draft-ietf-dime-doic-rate-control-10.txt   draft-ietf-dime-doic-rate-control-11.txt 
Diameter Maintenance and Extensions (DIME) S. Donovan, Ed. Diameter Maintenance and Extensions (DIME) S. Donovan, Ed.
Internet-Draft Oracle Internet-Draft Oracle
Intended status: Standards Track E. Noel Intended status: Standards Track E. Noel
Expires: April 6, 2019 AT&T Labs Expires: August 15, 2019 AT&T Labs
October 3, 2018 February 11, 2019
Diameter Overload Rate Control Diameter Overload Rate Control
draft-ietf-dime-doic-rate-control-10 draft-ietf-dime-doic-rate-control-11
Abstract Abstract
This specification documents an extension to the Diameter Overload This specification documents an extension to the Diameter Overload
Indication Conveyance (DOIC) [RFC7683] base solution. This extension Indication Conveyance (DOIC) [RFC7683] base solution. This extension
adds a new overload control abatement algorithm. This abatement adds a new overload control abatement algorithm. This abatement
algorithm allows for a DOIC reporting node to specify a maximum rate algorithm allows for a DOIC reporting node to specify a maximum rate
at which a DOIC reacting node sends Diameter requests to the DOIC at which a DOIC reacting node sends Diameter requests to the DOIC
reporting node. reporting node.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 6, 2019. This Internet-Draft will expire on August 15, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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5.3. Reporting Node Maintenance of Overload Control State . . 7 5.3. Reporting Node Maintenance of Overload Control State . . 7
5.4. Reacting Node Maintenance of Overload Control State . . . 8 5.4. Reacting Node Maintenance of Overload Control State . . . 8
5.5. Reporting Node Behavior for Rate Abatement Algorithm . . 8 5.5. Reporting Node Behavior for Rate Abatement Algorithm . . 8
5.6. Reacting Node Behavior for Rate Abatement Algorithm . . . 9 5.6. Reacting Node Behavior for Rate Abatement Algorithm . . . 9
6. Rate Abatement Algorithm AVPs . . . . . . . . . . . . . . . . 9 6. Rate Abatement Algorithm AVPs . . . . . . . . . . . . . . . . 9
6.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 9 6.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 9
6.1.1. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . 9 6.1.1. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . 9
6.2. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . 9 6.2. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . 9
6.2.1. OC-Maximum-Rate AVP . . . . . . . . . . . . . . . . . 10 6.2.1. OC-Maximum-Rate AVP . . . . . . . . . . . . . . . . . 10
6.3. Attribute Value Pair Flag Rules . . . . . . . . . . . . . 10 6.3. Attribute Value Pair Flag Rules . . . . . . . . . . . . . 10
7. Rate Based Abatement Algorithm . . . . . . . . . . . . . . . 10 7. Rate-Based Abatement Algorithm . . . . . . . . . . . . . . . 10
7.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 11 7.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 11
7.2. Reporting Node Behavior . . . . . . . . . . . . . . . . . 11 7.2. Reporting Node Behavior . . . . . . . . . . . . . . . . . 11
7.3. Reacting Node Behavior . . . . . . . . . . . . . . . . . 12 7.3. Reacting Node Behavior . . . . . . . . . . . . . . . . . 12
7.3.1. Default Algorithm for Rate-based Control . . . . . . 12 7.3.1. Default Algorithm for Rate-based Control . . . . . . 12
7.3.2. Priority Treatment . . . . . . . . . . . . . . . . . 15 7.3.2. Priority Treatment . . . . . . . . . . . . . . . . . 15
7.3.3. Optional Enhancement: Avoidance of Resonance . . . . 17 7.3.3. Optional Enhancement: Avoidance of Resonance . . . . 17
8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 18 8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . 18
8.1. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 18
8.2. New Registries . . . . . . . . . . . . . . . . . . . . . 18 8.2. OC-Supported-Features . . . . . . . . . . . . . . . . . . 18
8.3. New DOIC report types . . . . . . . . . . . . . . . . . . 18 8.3. New DOIC report types . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19 9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. Normative References . . . . . . . . . . . . . . . . . . 19 11.1. Normative References . . . . . . . . . . . . . . . . . . 19
11.2. Informative References . . . . . . . . . . . . . . . . . 19 11.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
This document defines a new Diameter overload control abatement This document defines a new Diameter overload control abatement
algorithm, the "rate" algorithm. algorithm, the "rate" algorithm.
The base Diameter overload specification [RFC7683] defines the "loss" The base Diameter overload specification [RFC7683] defines the "loss"
algorithm as the default Diameter overload abatement algorithm. The algorithm as the default Diameter overload abatement algorithm. The
loss algorithm allows a reporting node (see Section 2) to instruct a loss algorithm allows a reporting node (see Section 2) to instruct a
reacting node (see Section 2) to reduce the amount of traffic sent to reacting node (see Section 2) to reduce the amount of traffic sent to
the reporting node by abating (diverting or throttling) a percentage the reporting node by abating (diverting or throttling) a percentage
of requests sent to the server. While this can effectively decrease of requests sent to the server. While this can effectively decrease
the load handled by the server, it does not directly address cases the load handled by the server, it does not directly address cases
where the rate of arrival of service requests changes quickly. For where the rate of arrival of service requests changes quickly. For
instance, if the service requests that result in Diameter instance, if the service requests that result in Diameter
transactions increase quickly then the loss algorithm cannot transactions increase quickly then the loss algorithm cannot
guarantee the load presented to the server remains below a specific guarantee the load presented to the server remains below a specific
rate level. The loss algorithm can be slow to ensure the stability rate level. The loss algorithm can be slow to ensure the stability
of reporting nodes when subjected to rapidly changing loads. The of reporting nodes when subjected to rapidly-changing loads. The
"loss" algorithm errs both in throttling too much when there is a dip "loss" algorithm errs both in throttling too much when there is a dip
in offered load, and throttling not enough when there is a spike in in offered load, and throttling not enough when there is a spike in
offered load. offered load.
Consider the case where a reacting node is handling 100 service Consider the case where a reacting node is handling 100 service
requests per second, where each of these service requests results in requests per second, where each of these service requests results in
one Diameter transaction being sent to a reporting node. If the one Diameter transaction being sent to a reporting node. If the
reporting node is approaching an overload state, or is already in an reporting node is approaching an overload state, or is already in an
overload state, it will send a Diameter overload report requesting a overload state, it will send a Diameter overload report requesting a
percentage reduction in traffic sent when the loss algorithm is used percentage reduction in traffic sent when the loss algorithm is used
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report requesting that the reacting node abate 91% of requests to get report requesting that the reacting node abate 91% of requests to get
back to the desired 90 transactions per second. However, once the back to the desired 90 transactions per second. However, once the
spike has abated and the reacting node handled service requests spike has abated and the reacting node handled service requests
returns to 100 per second, this will result in just 9 transactions returns to 100 per second, this will result in just 9 transactions
per second being sent to the reporting node, requiring a new overload per second being sent to the reporting node, requiring a new overload
report setting the reduction percentage back to 10%. This control report setting the reduction percentage back to 10%. This control
feedback loop has the potential to make the situation worse by feedback loop has the potential to make the situation worse by
causing wide fluctuations in traffic on multiple nodes in the causing wide fluctuations in traffic on multiple nodes in the
Diameter network. Diameter network.
One of the benefits of a rate based algorithm over the loss algorithm One of the benefits of a rate-based algorithm over the loss algorithm
is that it better handles spikes in traffic. Instead of sending a is that it better handles spikes in traffic. Instead of sending a
request to reduce traffic by a percentage, the rate approach allows request to reduce traffic by a percentage, the rate approach allows
the reporting node to specify the maximum number of Diameter requests the reporting node to specify the maximum number of Diameter requests
per second that can be sent to the reporting node. For instance, in per second that can be sent to the reporting node. For instance, in
this example, the reporting node could send a rate-based request this example, the reporting node could send a rate-based request
specifying the maximum transactions per second to be 90. The specifying the maximum transactions per second to be 90. The
reacting node will send the 90 regardless of whether it is receiving reacting node will send the 90 regardless of whether it is receiving
100 or 1000 service requests per second. 100 or 1000 service requests per second.
It should be noted that one of the implications of the rate based It should be noted that one of the implications of the rate-based
algorithm is that the reporting node needs to determine how it wants algorithm is that the reporting node needs to determine how it wants
to distribute it's load over the set of reacting nodes from which it to distribute its load over the set of reacting nodes from which it
is receiving traffic. For instance, if the reporting node is is receiving traffic. For instance, if the reporting node is
receiving Diameter traffic from 10 reacting nodes and has a capacity receiving Diameter traffic from 10 reacting nodes and has a capacity
of 100 transactions per second then the reporting node could choose of 100 transactions per second then the reporting node could choose
to set the rate for each of the reacting nodes to 10 transactions per to set the rate for each of the reacting nodes to 10 transactions per
second. This, of course, is assuming that each of the reacting nodes second. This, of course, is assuming that each of the reacting nodes
has equal performance characteristics. The reporting node could also has equal performance characteristics. The reporting node could also
choose to have a high capacity reacting node send 55 transactions per choose to have a high capacity reacting node send 55 transactions per
second and the remaining 9 low capacity reacting nodes send 5 second and the remaining 9 low capacity reacting nodes send 5
transactions per second. The ability of the reporting node to transactions per second. The ability of the reporting node to
specify the amount of traffic on a per reacting node basis implies specify the amount of traffic on a per-reacting-node basis implies
that the reporting node must maintain state for each of the reacting that the reporting node must maintain state for each of the reacting
nodes. This state includes the current allocation of Diameter nodes. This state includes the current allocation of Diameter
traffic to that reacting node. If the number of reacting node traffic to that reacting node. If the number of reacting nodes
changes, either because new nodes are added, nodes are removed from changes, either because new nodes are added, nodes are removed from
service or nodes fail, then the reporting node will need to service or nodes fail, then the reporting node will need to
redistribute the maximum Diameter transactions over the new set of redistribute the maximum Diameter transactions over the new set of
reacting nodes. reacting nodes.
This document extends the base Diameter Overload Indication This document extends the base Diameter Overload Indication
Conveyance (DOIC) solution [RFC7683] to add support for the rate Conveyance (DOIC) solution [RFC7683] to add support for the rate-
based overload abatement algorithm. based overload abatement algorithm.
This document draws heavily on work in the SIP Overload Control This document draws heavily on work in the SIP Overload Control
working group. The definition of the rate abatement algorithm is working group. The definition of the rate abatement algorithm is
copied almost verbatim from the SIP Overload Control (SOC) document copied almost verbatim from the SIP Overload Control (SOC) document
[RFC7415], with changes focused on making the wording consistent with [RFC7415], with changes focused on making the wording consistent with
the DOIC solution and the Diameter protocol. the DOIC solution and the Diameter protocol.
2. Terminology 2. Terminology
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4. Capability Announcement 4. Capability Announcement
This document defines the rate abatement algorithm (referred to as This document defines the rate abatement algorithm (referred to as
rate in this document) feature. Support for the rate feature by a rate in this document) feature. Support for the rate feature by a
DOIC node will be indicated by a new value of the OC-Feature-Vector DOIC node will be indicated by a new value of the OC-Feature-Vector
AVP, as described in Section 6.1.1, per the rules defined in AVP, as described in Section 6.1.1, per the rules defined in
[RFC7683]. [RFC7683].
Since all nodes that support DOIC are required to support the loss Since all nodes that support DOIC are required to support the loss
algorithm, DOIC nodes supporting the rate feature will support both algorithm, DOIC nodes supporting the rate feature will support both
the loss and rate based abatement algorithms. the loss and rate-based abatement algorithms.
DOIC reacting nodes supporting the rate feature MUST indicate support DOIC reacting nodes supporting the rate feature MUST indicate support
for both the loss and rate algorithms in the OC-Feature-Vector AVP. for both the loss and rate algorithms in the OC-Feature-Vector AVP
and MAY indicate support for other algorithms.
As defined in [RFC7683], a DOIC reporting node supporting the rate As defined in [RFC7683], a DOIC reporting node supporting the rate
feature MUST select a single abatement algorithm in the OC-Feature- feature selects a single abatement algorithm in the OC-Feature-Vector
Vector AVP and OC-Peer-Algo AVP in the answer message sent to the AVP and OC-Peer-Algo AVP in the answer message sent to the DOIC
DOIC reacting nodes. reacting nodes.
A reporting node can select one abatement algorithm to apply to host A reporting node can select one abatement algorithm to apply to host
and realm reports and a different algorithm to apply to peer reports. and realm reports and a different algorithm to apply to peer reports.
For host or realm reports the selected algorithm is reflected in For host or realm reports the selected algorithm is reflected in
the OC-Feature-Vector AVP sent as part of the OC-Supported- the OC-Feature-Vector AVP sent as part of the OC-Supported-
Features AVP included in answer messages for transaction where the Features AVP included in answer messages for transaction where the
request contained an OC-Supported-Features AVP. This is per the request contained an OC-Supported-Features AVP. This is per the
procedures defined in [RFC7683]. procedures defined in [RFC7683].
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[RFC7683] for handling of overload reports when the rate overload [RFC7683] for handling of overload reports when the rate overload
abatement algorithm is used. abatement algorithm is used.
5.1. Reporting Node Overload Control State 5.1. Reporting Node Overload Control State
A reporting node that uses the rate abatement algorithm SHOULD A reporting node that uses the rate abatement algorithm SHOULD
maintain reporting node Overload Control State (OCS) for each maintain reporting node Overload Control State (OCS) for each
reacting node to which it sends a rate Overload Report (OLR). reacting node to which it sends a rate Overload Report (OLR).
This is different from the behavior defined in [RFC7683] where a This is different from the behavior defined in [RFC7683] where a
single loss percentage sent to all reacting nodes. reporting node sends a single loss percentage to all reacting
nodes.
A reporting node SHOULD maintain OCS entries when using the rate A reporting node SHOULD maintain OCS entries when using the rate
abatement algorithm per supported Diameter application, per targeted abatement algorithm per supported Diameter application, per targeted
reacting node and per report type. reacting node and per report type.
A rate OCS entry is identified by the tuple of Application-Id, report A rate OCS entry is identified by the tuple of Application-Id, report
type and DiameterIdentity of the target of the rate OLR. type and DiameterIdentity of the target of the rate OLR.
The rate OCS entry SHOULD include the rate allocated to the reacting The rate OCS entry SHOULD include the rate allocated to the reacting
note. note.
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5.2. Reacting Node Overload Control State 5.2. Reacting Node Overload Control State
A reacting node that supports the rate abatement algorithm MUST A reacting node that supports the rate abatement algorithm MUST
indicate rate as the selected abatement algorithm in the reacting indicate rate as the selected abatement algorithm in the reacting
node OCS based on the OC-Feature-Vector AVP or the OC-Peer-Algo AVP node OCS based on the OC-Feature-Vector AVP or the OC-Peer-Algo AVP
in the received OC-Supported-Features AVP. in the received OC-Supported-Features AVP.
A reacting node that supports the rate abatement algorithm MUST A reacting node that supports the rate abatement algorithm MUST
include the rate specified in the OC-Maximum-Rate AVP included in the include the rate specified in the OC-Maximum-Rate AVP included in the
OC-OLR AVP as an element of the abatement algorithm specific portion OC-OLR AVP as an element of the abatement-algorithm-specific portion
of reacting node OCS entries. of reacting node OCS entries.
All other elements for the OCS defined in [RFC7683] and All other elements for the OCS defined in [RFC7683] and
[I-D.ietf-dime-agent-overload] also apply to the reporting nodes OCS [I-D.ietf-dime-agent-overload] also apply to the reporting nodes OCS
when using the rate abatement algorithm. when using the rate abatement algorithm.
5.3. Reporting Node Maintenance of Overload Control State 5.3. Reporting Node Maintenance of Overload Control State
A reporting node that has selected the rate overload abatement A reporting node that has selected the rate overload abatement
algorithm and enters an overload condition MUST indicate rate as the algorithm and enters an overload condition MUST indicate rate as the
abatement algorithm in the resulting reporting node OCS entries. abatement algorithm and MUST indicate the selected rate in the
A reporting node that has selected the rate abatement algorithm and
enters an overload condition MUST indicate the selected rate in the
resulting reporting node OCS entries. resulting reporting node OCS entries.
When selecting the rate algorithm in the response to a request that When selecting the rate algorithm in the response to a request that
contained an OC-Supporting-Features AVP with an OC-Feature-Vector AVP contained an OC-Supporting-Features AVP with an OC-Feature-Vector AVP
indicating support for the rate feature, a reporting node MUST ensure indicating support for the rate feature, a reporting node MUST ensure
that a reporting node OCS entry exists for the target of the overload that a reporting node OCS entry exists for the target of the overload
report. The target is defined as follows: report. The target is defined as follows:
o For Host reports, the target is the DiameterIdentity contained in o For Host reports, the target is the DiameterIdentity contained in
the Origin-Host AVP received in the request. the Origin-Host AVP received in the request.
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5.5. Reporting Node Behavior for Rate Abatement Algorithm 5.5. Reporting Node Behavior for Rate Abatement Algorithm
When in an overload condition with rate selected as the overload When in an overload condition with rate selected as the overload
abatement algorithm and when handling a request that contained an OC- abatement algorithm and when handling a request that contained an OC-
Supported-Features AVP that indicated support for the rate abatement Supported-Features AVP that indicated support for the rate abatement
algorithm, a reporting node SHOULD include an OC-OLR AVP for the rate algorithm, a reporting node SHOULD include an OC-OLR AVP for the rate
algorithm using the parameters stored in the reporting node OCS for algorithm using the parameters stored in the reporting node OCS for
the target of the overload report. the target of the overload report.
Note: It is also possible for the reporting node to send overload Note: It is also possible for the reporting node to send overload
reports with the rate algorithm indicated when the reporting node reports with the rate algorithm indicated even when the reporting
is not in an overloaded state. This could be a strategy to node is not in an overloaded state. This could be a strategy to
proactively avoid entering into an overloaded state. Whether to proactively avoid entering into an overloaded state. Whether to
do so is up to local policy. do so is up to local policy.
When sending an overload report for the rate algorithm, the OC- When sending an overload report for the rate algorithm, the OC-
Maximum-Rate AVP MUST be included in the OC-OLR AVP and the OC- Maximum-Rate AVP MUST be included in the OC-OLR AVP and the OC-
Reduction-Percentage AVP MUST NOT be included. Reduction-Percentage AVP MUST NOT be included.
5.6. Reacting Node Behavior for Rate Abatement Algorithm 5.6. Reacting Node Behavior for Rate Abatement Algorithm
When determining if abatement treatment should be applied to a When determining if abatement treatment should be applied to a
request being sent to a reporting node that has selected the rate request being sent to a reporting node that has selected the rate
overload abatement algorithm, the reacting node MAY use the algorithm overload abatement algorithm, the reacting node can choose to use the
detailed in Section 7. algorithm detailed in Section 7.
Other algorithms for controlling the rate MAY be implemented by Other algorithms for controlling the rate MAY be implemented by the
the reacting node. Any algorithm implemented MUST result in the reacting node. Any algorithm implemented MUST correctly limit the
correct rate of traffic being sent to the reporting node. maximum rate of traffic being sent to the reporting node.
Once a determination is made by the reacting node that an individual Once a determination is made by the reacting node that an individual
Diameter request is to be subjected to abatement treatment then the Diameter request is to be subjected to abatement treatment then the
procedures for throttling and diversion defined in [RFC7683] and procedures for throttling and diversion defined in [RFC7683] and
[I-D.ietf-dime-agent-overload] apply. [I-D.ietf-dime-agent-overload] apply.
6. Rate Abatement Algorithm AVPs 6. Rate Abatement Algorithm AVPs
6.1. OC-Supported-Features AVP 6.1. OC-Supported-Features AVP
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+---------+ +---------+
|AVP flag | |AVP flag |
|rules | |rules |
+----+----+ +----+----+
AVP Section | |MUST| AVP Section | |MUST|
Attribute Name Code Defined Value Type |MUST| NOT| Attribute Name Code Defined Value Type |MUST| NOT|
+---------------------------------------------------------+----+----+ +---------------------------------------------------------+----+----+
|OC-Maximum-Rate TBD1 6.2 Unsigned32 | | V | |OC-Maximum-Rate TBD1 6.2 Unsigned32 | | V |
+---------------------------------------------------------+----+----+ +---------------------------------------------------------+----+----+
7. Rate Based Abatement Algorithm 7. Rate-Based Abatement Algorithm
This section is pulled from [RFC7415], with minor changes needed to This section is pulled from [RFC7415], with minor changes needed to
make it apply to the Diameter protocol. make it apply to the Diameter protocol.
7.1. Overview 7.1. Overview
The reporting node is the one protected by the overload control The reporting node is the one protected by the overload control
algorithm defined here. The reacting node is the one that abates algorithm defined here. The reacting node is the one that abates
traffic towards the server. traffic towards the server.
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(e.g. CPU utilization or queuing delay) to evaluate its overload (e.g. CPU utilization or queuing delay) to evaluate its overload
state and estimate a target maximum Diameter request rate in number state and estimate a target maximum Diameter request rate in number
of requests per second (as opposed to target percent reduction in the of requests per second (as opposed to target percent reduction in the
case of loss-based abatement). case of loss-based abatement).
When in an overloaded state, the reporting node uses the OC-OLR AVP When in an overloaded state, the reporting node uses the OC-OLR AVP
to inform reacting nodes of its overload state and of the target to inform reacting nodes of its overload state and of the target
Diameter request rate. Diameter request rate.
Upon receiving the overload report with a target maximum Diameter Upon receiving the overload report with a target maximum Diameter
request rate, each reacting node applies abatement treatment for new request rate, each reacting node applies overload abatement for new
Diameter requests towards the reporting node. Diameter requests towards the reporting node.
7.2. Reporting Node Behavior 7.2. Reporting Node Behavior
The actual algorithm used by the reporting node to determine its The actual algorithm used by the reporting node to determine its
overload state and estimate a target maximum Diameter request rate is overload state and estimate a target maximum Diameter request rate is
beyond the scope of this document. beyond the scope of this document.
However, the reporting node MUST periodically evaluate its overload However, the reporting node MUST periodically evaluate its overload
state and estimate a target Diameter request rate beyond which it state and estimate a target Diameter request rate beyond which it
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When setting the maximum rate for a particular reacting node, the When setting the maximum rate for a particular reacting node, the
reporting node may need take into account the workload (e.g. CPU reporting node may need take into account the workload (e.g. CPU
load per request) of the distribution of message types from that load per request) of the distribution of message types from that
reacting node. Furthermore, because the reacting node may prioritize reacting node. Furthermore, because the reacting node may prioritize
the specific types of messages it sends while under overload the specific types of messages it sends while under overload
restriction, this distribution of message types may be different from restriction, this distribution of message types may be different from
the message distribution for that reacting node under non-overload the message distribution for that reacting node under non-overload
conditions (e.g., either higher or lower CPU load). conditions (e.g., either higher or lower CPU load).
Note that the value of OC-Maximum-Rate AVP (in request messages per Note that the value of OC-Maximum-Rate AVP (in request messages per
second) for the rate algorithm provides an upper bound on the traffic second) for the rate algorithm provides a loose upper bound on the
sent by the reacting node to the reporting node. traffic sent by the reacting node to the reporting node.
In other words, when multiple reacting nodes are being controlled by In other words, when multiple reacting nodes are being controlled by
an overloaded reporting node, at any given time, some reporting nodes an overloaded reporting node, at any given time, some reporting nodes
may receive requests at a rate below its target maximum Diameter may receive requests at a rate below its target maximum Diameter
request rate while others above that target rate. But the resulting request rate while others above that target rate. But the resulting
request rate presented to the overloaded reporting node will converge request rate presented to the overloaded reporting node will converge
towards the target Diameter request rate or a lower rate. towards the target Diameter request rate or a lower rate.
Upon detection of overload, and the determination to invoke overload Upon detection of overload, and the determination to invoke overload
controls, the reporting node follows the specifications in [RFC7683] controls, the reporting node follows the specifications in [RFC7683]
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The reporting node uses the OC-Maximum-Rate AVP defined in this The reporting node uses the OC-Maximum-Rate AVP defined in this
specification to communicate a target maximum Diameter request rate specification to communicate a target maximum Diameter request rate
to each of its clients. to each of its clients.
7.3. Reacting Node Behavior 7.3. Reacting Node Behavior
7.3.1. Default Algorithm for Rate-based Control 7.3.1. Default Algorithm for Rate-based Control
A reference algorithm is shown below. A reference algorithm is shown below.
Note that use of // below inidcates a comment.
No priority case: No priority case:
// T: inter-transmission interval, set to 1 / OC-Maximum-Rate // T: inter-transmission interval, set to 1 / OC-Maximum-Rate
// TAU: tolerance parameter // TAU: tolerance parameter
// ta: arrival time of the most recent arrival // ta: arrival time of the most recent arrival
// LCT: arrival time of last Diameter request that // LCT: arrival time of last Diameter request that
// was sent to the server // was sent to the server
// (initialized to the first arrival time) // (initialized to the first arrival time)
// X: current value of the leaky bucket counter (initialized to // X: current value of the leaky bucket counter (initialized to
// TAU0) // TAU0)
skipping to change at page 16, line 18 skipping to change at page 16, line 18
// ta: arrival time of the most recent arrival // ta: arrival time of the most recent arrival
// LCT: arrival time of last Diameter request that // LCT: arrival time of last Diameter request that
// was sent to the server // was sent to the server
// (initialized to the first arrival time) // (initialized to the first arrival time)
// X: current value of the leaky bucket counter (initialized to // X: current value of the leaky bucket counter (initialized to
// TAU0) // TAU0)
// After most recent arrival, calculate auxiliary variable Xp // After most recent arrival, calculate auxiliary variable Xp
Xp = X - (ta - LCT); Xp = X - (ta - LCT);
if (AnyRequestReceived && Xp <= TAU1) || (PriorityRequestReceived && if (AnyRequestReceived && Xp <= TAU1) || (PriorityRequestReceived &&
Xp <= TAU2 && Xp > TAU1) { Xp <= TAU2 && Xp > TAU1) {
// Transmit Diameter request // Transmit Diameter request
// Update X and LCT // Update X and LCT
X = max (0, Xp) + T; X = max (0, Xp) + T;
LCT = ta; LCT = ta;
} else { } else {
// Apply abatement treatment to Diameter request // Apply abatement treatment to Diameter request
// Do not update X and LCT // Do not update X and LCT
} }
skipping to change at page 18, line 43 skipping to change at page 18, line 43
'phasing' of the buckets remains. 'phasing' of the buckets remains.
8. IANA Consideration 8. IANA Consideration
8.1. AVP Codes 8.1. AVP Codes
New AVPs defined by this specification are listed in Section 6. All New AVPs defined by this specification are listed in Section 6. All
AVP codes are allocated from the 'Authentication, Authorization, and AVP codes are allocated from the 'Authentication, Authorization, and
Accounting (AAA) Parameters' AVP Codes registry. Accounting (AAA) Parameters' AVP Codes registry.
8.2. New Registries 8.2. OC-Supported-Features
There are no new IANA registries introduced by this document. As indicated in Section 6.1.1, a new allocation is required in the
OC-Feature-Vector AVP.
8.3. New DOIC report types 8.3. New DOIC report types
All DOIC report types defined in the future MUST indicate whether or All DOIC report types defined in the future MUST indicate whether or
not the rate algorithm can be used with that report type. not the rate algorithm can be used with that report type.
9. Security Considerations 9. Security Considerations
The rate overload abatement mechanism is an extension to the base The rate overload abatement mechanism is an extension to the base
Diameter overload mechanism. As such, all of the security Diameter overload mechanism. As such, all of the security
considerations outlined in [RFC7683] apply to the rate overload considerations outlined in [RFC7683] apply to the rate overload
abatement mechanism. abatement mechanism.
In addition, the rate algorithm could be used to handle DoS attacks
more effectively than the loss algorithm.
10. Acknowledgements 10. Acknowledgements
Lionel Morand for his contributions to the document.
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-dime-agent-overload] [I-D.ietf-dime-agent-overload]
Donovan, S., "Diameter Agent Overload", draft-ietf-dime- Donovan, S., "Diameter Agent Overload", draft-ietf-dime-
agent-overload-00 (work in progress), December 2014. agent-overload-00 (work in progress), December 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
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