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Versions: (draft-aldrin-sfc-oam-framework) 00 01 02 03 04 05 06

Internet Engineering Task Force                                S. Aldrin
Internet-Draft                                                    Google
Intended status: Informational                         C. Pignataro, Ed.
Expires: January 4, 2018                                   N. Kumar, Ed.
                                                                   Cisco
                                                                N. Akiya
                                                     Big Switch Networks
                                                             R. Krishnan
                                                             A. Ghanwani
                                                                    Dell
                                                            July 3, 2017


                       Service Function Chaining
          Operation, Administration and Maintenance Framework
                    draft-ietf-sfc-oam-framework-02

Abstract

   This document provides reference framework for Operations,
   Administration and Maintenance (OAM) for Service Function Chaining
   (SFC).

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

   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."

   This Internet-Draft will expire on January 4, 2018.






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Copyright Notice

   Copyright (c) 2017 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
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Document Scope  . . . . . . . . . . . . . . . . . . . . .   3
   2.  SFC Layering Model  . . . . . . . . . . . . . . . . . . . . .   4
   3.  SFC OAM Components  . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Service Function Component  . . . . . . . . . . . . . . .   5
       3.1.1.  Service Function Availability . . . . . . . . . . . .   5
       3.1.2.  Service Function Performance Measurement  . . . . . .   6
     3.2.  Service Function Chain Component  . . . . . . . . . . . .   6
       3.2.1.  Service Function Chain Availability . . . . . . . . .   6
       3.2.2.  Service Function Chain Performance Measurement  . . .   7
     3.3.  Classifier Component  . . . . . . . . . . . . . . . . . .   7
   4.  SFC OAM Functions . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Connectivity Functions  . . . . . . . . . . . . . . . . .   7
     4.2.  Continuity Functions  . . . . . . . . . . . . . . . . . .   8
     4.3.  Trace Functions . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Performance Measurement Function  . . . . . . . . . . . .   9
   5.  Gap Analysis  . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Existing OAM Functions  . . . . . . . . . . . . . . . . .   9
     5.2.  Missing OAM Functions . . . . . . . . . . . . . . . . . .  10
     5.3.  Required OAM Functions  . . . . . . . . . . . . . . . . .  10
   6.  SFC OAM Model . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  SFC OAM packet Marker . . . . . . . . . . . . . . . . . .  11
     6.2.  OAM packet processing and forwarding semantic . . . . . .  11
     6.3.  OAM Function Types  . . . . . . . . . . . . . . . . . . .  12
     6.4.  OAM toolset applicability . . . . . . . . . . . . . . . .  12
       6.4.1.  ICMP Applicability  . . . . . . . . . . . . . . . . .  12
       6.4.2.  Seamless BFD Applicability  . . . . . . . . . . . . .  12
       6.4.3.  In-Situ OAM . . . . . . . . . . . . . . . . . . . . .  13
       6.4.4.  SFC Traceroute  . . . . . . . . . . . . . . . . . . .  13
     6.5.  Security Considerations . . . . . . . . . . . . . . . . .  13
     6.6.  IANA Considerations . . . . . . . . . . . . . . . . . . .  14



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     6.7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . .  14
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Service Function Chaining (SFC) enables the creation of composite
   services that consist of an ordered set of Service Functions (SF)
   that are to be applied to packets and/or frames selected as a result
   of classification.  Service Function Chaining is a concept that
   provides for more than just the application of an ordered set of SFs
   to selected traffic; rather, it describes a method for deploying SFs
   in a way that enables dynamic ordering and topological independence
   of those SFs as well as the exchange of metadata between
   participating entities.  The foundations of SFC are described in the
   following documents:

   o  SFC Problem Statement [RFC7498]

   o  SFC Architecture [RFC7665]

   The reader is assumed to familiar with the material in these
   documents.

   This document provides reference framework for Operations,
   Administration and Maintenance (OAM, [RFC6291]) of SFC.
   Specifically, this document provides:

   o  In Section 2, an SFC layering model;

   o  In Section 3, aspects monitored by SFC OAM;

   o  In Section 4, functional requirements for SFC OAM;

   o  In Section 5, a gap analysis for SFC OAM.

1.1.  Document Scope

   The focus of this document is to provide an architectural framework
   for SFC OAM, particularly focused on the aspect of the Operations
   component within OAM.  Actual solutions and mechanisms are outside
   the scope of this document.







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2.  SFC Layering Model

   Multiple layers come into play for implementing the SFC.  These
   include the service layer at SFC layer and the underlying Network,
   Transport, Link, etc., layers.

   o  The service layer, refer to as the "Service Layer" in Figure 1,
      consists of classifiers and service functions, and uses the
      overlay network reach from a classifier to service functions and
      service functions to service functions.

   o  The overlay network layer, refer to as the "Network" in Figure 1,
      extends in between various service functions and is mostly
      transparent to the service functions.  It leverages various
      overlay network technologies interconnecting service functions and
      allows establishing of service function paths.

   o  The underlay network layer, refer to as the "Transport" in
      Figure 1, is dictated by the networking technology of the PSN.  It
      may be either based on MPLS LSPs or IP.

   o  The link layer, refer to as the "Link" in Figure 1, is dependent
      upon the physical technology used.  Ethernet is a popular choice
      for this layer, but other alternatives are deployed (e.g.  POS,
      DWDM etc...).

      o----------------------Service Layer----------------------o

   +------+   +---+   +---+   +---+   +---+   +---+   +---+   +---+
   |Classi|---|SF1|---|SF2|---|SF3|---|SF4|---|SF5|---|SF6|---|SF7|
   |fier  |   +---+   +---+   +---+   +---+   +---+   +---+   +---+
   +------+
                o------VM1------o       o--VM2--o       o--VM3--o

      o-----------------o-------------------o---------------o  Network

      o-----------------o-----------------------------------o  Transport

      o--------o--------o--------o--------o--------o--------o  Link

                Figure 1: SFC Layering Example

3.  SFC OAM Components

   The SFC operates at the service layer.  For the purpose of defining
   the OAM framework, the service layer is broken up into three distinct
   components.




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   1.  Service function component: A function providing a specific
       service.  OAM solutions for this component are to test the
       service functions from any SFC aware network devices (i.e.
       classifiers, controllers, other service nodes).

   2.  Service function chain component: An ordered set of service
       functions.  OAM solution for this component are to test the
       service function chains and the service function paths.

   3.  Classifier component: A policy that describes the mapping from
       flows to service function chains.  OAM solutions for this
       component are to test the validity of the classifiers.

   Below figure illustrates an example where OAM for the three defined
   components are used within the SFC environment.

   +-Classifier    +-Service Function Chain OAM
   | OAM           |
   |               |    _________________________________________
   |                \  /\         Service Function Chain         \
   |      +------+   \/  \  +---+   +---+   +---+   +---+   +---+ \
   +----> |Classi|...(+-> ) |SF1|---|SF2|---|SF4|---|SF6|---|SF7|  )
          |fier  |    \  /  +-^-+   +---+   +-|-+   +-^-+   +---+ /
          +----|-+     \/_____|_______________|_______|_________ /
               |              |               +-SF_OAM+
               +----SF_OAM----+         +---+   +---+
                                +SF_OAM>|SF3|   |SF5|
                                |       +-^-+   +-^-+
                         +------|---+     |       |
                         |Controller|     +-SF_OAM+
                         +----------+
                              Service Function OAM (SF_OAM)

                Figure 2: SFC OAM for Three Components

   It is expected that multiple SFC OAM solutions will be defined, many
   targeting one specific component of the service layer.  However, it
   is critical that SFC OAM solutions together provide the coverage of
   all three SFC OAM components: the service function component, the
   service function chain component and the classifier component.

3.1.  Service Function Component

3.1.1.  Service Function Availability

   One SFC OAM requirement for the service function component is to
   allow an SFC aware network device to check the availability to a
   specific service function, located on the same or different network



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   devices.  Service function availability is an aspect which raises an
   interesting question.  How does one determine that a service function
   is available?  On one end of the spectrum, one might argue that a
   service function is sufficiently available if the service node
   (physical or virtual) hosting the service function is available and
   is functional.  On the other end of the spectrum, one might argue
   that the service function availability can only be concluded if the
   packet, after passing through the service function, was examined and
   verified that the packet got expected service applied.

   The former approach will likely not provide sufficient confidence to
   the actual service function availability, i.e. a service node and a
   service function are two different entities.  The latter approach is
   capable of providing an extensive verification, but comes with a
   cost.  Some service functions make direct modifications to packets,
   while other service functions do not make any modifications to
   packets.  Additionally, purpose of some service functions is to,
   conditionally, drop packets intentionally.  In such case, packets
   will not be coming out from the service function.  The fact is that
   there are many flavors of service functions available, and many more
   flavors of service functions will likely be introduced in future.
   Even a given service function may introduce a new functionality
   within a service function (ex: a new signature in a firewall).  The
   cost of this approach is that verifier functions will need to be
   continuously modified to "keep up" with new services coming out: lack
   of extendibility.

   This framework document provides a RECOMMENDED architectural model
   where generalized approach is taken to verify that a service function
   is sufficiently available.  TBD - details will be provided in a later
   revision.

3.1.2.  Service Function Performance Measurement

   Second SFC OAM requirement for the service function component is to
   allow an SFC aware network device to check the loss and delay of a
   specific service function, located on the same or different network
   devices.  TBD - details will be provided in a later revision.

3.2.  Service Function Chain Component

3.2.1.  Service Function Chain Availability

   Verifying an SFC is a complicated process as the SFC could be
   comprised of varying SF's.  Thus, SFC requires the OAM layer to
   perform validation and verification of SF's within an SFC Path, as
   well as connectivity and fault isolation.




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   In order to perform service connectivity verification of an SFC, the
   OAM could be initiated from any SFC aware network devices for end-to-
   end paths or partial path terminating on a specific SF within the
   SFC.  This OAM function is to ensure the SF's chained together has
   connectivity as it is intended to when SFC was established.
   Necessary return code should be defined to be sent back in the
   response to OAM packet, in order to qualify the verification.

   When ECMP exists at the service layer on a given SFC, there must be
   an ability to discover and traverse all available paths.

   TBD - further details will be provided in a later revision.

3.2.2.  Service Function Chain Performance Measurement

   The ingress of the service function chain or an SFC aware network
   device must have an ability to perform loss and delay measurements
   over the service function chain as a unit (i.e. end-to-end) or to a
   specific service function through the SFC.

3.3.  Classifier Component

   A classifier defines a flow and maps incoming traffic to a specific
   SFC, and it is vital that the classifier is correctly defined and
   functioning.  The SFC OAM must be able to test the definition of
   flows and the mapping functionality to expected SFCs.

4.  SFC OAM Functions

   Section 3 described SFC OAM operations required on each SFC
   component.  This section explores the same from the OAM functionality
   point of view, which many will be applicable to multiple SFC
   components.

   Various SFC OAM requirements provides the need for various OAM
   functions at different layers.  Many of the OAM functions at
   different layers are already defined and in existence.  In order to
   support SFC and SF's, these functions have to be enhanced to operate
   a single SF to multiple SF's in an SFC and also multiple SFC's.

4.1.  Connectivity Functions

   Connectivity is mainly an on-demand function to verify that the
   connectivity exists between network elements and the availability
   exists to service functions.  Ping is a common tool used to perform
   this function.  OAM messages SHOULD be encapsulated with necessary
   SFC header and with OAM markings when testing the service function
   chain component.  OAM messages MAY be encapsulated with necessary SFC



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   header and with OAM markings when testing the service function
   component.  Some of the OAM functions performed by connectivity
   functions are as follows:

   o  Verify the MTU size from a source to the destination SF or through
      the SFC.  This requires the ability for OAM packet to take
      variable length packet size.

   o  Verify the packet re-ordering and corruption.

   o  Verify the policy of an SFC or SF using OAM packet.

   o  Verification and validating forwarding paths.

   o  Proactively test alternate or protected paths to ensure
      reliability of network configurations.

4.2.  Continuity Functions

   Continuity is a model where OAM messages are sent periodically to
   validate or verify the reachability to a given SF or through a given
   SFC.  This allows monitor network device to quickly detect failures
   like link failures, network failures, service function outages or
   service function chain outages.  BFD is one such function which helps
   in detecting failures quickly.  OAM functions supported by continuity
   check are as follows:

   o  Ability to provision continuity check to a given SF or through a
      given SFC.

   o  Notifying the failure upon failure detection for other OAM
      functions to take appropriate action.

4.3.  Trace Functions

   Tracing is an important OAM function that allows the operation to
   trigger an action (ex: response generation) from every transit device
   on the tested layer.  This function is typically useful to gather
   information from every transit devices or to isolate the failure
   point towards an SF or through an SFC.  Some of the OAM functions
   supported by trace functions are:

   o  Ability to trigger action from every transit device on the tested
      layer towards an SF or through an SFC, using TTL or other means.

   o  Ability to trigger every transit device to generate response with
      OAM code(s) on the tested layer towards an SF or through an SFC,
      using TTL or other means.



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   o  Ability to discover and traverse ECMP paths within an SFC.

   o  Ability to skip un-supported SF's while tracing SF's in an SFC.

4.4.  Performance Measurement Function

   Performance management functions involve measuring of packet loss,
   delay, delay variance, etc.  These measurements could be measured
   pro-actively and on-demand.

   SFC OAM framework should provide the ability to perform packet loss
   for an SFC.  In an SFC, there are various SF's chained together.
   Measuring packet loss is very important function.  Using on-demand
   function, the packet loss could be measured using statistical means.
   Using OAM packets, the approximation of packet loss for a given SFC
   could be measured.

   Delay within an SFC could be measured from the time it takes for a
   packet to traverse the SFC from ingress SF to egress SF.  As the
   SFC's are generally unidirectional in nature, measurement of one-way
   delay is important.  In order to measure one-way delay, the clocks
   have to be synchronized using NTP, GPS, etc.

   Delay variance could also be measured by sending OAM packets and
   measuring the jitter between the packets passing through the SFC.

   Some of the OAM functions supported by the performance measurement
   functions are:

   o  Ability to measure the packet processing delay of a service
      function or a service function path along an SFC.

   o  Ability to measure the packet loss of a service function or a
      service function path along an SFC.

5.  Gap Analysis

   This Section identifies various OAM functions available at different
   levels.  It will also identify various gaps, if not all, existing
   within the existing toolset, to perform OAM function on an SFC.

5.1.  Existing OAM Functions

   There are various OAM tool sets available to perform OAM function and
   network layer, protocol layers and link layers.  These OAM functions
   could validate some of the underlay and overlay networks.  Tools like
   ping and trace are in existence to perform connectivity check and
   tracing intermediate hops in a network.  These tools support



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   different network types like IP, MPLS, TRILL etc.  There is also an
   effort to extend the tool set to provide connectivity and continuity
   checks within overlay networks.  BFD is another tool which helps in
   detection of data forwarding failures.

   +----------------+--------------+-------------+--------+------------+
   | Layer          | Connectivity |  Continuity |  Trace | Performance|
   +----------------+--------------+-------------+--------+------------+
   | Underlay N/w   | Ping         | E-OAM, BFD  |  Trace | IPPM, MPLS |
   +----------------+--------------+-------------+--------+------------+
   | Overlay N/w    | Ping         | BFD, NVo3   | Trace  | IPPM       |
   +----------------+--------------+-------------+--------+------------+
   | SF             | None         + None        + None   + None       |
   +----------------+--------------+-------------+--------+------------+
   | SFC            | None         + None        + None   + None       |
   +----------------+--------------+-------------+--------+------------+
                Figure 3: OAM Tool GAP Analysis

   +----------------+--------------+-------------+--------+------------+
   | Layer          |Configuration |Orchestration|Topology|Notification|
   +----------------+--------------+-------------+--------+------------+
   | Underlay N/w   |CLI, Netconf  | CLI, Netconf|SNMP    |SNMP, Syslog|
   +----------------+--------------+-------------+--------+------------+
   | Overlay N/w    |CLI, Netconf  | CLI, Netconf|SNMP    |SNMP, Syslog|
   +----------------+--------------+-------------+--------+------------+
   | SF             |CLI           + CLI         + None   + None       |
   +----------------+--------------+-------------+--------+------------+
   | SFC            |CLI           + CLI         + None   + None       |
   +----------------+--------------+-------------+--------+------------+
                Figure 4: OAM Tool GAP Analysis (contd.)

5.2.  Missing OAM Functions

   As shown in Figure 3, OAM functions for SFC are not standardized yet.
   Hence, there are no standard based tools available to verify SF and
   SFC.

5.3.  Required OAM Functions

   Primary OAM functions exist for network, transport, link and other
   layers.  Tools like ping, trace, BFD, etc., exist in order to perform
   these OAM functions.  Configuration, orchestration and manageability
   of SF and SFC could be performed using CLI, Netconf etc.

   As seen in Figure 3 and 4, for configuration, manageability and
   orchestration, providing data and information models for SFC is very
   much needed.  With virtualized SF and SFC, manageability of these
   functions has to be done programmatically.



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6.  SFC OAM Model

   This section describes the operational aspects of SFC OAM at Service
   layer to perform the SFC OAM function defined in Section 4 and
   analyze the applicability of various existing OAM toolsets in the
   Service layer.

6.1.  SFC OAM packet Marker

   SFC OAM function described in Section 4 performed at service layer or
   overlay network layer must mark the packet as OAM packet that can be
   used by the relevant nodes to differentiate the OAM packet from data
   packets.  The base header defined in Section 3.2 of
   [I-D.ietf-sfc-nsh] assigns a bit to indicate OAM packets.  When NSH
   encapsulation is used at the service layer, the O bit must be set to
   differentiate the OAM packet.  Any other overlay encapsulations used
   in future must have a way to mark the packet as OAM packet.

6.2.  OAM packet processing and forwarding semantic

   Upon receiving OAM packet, SF may choose to discard the packet if it
   does not support OAM functionality or if the local policy prevent it
   from processing OAM packet.  When SF supports OAM functionality, it
   is desired to process the packet and respond back accordingly that
   helps with end-to-end verification.  To avoid hitting any performance
   impact, SF can rate limit the number of OAM packets processed.

   Service Function Forwarder (SFF) may choose not to forward the OAM
   packet to SF if the SF does not support OAM function or if the policy
   does not allow to forward OAM packet to SF.  SFF may choose to skip
   the SF, modify the header and forward to next SFC node in the chain.
   How SFF detects if the connected SF supports or allowed to process
   OAM packet is outside the scope of this document.  It could be a
   configuration paramater instructed by the controller or can be a
   dynamic negotiation between SF and SFF.

   If the SFF receiving the OAM packet is the last SFF in the chain, it
   must send a relevant response to the initiator of the OAM packet.
   Depending on the type of OAM solution and tool set used, the response
   could be a simple response (ICMP reply or BFD reply packet) or could
   include additional data from the received OAM packet (like stats data
   consolidated along the path).  The proposed solution should detail it
   further.

   The classifier will normally be the node that initiates the OAM
   packet in order to validate the local classification policy or to
   validate the SFC or SFP.  When the classifier initiates OAM packet,
   it must set the OAM marker in the overlay encapsulation.



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6.3.  OAM Function Types

   As described in Section 4, there are different OAM functions that may
   require different OAM solution or tool sets.  While the presence of
   OAM marker in overlay header (For ex: O bit in NSH header) indicates
   it as OAM packet, it is not sufficient to indicate what OAM function
   the packet is intended for.  We can use the Next Protocol field in
   NSH header to indicate what OAM function is it intended to or what
   toolset is used.

6.4.  OAM toolset applicability

   As described in Section 5.1, there are different tool sets available
   to perform OAM functions at different layers.  This section describes
   the applicability of some of the available tool sets in service
   layer.

6.4.1.  ICMP Applicability

   [RFC0792] and [RFC4443] describes the use of ICMP in IPv4 and IPv6
   network respectively.  It explains how ICMP messages can be used to
   test the network reachability between different end points and
   perform basic network diagnostics.

   ICMP could be leveraged for basic OAM functions like SF availability
   or SFC availability.  Initiator can generate ICMP echo message and
   control the overlay encapsulation header to get the response from
   relevant node.  For example, a classifier initiating OAM can generate
   ICMP echo message can set the TTL field in NSH header to 255 to get
   the response from last SFF and thereby test the SFC availability.
   Alternately, Initiator can set the TTL to other value to get the
   response from specific SF and there by test the SF availability.
   Alternately, Initiator could send OAM packets with sequentially
   incrementing the TTL in NSH header to trace the Service Function
   Path.

   It could be observed that ICMP at its current stage may not be able
   to perform all SFC OAM functions, but as explained above, it can be
   used to test the basic OAM functions.

6.4.2.  Seamless BFD Applicability

   [RFC5880] defines Bidirectional Forwarding Detection (BFD) mechanism
   for fast failure detection.  [RFC5881] and [RFC5884] defines the
   applicability of BFD in IPv4, IPv6 and MPLS networks.  [RFC7880]
   defines Seamless BFD (S-BFD), a simplified mechanism of using BFD.
   [RFC7881] explains its applicability in IPv4, IPv6 and MPLS network.




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   S-BFD could be leveraged to perform SF or SFC availability.
   Classifier or Initiator could generate BFD control packet and set the
   "Your Discriminator" value as last SFF in the control packet.  Upon
   receiving the control packet, last SFF will reply back with relevant
   DIAG code.  We could also use the TTL field in NSH header to perform
   the SF availability.  For example, Initiator can set the "Your
   Discriminator" value to the SF that is intended to be tested and set
   the TTL field in NSH header in a way that it will be expired on the
   relevant SF.  How the initiator gets the Discriminator value of the
   SF is outside the scope of this document.

6.4.3.  In-Situ OAM

   [I-D.brockners-proof-of-transit] defines the mechanism to perform
   proof of transit to securely verify if a packet traversed the
   relevant path or chain.  While the mechanism is defined inband (i.e,
   it will be included in data packets), it can be used to perform
   various SFC OAM functions as well.

   In-Situ OAM could be used with O bit set and perform SF availability,
   SFC availability of performance measurement.

6.4.4.  SFC Traceroute

   [I-D.penno-sfc-trace] defines a protocol that checks for path
   liveliness and trace the service hops in any SFP.  Section 3 of
   [I-D.penno-sfc-trace]  defines the SFC trace packet format while
   section 4 and 5 of [I-D.penno-sfc-trace]  defines the behavior of SF
   and SFF respectively.

   Initiator can control the SIL in SFC trace packet to perform SF and
   SFC availability test.

6.5.  Security Considerations

   SFC and SF OAM must provide mechanisms for:

   o  Preventing usage of OAM channel for DDOS attacks.

   o  OAM packets meant for a given SFC should not get leaked beyond
      that SFC.

   o  Prevent OAM packets to leak the information of an SFC beyond its
      administrative domain.







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6.6.  IANA Considerations

   No action is required by IANA for this document.

6.7.  Acknowledgements

   TBD

7.  References

7.1.  Normative References

   [I-D.brockners-proof-of-transit]
              Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
              Leddy, J., Youell, S., Mozes, D., and T. Mizrahi, "Proof
              of Transit", draft-brockners-proof-of-transit-03 (work in
              progress), March 2017.

   [I-D.ietf-sfc-nsh]
              Quinn, P. and U. Elzur, "Network Service Header", draft-
              ietf-sfc-nsh-13 (work in progress), June 2017.

   [I-D.penno-sfc-trace]
              Penno, R., Quinn, P., Pignataro, C., and D. Zhou,
              "Services Function Chaining Traceroute", draft-penno-sfc-
              trace-03 (work in progress), September 2015.

   [RFC0792]  Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <http://www.rfc-editor.org/info/rfc792>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", RFC 4443,
              DOI 10.17487/RFC4443, March 2006,
              <http://www.rfc-editor.org/info/rfc4443>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <http://www.rfc-editor.org/info/rfc5880>.






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   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              DOI 10.17487/RFC5881, June 2010,
              <http://www.rfc-editor.org/info/rfc5881>.

   [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, <http://www.rfc-editor.org/info/rfc5884>.

   [RFC7498]  Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for
              Service Function Chaining", RFC 7498,
              DOI 10.17487/RFC7498, April 2015,
              <http://www.rfc-editor.org/info/rfc7498>.

   [RFC7665]  Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665,
              DOI 10.17487/RFC7665, October 2015,
              <http://www.rfc-editor.org/info/rfc7665>.

   [RFC7880]  Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S.
              Pallagatti, "Seamless Bidirectional Forwarding Detection
              (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016,
              <http://www.rfc-editor.org/info/rfc7880>.

   [RFC7881]  Pignataro, C., Ward, D., and N. Akiya, "Seamless
              Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6,
              and MPLS", RFC 7881, DOI 10.17487/RFC7881, July 2016,
              <http://www.rfc-editor.org/info/rfc7881>.

   [RFC8029]  Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
              Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
              Switched (MPLS) Data-Plane Failures", RFC 8029,
              DOI 10.17487/RFC8029, March 2017,
              <http://www.rfc-editor.org/info/rfc8029>.

7.2.  Informative References

   [RFC6291]  Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
              D., and S. Mansfield, "Guidelines for the Use of the "OAM"
              Acronym in the IETF", BCP 161, RFC 6291,
              DOI 10.17487/RFC6291, June 2011,
              <http://www.rfc-editor.org/info/rfc6291>.








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Authors' Addresses

   Sam K. Aldrin
   Google

   Email: aldrin.ietf@gmail.com


   Carlos Pignataro (editor)
   Cisco Systems, Inc.

   Email: cpignata@cisco.com


   Nagendra Kumar (editor)
   Cisco Systems, Inc.

   Email: naikumar@cisco.com


   Nobo Akiya
   Big Switch Networks

   Email: nobo.akiya.dev@gmail.com


   Ram Krishnan
   Dell

   Email: ramkri123@gmail.com


   Anoop Ghanwani
   Dell

   Email: anoop@alumni.duke.edu















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