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Versions: (draft-wei-tsvwg-tunnel-congestion-feedback) 00 01 02 03 04 05 06 07

Internet Engineering Task Force                                   X. Wei
INTERNET-DRAFT                                       Huawei Technologies
Intended Status: Informational                                     L.Zhu
Expires: July 29, 2017                               Huawei Technologies
                                                                  L.Deng
                                                            China Mobile
                                                        January 25, 2017





                       Tunnel Congestion Feedback
             draft-ietf-tsvwg-tunnel-congestion-feedback-04


Abstract

   This document describes a method to measure congestion on a tunnel
   segment based on recommendations from RFC 6040, "Tunneling of
   Explicit Congestion Notification", and to use IPFIX to communicate
   the congestion measurements from the tunnel's egress to a controller
   which can respond by modifying the traffic control policies at the
   tunnel's ingress.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html


Copyright and License Notice



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   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
   2. Conventions And Terminologies . . . . . . . . . . . . . . . . .  3
   3. Congestion Information Feedback Models  . . . . . . . . . . . .  3
   4. Congestion Level Measurement  . . . . . . . . . . . . . . . . .  4
   5. Congestion Information Delivery . . . . . . . . . . . . . . . .  6
     5.1 IPFIX Extensions . . . . . . . . . . . . . . . . . . . . . .  7
       5.1.1 tunnelEcnCeCePacketTotalCount  . . . . . . . . . . . . .  8
       5.1.2 tunnelEcnEct0NectPacketTotalCount  . . . . . . . . . . .  8
       5.1.3 tunnelEcnEct1NectPacketTotalCount  . . . . . . . . . . .  8
       5.1.4 tunnelEcnCeNectPacketTotalCount  . . . . . . . . . . . .  9
       5.1.5 tunnelEcnCeEct0PacketTotalCount  . . . . . . . . . . . .  9
       5.1.6 tunnelEcnCeEct1PacketTotalCount  . . . . . . . . . . . .  9
       5.1.7 tunnelEcnEct0Ect0PacketTotalCount  . . . . . . . . . . . 10
       5.1.8 tunnelEcnEct1Ect1PacketTotalCount  . . . . . . . . . . . 10
   6. Congestion Management . . . . . . . . . . . . . . . . . . . . . 10
     6.1 Example  . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   7. Security Considerations . . . . . . . . . . . . . . . . . . . . 14
   8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 14
   9. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     9.1  Normative References  . . . . . . . . . . . . . . . . . . . 16
     9.2  Informative References  . . . . . . . . . . . . . . . . . . 17
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18











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1. Introduction

   In IP networks, persistent congestion[RFC2914] lowers transport
   throughput, leading to waste of network resource. Appropriate
   congestion control mechanisms are therefore critical to prevent the
   network from falling into the persistent congestion state. Currently,
   transport protocols such as TCP[RFC793], SCTP[RFC4960],
   DCCP[RFC4340], have their built-in congestion control mechanisms, and
   even for certain single transport protocol like TCP there can be a
   couple of different congestion control mechanisms to choose from. All
   these congestion control mechanisms are implemented on host side, and
   there are reasons that only host side congestion control is not
   sufficient for the whole network to keep away from persistent
   congestion. For example, (1) some protocol's congestion control
   scheme may have internal design flaws; (2) improper software
   implementation of protocol; (3) some transport protocols, e.g.
   RTP[RFC3550] do not even provide congestion control at all.

   Tunnels are widely deployed in various networks including public
   Internet, data center network, and enterprise network etc. A tunnel
   consists of ingress, egress and a set of intermediate routers. For
   the tunnel scenario, a tunnel-based mechanism is introduced for
   network traffic control to keep the network from persistent
   congestion. Here, tunnel ingress will implement  congestion
   management function to control the traffic entering the tunnel.

   This document provides a mechanism of feeding back inner tunnel
   congestion level to the ingress. Using this mechanism the egress can
   feed the tunnel congestion level information it collects back to the
   ingress. After receiving this information the ingress will be able to
   perform congestion management according to network management policy.

2. Conventions And Terminologies

   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]

   DP: Decision Point, an logical entity that makes congestion
   management decision based on the received congestion feedback
   information.

   AP: Action Point, an logical entity that implements congestion
   management action according to the decision made by Decision Point.

   ECT: ECN-Capable Transport code point defined in RFC3168.

3. Congestion Information Feedback Models



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   The feedback model mainly consists of tunnel egress and tunnel
   ingress. The tunnel egress composes of meter function and exporter
   function; tunnel ingress composes AP (Action Point) function,
   collector function and DP (Decision Point) function.

   The Meter function collects network congestion level information, and
   conveys the information to Exporter which feeds back the information
   to the collector function.

   The collector collects congestion level information from exporter,
   after that congestion management Decision Point (DP) function will
   make congestion management decision based on the information from
   collector.

   The action point controls the traffic entering tunnel, and it
   implements traffic control decision of DP.

                          Feedback
              +-----------------------------------+
              |                                   |
              |                                   |
              |                                   V
       +--------------+                   +-------------+
       |  +--------+  |                   | +---------+ |
       |  |Exporter|  |                   | |Collector| |
       |  +---|----+  |                   | +---|-----+ |
       |   +--|--+    |                   |    +|-+     |
       |   |Meter|    |                   |    |DP|     |
       |   +-----+    |                   |    +--+     |
       |              |                   |    +--+     |
       |              |                   |    |AP|     |
       |              |                   |    +--+     |
       |Egress        |                   |  Ingress    |
       +--------------+                   +-------------+
                       Figure 1: Feedback Model.



4. Congestion Level Measurement

      This section describes how to measure congestion level in a
      tunnel.

      The congestion level measurement is based on ECN (Explicit
      Congestion Notification) [RFC3168] and packet drop. If the routers
      support ECN, after router's queue length is over a predefined
      threshold, the routers will mark the ECN-capable packets as
      Congestion Experienced (CE) or drop not-ECT packets with the



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      probability proportional to queue length; if the queue overflows
      all packets will be dropped. If the routers do not support ECN,
      after router's queue length is over a predefined threshold, the
      routers will drop both the ECN-capable packets and the not-ECT
      packets with the probability proportional to the queue length.

      The network congestion level could be indicated through the ratio
      of CE-marked packet and the ratio of packet drop, the relationship
      between these two kinds of indicator is complementary. If the
      congestion level in tunnel is not high enough, the packets would
      be marked as CE instead of being dropped, and then it is easy to
      calculate congestion level according to the ratio of CE-marked
      packets. If the congestion level is so high that ECT packet will
      be dropped, then the packet loss ratio could be calculated by
      comparing total packets entering ingress and total packets
      arriving at egress over the same span of packets, if packet loss
      is detected, it could be assumed that severe congestion has
      occurred in the tunnel. Because loss is only ever a sign of
      serious congestion, so it doesn't need to measure loss ratio
      accurately.

      Faked ECN-capable transport (ECT) is used at ingress to defer
      packet loss to egress. The basic idea of faked ECT is that, when
      encapsulating packets, ingress first marks tunnel outer header
      according to RFC6040, and then remarks outer header of Not-ECT
      packet as ECT, there will be three kinds of combination of outer
      header ECN field and inner header ECN field: CE|CE, ECT|N-ECT,
      ECT|ECT (in the form of outer ECN| inner ECN); when decapsulating
      packets at egress, RFC6040 defined decapsulation behavior is used,
      and according to RFC6040, the packets marked as CE|N-ECT will be
      dropped by egress.

      To calculate congestion level, for the same span of packets, the
      number of each kind of ECN marking packet at ingress and egress
      will be compared to get the volume of CE-marked packet in the
      tunnel; and the total number of packets at ingress and egress will
      be compared to detect the packet loss.

      The basic procedure of congestion level measurement is as follows:












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           +-------+                 +------+
           |Ingress|                 |Egress|
           +-------+                 +------+
               |                         |
       +----------------+                |
       |cumulative count|                |
       +----------------+                |
               |                         |
               | <node id-i, ECN counts> |
               |------------------------>|
               |<node id-e, ECN counts>  |
               |<------------------------|
               |                         |
               |                         |


          Figure 2: Procedure of Congestion Level Measurement

   Ingress encapsulates packets and marks outer header according to
   faked ECT as described above. Ingress cumulatively counts packets for
   three types of ECN combination (CE|CE, ECT|N-ECT, ECT|ECT) and then
   the ingress regularly sends cumulative packet counts message of each
   type of ECN combination to the egress. When each message arrives, the
   egress cumulatively counts packets coming from the ingress and adds
   its own packet counts of each type of ECN combination (CE|CE, ECT|N-
   ECT, CE|N-ECT, CE|ECT, ECT|ECT) to the message and returns the whole
   message to the ingress.

   The counting of packets can be at the granularity of the all traffic
   from the ingress to the egress to learn about the overall congestion
   status of the path between the ingress and the egress. The counting
   can also be at the granularity of individual customer's traffic or a
   specific set of flows to learn about their congestion contribution.

5. Congestion Information Delivery

   As described above, the tunnel ingress needs to convey a message
   containing cumulative packet counts of each type of ECN combination
   to tunnel egress, and the tunnel egress also needs to feed back the
   message of cumulative packet counts of each type of ECN combination
   to the ingress. This section describes how the messages should be
   conveyed.

   The message travels along the same path with network data traffic,
   referred as in-band signal. Because the message is transmitted in
   band, so the message packet may get lost in case of network
   congestion. To cope with the situation that the message packet gets
   lost, the packet counts values are sent as cumulative counters. Then



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   if a message is lost the next message will recover the missing
   information. Even though the missing information could be recovered,
   the message should be transmitted in a much higher priority than
   users' traffic flows.

   IPFIX [RFC7011] is selected as information feedback protocol. IPFIX
   uses preferably SCTP as transport. SCTP allows partially reliable
   delivery [RFC3758], which ensures the feedback message will not be
   blocked in case of packet loss due to network congestion.

   Ingress can do congestion management at different granularity which
   means both the overall aggregated inner tunnel congestion level and
   congestion level contributed by certain traffic(s) could be measured
   for different congestion management purpose. For example, if the
   ingress only wants to limit congestion volume caused by certain
   traffic(s),e.g UDP-based traffic, then congestion volume for the
   traffic will be fed back; or if the ingress do overall congestion
   management, the aggregated congestion volume will be fed back.

   When sending message from ingress to egress, the ingress acts as
   IPFIX exporter and egress acts as IPFIX collector; When feedback
   congestion level information from egress to ingress, then the egress
   acts as IPFIX exporter and ingress acts as IPFIX collector.

   The combination of congestion level measurement and congestion
   information delivery procedure should be as following:

   # The ingress determines IPFIX template record to be used. The
   template record can be preconfigured or determined at runtime, the
   content of template record will be determined according to the
   granularity of congestion management, if the ingress wants to limit
   congestion volume contributed by specific traffic flow then the
   elements such as source IP address, destination IP address, flow id
   and CE-marked packet volume of the flow etc will be included in the
   template record.

   # Meter on ingress measures traffic volume according to template
   record chosen and then the measurement records are sent to egress in
   band.

   # Meter on egress measures congestion level information according to
   template record, the content of template record should  be the same
   as template record of ingress.

   # Exporter of egress sends measurement record together with the
   measurement record of ingress back to the ingress.

5.1 IPFIX Extensions



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   This sub-section defines a list of new IPFIX Information Elements
   according to RFC7013 [RFC7013].

5.1.1 tunnelEcnCeCePacketTotalCount

   Description: The total number of incoming packets with CE|CE ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD1

   Statues: current

   Units: packets

5.1.2 tunnelEcnEct0NectPacketTotalCount

   Description: The total number of incoming packets with ECT(0)|N-ECT
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD2

   Statues: current

   Units: packets

5.1.3 tunnelEcnEct1NectPacketTotalCount

   Description: The total number of incoming packets with ECT(1)|N-ECT
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD3

   Statues: current



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   Units: packets

5.1.4 tunnelEcnCeNectPacketTotalCount

   Description: The total number of incoming packets with CE|N-ECT ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD4

   Statues: current

   Units: packets

5.1.5 tunnelEcnCeEct0PacketTotalCount

   Description: The total number of incoming packets with CE|ECT(0) ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD5

   Statues: current

   Units: packets

5.1.6 tunnelEcnCeEct1PacketTotalCount

   Description: The total number of incoming packets with CE|ECT(1) ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD6

   Statues: current




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   Units: packets

5.1.7 tunnelEcnEct0Ect0PacketTotalCount

   Description: The total number of incoming packets with ECT(0)|ECT(0)
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD7

   Statues: current

   Units: packets

5.1.8 tunnelEcnEct1Ect1PacketTotalCount

   Description: The total number of incoming packets with ECT(1)|ECT(1)
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.

   Abstract Data Type: unsigned64

   Data Type Semantics: totalCounter

   ElementId: TBD8

   Statues: current

   Units: packets

6. Congestion Management

   After tunnel ingress receives congestion level information, then
   congestion management actions could be taken based on the
   information, e.g. if the congestion level is higher than a predefined
   threshold, then action could be taken to reduce the congestion level.

   The design of network side congestion management SHOULD take host
   side e2e congestion control mechanism into consideration, which means
   the congestion management needs to avoid the impacts on e2e
   congestion control. For instance, congestion management action must
   be delayed by more than a worst-case global RTT (e.g. 100ms),
   otherwise tunnel traffic management will not give normal e2e
   congestion control enough time to do its job, and the system could go



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   unstable.

   The detailed description of congestion management is out of scope of
   this document, as examples, congestion management such as circuit
   breaker [CB] could be applied. Circuit breaker is an automatic
   mechanism to estimate congestion, and to terminate flow(s) when
   persistent congestion is detected to prevent network congestion
   collapse.

6.1 Example

   This subsection provides an example of how the solution described in
   this document could work.

   First of all, IPFIX template records are exchanged between ingress
   and egress to negotiate the format of data record, the example here
   is to measure the congestion level for the overall tunnel (caused by
   all the traffic in tunnel). After the negotiation is finished,
   ingress sends in-band message to egress, the message contains the
   number of each kind of ECN-marked packets (i.e. CE|CE, ECT|N-ECT and
   ECT|ECT) received until the sending of message.

   After egress receives the message, the egress counts number of
   different kinds of ECN-marking packets received until receiving the
   message, then the egress sends a feedback message containing the
   counts together with the information in ingress's message to ingress.

   Figure 3 to Figure 6 below show the example procedure between ingress
   and egress.






















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      +---------------------------------+----------------------+
      |Set ID=2                              Length=40         |
      |---------------------------------|----------------------|
      |Template ID=256                       Field Count =8    |
      |---------------------------------|----------------------|
      |tunnelEcnCeCePacketTotalCount         Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnEctNectPacketTotalCount      Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnEctEctPacketTotalCount       Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnCeCePacketTotalCount         Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnEctNectPacketTotalCount      Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnEctEctPacketTotalCount       Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnCeNectPacketTotalCount       Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnCeEctPacketTotalCount   |    Field Length=8    |
      +---------------------------------+----------------------+
         Figure 3: Template Record Sent From Egress to Ingress


      +---------------------------------+----------------------+
      |Set ID=2                              Length=28         |
      |---------------------------------|----------------------|
      |Template ID=257                       Field Count =3    |
      |---------------------------------|----------------------|
      |tunnelEcnCeCePacketTotalCount         Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnEctNectPacketTotalCount      Field Length=8    |
      |---------------------------------|----------------------|
      |tunnelEcnEctEctPacketTotalCount       Field Length=8    |
      |---------------------------------|----------------------|
         Figure 4: Template Record Sent From Ingress to Egress















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       +-------+         +-+  +-+ +-+ +-+  +-+ +-+ +-+  +-------+
       |       |         |M|  |P| |P| |P|  |M| |P| |P|  |       |
       |       |         +-+  +-+ +-+ +-+  +-+ +-+ +-+  |       |
       |       |<---------------------------------------|       |
       |       |                                        |       |
       |       |                                        |       |
       |egress |         +-+             +-+            |ingress|
       |       |         |M|             |M|            |       |
       |       |         +-+             +-+            |       |
       |       |--------------------------------------->|       |
       |       |                                        |       |
       |       |                                        |       |
       +-------+                                        +-------+

      +-+
      |M| : Message Packet
      +-+

      +-+
      |P| : User Packet
      +-+


            Figure 5 Traffic flow Between Ingress and Egress


                     Set ID=257, Length=28
       +------+             A1                    +------+
       |      |             B1                    |      |
       |      |             C1                    |      |
       |      |  <-----------------------------   |      |
       |      |                                   |      |
       |      |                                   |      |
       |      |      SetID=256, Length=68         |      |
       |      |             A1                    |      |
       |      |             B1                    |      |
       |egress|             C1                    ingress|
       |      |             A2                    |      |
       |      |             B2                    |      |
       |      |             C2                    |      |
       |      |             D                     |      |
       |      |             E                     |      |
       |      |    ---------------------------->  |      |
       |      |                                   |      |
       +------+                                   +------+

              Figure 6: Message Between Ingress and Egress




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   The following provides an example of how tunnel congestion level
   could be calculated:

   Congestion Level could be divided into two categories:(1)slight
   congestion(no packets dropped); (2)serious congestion (packet
   dropping happen).

   For slight congestion, the congestion level is indicated as the
   number  of CE-marked packet:

   ce_marked = (A2 + D + E) - A1;

   For serious congestion, the congestion level is indicated as the
   number of lost packets:

   total_ingress = (A1 + B1 + C1)

   total_egress = (A2 + B2 + C2 + D + E)

   packet_loss = (total_ingress - total_egress)

7. Security Considerations

   This document describes the tunnel congestion calculation and
   feedback.

   The tunnel endpoints are assumed to be deployed in the same
   administrative domain, so the ingress and egress will trust each
   other, the signaling traffic between ingress and egress will be
   protected utilizing security mechanism provided IPFIX (see section 11
   in RFC7011).

   From the consideration of privacy point of view, in case of fine
   grained congestion management, ingress is aware of the amount of
   traffic for specific application flows inside the tunnel which seems
   to be an invasion of privacy. But in any way, the ingress could The
   solution doesn't introduce more privacy problem.


8. IANA Considerations

   This document defines a set of new IPFIX Information Elements
   (IE),which need to be registered at IANA IPFIX Information Element
   Registry.

   ElementID: TBD1
   Name:tunnelEcnCeCePacketTotalCount
   Data Type: unsigned64



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   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with CE|CE ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD2
   Name:tunnelEcnEct0NectPacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with ECT(0)|N-ECT
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD3
   Name: tunnelEcnEct1NectPacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with ECT(1)|N-ECT
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD4
   Name:tunnelEcnCeNectPacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with CE|N-ECT ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD5
   Name:tunnelEcnCeEct0PacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with CE|ECT(0) ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD6



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   Name:tunnelEcnCeEct1PacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with CE|ECT(1) ECN
   marking combination for this Flow at the Observation Point since the
   Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD7
   Name:tunnelEcnEct0Ect0PacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with ECT(0)|ECT(0)
   ECN marking combination for this Flow at the Observation Point since
   the Metering Process (re-)initialization for this Observation Point.
   Units: packets

   ElementID: TBD8
   Name:tunnelEcnEct1Ect1PacketTotalCount
   Data Type: unsigned64
   Data Type Semantics: totalCounter
   Status: current
   Description:The total number of incoming packets with
   ECT(1)|ECT(1)ECN marking combination for this Flow at the Observation
   Point since the Metering Process (re-)initialization for this
   Observation Point.
   Units: packets


   [TO BE REMOVED: This registration should take place at the following
   location: http://www.iana.org/assignments/ipfix/ipfix.xhtml#ipfix-
   information-elements]

9. References

9.1  Normative References

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

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, September 2001, <http://www.rfc-
              editor.org/info/rfc3168>.




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   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003,
              <http://www.rfc-editor.org/info/rfc3550>.

   [RFC3758]  Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
              Conrad, "Stream Control Transmission Protocol (SCTP)
              Partial Reliability Extension", RFC 3758, May 2004,
              <http://www.rfc-editor.org/info/rfc3758>.

   [RFC4340]  Kohler, E., Handley, M., and S. Floyd, "Datagram
              Congestion Control Protocol (DCCP)", RFC 4340, March 2006,
              <http://www.rfc-editor.org/info/rfc4340>.

   [RFC4960]  Stewart, R., Ed., "Stream Control Transmission Protocol",
              RFC 4960, September 2007, <http://www.rfc-
              editor.org/info/rfc4960>.

   [RFC6040]  Briscoe, B., "Tunnelling of Explicit Congestion
              Notification", RFC 6040, November 2010, <http://www.rfc-
              editor.org/info/rfc6040>.

   [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, September 2013, <http://www.rfc-
              editor.org/info/rfc7011>.

   [RFC7013]  Trammell, B. and B. Claise, "Guidelines for Authors and
              Reviewers of IP Flow Information Export (IPFIX)
              Information Elements", BCP 184, RFC 7013, September 2013,
              <http://www.rfc-editor.org/info/rfc7013>.

   [CONEX] Matt Mathis, Bob Briscoe. "Congestion Exposure (ConEx)
              Concepts, Abstract Mechanism and Requirements", RFC7713,
              December 2015

9.2  Informative References


   [CB] G. Fairhurst. "Network Transport Circuit Breakers", draft-ietf-
              tsvwg-circuit-breaker-01, April 02, 2015

10. Acknowledgements

   Thanks Bob Briscoe for his insightful suggestions on the basic
   mechanisms of congestion information collection and many other useful
   comments. Thanks David Black for his useful technical suggestions.



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   Also, thanks Anthony Chan, Jake Holland, John Kaippallimalil and
   Vincent Roca for their careful reviews.

Authors' Addresses

   Xinpeng Wei
   Beiqing Rd. Z-park No.156, Haidian District,
   Beijing,  100095, P. R. China
   E-mail: weixinpeng@huawei.com



   Zhu Lei
   Beiqing Rd. Z-park No.156, Haidian District,
   Beijing,  100095, P. R. China
   E-mail:lei.zhu@huawei.com



   Lingli Deng
   Beijing,  100095, P. R. China
   E-mail: denglingli@gmail.com





























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