IPPM                                                        H. Song, Ed.
Internet-Draft                                                   T. Zhou
Intended status: Standards Track                                   Z. Li
Expires: June 14, 2019                                            Huawei
                                                                 J. Shin
                                                              SK Telecom
                                                       December 11, 2018


               Postcard-based In-band Flow Data Telemetry
              draft-song-ippm-postcard-based-telemetry-01

Abstract

   The Postcard-Based Telemetry (PBT) allows network OAM applications to
   collect telemetry data about any user packet.  Unlike similar
   techniques such as in-situ OAM (IOAM), PBT does not require user
   packets to carry the telemetry data, but directly exports the
   telemetry data from the data collecting node to a collector through
   separated OAM packets called postcards.  Two variations of PBT are
   described: one requires inserting an instruction header to user
   packets to guide the data collection and the other only marks the
   user packets or configure the flow filter to invoke the data
   collection.  PBT provides an alternative to IOAM and address several
   implementation and deployment challenges of it.

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 June 14, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  PBT-M: Postcard-based Telemetry with Packet Marking . . . . .   4
     2.1.  New Requirements  . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Solution Description  . . . . . . . . . . . . . . . . . .   6
     2.3.  New Challenges  . . . . . . . . . . . . . . . . . . . . .   7
     2.4.  Considerations on PBT-M Design  . . . . . . . . . . . . .   7
       2.4.1.  Packet Marking  . . . . . . . . . . . . . . . . . . .   7
       2.4.2.  Flow Path Discovery . . . . . . . . . . . . . . . . .   8
       2.4.3.  Packet Identity for Export Data Correlation . . . . .   8
     2.5.  Avoid Packet Marking through Node Configuration . . . . .   9
   3.  PBT-I: Postcard-based Telemetry with Instruction Header . . .   9
     3.1.  Solution Description  . . . . . . . . . . . . . . . . . .  10
     3.2.  PBT-I Telemetry Instruction Header  . . . . . . . . . . .  11
     3.3.  Considerations on PBT-I Design  . . . . . . . . . . . . .  12
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  12
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  13
   8.  Informative References  . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Motivation

   In order to gain detailed data plane visibility to support effective
   network OAM, it is important to be able to examine the trace of user
   packets along their forwarding paths.  Such in-band flow data reflect
   the state and status of each user packet's real-time experience and
   provide valuable information for network monitoring, measurement, and
   diagnosis.

   The telemetry data include but not limited to the detailed forwarding
   path, the timestamp/latency at each network node, and, in case of
   packet drop, the drop location and reason.  The emerging programmable
   data plane devices allow user-defined data
   collection[I-D.song-opsawg-dnp4iq] or conditional data collection
   based on trigger events.  Such in-band flow data are from and about



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   the live user traffic, which complement with the data acquired
   through other passive and active OAM mechanisms such as IPFIX
   [RFC7011] and ICMP [RFC2925].

   In-band Network Telemetry (INT) was designed to cater this need. in-
   situ OAM (iOAM) [I-D.brockners-inband-oam-requirements] represents
   the related standardization efforts.  In essence, INT augments user
   packets with instructions to tell each network node on their
   forwarding paths what data to collect.  The requested data are
   inserted into and travel along with the user packets.  Some end nodes
   are responsible to strip off the data trace and export it to a data
   collector for processing.

   While the concept is simple and straightforward, INT faces several
   technical challenges:

   o  Issue 1: INT header and data processing needs to be done in data
      plane fast path.  It may interfere with the normal traffic
      forwarding (e.g., leading to forwarding performance degradation)
      and lead to inaccurate measurements (e.g., resulting in longer
      latency measurements than usual).  This undesirable "observer
      effect" is problematic to carrier networks where stringent SLA
      must be observed.

   o  Issue 2: INT may significantly increase the user packet's original
      size by adding the instruction header and data at each traversed
      node.  The longer the forwarding path and the more the data
      collected, the larger the packet will become.  The size may exceed
      the path MTU so either INT cannot apply or the packet needs to be
      fragmented.  Limiting the data size or path length reduces the
      effectiveness of INT.  On the other hand, the INT header and data
      can be deeply embedded in a packet due to various transport
      protocol and tunnel configurations.  The required deep packet
      header inspection and processing may be infeasible to some data
      plane fast path where only a limited number of header bytes are
      accessible.

   o  Issue 3: INT requires attaching an instruction header to user
      packets to inform network nodes what types of data to collect.
      Due to the header overhead constraint and hardware-friendly
      consideration, TLV is undesirable for data type encoding.
      Instead, iOAM use a bitmap where each bit indicates one pre-
      defined data type [I-D.ietf-ippm-ioam-data].  However, new use
      cases may require new data types.  The current allocated 16-bit
      bitmap limits the data type scalability.  The proposed bitmap
      extension in [I-D.song-ippm-ioam-data-extension] provides a method
      to support more data types but it also increases the iOAM header
      size.



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   o  Issue 4: INT header need to be encapsulated into user packets for
      transport.  [I-D.brockners-inband-oam-transport] has discussed
      several encapsulation approaches for different transport
      protocols.  However, it is difficult to encapsulate extra header
      in MPLS and IPv4 networks which happens to be the most widely
      deployed and where the path-associated telemetry data is most
      wanted by operators.  The proposed NVGRE encapsulation for IPv4 in
      [I-D.brockners-inband-oam-transport] requires a tunnel to be built
      between each pair of nodes which may be unrealistic for plain IP
      networks.

   o  Issue 5: The INT header and data are vulnerable to eavesdropping
      and tampering as well as DoS attack.  Extra protective measurement
      is difficult on the fast data path.

   o  Issue 6: Since INT only exports the telemetry data at the
      designated end node, if the packet is dropped in the network, the
      data will be lost as well.  It cannot pinpoint the packet drop
      location which is required for fault diagnosis.

   The above issues are inherent to the INT-based solutions.
   Nevertheless, the path-associated data acquired by INT are valuable
   for network operators.  Therefore, alternative approaches which can
   collect the same data but avoid or mitigate the above issues are
   desired.  This document provides a new approach named Postcard-Based
   Telemetry (PBT) with two different implementation variations, each
   having its own trade-off and addressing some or all of the above
   issues.  The basic idea of PBT is simple: at each node, instead of
   inserting the collected data into the user packets, the data are
   directly exported through dedicated OAM packets.  Such "postcard"
   approach is in contrast to the "passport stamps" approach adopted by
   INT [DOI_10.1145_2342441.2342453].  The OAM packets or postcards can
   be transported in band or out of band, independent of the original
   user packets.

2.  PBT-M: Postcard-based Telemetry with Packet Marking

   This section describes the first variation of PBT.  PBT-M aims to
   address all the challenges of INT listed above and introduce some new
   benefits.  We first list all the design requirements of PBT-M.

2.1.  New Requirements

   o  Req. 1: We should avoid augmenting user packets with new headers
      or introducing new data plane protocols.  This helps to alleviate
      or eliminate the issue 1, 2, 4, and 5.  We expect the OAM data
      collecting signaling remains in data plane.  Simple packet marking




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      techniques suffice to serve this purpose.  It is also possible to
      configure the OAM data collecting from the control plane.

   o  Req. 2: We should make the scheme extensible for collecting
      arbitrary new data to support possible future use cases.  The data
      set to be collected is preferred to be configured through
      management plane or control plane.  Since there is no limitation
      on the types of data, any data including those generated by
      customized DNPs [I-D.song-opsawg-dnp4iq] can be collected.  Since
      there is no size constraints any more, it is free to use the more
      flexible TLV for data type definition.  This addresses the issue 2
      and 3.

   o  Req. 3: We should avoid interfering the normal forwarding and
      affecting the forwarding performance when conducting data plane
      OAM tasks.  Hence, the collected data are better to be transported
      independently by dedicated OAM packets through in-band or out-of-
      band channels.  The data collecting, processing, assembly,
      encapsulation, and transport are therefore decoupled from the
      forwarding of the corresponding user packets and can be performed
      in data plane slow path if necessary.  This addresses the issue 1,
      4, and 5.

   o  Req. 4: The data collected from each node is not necessarily
      identical, depending on application requirements and node
      capability.  Data for different operation modes can be collected
      at the same time.  These requirements are either impossible or
      very difficult to be supported by INT in which data types
      collected per node are supposed to be identical and for a single
      mode.

   o  Req. 5: The flow's path-associated data can be sensitive and the
      security concerns need to be carefully addressed.  Sending OAM
      data with independent packets also makes it easy to secure the
      collected data without exposing it to unnecessary entities.  For
      example, the data can be encrypted before being sent to the
      collector so passive eavesdropping and man-in-the-middle attack
      can both be deterred.  This addresses the issue 5.

   o  Req. 6: Even if a user packet under inspection is dropped in
      network, the OAM data that have been collected should still be
      exported and help to diagnose the packet drop location and reason.
      This addresses the issue 6.








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2.2.  Solution Description

   In light of the above discussion, the sketch of the proposed
   solution, PBT-M, is as follows.  The user packet, if its path-
   associated data need to be collected, is marked at the path head
   node.  At each PBT-aware node, a postcard (i.e., the dedicated OAM
   packet triggered by a marked user packet) is generated and sent to a
   collector.  The postcard contains the data requested by the
   management plane.  The requested data are configured by the
   management plane through data templates (as in IPFIX [RFC7011]) or
   other means.  Once the collector receives all the postcards for a
   single user packet, it can infer the packet's forwarding path and
   analyze the data set.  The path end node is configured to unmark the
   packets to its original format if necessary.

   The overall architecture of PBT-M is depict in Figure 1.


                          +------------+        +-----------+
                          | Network    |        | Telemetry |
                          | Management |(-------| Data      |
                          |            |        | Collector |
                          +-----:------+        +-----------+
                                :                     ^
                                :configurations       |postcards (OAM pkts)
                                :                     |
                 ...............:.....................|........
                 :             :               :      |       :
                 :   +---------:---+-----------:---+--+-------:---+
                 :   |         :   |           :   |          :   |
                 V   |         V   |           V   |          V   |
              +------+-+     +-----+--+     +------+-+     +------+-+
    usr pkts  | Head   |     | Path   |     | Path   |     | End    |
         ====>| Node   |====>| Node   |====>| Node   |====>| Node   |====>
              |        |     | A      |     | B      |     |        |
              +--------+     +--------+     +--------+     +--------+
              gen postcards  gen postcards  gen postcards  gen postcards
              mark usr pkts                                unmark usr pkts


                      Figure 1: Architecture of PBT-M

   Next we discuss the details of the PBT-M solution and the potential
   standard gaps.







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2.3.  New Challenges

   Although PBT-M solves the issues of INT, it does introduce a few new
   challenges.

   o  Challenge 1: A user packet needs to be marked in order to trigger
      the path-associated data collection.  Since we do not want to
      augment user packets with any new header fields (i.e., Req. 1), we
      must take advantage of the existing header fields.

   o  Challenge 2: Since the packet header will not carry OAM
      instructions any more, the data plane devices need to be
      configured to know what data to collect.  However, in general, the
      forwarding path of a flow packet (due to ECMP or dynamic routing)
      is unknown beforehand.  Configuring the data set for each flow at
      all data plane devices is expensive in terms of configuration load
      and data plane resources.

   o  Challenge 3: Due to the variable transport latency, the dedicated
      OAM packets for a single packet may arrive at the collector out of
      order or be dropped in networks for some reason.  In order to
      infer the packet forwarding path, the collector needs some
      information from the OAM packets to identify the user packet
      affiliation and the order of path node traversal.

2.4.  Considerations on PBT-M Design

   To address the above challenges, we propose several design details of
   PBT-M.

2.4.1.  Packet Marking

   Instead of stuffing new header fields into user packets, it is
   preferred to reuse some existing header fields.  To trigger the path-
   associated data collection, usually a single bit is sufficient.
   While no such bit is available, other packet marking techniques are
   needed.  we discuss three possible application scenarios.

   o  IPv4.  IPFPM [I-D.ietf-ippm-alt-mark] is an IP flow performance
      measurement framework which also requires a single bit for packet
      coloring.  The difference is that IPFPM does in-network
      measurement while PBT only collects and exports data at network
      nodes (i.e., the data analysis is done at the collector).  IPFPM
      suggests to use some reserved bit of the Flag field or some unused
      bit of the TOS field.  Actually, IPFPM can be considered a subcase
      of PBT so the same bit can be used for PBT.  The management plane
      is responsible to configure the actual operation mode.




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   o  SFC NSH.  The OAM bit in NSH header can be used to trigger the
      path-associated data collection [I-D.ietf-sfc-nsh].  PBT does not
      add any other metadata to NSH.

   o  MPLS.  Instead of choosing a header bit, we take advantage of the
      synonymous flow label [I-D.bryant-mpls-synonymous-flow-labels]
      approach to mark the packets.  A synonymous flow label indicates
      the path-associated data should be collected and forwarded through
      a postcard.

2.4.2.  Flow Path Discovery

   By default, all PBT-aware nodes are configured to react to the marked
   packets by exporting some basic data such as node ID and TTL before a
   data set template for that flow is configured.  This way, the
   management plane can learn the flow path.

   If the management plane wants to collect the path-associated data for
   some flow, it configures the head node(s) with a probability or time
   interval for the flow packet marking.  When the first marked packet
   is forwarded in the network, the PBT-aware nodes will export the
   basic data to the collector.  Hence, the flow path is identified.  If
   other types of data need to be collected, the management plane can
   further configure the data set template to the target nodes.  The
   PBT-aware nodes would collect and export data accordingly if the
   packet is marked and a data set template is present.

   If for any reason, the flow path is changed.  The new path nodes can
   be learnt immediately by the collector, so the management plane
   controller can be informed to configure the new path nodes.  The
   outdated configuration can be automatically timed out or explicitly
   revoked by the management plane controller.

2.4.3.  Packet Identity for Export Data Correlation

   The collector needs to correlate all the OAM packets for a single
   user packet.  Once this is done, the TTL (or the timestamp, if the
   network time is synchronized) can be used to infer the flow
   forwarding path.  The key issue here is to uniquely identify the user
   packet affiliation of the OAM packet.

   The first possible approach is to include the flow ID plus the user
   packet ID in the OAM packets.  The user packet ID can be some unique
   information pertaining to a user packet (e.g., the sequence number of
   a TCP packet).

   If the packet marking interval is long enough, then the flow ID
   itself is enough to identify the user packet.  That is, we can assume



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   all the exported OAM packets for the same flow during a short period
   of time belong to the same user packet.

   If the network is synchronized, then the flow ID plus the timestamp
   at each node can also infer the packet identity.  However, some
   errors may occur under some circumstances.  For example, if two
   consecutive user packets from the same flows are both marked and one
   exported OAM packet from a node is lost, then it is difficult for the
   collector to decide which user packet the remaining OAM packet
   belongs to.  In many cases, such rare errors may be tolerable.

2.5.  Avoid Packet Marking through Node Configuration

   It is possible to avoid needing to mark user packets yet still
   allowing in-band flow data collection.  We could simply configure the
   Access Controll List (ACL) to filter out the set of target flows.
   This approach has two potential issues: (1) Since the packet
   forwarding path is unknown in advance, one needs to configure all the
   nodes in a network to capture the complete data set; (2) If a node
   cannot collect data for all the filtered packets of a flow, it needs
   to determine which packets to sample independently, so the collector
   may not be able to receive the full set of postcards for a same user
   packet.

   Nevertheless, since this approach does not require to touch the user
   packets at all, it has its unique merits: (1) User can freely choose
   any nodes as vatage points for data collection; (2) No need to worry
   that any "modified" user packets to leak out of the PBT domain; (3)
   It has the minimum impact to the forwarding of the user traffic.

3.  PBT-I: Postcard-based Telemetry with Instruction Header

   Since PBT-M has some challenges as listed in Section 2.3, this
   section describes another variation of PBT, which essentially
   compromises some of the design requirements listed in Section 2.1,
   yet retains most of the benefits of PBT.

   PBT-I can be seen as a trade-off between INT/iOAM and PBT-M.  PBT-I
   needs to add a fixed length instruction header to user packets for
   OAM data collection.  However, the collected data will be exported
   through dedicated OAM packets.  On the one hand, PBT-I violates the
   Req. 1 in Section 2.1.  It also makes it harder to meet the Req. 2.
   On the other hand, the overhead of the instruction header is under
   control and user packets will not inflate with path length or
   telemetry data amount.  We also introduce an optimization to mitigate
   the impact on Req. 2.  In return, PBT-I addresses all the challenges
   of PBT-M:




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   o  There is no need to find an existing header field to mark a user
      packet.  The encapsulation of the PBT-I instruction header can use
      the same method for iOAM.  So far, the iOAM header encapsulation
      methods have been defined for several protocols, including IPv6,
      VXLAN-GPE, NSH, SRv6
      [I-D.brockners-inband-oam-transport],[I-D.ietf-sfc-ioam-nsh],
      GENEVE [I-D.brockners-ippm-ioam-geneve], and GRE
      [I-D.weis-ippm-ioam-gre].  [I-D.song-mpls-extension-header]
      describes the approach to encapuslate the instruction header into
      MPLS packets.

   o  There is no need to configure the nodes about the data to be
      collected since the data set information is carried in the
      instruction header.  Instead of using a bitmap to indicate the
      data set as in IOAM, here we adopt a more scalable way which uses
      a template ID to indicate the data set.

   o  The instruction header contains enough information to help
      correlate the OAM packets belonging to a user packets.  Even
      better, new fields are added to track the flow and the packet, so
      any packet under inspection can be easily identified even in
      tunnels and the collector can easily check if any user packet
      under inspection or its OAM data packet is missing.

3.1.  Solution Description

   The sketch of the proposed solution, PBT-I, is as follows.  If the
   path-associated data need to be collected for a user packet, an
   instruction header named Telemetry Instruction Header (TIH) is
   inserted into the packet at the path head node.  At each PBT-aware
   node, a postcard is generated and sent to a collector.  Once the
   collector receives all the postcards for a single user packet, it can
   combine and analyze the data set.  The path end node is configured to
   remove the TIH.

   The overall architecture of PBT-I is depict in Figure 2.















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                                  +-----------+
                                  | Telemetry |
                                  | Data      |
                                  | Collector |
                                  +-----------+
                                        ^
                                        |postcards (OAM pkts)
                                        |
                                        |
                                        |
                  +--------------+------+-------+--------------+
                  |              |              |              |
                  |              |              |              |
              +---+----+     +---+----+     +---+----+     +---+----+
    usr pkts  | Head   |     | Path   |     | Path   |     | End    |
         ====>| Node   |====>| Node   |====>| Node   |====>| Node   |====>
              |        |     | A      |     | B      |     |        |
              +--------+     +--------+     +--------+     +--------+
              insert TIH                                   remove TIH
              gen postcards  gen postcards  gen postcards  gen postcards



                      Figure 2: Architecture of PBT-I

3.2.  PBT-I Telemetry Instruction Header

   The proposed format of TIH is shown in Figure 3.


       0             0 0             1 1             2 2             3
       0             7 8             5 6             3 4             1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Next Header   |  TIH Length   |   Reserved    |   Hop Count   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flow ID                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flow ID                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Sequence Number                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Data Set ID                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                           Figure 3: TIH Format





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   o  Next Header: the 8-bit indicator indicating the next protocol
      after TIH.

   o  TIH Length: the 8-bit Instruction Header Length field.  The value
      is in the unit of 4-octet words.

   o  Hop Count: the 8-bit Hop Count field.  It is used to count the
      hops of the TIH-aware nodes, starting for 0 and incremented by 1
      at each PBT-aware node.

   o  Flow ID: the 64-bit flow ID field.  If the actual flow ID is
      shorter than 64 bits, it is right aligned with the leading bits
      being filled with 0.  The field is set at the head node.

   o  Sequence Number: the 32-bit sequence number starting from 0 and
      increasing by 1 for each following monitored packet from the same
      flow at the head node.

   o  Data Set ID: This field defines the set of data that are required
      to be collected at each node.  It can be further partitioned into
      two subfields, the name space ID and the data template ID, for
      hierarchical scalability.

3.3.  Considerations on PBT-I Design

4.  Security Considerations

   Several security issues need to be considered.

   o  Eavesdrop and tamper: the OAM packets can be encrypted and
      authenticated.

   o  DoS attack: PBT can be limited to a single administration domain,
      or the enforce mark or instruction header are checked at the
      domain edge.  The node can rate limit the extra traffic incurred
      by the OAM data.

5.  IANA Considerations

   TBD.

6.  Contributors

   TBD.







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7.  Acknowledgments

   TBD.

8.  Informative References

   [DOI_10.1145_2342441.2342453]
              Handigol, N., Heller, B., Jeyakumar, V., MaziA(C)res, D.,
              and N. McKeown, "Where is the debugger for my software-
              defined network?", Proceedings of the first workshop on
              Hot topics in software defined networks - HotSDN '12,
              DOI 10.1145/2342441.2342453, 2012.

   [I-D.brockners-inband-oam-requirements]
              Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
              Gredler, H., Leddy, J., Youell, S., Mozes, D., Mizrahi,
              T., Lapukhov, P., and r. Chang, "Requirements for In-situ
              OAM", draft-brockners-inband-oam-requirements-03 (work in
              progress), March 2017.

   [I-D.brockners-inband-oam-transport]
              Brockners, F., Bhandari, S., Govindan, V., Pignataro, C.,
              Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Mozes,
              D., Lapukhov, P., and R. Chang, "Encapsulations for In-
              situ OAM Data", draft-brockners-inband-oam-transport-05
              (work in progress), July 2017.

   [I-D.brockners-ippm-ioam-geneve]
              Brockners, F., Bhandari, S., Govindan, V., Pignataro, C.,
              Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Mozes,
              D., Lapukhov, P., and R. Chang, "Geneve encapsulation for
              In-situ OAM Data", draft-brockners-ippm-ioam-geneve-01
              (work in progress), June 2018.

   [I-D.bryant-mpls-synonymous-flow-labels]
              Bryant, S., Swallow, G., Sivabalan, S., Mirsky, G., Chen,
              M., and Z. Li, "RFC6374 Synonymous Flow Labels", draft-
              bryant-mpls-synonymous-flow-labels-01 (work in progress),
              July 2015.

   [I-D.clemm-netconf-push-smart-filters-ps]
              Clemm, A., Voit, E., Liu, X., Bryskin, I., Zhou, T.,
              Zheng, G., and H. Birkholz, "Smart filters for Push
              Updates - Problem Statement", draft-clemm-netconf-push-
              smart-filters-ps-00 (work in progress), October 2017.






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   [I-D.ietf-ippm-alt-mark]
              Fioccola, G., Capello, A., Cociglio, M., Castaldelli, L.,
              Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
              "Alternate Marking method for passive and hybrid
              performance monitoring", draft-ietf-ippm-alt-mark-14 (work
              in progress), December 2017.

   [I-D.ietf-ippm-ioam-data]
              Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
              P., Chang, R., and d. daniel.bernier@bell.ca, "Data Fields
              for In-situ OAM", draft-ietf-ippm-ioam-data-00 (work in
              progress), September 2017.

   [I-D.ietf-netconf-udp-pub-channel]
              Zheng, G., Zhou, T., and A. Clemm, "UDP based Publication
              Channel for Streaming Telemetry", draft-ietf-netconf-udp-
              pub-channel-01 (work in progress), November 2017.

   [I-D.ietf-netconf-yang-push]
              Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
              Nygaard, E., Bierman, A., and B. Lengyel, "YANG Datastore
              Subscription", draft-ietf-netconf-yang-push-12 (work in
              progress), December 2017.

   [I-D.ietf-sfc-ioam-nsh]
              Brockners, F., Bhandari, S., Govindan, V., Pignataro, C.,
              Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Mozes,
              D., Lapukhov, P., and R. Chang, "NSH Encapsulation for In-
              situ OAM Data", draft-ietf-sfc-ioam-nsh-00 (work in
              progress), May 2018.

   [I-D.ietf-sfc-nsh]
              Quinn, P., Elzur, U., and C. Pignataro, "Network Service
              Header (NSH)", draft-ietf-sfc-nsh-28 (work in progress),
              November 2017.

   [I-D.sambo-netmod-yang-fsm]
              Sambo, N., Castoldi, P., Fioccola, G., Cugini, F., Song,
              H., and T. Zhou, "YANG model for finite state machine",
              draft-sambo-netmod-yang-fsm-00 (work in progress), October
              2017.

   [I-D.song-ippm-ioam-data-extension]
              Song, H. and T. Zhou, "In-situ OAM Data Type Extension",
              draft-song-ippm-ioam-data-extension-00 (work in progress),
              October 2017.




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   [I-D.song-ippm-ioam-tunnel-mode]
              Song, H., Li, Z., Zhou, T., and Z. Wang, "In-situ OAM
              Processing in Tunnels", draft-song-ippm-ioam-tunnel-
              mode-00 (work in progress), June 2018.

   [I-D.song-mpls-extension-header]
              Song, H., Li, Z., Zhou, T., and L. Andersson, "MPLS
              Extension Header", draft-song-mpls-extension-header-01
              (work in progress), August 2018.

   [I-D.song-opsawg-dnp4iq]
              Song, H. and J. Gong, "Requirements for Interactive Query
              with Dynamic Network Probes", draft-song-opsawg-dnp4iq-01
              (work in progress), June 2017.

   [I-D.talwar-rtgwg-grpc-use-cases]
              Specification, g., Kolhe, J., Shaikh, A., and J. George,
              "Use cases for gRPC in network management", draft-talwar-
              rtgwg-grpc-use-cases-01 (work in progress), January 2017.

   [I-D.weis-ippm-ioam-gre]
              Weis, B., Brockners, F., crhill@cisco.com, c., Bhandari,
              S., Govindan, V., Pignataro, C., Gredler, H., Leddy, J.,
              Youell, S., Mizrahi, T., Kfir, A., Gafni, B., Lapukhov,
              P., and M. Spiegel, "GRE Encapsulation for In-situ OAM
              Data", draft-weis-ippm-ioam-gre-00 (work in progress),
              March 2018.

   [RFC2925]  White, K., "Definitions of Managed Objects for Remote
              Ping, Traceroute, and Lookup Operations", RFC 2925,
              DOI 10.17487/RFC2925, September 2000,
              <https://www.rfc-editor.org/info/rfc2925>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.








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Authors' Addresses

   Haoyu Song (editor)
   Huawei
   2330 Central Expressway
   Santa Clara, 95050
   USA

   Email: haoyu.song@huawei.com


   Tianran Zhou
   Huawei
   156 Beiqing Road
   Beijing, 100095
   P.R. China

   Email: zhoutianran@huawei.com


   Zhenbin Li
   Huawei
   156 Beiqing Road
   Beijing, 100095
   P.R. China

   Email: lizhenbin@huawei.com


   Jongyoon Shin
   SK Telecom
   South Korea

   Email: jongyoon.shin@sk.com

















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