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Versions: (draft-sfc-agv-packet-loss-measurement) 00 01

SFC Working Group                                         Anil Kumar S N
INTERNET-DRAFT                                            Gaurav Agrawal
Intended Status: Standards Track                           Vinod Kumar S
Expires: December 30, 2016                     Huawei Technologies India
                                                           June 28, 2016


                    Packet Loss Measurement for SFC
                draft-agv-sfc-packet-loss-measurement-01


Abstract

   This document describes performance measurement(PM) packet loss
   measurement for Service Function Chains (SFCs) to assess the
   operational status and behavior of a SF, a subset of SFs, a whole SFC
   as a function of the actual deterministic SF/SFC. Packet loss
   mechanism described in this document is based on [SFC-PM-arch]

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 December 30, 2016
















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Copyright and License Notice

   Copyright (c) 2016 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 Terminology  . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2 Terms & Definition . . . . . . . . . . . . . . . . . . . . .  4
     1.3 Applicability and Scope  . . . . . . . . . . . . . . . . . .  4
   2 Massage Format . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1 Performance Measurement Context Header . . . . . . . . . . .  5
     2.2 Packet Loss PM Context Header  . . . . . . . . . . . . . . .  6
     2.3 Performance Measurement Flow ID  . . . . . . . . . . . . . .  8
   3 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     3.1 Packet Loss Statistics Counter . . . . . . . . . . . . . . .  9
     3.2 Initiating a Packet Loss Measurement . . . . . . . . . . . .  9
     3.3 Encapsulation of Classified Packets  . . . . . . . . . . . . 10
     3.4 Incoming Packets Processing at MA  . . . . . . . . . . . . . 10
     3.5 Outgoing Packets Processing at MA  . . . . . . . . . . . . . 11
     3.6 MA Reporting the statistics to Collector . . . . . . . . . . 11
     3.7 Packet Loss Calculation at Collector . . . . . . . . . . . . 11
   4 Security Considerations  . . . . . . . . . . . . . . . . . . . . 12
   5 IANA Considerations  . . . . . . . . . . . . . . . . . . . . . . 12
     5.1 TLV Class  . . . . . . . . . . . . . . . . . . . . . . . . . 12
   7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     7.1 Normative References . . . . . . . . . . . . . . . . . . . . 13
     7.2 Informative References . . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14






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1 Introduction


   The delivery of end-to-end services often requires various service
   functions.  These include traditional network service functions such
   as firewalls and traditional IP Network Address Translators (NATs),
   as well as application-specific functions.  The definition and
   instantiation of an ordered set of service functions and subsequent
   "steering" of traffic through them is termed Service Function
   Chaining (SFC).

   The common reasons for packet drop are traffic congestion, service
   function (DPI/Firewall/Router etc.) performance issue, software
   issues (bugs), faulty hardware or cabling and service function
   processing errors.

   Proper operation of a SFC depends on the ability to monitor and
   quickly identify faults and focus attention on the root cause of the
   problem. Also service provider service level agreements (SLAs)
   depends on the capability to measure and monitor performance metrics
   for packet delay. SFC delay measurement is one of the important tool
   to achieve above requirements.

   Packet loss measurement capability provides operators with greater
   visibility into the performance characteristics of their networks,
   thereby facilitating planning, troubleshooting, and network
   performance evaluation.

   This document specifies best possible efficient and accurate
   mechanism for packet loss measurement for service function chains
   (SFCs) for a SFC network domain.

   The packet loss measurement described in this document is realized by
   adding a new context header in the network service header.

















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1.1 Terminology

   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].

1.2 Terms & Definition

   Refer to RFC 7665 for definitions of SFC terms.

   Measurement Collector: An operational function that collects
           measurement data from a measurement agent. Measurement
           collector is responsible for collecting the performance
           measurement data from measurement agent. Measurement
           collector functionality could be integrated with one of
           the MA or with the controller itself.

   Measurement Agent: An operational function that contains one or
           more measurement functions. Measurement agents is
           responsible for understand and analyze performance
           measurement control information encoded in NSH metadata
           and perform the performance data collecting and report the
           same to measurement collector with key information to
           identify performance measurement instance along with data
           collected.

   Measurement Controller: An operational function that controls
           running, scheduling, and general coordination of measurement
           functions by instructing a measurement agent using NSH
           metadata. Measurement controller is responsible for
           configuring the performance measurement instance.
           Optionally performance measurement instance can be
           configured manually at the ingress in which case
           controller is not required


1.3 Applicability and Scope

   This document defines the implementation mechanism for the packet
   loss measurement as per performance measurement architecture [SFC-PM-
   arch]. This document defines a new NSH message format for carrying
   packet loss measurement related control information. It also defines
   operations to be carried out for packet loss measurement.
   communication mechanism between measurement controller, measurement
   collector and MA is out of scope of this document.






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2 Massage Format

2.1 Performance Measurement Context Header

   The format of the Performance measurement context headers, is as
   described below.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | TLV Class = (IANA PM Class)   |C|   PM Type   |R|R|R|   Len   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            PM Metadata                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure 1: Performance Measurement Context Header

   TLV Class: As per [I-D.ietf-sfc-nsh] the TLV class value for
   performance measurement needs to be applied from IANA.

   PM Type: indicates the type of performance measurement that
   needs to be carried out by the MA.

   Length: Length of the variable PM metadata, in 4-byte words.



























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2.2 Packet Loss PM Context Header

      The format of the packet loss PM context headers, is as
      described below.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | TLV Class = (IANA PM Class)   |C|  PM Type    |R|R|R|   Len   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Measurement Window Index  |           Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         MA Identifier1                        |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         MA IdentifierN                        |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 2: Packet Loss PM Context Header

   TLV Class: As per [I-D.ietf-sfc-nsh] the TLV class value for
   performance measurement needs to be applied from IANA.


   PM Type: Indicates the type of performance measurement that needs
   to be carried out by the MA. (IANA assigned PM Type PM Loss value)

   This memo defines the following values.
      0x1 - Packet Loss : indicates PM meta data contains info for
      packet loss. Specified SF(s) SHOULD participate in packet loss PM.

      0x2 - SF Hop by Hop Packet Loss : indicates PM meta data
      contains info for packet loss. All the SF(s) in the SFP SHOULD
      participate in the packet loss PM

      0x3 - SFF Hop by Hop Packet Loss : indicates PM meta data contains
      info for packet loss. All the SFF(s) in the SFP SHOULD participate
      in the packet loss PM

      0x4 - All Hop by Hop Packet Loss : indicates PM meta data contains
      info for packet loss. All the SF(s) and SFF(s)in the SFP SHOULD
      participate in the packet loss PM



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      0x5 - SFP as a whole : indicates PM meta data contains information
   for packet delay. Classifier (source MA) and SF domain boundary SFF
   (sink MA) SHOULD participate in the packet delay computation.

   Additional values can be added for future PM types and scenarios.

   Length: Length of the variable PM metadata, in 4-byte words. It will
   have a minimum length of 1 indicating the presence of measurement
   window index.

   Measurement Window Index: 16 bit number to denote the current
   measurement window to which the packet belongs.

   Reserved: Reserved 16 bits for future purpose.

   Reserved: Reserved 16 bits for future purpose.
      MA identifier list: List of participating MA in the SFP.

      MA identifier has two parts
      1) Node identifier - 24 bit
         a) For SFF: MUST be unique number assigned by controller
         b) For SF: All zero. Context identifier itself identifies
                       SF node.
      2) Context identifier - 8 bit
         a) For SFF: Service index of next SF.
         b) For SF: Service index

      MA identifier SHOULD be in decreasing order of the SI for
      optimized traversal of the SI participation.

   The Length of the packet loss PM context headers, is fixed to 1 as
   described below, when the PM Type is 2 to 5. Since all SF's in the
   SFP has to perform the loss measurement specified in PM type field.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | TLV Class = (IANA PM Class)   |C| Type 2to5   |R|R|R| Len=0x1 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Measurement Window Index  |           Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+










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2.3 Performance Measurement Flow ID

   The method of encoding the PMF id is done using the flow id defined
   in [I-D.ietf-sfc-nsh].

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         TLV Class = 0x0       |C|    Type=0x7 |R|R|R|   L=0x1 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Performance Measurement Flow ID           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Sample encoding of PMF using flow ID

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Ver|O|C|R|R|R|R|R|R|   Length  |  MD-type=0x2  | Next Protocol |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Service Path ID                      | Service Index |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          TLV Class=IANA       |C|  Type=0x2   |R|R|R|   Len   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Measurement Window Index  |           Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         TLV Class = 0x0       |C|    Type=0x7 |R|R|R|   L=0x1 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Performance Measurement Flow ID                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





















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3 Operations

3.1 Packet Loss Statistics Counter

   Every MA needs to maintain the packet loss statistics which they
   immediately report it to collector or may accumulate and report to
   collector at a reporting interval which depends on local policy.

   Below 2 packet statistics counters will be created and maintained at
   every MA

   1) Rx-STAT[P][M][W]

   2) Tx-STAT[P][M][W]

   Rx-STAT[P][M][W]: This 2 dimensional statistics counter is maintained
   at every MA. Where P stands for PMF ID, M stands for MA identifier
   and W stands for window ID. Rx- STAT[P][M][W] counter maintains the
   number of packets received for a given PMF ID + MA identifier +
   window. PMF ID is unique within a SFC Domain, for a given PMF ID
   there could be multiple windows. Rx-STAT[P][M][W] statistics counter
   is created when first PM packet for loss measurement is received for
   PMF ID + MA identifier + window within a Reporting interval. Rx-
   STAT[P][M][W] statistics counter is deleted at expiry of current
   reporting interval after Rx-STAT[P][M][W] statistics counters are
   reported to collector.


   Tx-STAT[P][M][W]: This 2 dimensional statistics counter is maintained
   at every MA. Where P stands for PMF ID and W stands for window ID.
   Tx- STAT[P][M][W] counter maintains the number of packets sent out
   for a given PMF ID + MA identifier + window. PMF ID is unique within
   a SFC Domain, for a given PMF ID there could be multiple Windows. Tx-
   STAT[P][M][W] statistics counter is created when first PM packet for
   loss measurement is sent for PMF ID + MA identifier + window within a
   Reporting interval. Rx-STAT[P][M][W] statistics counter is deleted at
   expiry of current reporting interval after Tx-STAT[P][M][W]
   statistics counters are reported to collector.


3.2 Initiating a Packet Loss Measurement

   Measurement Controller programs the PM Instance at the classifier.
   Classifier starts the packet classification (based on the
   classification rule/policy). The packet classification policy may be
   customer/network/service specific. Classifier updates/encodes
   corresponding PM instance for classified packets for each PM schedule
   in PM context header.



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3.3 Encapsulation of Classified Packets

   For the classified packet, PM Context Header is prepared with
   following information

   - Set the type class value to the IANA allocated PM class.
   - Set the type value to the required packet loss measurement type.
   - If type value = 0x1
       o Encode the list of MA identifier that need to participate in
         Packet Loss Measurement.
   - If Value = 0x2, 0x3, 0x4, 0x5
       o No need to encode MA identifier, since the type dictates the
         involved participating MA
   - Set the window identifier as the current running window number
   - Encode the 32 bit globally unique PMF ID using the flow ID
     context header as defined in [I-D quinn-sfc-nsh-tlv].


3.4 Incoming Packets Processing at MA

   On receiving the packet with NSH header following operations are
   carried out:

   Step 1: Detection of PM context header in a packet, by verifying
           the PM TLV class as allocated by IANA.
           (If not detected, move to step 6)

   Step 2: Check if PM type field value is 1 to 5.
           (If not move to step 6).

   Step 3: If PM type value = 2 to 5 move directly to Step 5

   Step 4: Check presence of self MA identifier in MA identifier List.
           (If not present, move to step 6)

   Step 5: Record the value of PMF ID and window ID; increment the value
           of statistics counter Rx-STAT[P][M][W] by 1. If statistics
           counter doesn't exist, create it and initialize it with 1.

   Step 6: Packet is sent for normal processing











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3.5 Outgoing Packets Processing at MA

   At outgoing port of MA following operations are carried out.

   Step 1: Record the value of PMF ID and window ID; increment the value
           of statistics counter Tx-STAT[P][M][W] by 1. If statistics
           counter doesn't exist, create it and initialize it with 1.

   Step 2: Packet is sent for normal processing

3.6 MA Reporting the statistics to Collector

   Reporting timer will run on Each MA. Consistency of this timer
   should be ensured across the entire MA in the SFP, ensuring the
   same is out of scope of this document.

   On expiry of this timer following information needs to be sent
   to the Collector.

      - MA identifier
      - PM Type Value
      - Value of all the accumulated Tx-STAT[P][M][W] statistics
        counter along with the corresponding PMF ID and Window Id
      - Value of all the accumulated Rx-STAT[P][M][W] statistics counter
        along with the corresponding PMF ID and window Id

      MA may delete the Tx-STAT[P][M][W], Rx-STAT[P][M][W] after sending
      the same to collector.

3.7 Packet Loss Calculation at Collector

   Collector accumulates the statistics counters per PMF per MA
   identifier per MA per window. On receipt of report from a MA for a
   PMF if it has statistics related for an already collected window,
   received statistics will be summed up, otherwise a new entry is
   created. Collector computes the packet loss using the accumulated
   statistics per PMF per MA per window.

   Packet Loss between MA (for example from MA1 to MA2) = (MA1)Tx-
   STAT[P][M][W] - (MA2)Rx-STAT[P][M][W]

   Packet Loss at MA = (MA)Tx-STAT[P][M][W] - (MA)Rx-STAT[P][M][W]









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4 Security Considerations

   No specific security considerations for this document


5 IANA Considerations

5.1 TLV Class

   IANA is requested to allocate a new class value for performance
   measurement from "Network Service Header (NSH) Parameters" registry.

      Value     Description                   Reference
      -----     -----------                   ---------
      New       Performance Measurement       [SFC-PM-arch]

6.  Acknowledgments
      We would like to thank Nobin Mathew for his review and comments.

































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7 References

7.1 Normative References

   [I-D.ietf-sfc-nsh]           Quinn, P. and U. Elzur, "Network Service
   Header", draft-           ietf-sfc-nsh-01 (work in progress), July
   2015.

7.2 Informative References

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784
              DOI 10.17487/RFC2784, March 2000,
              <http://www.rfc-editor.org/info/rfc2784>.

   [RFC5226]  Narten, T. and H. Alvestrand,"Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [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>.

   [SFC-arch]
              Quinn, P., Ed. and J. Halpern, Ed., "Service Function
              Chaining (SFC) Architecture", 2014,
              <http://datatracker.ietf.org/doc/draft-quinn-sfc-arch>.

   [SFC-PM-arch]
              Anil, Gaurav and Vinod., "Performance Measurement
              Architecture for SFC", 2015,

   [SFC-PM-Delay]
              Anil, Gaurav and Vinod., "Packet Delay Measurement for
              SFC", 2015,














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Authors' Addresses


   Anil Kumar S N
   Huawei Technologies India Pvt. Ltd,
   Near EPIP Industrial Area,
   Kundalahalli Village,
   Whitefield,
   Bangalore - 560037

   EMail: anil.sn@huawei.com



   Gaurav Agrawal
   Huawei Technologies India Pvt. Ltd,
   Near EPIP Industrial Area,
   Kundalahalli Village,
   Whitefield,
   Bangalore - 560037

   EMail: gaurav.agrawal@huawei.com




   Vinod Kumar S
   Huawei Technologies India Pvt. Ltd,
   Near EPIP Industrial Area,
   Kundalahalli Village,
   Whitefield,
   Bangalore - 560037

   EMail: vinods.kumar@huawei.com

















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