Internet DRAFT - draft-ietf-tsvwg-tunnel-congestion-feedback
draft-ietf-tsvwg-tunnel-congestion-feedback
Internet Engineering Task Force X. Wei
INTERNET-DRAFT Y. Li
Intended Status: Informational Huawei Technologies
Expires: November 7, 2019 S. Boutros
VMware
L. Geng
China Mobile
May 6, 2019
Tunnel Congestion Feedback
draft-ietf-tsvwg-tunnel-congestion-feedback-07
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.
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Copyright and License Notice
Copyright (c) 2019 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions And Terminologies . . . . . . . . . . . . . . . . . 3
3. Congestion Information Feedback Models . . . . . . . . . . . . 4
4. Congestion Level Measurement . . . . . . . . . . . . . . . . . 5
5. Congestion Information Delivery . . . . . . . . . . . . . . . . 7
5.1 IPFIX Extensions . . . . . . . . . . . . . . . . . . . . . . 8
5.1.1 tunnelEcnCeCeByteTotalCount . . . . . . . . . . . . . . 8
5.1.2 tunnelEcnEct0NectBytetTotalCount . . . . . . . . . . . . 8
5.1.3 tunnelEcnEct1NectByteTotalCount . . . . . . . . . . . . 9
5.1.4 tunnelEcnCeNectByteTotalCount . . . . . . . . . . . . . 9
5.1.5 tunnelEcnCeEct0ByteTotalCount . . . . . . . . . . . . . 9
5.1.6 tunnelEcnCeEct1ByteTotalCount . . . . . . . . . . . . . 10
5.1.7 tunnelEcnEct0Ect0ByteTotalCount . . . . . . . . . . . . 10
5.1.8 tunnelEcnEct1Ect1PacketTotalCount . . . . . . . . . . . 10
5.1.9 tunnelEcnCEMarkedRatio . . . . . . . . . . . . . . . . . 11
6. Congestion Management . . . . . . . . . . . . . . . . . . . . . 11
6.1 Example . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1 Normative References . . . . . . . . . . . . . . . . . . . 17
9.2 Informative References . . . . . . . . . . . . . . . . . . 18
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
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; (4)a
heavy load from a much larger than expected number of responsive
flows could also lead to persistent congestion.
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.
The following subjects are out of scope of current document: it gives
no advice on how to select which tunnel endpoints should be used in
order to manage traffic over a network criss-crossed by multiple
tunnels; if a congested node is part of multiple tunnels, and it
causes congestion feedback to multiple traffic management functions
at the ingresses of all the tunnels, the draft gives no advice on how
all the traffic management functions should respond.
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]
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DP: Decision Point, an logical entity that makes congestion
management decision based on the received congestion feedback
information.
EP: Enforcement 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
The feedback model mainly consists of tunnel egress and tunnel
ingress. The tunnel egress composes of meter function and exporter
function; tunnel ingress composes EP (Enforcement 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 feedback message contains CE-marked packet ratio, the traffic
volumes of all kinds of ECN marking packets.
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 Enforcement Point controls the traffic entering tunnel, and it
implements traffic control decision of DP.
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Feedback
+-----------------------------------+
| |
| |
| V
+--------------+ +-------------+
| +--------+ | | +---------+ |
| |Exporter| | | |Collector| |
| +---|----+ | | +---|-----+ |
| +--|--+ | | +|-+ |
| |Meter| | traffic | |DP| |
| +-----+ |<==================| +--+ |
| | | +--+ |
| | | |EP| |
| | | +--+ |
|Egress | | Ingress |
+--------------+ +-------------+
Figure 1: Feedback Model.
4. Congestion Level Measurement
The congestion level measurement is based on ECN (Explicit
Congestion Notification) [RFC3168] and packet drop. The network
congestion level could be indicated through the ratio of CE-marked
packet and the volumes 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.
Egress calculates CE-marked packet ratio by counting different
kinds of ECN-marked packet, the CE-marked packet ratio will be
used as an indication of tunnel load level. It's assumed that
routers in the tunnel will not drop packets biased towards certain
ECN codepoint, so calculating of CE-marked packet ratio is not
affect by packet drop.
The calculation of volumes of packet drop is by comparing the
traffic volumes between ingress and egress.
Faked ECN-capable transport (ECT) is used at ingress to defer
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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. Faked-ECT is used to shift some drops to the
egress in order to calculate CE-marked packet ratio more precisely
by egress.
To calculate congestion level, for the same span of packets, the
ratio of CE-marked packets will be calculated by egress, and the
total bytes count of packets at ingress and egress will be
compared to detect the traffic volume loss in tunnel.
The basic procedure of packets loss measurement is as follows:
+-------+ +------+
|Ingress| |Egress|
+-------+ +------+
| |
+----------------+ |
|cumulative count| |
+----------------+ |
| |
| <node id-i, ECN counts> |
|------------------------>|
|<node id-e, ECN counts> |
|<------------------------|
| |
| |
Figure 2: Procedure of Packet Loss Measurement
Ingress encapsulates packets and marks outer header according to
faked ECT as described above. Ingress cumulatively counts packet
bytes for three types of ECN combination (CE|CE, ECT|N-ECT, ECT|ECT)
and then the ingress regularly sends cumulative bytes counts message
of each type of ECN combination to the egress.
When each message arrives at egress, (1)egress calculates the ratio
of CE-marked packet; (2)the egress cumulatively counts packet bytes
coming from the ingress and adds its own bytes counts of each type of
ECN combination (CE|CE, ECT|N-ECT, CE|N-ECT, CE|ECT, ECT|ECT) to the
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message for ingress to calculate packet loss. Egress feeds back CE-
marked packet ratio and bytes counts information to the ingress for
evaluating congestion level in the tunnel.
The counting of bytes 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 bytes counts of packets of each type of ECN
combination to tunnel egress, and the tunnel egress also needs to
feed back the message of cumulative bytes counts of packets of each
type of ECN combination and CE-marked packet ratio 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 bytes counts values are sent as cumulative counters. Then
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 a candidate 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.
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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 pre-configured 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
This sub-section defines a list of new IPFIX Information Elements
according to RFC7013 [RFC7013].
5.1.1 tunnelEcnCeCeByteTotalCount
Description: The total number of bytes of incoming packets with CE|CE
ECN marking combination 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: bytes
5.1.2 tunnelEcnEct0NectBytetTotalCount
Description: The total number of bytes of incoming packets with
ECT(0)|N-ECT ECN marking combination at the Observation Point since
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the Metering Process (re-)initialization for this Observation Point.
Abstract Data Type: unsigned64
Data Type Semantics: totalCounter
ElementId: TBD2
Statues: current
Units: bytes
5.1.3 tunnelEcnEct1NectByteTotalCount
Description: The total number of bytes of incoming packets with
ECT(1)|N-ECT ECN marking combination 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
Units: bytes
5.1.4 tunnelEcnCeNectByteTotalCount
Description: The total number of bytes of incoming packets with CE|N-
ECT ECN marking combination 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: bytes
5.1.5 tunnelEcnCeEct0ByteTotalCount
Description: The total number of bytes of incoming packets with
CE|ECT(0) ECN marking combination at the Observation Point since the
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Metering Process (re-)initialization for this Observation Point.
Abstract Data Type: unsigned64
Data Type Semantics: totalCounter
ElementId: TBD5
Statues: current
Units: bytes
5.1.6 tunnelEcnCeEct1ByteTotalCount
Description: The total number of bytes of incoming packets with
CE|ECT(1) ECN marking combination 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
Units: bytes
5.1.7 tunnelEcnEct0Ect0ByteTotalCount
Description: The total number of bytes of incoming packets with
ECT(0)|ECT(0) ECN marking combination 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: bytes
5.1.8 tunnelEcnEct1Ect1PacketTotalCount
Description: The total number of bytes of incoming packets with
ECT(1)|ECT(1) ECN marking combination at the Observation Point since
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the Metering Process (re-)initialization for this Observation Point.
Abstract Data Type: unsigned64
Data Type Semantics: totalCounter
ElementId: TBD8
Statues: current
Units: bytes
5.1.9 tunnelEcnCEMarkedRatio
Description: The ratio of CE-marked Packet at the Observation Point.
Abstract Data Type: float32
ElementId: TBD8
Statues: current
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
unstable.
The detailed description of congestion management is out of scope of
this document, as examples, congestion management such as circuit
breaker [RFC8084] 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
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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 calculates CE-marked
packet ratio and 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.
+---------------------------------+----------------------+
|Set ID=2 Length=40 |
|---------------------------------|----------------------|
|Template ID=256 Field Count =8 |
|---------------------------------|----------------------|
|tunnelEcnCeCeByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnEctNectByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnEctEctByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnCeCeByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnEctNectByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnEctEctByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnCeNectByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnCeEctByteTotalCount | Field Length=8 |
+---------------------------------+----------------------+
|tunnelEcnCEMarkedRatio | Field Length=4 |
+---------------------------------+----------------------+
Figure 3: Template Record Sent From Egress to Ingress
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+---------------------------------+----------------------+
|Set ID=2 Length=28 |
|---------------------------------|----------------------|
|Template ID=257 Field Count =3 |
|---------------------------------|----------------------|
|tunnelEcnCeCeByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnEctNectByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
|tunnelEcnEctEctByteTotalCount Field Length=8 |
|---------------------------------|----------------------|
Figure 4: Template Record Sent From Ingress to Egress
+-------+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-------+
| | |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
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Set ID=257, Length=28
+------+ A1 +------+
| | B1 | |
| | C1 | |
| | <----------------------------- | |
| | | |
| | | |
| | SetID=256, Length=72 | |
| | A1 | |
| | B1 | |
|egress| C1 ingress|
| | A2 | |
| | B2 | |
| | C2 | |
| | D | |
| | E
| | R | |
| | ----------------------------> | |
| | | |
+------+ +------+
Figure 6: Message Between Ingress and Egress
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 ratio
of CE-marked packet:
ce_marked = R;
For serious congestion, the congestion level is indicated as the
number of volume loss:
total_ingress = (A1 + B1 + C1)
total_egress = (A2 + B2 + C2 + D + E)
volume_loss = (total_ingress - total_egress)
7. Security Considerations
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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
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with CE|CE
ECN marking combination at the Observation Point since the Metering
Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD2
Name:tunnelEcnEct0NectPacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with
ECT(0)|N-ECT ECN marking combination at the Observation Point since
the Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD3
Name: tunnelEcnEct1NectPacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with
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ECT(1)|N-ECT ECN marking combination at the Observation Point since
the Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD4
Name:tunnelEcnCeNectPacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with CE|N-
ECT ECN marking combination at the Observation Point since the
Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD5
Name:tunnelEcnCeEct0PacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with
CE|ECT(0) ECN marking combination at the Observation Point since the
Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD6
Name:tunnelEcnCeEct1PacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with
CE|ECT(1) ECN marking combination at the Observation Point since the
Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD7
Name:tunnelEcnEct0Ect0PacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
Status: current
Description:The total number of bytes of incoming packets with
ECT(0)|ECT(0) ECN marking combination at the Observation Point since
the Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD8
Name:tunnelEcnEct1Ect1PacketTotalCount
Data Type: unsigned64
Data Type Semantics: totalCounter
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Status: current
Description:The total number of bytes of incoming packets with
ECT(1)|ECT(1)ECN marking combination at the Observation Point since
the Metering Process (re-)initialization for this Observation Point.
Units: octets
ElementID: TBD9
Name: tunnelEcnCEMarkedRatio
Data Type: float32
Status: current
Description: The ratio of CE-marked Packet at the Observation Point.
[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.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, September 2001.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, May 2004.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
Congestion Control Protocol (DCCP)", RFC 4340, March 2006.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, September 2007.
[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
Notification", RFC 6040, November 2010.
[CONEX] Matt Mathis, Bob Briscoe. "Congestion Exposure (ConEx)
Concepts, Abstract Mechanism and Requirements", RFC7713,
December 2015
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INTERNET DRAFT Tunnel Congestion Feedback May 6, 2019
9.2 Informative References
[RFC8084] 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.
Also, thanks Lei Zhu, Lingli Deng, 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
EMail: weixinpeng@huawei.com
Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012
China
Phone: +86-25-56624584
EMail: liyizhou@huawei.com
Sami Boutros
VMware, Inc.
EMail: boutross@vmware.com
Liang Geng
China Mobile
EMail: gengliang@chinamobile.com
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