Internet Engineering Task Force A. Charny
Internet-Draft J. Zhang
Intended status: Informational Cisco Systems
Expires: March 18, 2011 G. Karagiannis
U. Twente
M. Menth
University of Wuerzburg
T. Taylor, Ed.
Huawei Technologies
September 14, 2010
PCN Boundary Node Behaviour for the Single Marking (SM) Mode of
Operation
draft-ietf-pcn-sm-edge-behaviour-04
Abstract
Pre-congestion notification (PCN) is a means for protecting the
quality of service for inelastic traffic admitted to a Diffserv
domain. The overall PCN architecture is described in RFC 5559. This
memo is one of a series describing possible boundary node behaviours
for a PCN-domain. The behaviour described here is that for a form of
measurement-based load control using two PCN marking states, not-
marked, and excess-traffic-marked. This behaviour is known
informally as the Single Marking (SM) PCN edge behaviour.
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 March 18, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Assumed Core Network Behaviour for SM . . . . . . . . . . . . 5
3. Node Behaviours . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Behaviour of the PCN-Egress-Node . . . . . . . . . . . . . 6
3.2.1. Data Collection . . . . . . . . . . . . . . . . . . . 6
3.2.2. Reporting the PCN Data . . . . . . . . . . . . . . . . 7
3.2.3. Optional Report Suppression . . . . . . . . . . . . . 7
3.3. Behaviour at the Decision Point . . . . . . . . . . . . . 8
3.3.1. Flow Admission . . . . . . . . . . . . . . . . . . . . 8
3.3.2. Flow Termination . . . . . . . . . . . . . . . . . . . 9
3.3.3. Decision Point Action For Missing
PCN-Boundary-Node Reports . . . . . . . . . . . . . . 10
3.4. Behaviour of the Ingress Node . . . . . . . . . . . . . . 10
3.5. Summary of Timers . . . . . . . . . . . . . . . . . . . . 10
4. Identifying Ingress and Egress Nodes For PCN Traffic . . . . 12
5. Specification of Diffserv Per-Domain Behaviour . . . . . . . . 12
5.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 12
5.2. Technical Specification . . . . . . . . . . . . . . . . . 12
5.3. Attributes . . . . . . . . . . . . . . . . . . . . . . . . 13
5.4. Parameters . . . . . . . . . . . . . . . . . . . . . . . . 13
5.5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 14
5.6. Example Uses . . . . . . . . . . . . . . . . . . . . . . . 14
5.7. Environmental Concerns . . . . . . . . . . . . . . . . . . 14
5.8. Security Considerations . . . . . . . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
The objective of Pre-Congestion Notification (PCN) is to protect the
quality of service (QoS) of inelastic flows within a Diffserv domain,
in a simple, scalable, and robust fashion. Two mechanisms are used:
admission control, to decide whether to admit or block a new flow
request, and (in abnormal circumstances) flow termination to decide
whether to terminate some of the existing flows. To achieve this,
the overall rate of PCN-traffic is metered on every link in the PCN-
domain, and PCN-packets are appropriately marked when certain
configured rates are exceeded. These configured rates are below the
rate of the link thus providing notification to PCN-boundary-nodes
about overloads before any congestion occurs (hence the "pre" part of
"pre-congestion notification"). The level of marking allows
decisions to be made about whether to admit or terminate individual
flows. For more details see [RFC5559].
PCN-boundary-node behaviours specify a detailed set of algorithms and
procedures used to implement the PCN mechanisms. Since the
algorithms depend on specific metering and marking behaviour at the
interior nodes, it is also necessary to specify the assumptions made
about PCN-interior-node behaviour. Finally, because PCN uses DSCP
values to carry its markings, a specification of PCN-boundary-node
behaviour must include the per domain behaviour (PDB) template
specified in [RFC3086], filled out with the appropriate content. The
present document accomplishes these tasks for the Single Marking (SM)
mode of operation.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [RFC2119].
In addition to the terms defined in [RFC5559], this document uses the
following terms:
Decision Point
The node that makes the decision about which flows to admit and to
terminate. In a given network deployment, this may be the PCN-
ingress-node or a centralized control node. Regardless of the
location of the Decision Point, the PCN-ingress-node is the point
where the decisions are enforced.
NM-rate
The rate of not-marked PCN-traffic received at a PCN-egress-node
for a given ingress-egress-aggregate in octets per second. For
further details see Section 3.2.1.
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ETM-rate
The rate of excess-traffic-marked PCN traffic received at a PCN-
egress-node for a given ingress-egress-aggregate in octets per
second. For further details see Section 3.2.1.
PCN-sent-rate
The rate of PCN-traffic received at a PCN-ingress-node and
destined for a given ingress-egress-aggregate in octets per
second. For further details see Section 3.4.
Congestion level estimate (CLE)
A value derived from the measurement of PCN-packets received at a
PCN-egress-node for a given ingress-egress-aggregate, representing
the ratio of excess-traffic-marked to total PCN traffic (measured
in octets) over a short period. The CLE is used to derive the
PCN-admission-state (Section 3.3.1) and also by the report
suppression procedure (Section 3.2.3) if report suppression is
activated.
PCN-admission-state
The state ("admit" or "block") derived by the Decision Point for a
given ingress-egress-aggregate based on PCN packet marking
statistics. The Decision Point decides to admit or block new
flows offered to the aggregate based on the current value of the
PCN-admission-state. For further details see Section 3.3.1.
Sustainable aggregate rate (SAR)
The estimated maximum rate of PCN-traffic that can be admitted to
a given ingress-egress-aggregate at a given moment without risking
degradation of quality of service for the admitted flows. The
intention is that if the PCN-sent-rate of every ingress-egress-
aggregate passing through a given link is limited to its
sustainable aggregate rate, the total rate of PCN-traffic flowing
through the link will be limited to the PCN-supportable-rate for
that link. An estimate of the sustainable aggregate rate for a
given ingress-egress-aggregate is derived as part of the flow
termination procedure, and is used to determine how much PCN-
traffic must be terminated. For further details see
Section 3.3.2.
CLE-reporting-threshold
A configurable value against which the CLE is compared as part of
the report suppression procedure. For further details, see
Section 3.2.3.
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CLE-limit
A configurable value against which the CLE is compared in order to
derive the PCN-admission-state for a given ingress-egress-
aggregate. For further details see Section 3.3.1.
T-meas
An interval, the value of which is configurable, defining the
measurement period at the PCN-egress-node during which statistics
relating to PCN-traffic marking are collected. At the end of the
interval the values NM-rate and ETM-rate as defined above are
calculated and a report is sent to the Decision Point, subject to
the operation of the report suppression feature. For further
details see Section 3.2.
T-maxsuppress
An interval, the value of which is configurable, after which the
PCN-egress-node must send a report to the Decision Point for a
given ingress-egress-aggregate regardless of the most recent
values of the CLE. This is used as a keep-alive mechanism for
signalling between the PCN-egress-node and the Decision Point when
report suppression is activated. For further details, see
Section 3.2.3.
T-fail
An interval, the value of which is configurable, after which the
Decision Point concludes that communication from a given PCN-
egress-node has failed if it has received no reports from the PCN-
egress-node during that interval. For further details see
Section 3.3.3.
2. Assumed Core Network Behaviour for SM
This section describes the assumed behaviour for nodes of the PCN-
domain when acting in their role as PCN-interior-nodes. The SM mode
of operation assumes that:
o PCN-interior-nodes perform excess-traffic-marking of packets
according to the rules specified in [RFC5670].
o excess-traffic-marking of packets uses the PCN-Marked (PM)
codepoint defined in [RFC5696];
o on each link the reference rate for the excess-traffic-meter is
configured with a PCN-excess-rate to be equal to the PCN-
admissible-rate for the link;
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o no link PCN-threshold-rate is configured, and PCN interior nodes
perform no threshold-metering.
3. Node Behaviours
3.1. Overview
This section describes the behaviour of the PCN-ingress-node, PCN-
egress-node and the Decision Point (which may be collocated with the
PCN-ingress-node).
The PCN-egress-node collects and reports the rates of not-marked and
excess-traffic-marked PCN-traffic to the Decision Point. For a
detailed description, see Section 3.2.
The PCN-ingress-node enforces flow admission and termination
decisions. It also reports the rate of PCN-traffic sent to a given
ingress-egress-aggregate when requested by the Decision Point. For
details, see Section 3.4.
Finally, the Decision Point makes flow admission decisions and
selects flows to terminate based on the information provided by the
PCN-ingress-node and PCN-egress-node for a given ingress-egress-
aggregate. For details, see Section 3.3.
3.2. Behaviour of the PCN-Egress-Node
3.2.1. Data Collection
The PCN-egress-node MUST meter received PCN-traffic in order to
derive periodically the following rates for each ingress-egress-
aggregate passing through it:
o NM-rate: octets per second of PCN-traffic in PCN-packets that are
not PCN-Marked;
o ETM-rate: octets per second of PCN traffic in PCN-Marked packets.
It is RECOMMENDED that the measurement interval, T-meas, between
successive calculations of these quantities be in the range of 100 to
500 ms to provide a reasonable tradeoff between signalling demands on
the network and the time taken to react to impending congestion.
The PCN-traffic SHOULD be metered continuously and the intervals
themselves SHOULD be of equal length, to minimize the statistical
variance introduced by the measurement process itself. The starting
and ending times of the measurement intervals for different ingress-
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egress-aggregates MAY be the same or MAY be different.
3.2.2. Reporting the PCN Data
If the report suppression option described in the next sub-section is
not activated, the PCN-egress-node MUST report the latest values of
NM-rate and ETM-rate to the Decision Point each time that it
calculates them.
3.2.3. Optional Report Suppression
Report suppression MUST be provided as a configurable option, along
with two configurable parameters, the CLE-reporting-threshold and the
maximum report suppression interval T-maxsuppress. The default value
of the CLE-reporting-threshold is zero. T-maxsuppress is discussed
further at the end of this sub-section, but functions as a keep-alive
mechanism for signalling between the PCN-egress-node and the Decision
Point.
If the report suppression option is enabled, the PCN-egress-node MUST
apply the following procedure to decide whether to send a report to
the Decision Point, rather than sending a report automatically at the
end of each measurement interval.
1. As well as the quantities NM-rate and ETM-rate, the PCN-egress-
node MUST calculate the congestion level estimate (CLE) for each
measurement interval. The CLE is equal to the ratio:
ETM-rate / (NM-rate + ETM-rate)
if any PCN-traffic was observed, or zero otherwise.
2. If the calculated CLE for the latest measurement interval or for
the immediately previous interval is greater than the CLE-
reporting-threshold, then the PCN-egress-node MUST send a report
to the Decision Point. The contents of the report are described
below.
3. If an interval T-maxsuppress has elapsed since the last report
was sent to the Decision Point, then the PCN-egress-node MUST
send a report to the Decision Point regardless of the CLE value.
4. If neither of the preceding conditions holds, the PCN-egress-node
MUST NOT send a report for the latest measurement interval.
Each report sent to the Decision Point when report suppression has
been activated MUST contain the values of NM-rate, ETM-rate, and CLE
that were calculated for the most recent measurement interval.
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The above procedure ensures that at least one report is sent per
interval (T-maxsuppress + T-meas). This provides some protection
against loss of egress reports and also demonstrates to the Decision
Point that both the PCN-egress-node and the communication path
between the two nodes are in operation. However, depending on the
transport used for reporting, the operator may choose to set
T-maxsuppress to an effectively infinite value. For example, the
transport may include its own keep-alive signalling at a frequency
such that PCN keep-alive is redundant.
3.3. Behaviour at the Decision Point
Operators may choose to use PCN procedures just for flow admission,
or just for flow termination, or for both. The Decision Point MUST
implement both mechanisms, but configurable options MUST be provided
to activate or deactivate PCN-based flow admission and flow
termination independently of each other at a given Decision Point.
If PCN-based flow termination is enabled but PCN-based flow admission
is not, flow termination operates as specified in this document.
Logically, some other system of flow admission control must be in
operation, but the description of such a system is out of scope of
this document and depends on local arrangements.
3.3.1. Flow Admission
The Decision Point determines the PCN-admission-state for a given
ingress-egress-aggregate each time it receives a report from the
egress node. It makes this determination on the basis of the
congestion level estimate (CLE). If the CLE is provided in the
egress node report, the Decision Point SHOULD use the reported value.
If the CLE was not provided in the report, the Decision Point MUST
calculate it based on the other values provided in the report, using
the formula:
CLE = ETM-rate / (NM-rate + ETM-rate)
if any PCN-traffic was observed, or CLE = 0 if all the rates are
zero.
The Decision Point MUST compare the reported or calculated CLE to a
configurable value, the CLE-limit. If the CLE is less than the CLE-
limit, the PCN-admission-state for that aggregate MUST be set to
"admit"; otherwise it MUST be set to "block".
It is RECOMMENDED that the CLE-limit for SM be set fairly low, in
the order of 0.05. The CLE-limit MAY vary for different flows
based on policy.
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If the PCN-admission-state for a given ingress-egress-aggregate is
"admit", the Decision Point SHOULD allow new flows to be admitted to
that aggregate. If the PCN-admission-state for a given ingress-
egress-aggregate is "block", the Decision Point SHOULD NOT allow new
flows to be admitted to that aggregate. These actions MAY be
modified by policy in specific cases, but such policy intervention
risks defeating the purpose of using PCN.
3.3.2. Flow Termination
When the report from the egress node that the PCN-admission-state
computed on the basis of the CLE is "block" for the given ingress-
egress-aggregate, the Decision Point MUST request the PCN-ingress-
node to provide an estimate of the rate (PCN-sent-rate) at which the
PCN-ingress-node is receiving PCN-traffic that is destined for the
given ingress-egress-aggregate.
If the Decision Point is collocated with the PCN-ingress-node, the
request and response are internal operations.
The Decision Point MUST then wait, for both the requested rate from
the PCN-ingress-node and the next report from the PCN-egress-node for
the ingress-egress-aggregate concerned. If this next egress node
report also includes a non-zero value for the ETM-Rate, the Decision
Point MUST determine an amount of flow to terminate in the following
steps:
1. The sustainable aggregate rate (SAR) for the given ingress-
egress-aggregate is estimated by the product:
SAR = U * NM-Rate
for the latest reported interval, where U is a configurable
factor less than one which is the same for all ingress-egress-
aggregates.
2. The amount of traffic that must be terminated is the difference:
PCN-sent-rate - SAR,
where PCN-sent-rate is the value provided by the ingress node.
If the difference calculated in the second step is positive, the
Decision Point SHOULD select PCN-flows to terminate, until it
determines that the PCN-traffic admission rate will no longer be
greater than the estimated sustainable aggregate rate. If the
Decision Point knows the bandwidth required by individual flows
(e.g., from resource signalling used to establish the flows), it MAY
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choose to complete its selection of flows to terminate in a single
round of decisions.
Alternatively, the Decision Point MAY spread flow termination over
multiple rounds to avoid over-termination. If this is done, it is
RECOMMENDED that enough time elapse between successive rounds of
termination to allow the effects of previous rounds to be reflected
in the measurements upon which the termination decisions are based
(see [IEEE-Satoh] and sections 4.2 and 4.3 of [Menth08-sub-9]).
3.3.3. Decision Point Action For Missing PCN-Boundary-Node Reports
If the Decision Point fails to receive any report from a given PCN-
egress-node for a configurable interval T-fail, it SHOULD raise an
alarm to management. A Decision Point collocated with a PCN-ingress-
node SHOULD cease to admit flows to the ingress-egress-aggregate
passing from the PCN-ingress-node to the given PCN-egress-node, until
it again receives a report from that node. A centralized Decision
Point MAY cease to admit PCN-flows to all ingress-egress-aggregates
destined to the PCN-egress-node concerned, until it again receives a
report from that node.
If a centralized Decision Point fails to receive a reply within a
reasonable period of time to a request for a PCN-sent-rate value sent
to a given PCN-ingress-node, it SHOULD raise an alarm to management.
3.4. Behaviour of the Ingress Node
The PCN-ingress-node MUST provide the estimated current rate of PCN-
traffic received at that node and destined for a given ingress-
egress-aggregate in octets per second (the PCN-sent-rate) when the
Decision Point requests it. The way this rate estimate is derived is
a matter of implementation.
For example, the rate that the PCN-ingress-node supplies MAY be
based on a quick sample taken at the time the information is
required. It is RECOMMENDED that such a sample be based on
observation of at least 30 PCN packets to achieve reasonable
statistical reliability.
3.5. Summary of Timers
Table 1 summarizes the timers implied by the preceding procedures.
The three limits T-meas, T-maxsuppress, and T-fail apply to the three
timers t-meas, t-maxsuppress, and t-fail respectively. t-meas and
t-maxsuppress are reset upon expiry. T-fail is reset by management
action or by receipt of a report from the PCN-egress-node concerned.
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+-------------+---------+-------------+--------------+--------------+
| Timer | Locatio | Incidence | Limit | Action on |
| | n | | | Expiry |
+-------------+---------+-------------+--------------+--------------+
| t-meas | Egress | One per | T-meas | Calculate |
| | node | node | | and possibly |
| | | | | report |
| | | | | NM-rate, |
| | | | | ETM-rate and |
| | | | | conditionall |
| | | | | yCLE for eac |
| | | | | hIEA. |
| - | - | - | - | - |
| t-maxsuppre | Egress | One per IEA | T-maxsuppres | Send a |
| ss | node | if report | s | report for |
| | | suppression | | that IEA at |
| | | is enabled. | | the next |
| | | | | expiry of |
| | | | | t-meas. |
| - | - | - | - | - |
| t-fail | Decisio | One per | T-fail | Assume |
| | npoint | egress node | | failure and |
| | | | | cease to |
| | | | | admit flows |
| | | | | passing |
| | | | | through that |
| | | | | egress node. |
+-------------+---------+-------------+--------------+--------------+
IEA = ingress-egress-aggregate
Table 1: Timers Used For the SM Boundary Node Behaviour
The value of T-meas SHOULD be configurable, and is RECOMMENDED to be
of the order of 100 to 500 ms.
t-maxsuppress is active only when report suppression is enabled. The
value of T-maxsuppress SHOULD be configurable. The appropriate value
depends on the transport used to carry the egress node reports. For
unreliable transport, T-maxsuppress is RECOMMENDED to be of the order
of one second.
The value of T-fail MUST be configurable. When unreliable transport
is used, the value of T-fail is RECOMMENDED to be of the order of 3 *
T-maxsuppress if report suppression is activated, and of the order of
3 * T-meas if report suppression is not activated. When reliable
transport is used, the operator may choose to provide similar values
for T-fail or may choose to disable report timing by setting an
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effectively infinite value for T-fail.
4. Identifying Ingress and Egress Nodes For PCN Traffic
The operation of PCN depends on the ability of the PCN-ingress-node
to identify the ingress-egress-aggregate to which each new PCN-flow
belongs and the ability of the egress node to identify the ingress-
egress-aggregate to which each received PCN-packet belongs. If the
Decision Point is collocated with the PCN-ingress-node, the PCN-
egress-node also needs to associate each ingress-egress-aggregate
with the address of the PCN-ingress-node to which it must send its
reports.
The means by which this is done depends on the packet routing
technology in use in the network.The procedure to provide the
required information is out of the scope of this document.
5. Specification of Diffserv Per-Domain Behaviour
This section provides the specification required by [RFC3086] for a
per-domain behaviour.
5.1. Applicability
This section draws heavily upon points made in the PCN architecture
document, [RFC5559].
The PCN SM boundary node behaviour specified in this document is
applicable to inelastic traffic (particularly video and voice) where
quality of service for admitted flows is protected primarily by
admission control at the ingress to the domain. In exceptional
circumstances (e.g., due to network failures) already-admitted flows
may be terminated to protect the quality of service of the remainder.
The SM boundary node behaviour is more likely to terminate too many
flows under such circumstances than some alternative PCN boundary
node behaviours.
Single-Marking requires no extension to the baseline PCN encoding
described in [RFC5696], thus reducing the work expected to be
performed in the data path of the high-speed routing equipment, and
saving valuable real estate in the packet header.
5.2. Technical Specification
The technical specification of the PCN SM per domain behaviour is
provided by the contents of [RFC5559], [RFC5696], [RFC5670], and the
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present document.
5.3. Attributes
The purpose of this per-domain behaviour is to achieve low loss and
jitter for the target class of traffic. The design requirement for
PCN was that recovery from overloads by flow termination should
happen within 1-3 seconds. PCN probably does better than this.
5.4. Parameters
In the list that follows, note that most PCN-ingress-nodes are also
PCN-egress-nodes, and vice versa. Furthermore, the PCN-ingress-nodes
may be collocated with Decision Points.
Parameters at the PCN-ingress-node:
----------------------------------
o Filters for distinguishing PCN from non-PCN inbound traffic.
o The marking to be applied to PCN-traffic.
o Reference rates on each inward link for the PCN-excess-rate; see
Section 2.
o The information needed to distinguish PCN-traffic belonging to a
given ingress-egress-aggregate.
Parameters at the PCN-egress-node:
---------------------------------
o The measurement interval T-meas.
o Whether report suppression is enabled and, if so, the values of
the CLE-reporting-threshold and T-maxsuppress.
o The information needed to distinguish PCN-traffic belonging to a
given ingress-egress-aggregate.
o The marking rules for re-marking PCN traffic leaving the PCN
domain.
Parameters at each interior node:
--------------------------------
o A reference rate on each link for the PCN-excess-rate; see
Section 2.
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o The markings to be applied to PCN-traffic, including the
identification of PCN-packets and the encoding to indicate excess-
traffic-marking.
Parameters at the Decision Point:
--------------------------------
o Activation/deactivation of PCN-based flow admission.
o Activation/deactivation of PCN-based flow termination.
o The value of CLE-limit.
o The fraction U used to derive the supportable aggregate rate from
the NM-rate;
o The maximum interval Tfail between reports from a given egress
node, for detecting failure of communications with that node.
o The information needed to map between each ingress-egress-
aggregate and the corresponding PCN-ingress-node and PCN-egress-
node.
5.5. Assumptions
Assumed that a specific portion of link capacity has been reserved
for PCN-traffic.
5.6. Example Uses
The PCN SM behaviour may be used to carry real-time traffic,
particularly voice and video.
5.7. Environmental Concerns
The PCN SM per-domain behaviour may interfere with the use of end-to-
end ECN due to reuse of ECN bits for PCN marking. See Appendix B of
[RFC5696] for details.
5.8. Security Considerations
Please see the security considerations in Section 6 as well as those
in [RFC2474] and [RFC2475].
6. Security Considerations
[RFC5559] provides a general description of the security
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considerations for PCN. This memo introduces no new considerations.
7. IANA Considerations
This memo includes no request to IANA.
8. Acknowledgements
The authors thank Ruediger Geib for his useful comments. The
acknowledgements in the CL boundary node behaviour draft really apply
here, too.
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.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
December 1998.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC5559] Eardley, P., "Pre-Congestion Notification (PCN)
Architecture", RFC 5559, June 2009.
[RFC5670] Eardley, P., "Metering and Marking Behaviour of PCN-
Nodes", RFC 5670, November 2009.
[RFC5696] Moncaster, T., Briscoe, B., and M. Menth, "Baseline
Encoding and Transport of Pre-Congestion Information",
RFC 5696, November 2009.
9.2. Informative References
[IEEE-Satoh]
Satoh, D. and H. Ueno, ""Cause and Countermeasure of
Overtermination for PCN-Based Flow Termination",
Proceedings of IEEE Symposium on Computers and
Communications (ISCC '10), pp. 155-161, Riccione, Italy",
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June 2010.
[Menth08-sub-9]
Menth, M. and F. Lehrieder, "PCN-Based Measured Rate
Termination", July 2009, <http://www3.informatik.uni-
wuerzburg.de/~menth/Publications/papers/
Menth08-Sub-9.pdf>.
[RFC3086] Nichols, K. and B. Carpenter, "Definition of
Differentiated Services Per Domain Behaviors and Rules for
their Specification", RFC 3086, April 2001.
Authors' Addresses
Anna Charny
Cisco Systems
300 Apollo Drive
Chelmsford, MA 01824
USA
Email: acharny@cisco.com
Xinyan (Joy) Zhang
Cisco Systems
300 Apollo Drive
Chelmsford, MA 01824
USA
Georgios Karagiannis
U. Twente
Phone:
Email: karagian@cs.utwente.nl
Michael Menth
University of Wuerzburg
Am Hubland
Wuerzburg D-97074
Germany
Phone: +49-931-888-6644
Email: menth@informatik.uni-wuerzburg.de
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Tom Taylor (editor)
Huawei Technologies
1852 Lorraine Ave
Ottawa, Ontario K1H 6Z8
Canada
Phone: +1 613 680 2675
Email: tom111.taylor@bell.net
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