  Segment Routing Policy Architecture [RFC9256].

   A routing protocol (OSPF or IS-IS) SHOULD be used for the
   construction of the simplest SRH with 1 SID.  It is RECOMMENDED that
   SR policy should be used for the construction of SRH with 2 SIDs.  It



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   is OPTIONAL to test longer SRH if there is an interest.  For longer
   SRH lists, it is suggested to consider DUT maximum, or "network
   diameter" plus one SID for the service, where "network diameter" is
   the maximum number of SR hops that the target SRv6 network have, it
   is typically between 3 to 7 hops.

   It is RECOMMENDED that the top SID on the list should have an End.X
   flavor type to emulate traffic engineering scenario.  In all cases,
   SID stack configuration SHOULD happen before packet forwarding would
   be started.  Control plane convergence speed is not the subject of
   the present tests.

   The Locator and Endpoint construction method and SR policy
   construction method used MUST be reported according to Section 4.

3.3.  Frame Formats and Sizes

   SRv6 tests will use Frame characteristics similarly to section 4.1.5
   of [RFC5695], except the need for a bigger MTU to accommodate SRH.

   It is assumed that MTU is big enough to accommodate all frame sizes
   proposed below.  Fragmentation is not an option for SRv6.

   It is to be noted that [RFC5695] requires exactly a single entry in
   the MPLS label stack in an MPLS packet that is not enough to simulate
   a typical SR SID list.  The number of entries in SRH MUST be
   reported.

   According to section 4.1.4.2 of [RFC5695], the payload is RECOMMENDED
   to have an IP packet (IPv6 or IPv4 with UDP or TCP) to better
   represent the real environment.  The minimal Ethernet payload (46B)
   could not accommodate the whole IPv6 stack (not enough room for TCP
   or UDP), hence only IPv4 is possible to use if the test for minimal
   Ethernet payload is needed.  It is possible to choose the bigger
   payload size for the IPv6 only environment.

   It is assumed that the test would be for Ethernet media only.  Other
   media is possible (see section 4.1.5.2 of [RFC5695] for the POS
   example).  Some layer 2 technologies (like POS/PPP) have bit- or
   byte- stuffing then [RFC4814] may help to calculate real performance
   more accurately or else 1-2% error is expected.  The most popular
   layer 2 technology for SR is Ethernet, it does not have stuffing.









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   RECOMMENDED frame sizes are presented below.  Any other frame sizes
   may be added if suspected of abnormal behavior.  For example, some
   architectures may allocate buffer memory in big fixed chunks that may
   drop performance if frame sizes are chosen just a few octet more than
   the fixed chunk size (the second chunk would have a very low memory
   utilization).

   The resulting Ethernet frame structure is depicted in the next
   figure.

      <---18B---><-40B-><8+n*16B><--------46-1500-9000B----------->
      +---------+-------+-------+---------+-----------------------+
      |         | Outer |       |  Inner  |         |             |
      | Layer 2 | IPv6  |  SRH  | Layer 3 | Layer 4 | High layers |
      +---------+-------+-------+---------+-----------------------+

                     Figure 2: Ethernet Frame Structure

   RECOMMENDED payload sizes (encapsulated packet with L3 headers and
   above) are the following:

   *  Ethernet Minimal: 46

   *  DUT Minimal Wire Speed: typically 128-256 (it depends on the DUT
      specification)

   *  Ethernet Typical: 1500

   *  DUT Maximum: 9000 (or any claimed maximum)

   It is evident from the figure 2 that in all cases we need to add
   40+8+n*16 bytes for the needed frame size, where

      40 octets are added for the outer (tunnel) IPv6 header

      8 octets are added for the SRH header itself

      n is the number of segments multiplied on 16 octet SID size.

   The typical frame size values are listed above for the DUT minimal
   wire speed and maximum, but they can be modified according to the DUT
   characteristics.  The minimum wire speed frame size can be considered
   based on the DUT specification but, in some cases, many tests may be
   needed in the search for the real minimum wire speed frame size.
   VLAN tag may additionally increase the frame size.  VLAN tag tests
   are OPTIONAL.





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3.4.  Protocol Addresses

   IANA reserved an IPv6 address block 2001:0002::/48 for use with IPv6
   benchmark testing (see section 8 of [RFC5180]).  IPv6 source and
   destination addresses for the test streams SHOULD belong to the IPv6
   range assigned by IANA.  It is not principal what Locator blocks
   would be chosen for tests.  It may be /52, /56, /64, or even bigger.
   It is possible to test a few different Locator blocks if there is a
   need.

   As it is discussed in section 3.1, there is a need to load the whole
   forwarding engine (on all interfaces).  [RFC4814] discusses the
   importance to have many flows with address randomization for
   acceptable hash-based load balancing that is implemented in all
   forwarding engines.  Note that IPv6 flow label randomization can be
   used, according to [RFC6438].  In the context of this document, it
   may also be relevant for SIDs, because SIDs may be used for hash to
   choose the next link (depending on DUT default or desired
   configuration).  It is important to check what exactly is used for
   the hash load balancing algorithm on the DUT to keep these numbers
   sufficiently random and at volume.  It is very often that IP
   addresses and transport protocol ports are used instead of SIDs.

3.5.  Trial Duration

   The test portion of each trial must take into account the respective
   protocol configuration.  IGP protocols typically have a shorter hold
   time, while some BGP default configurations may be up to 180 seconds.
   It is needed to check the default hold time of the DUT for the
   respective protocol used.

   In general, the test portion of each trial SHOULD be no less than 250
   seconds, which is a reasonable value based on common hold time
   values.  But a test can also adapt to the real setup and select a
   different value if default configuration has been changed.  The test
   portion of each trial can be chosen at least 10 seconds longer than
   the hold time to verify that the DUT can maintain a stable control
   plane when the data-forwarding plane is under stress.

3.6.  Traffic Verification

   Traffic verification is following section 10 of [RFC2544] and section
   4.1.8 of [RFC5695].  The text is copied here for your convenience.

   "The test equipment SHOULD discard any frames received during a test
   run that are not actual forwarded test frames.  For example, keep-
   alive and routing update frames SHOULD NOT be included in the count
   of received frames.  In all cases, sent traffic MUST be accounted



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   for, whether it was received on the wrong port, the correct port, or
   not received at all.  In all cases, the test equipment SHOULD verify
   the length of the received frames and check that they match the
   expected length.

   Preferably, the test equipment SHOULD include sequence numbers (or
   signature) in the transmitted frames and check for these numbers on
   the received frames.  If this is done, the reported results SHOULD
   include in addition to the number of frames dropped, the number of
   frames that were received out of order, the number of duplicate
   frames received and the number of gaps in the received frame
   numbering sequence".

   Many test tools may, by default, only verify that they have received
   the embedded signature on the receive side.  However, some SRv6 tests
   assumes headers modifications (add or delete SRH, replace destination
   address, adjust "segments left").  All packets SHOULD be checked of
   the correct headers values on the receiving side.

3.7.  Buffer tests

   Back-to-back frame test was initially discussed in section 26.4
   [RFC2544] and later improved in [RFC9004] which is considered the
   comprehensive reference for Back-to-back frame test.  Modern
   forwarding engines are typically flexible in the buffer distribution
   between different interfaces.  Hence, like for all other benchmarking
   tests, it is important to stress the forwarding engine on all
   interfaces.  It should be necessary to perform throughput tests first
   because only frame sizes that stress DUT below wire-speed can be used
   for back-to-back tests.  Buffers would be filled with the rate equal
   to the difference between the theoretical maximum frame rate (wire-
   speed) and DUT measured throughput for the respective frame size.

   The test time could be much shorter than recommended in [RFC9004]
   because typical SR DUT is hardware-based with claimed buffers between
   30ms to 100ms.  It is better to consult with the vendor to find a
   good starting search point.  If DUT is software-based then [RFC9004]
   recommendation for 2-30 seconds is applied.

   Queuing SHOULD NOT have weighted random early detection (WRED) or any
   other mechanism that may start dropping packets before the buffer is
   filled.  Queuing SHOULD be configured for the tail drop which is
   typically a non-default configuration.  Back-to-back frame test is
   rather complex and expensive (50 runs for every frame size).  Hence,
   it is OPTIONAL for SRv6.






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4.  Reporting Format

   There are a few parameters that must be changed in section 5 of
   [RFC5695] for SRv6 tests.

   Reporting parameter preserved from [RFC5695]:

   *  Throughput in bytes per second and frames per second

   *  Frame sizes in Octets (see Section 3.3)

   *  Interface speed (10/50/100/400/800/etc GE)

   *  Interface encapsulation (Ethernet or Ethernet VLAN)

   *  Interface media type (probably Ethernet)

   Parameters changed from [RFC5695]:

   *  SRv6 Forwarding Operations (PUSH/ NEXT/ CONTINUE).

   *  Label Distribution protocol and IGP are the same in the context of
      SRv6.  Hence, it can be called "Locator and Endpoint behaviors
      methods".

   New parameters that MUST be reported are:

   *  Interface numbers involved for ingress and egress in the tests and
      their respective oversubscription ratio.

   *  Upstream/downstream traffic proportion (equal bidirectional or
      some other split).

   *  Number of Segments considered in the SRH.

   *  Behavior (H.Encaps, etc.) and Flavor (PSP, USP, USD) used for
      tests (according to [RFC8986]).

   *  SR Policy construction method (PCEP, BGP, manual configuration).

   *  Type of the payload (IPv6/IPv4, UDP/TCP).

   *  Time to recover from the overload state

   *  Time to recover from the reset state and reset type (particular
      module in reset)





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   *  Tested buffers size in frames with respective frame size (for the
      optional back-to-back test); it is possible to record calculated
      buffer time for wire-speed throughput in milliseconds.

   Some parameters may be the same for all tests (like Media type or
   Ethernet encapsulation) then it may be reported one time.

5.  SRv6 Forwarding Benchmarking Tests

   In general, tests are compliant with [RFC2544] but the important
   correction discussed in section 6 of [RFC2544] is applied: interfaces
   chosen for every test MUST stress all interfaces served by one
   forwarding engine.  It is better to check the DUT specification for
   the relationship between interfaces and the forwarding engine to
   minimize the number of interfaces involved.  But it is possible to
   understand the worst case by looking at the throughput and latency
   from the trial tests.  If any doubt exists about how full is the
   offered load for the forwarding engine then it is better to stress
   all interfaces of the line card or all interfaces for the whole
   router with a centralized forwarding engine.  A partial load on the
   forwarding engine would show optimistic results.  Controllable
   traffic distribution between many interfaces (as specified in section
   4 of [RFC5695]) would need separate SID announcements for separate
   interfaces.

   The performance of modern packet forwarding engines may be huge that
   may need to involve many testers to sufficiently load the DUT as
   presented on figure 3.  Then results correlation and recalculation of
   the real performance would be an additional burden.

                              +----------+
                      +-------|  Tester1 |<-------+
                      | +-----|          |<-----+ |
                      | |     +----------+      | |
                      | |                       | |
                      | |      +--------+       | |
                      | +----->|        |-------+ |
                      +------->|  DUT   |---------+
                      +------->|        |---------+
                      | +----->|        |-------+ |
                      | |      +--------+       | |
                      | |                       | |
                      | |     +----------+      | |
                      | +-----|  Tester2 |<-----+ |
                      +-------|          |<-------+
                              +----------+

                           Figure 3: Many testers



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   As specified in section 6 of [RFC5695], the traffic is sent from test
   tool Tx interface(s) to the DUT at a constant load for a fixed-time
   interval, and is received from the DUT on test tool Rx interface(s).
   If any frame loss is detected, then a new iteration is needed where
   the offered load is decreased and the sender will transmit again.  An
   iterative search algorithm MUST be used to determine the maximum
   offered frame rate with a zero frame loss (No-Drop Rate - NDR).  Each
   iteration should involve varying the offered load of the traffic,
   while keeping the other parameters (test duration, number of
   interfaces, number of addresses, frame size, etc.) constant, until
   the maximum rate at which none of the offered frames are dropped is
   determined.

   The test can be repeated with a varying number of Segments pushed on
   ingress in order to measure the resulting maximum number.  It can
   also be tested the maximum number of Segments that are correctly
   load-balanced in transit by only changing the Nth label in the stack
   and detect when load-balancing fails.

   Therefore, the two main parameters that can be evaluated are:

      Maximum offered frame rate,

      Maximum number of Segments that can be pushed and hashed by the SR
      node for load-balancing.

5.1.  Throughput

   This section contains a description of the tests that are related to
   the characterization of a DUT's SRv6 traffic forwarding throughput.

   The list of segments for SRv6 is represented as a list of IPv6
   addresses, included in the SRH.  There are three distinct types of
   nodes that are involved in segment routing networks that may
   represent four different cases.

5.1.1.  Throughput of a Source Node

   Objective: To obtain the DUT's Throughput during the packet
   processing of a Source Node.  It is when the Source SR node, which
   corresponds to the headend node, encapsulates a received packet into
   an outer IPv6 packet and inserts the SR Header (SRH) as a Routing
   Extension Header in the outer IPv6 header.  The Segment List in the
   SRH is composed of SIDs and the Source SR node sets the first SID of
   the SR Policy as the IPv6 Destination Address of the packet.  The
   RECOMMENDED headend behavior is H.Encaps, in case of interest for
   another behavior (H.Encaps.Red or H.Encaps.L2 or H.Encaps.L2.Red) it
   is OPTIONAL to test it with proper reporting.



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   Procedure: Similar to section 6.1 of [RFC5695] or section 26.1 of
   [RFC2544] with extension to test SID list longer than 1 SID (more
   than 2 are RECOMMENDED).  SID list can be from 1 to N SIDs.  N could
   be specified a priori or measured as part of the test.  The test tool
   must advertise and learn the IP prefix(es) and SID(s) on respective
   sides, as per Section 3.4, and must use one option for SID stack
   construction, as per Section 3.2, on its receive and transmit
   interfaces towards the DUT.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.1.2.  Throughput of a transit Segment Endpoint Node

   Objective: To obtain the DUT's Throughput during the packet
   processing of a Segment Endpoint Node.  It is when the SR Segment
   Endpoint node receives packets whose IPv6 destination address is
   locally configured as a segment.  The SR Segment Endpoint node
   inspects the SR header: it detects the new active segment, i.e. the
   next segment in the Segment List, modifies the IPv6 destination
   address of the outer IPv6 header and forwards the packet on the basis
   of the IPv6 forwarding table.  The RECOMMENDED endpoint behavior is
   End.X, in case of interest for another behavior (End, End.T, End.BM,
   End.B6.Encaps, End.B6.Encaps.Red) it is OPTIONAL to test it with
   proper reporting.  SRH SL (Segment Left) is assumed to be bigger than
   zero for this test.  Moreover, it is assumed that DUT would not need
   to delete headers (no PSP, USD, or USP).

   Procedure: Similar to section 6.1 of [RFC5695] or section 26.1 of
   [RFC2544] with extension to test SID list longer than 1 SID (more
   than 2 are RECOMMENDED).  SID list can be from 1 to N SIDs.  N could
   be specified a priori or measured as part of the test.  The test tool
   must advertise and learn the IP prefix(es) and SID(s) on respective
   sides, as per Section 3.4, and must use one option for SID stack
   construction, as per Section 3.2, on its receive and transmit
   interfaces towards the DUT.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.1.3.  Throughput of a Segment Endpoint Node with decapsulation

   Objective: To obtain the DUT's Throughput during the packet
   processing of a Segment Endpoint Node that needs decapsulation.  It
   is when the SR Segment Endpoint node receives packets whose IPv6
   destination address is locally configured as a segment and SL
   (segment left) in the SRH header is decremented to zero.  The SR
   Segment Endpoint node inspects the SR header: it detects the new



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   active segment, i.e. the next segment in the Segment List, modifies
   the IPv6 destination address of the outer IPv6 header, decapsulate
   the packet, and forwards the packet on the basis of the IPv6
   forwarding table.  The RECOMMENDED endpoint decapsulation behavior is
   End with USD flavor, in case of interest for another flavor (PSP,
   USP) it is OPTIONAL to test it with proper reporting.

   Procedure: Similar to section 6.1 of [RFC5695] or section 26.1 of
   [RFC2544] with extension to test SID list longer than 1 SID (more
   than 2 are RECOMMENDED).  SID list can be from 1 to N SIDs.  N could
   be specified a priori or measured as part of the test.  The test tool
   must advertise and learn the IP prefix(es) and SID(s) on respective
   sides, as per Section 3.4, and must use one option for SID stack
   construction, as per Section 3.2, on its receive and transmit
   interfaces towards the DUT.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.1.4.  Throughput of a Transit Node

   Objective: To obtain the DUT's Throughput during the packet
   processing of a Transit Node.  It is when a Transit node forwards the
   packet containing the SR header as a normal IPv6 packet because the
   IPv6 destination address does not locally match with a segment.

   Procedure: Similar to section 6.1 of [RFC5695] or section 26.1 of
   [RFC2544] with extension to test SID list longer than 1 SID (more
   than 2 are RECOMMENDED).  SID list can be from 1 to N SIDs.  N could
   be specified a priori or measured as part of the test.  The test tool
   must advertise and learn the IP prefix(es) and SID(s) on respective
   sides, as per Section 3.4, and must use one option for SID stack
   construction, as per Section 3.2, on its receive and transmit
   interfaces towards the DUT.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.2.  Buffers size

   Back-to-back frame test is OPTIONAL and SHOULD be performed only
   after throughput tests because it SHOULD use only frame sizes that
   DUT is not capable to forward wire-speed, as explained in
   Section 3.7.

   Objective: To determine the buffer size as defined in section 6 of
   [RFC9004] for each of the SRv6 forwarding operations.




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   Procedure: Should be inherited from [RFC9004] with 2 SIDs RECOMMENDED
   (many SIDs are possible).  Despite the simple general idea for
   filling the buffer until tail drop, [RFC9004] has many details for
   procedure, precautions, and calculations that would be too lengthy to
   copy here.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.3.  Latency

   Objective: To determine the latency as defined in section 6.2 of
   [RFC5695] and section 26.2 of [RFC2544] for each of the SRv6
   forwarding operations.  It is RECOMMENDED to test all four test types
   discussed in Section 5.1.

   Procedure: Similar to Section 5.1.  It is OPTIONAL to improve the
   procedure according to section 7.2 of [RFC8219] with calculations for
   typical and worst-case latency.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.4.  Frame Loss

   Objective: To determine the frame-loss rate (as defined in section
   6.3 of [RFC5695] or and section 26.3 of [RFC2544]) for each of the
   SRv6 forwarding operations of a DUT throughout the entire range of
   input data rates and frame sizes.  The primary idea is to see what
   would be the frame loss under the overload conditions.  It may be
   that overloaded forwarding engine would forward less traffic than in
   the situation close to the overload.  Throughput may drop below the
   possible maximum.  As for the section 26.3 of [RFC2544], it is
   RECOMMENDED to have the data for all tested frame sizes with 10% load
   step above the wire-speed throughput measured in Section 5.1.  It is
   RECOMMENDED to test all four test types discussed in Section 5.1.

   Procedure: Similar to Section 5.1.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.5.  System Recovery

   Objective: To characterize the speed at which a DUT recovers from an
   overload condition for each of the SRv6 forwarding operations.  It is
   RECOMMENDED to test all four test types discussed in Section 5.1.




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   Procedure: Similar to section 6.4 of [RFC5695] or section 26.5 of
   [RFC2544].  Send a stream of frames at a rate 110% of the recorded
   throughput rate or the maximum rate for the media, whichever is
   lower, for at least 60 seconds.  At Timestamp A reduce the frame rate
   to 50% of the above rate and record the time of the last frame lost
   (Timestamp B).  The system recovery time is determined by subtracting
   Timestamp B from Timestamp A.  The test SHOULD be repeated a number
   of times and the average of the recorded values being reported.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

5.6.  Reset

   All type of reset tests are OPTIONAL.

   Objective: To characterize the speed at which a DUT recovers from a
   device or software reset for each of the SRv6 forwarding operations.
   According to section 1.3 of [RFC6201] it is possible to measure frame
   loss or time stamps (depending on the test tool capability).
   According to section 4 of [RFC6201] reset could be: 1) hardware, 2)
   software, or 3) power interruption.  All resets may be partial, i.e.
   only for a particular part of hardware (line card) or software
   (module).  Especial interest may be to test redundant power supplies
   or routing engines to make sure that reset does not affect the
   traffic.  Hardware reset may be soft (command for reset) or hard
   (physical removal and insertion of the module).  These types of reset
   SHOULD be treated as different.  It is OPTIONAL to test all four test
   types discussed in Section 5.1, typically they would give the same
   result.

   Procedure: It is inherited from [RFC6201] (see it for more details).
   It is simple in essence: create the traffic, initiate a reset,
   measure the time for the traffic lost.

   Reporting Format: A table, similar to [RFC5180], with all parameters
   specified in Section 4.

6.  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
   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



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   traffic to the test management network.

   There are no specific security considerations within the scope of
   this document.

7.  IANA Considerations

   This document has no IANA actions.

8.  Acknowledgements

   The authors would like to thank Al Morton, Gabor Lencse, Boris
   Khasanov for the precious comments and suggestions.

9.  References

9.1.  Normative References

   [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>.

   [RFC4814]  Newman, D. and T. Player, "Hash and Stuffing: Overlooked
              Factors in Network Device Benchmarking", RFC 4814,
              DOI 10.17487/RFC4814, March 2007,
              <https://www.rfc-editor.org/info/rfc4814>.

   [RFC5180]  Popoviciu, C., Hamza, A., Van de Velde, G., and D.
              Dugatkin, "IPv6 Benchmarking Methodology for Network
              Interconnect Devices", RFC 5180, DOI 10.17487/RFC5180, May
              2008, <https://www.rfc-editor.org/info/rfc5180>.

   [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>.





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   [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>.

   [RFC8219]  Georgescu, M., Pislaru, L., and G. Lencse, "Benchmarking
              Methodology for IPv6 Transition Technologies", RFC 8219,
              DOI 10.17487/RFC8219, August 2017,
              <https://www.rfc-editor.org/info/rfc8219>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8754]  Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
              <https://www.rfc-editor.org/info/rfc8754>.

   [RFC8986]  Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
              D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
              (SRv6) Network Programming", RFC 8986,
              DOI 10.17487/RFC8986, February 2021,
              <https://www.rfc-editor.org/info/rfc8986>.

9.2.  Informative References

   [ETSI-GR-NFV-TST-007]
              ETSI, "ETSI GR NFV-TST 007: Network Functions
              Virtualisation (NFV) Release 3; Testing; Guidelines on
              Interoperability Testing for MANO", 2020,
              <https://www.etsi.org/deliver/etsi_gr/NFV-
              TST/001_099/007/03.01.01_60/gr_NFV-TST007v030101p.pdf>.

   [I-D.ietf-idr-segment-routing-te-policy]
              Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., and
              D. Jain, "Advertising Segment Routing Policies in BGP",
              Work in Progress, Internet-Draft, draft-ietf-idr-segment-
              routing-te-policy-25, 26 September 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              segment-routing-te-policy-25>.

   [I-D.ietf-lsr-ospfv3-srv6-extensions]
              Li, Z., Hu, Z., Talaulikar, K., and P. Psenak, "OSPFv3
              Extensions for SRv6", Work in Progress, Internet-Draft,
              draft-ietf-lsr-ospfv3-srv6-extensions-15, 21 June 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-lsr-
              ospfv3-srv6-extensions-15>.



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   [I-D.ietf-rtgwg-segment-routing-ti-lfa]
              Litkowski, S., Bashandy, A., Filsfils, C., Francois, P.,
              Decraene, B., and D. Voyer, "Topology Independent Fast
              Reroute using Segment Routing", Work in Progress,
              Internet-Draft, draft-ietf-rtgwg-segment-routing-ti-lfa-
              11, 30 June 2023, <https://datatracker.ietf.org/doc/html/
              draft-ietf-rtgwg-segment-routing-ti-lfa-11>.

   [I-D.ietf-spring-srv6-srh-compression]
              Cheng, W., Filsfils, C., Li, Z., Decraene, B., and F.
              Clad, "Compressed SRv6 Segment List Encoding in SRH", Work
              in Progress, Internet-Draft, draft-ietf-spring-srv6-srh-
              compression-08, 12 September 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
              srv6-srh-compression-08>.

   [RFC6201]  Asati, R., Pignataro, C., Calabria, F., and C. Olvera,
              "Device Reset Characterization", RFC 6201,
              DOI 10.17487/RFC6201, March 2011,
              <https://www.rfc-editor.org/info/rfc6201>.

   [RFC6438]  Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
              for Equal Cost Multipath Routing and Link Aggregation in
              Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
              <https://www.rfc-editor.org/info/rfc6438>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

   [RFC8664]  Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
              and J. Hardwick, "Path Computation Element Communication
              Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
              DOI 10.17487/RFC8664, December 2019,
              <https://www.rfc-editor.org/info/rfc8664>.

   [RFC9004]  Morton, A., "Updates for the Back-to-Back Frame Benchmark
              in RFC 2544", RFC 9004, DOI 10.17487/RFC9004, May 2021,
              <https://www.rfc-editor.org/info/rfc9004>.

   [RFC9256]  Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
              A., and P. Mattes, "Segment Routing Policy Architecture",
              RFC 9256, DOI 10.17487/RFC9256, July 2022,
              <https://www.rfc-editor.org/info/rfc9256>.






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   [RFC9352]  Psenak, P., Ed., Filsfils, C., Bashandy, A., Decraene, B.,
              and Z. Hu, "IS-IS Extensions to Support Segment Routing
              over the IPv6 Data Plane", RFC 9352, DOI 10.17487/RFC9352,
              February 2023, <https://www.rfc-editor.org/info/rfc9352>.

Authors' Addresses

   Giuseppe Fioccola
   Huawei Technologies
   Palazzo Verrocchio, Centro Direzionale Milano 2
   20054 Segrate (Milan)
   Italy
   Email: giuseppe.fioccola@huawei.com


   Eduard Vasilenko
   Huawei Technologies
   17/4 Krylatskaya str.
   Moscow
   Email: vasilenko.eduard@huawei.com


   Paolo Volpato
   Huawei Technologies
   Palazzo Verrocchio, Centro Direzionale Milano 2
   20054 Segrate (Milan)
   Italy
   Email: paolo.volpato@huawei.com


   Luis Miguel Contreras Murillo
   Telefonica
   Spain
   Email: luismiguel.contrerasmurillo@telefonica.com


   Bruno Decraene
   Orange
   France
   Email: bruno.decraene@orange.com











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