draft-ietf-dime-ovli-01.txt   draft-ietf-dime-ovli-02.txt 
Diameter Maintenance and Extensions J. Korhonen, Ed. Diameter Maintenance and Extensions (DIME) J. Korhonen, Ed.
(DIME) Broadcom Internet-Draft Broadcom
Internet-Draft S. Donovan Intended status: Standards Track S. Donovan, Ed.
Intended status: Standards Track B. Campbell Expires: September 28, 2014 B. Campbell
Expires: June 20, 2014 Oracle Oracle
L. Morand L. Morand
Orange Labs Orange Labs
December 17, 2013 March 27, 2014
Diameter Overload Indication Conveyance Diameter Overload Indication Conveyance
draft-ietf-dime-ovli-01.txt draft-ietf-dime-ovli-02.txt
Abstract Abstract
This specification documents a Diameter Overload Control (DOC) base This specification documents a Diameter Overload Control (DOC) base
solution and the dissemination of the overload report information. solution and the dissemination of the overload report information.
Requirements Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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 June 20, 2014. This Internet-Draft will expire on September 28, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 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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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Abbreviations . . . . . . . . . . . . . . . . 4 2. Terminology and Abbreviations . . . . . . . . . . . . . . . . 3
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5 3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Architectural Assumptions . . . . . . . . . . . . . . . . 5 3.1. Architectural Assumptions . . . . . . . . . . . . . . . . 6
3.1.1. Application Classification . . . . . . . . . . . . . . 5 3.1.1. Application Classification . . . . . . . . . . . . . 6
3.1.2. Application Type Overload Implications . . . . . . . . 6 3.1.2. Application Type Overload Implications . . . . . . . 7
3.1.3. Request Transaction Classification . . . . . . . . . . 8 3.1.3. Request Transaction Classification . . . . . . . . . 8
3.1.4. Request Type Overload Implications . . . . . . . . . . 9 3.1.4. Request Type Overload Implications . . . . . . . . . 9
3.1.5. Diameter Agent Behaviour . . . . . . . . . . . . . . . 10 3.1.5. Diameter Agent Behavior . . . . . . . . . . . . . . . 10
3.1.6. Simplified Example Architecture . . . . . . . . . . . 11 3.1.6. Simplified Example Architecture . . . . . . . . . . . 11
3.2. Conveyance of the Overload Indication . . . . . . . . . . 11 3.2. Conveyance of the Overload Indication . . . . . . . . . . 12
3.2.1. DOIC Capability Discovery . . . . . . . . . . . . . . 12 3.2.1. DOIC Capability Discovery . . . . . . . . . . . . . . 12
3.3. Overload Condition Indication . . . . . . . . . . . . . . 12 3.3. Overload Condition Indication . . . . . . . . . . . . . . 13
4. Attribute Value Pairs . . . . . . . . . . . . . . . . . . . . 12 4. Attribute Value Pairs . . . . . . . . . . . . . . . . . . . . 13
4.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 13 4.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 13
4.2. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . . . 14 4.2. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . . . 14
4.3. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . . 14 4.3. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . 15
4.4. OC-Sequence-Number AVP . . . . . . . . . . . . . . . . . . 15 4.4. OC-Sequence-Number AVP . . . . . . . . . . . . . . . . . 16
4.5. OC-Validity-Duration AVP . . . . . . . . . . . . . . . . . 15 4.5. OC-Validity-Duration AVP . . . . . . . . . . . . . . . . 16
4.6. OC-Report-Type AVP . . . . . . . . . . . . . . . . . . . . 16 4.6. OC-Report-Type AVP . . . . . . . . . . . . . . . . . . . 17
4.7. OC-Reduction-Percentage AVP . . . . . . . . . . . . . . . 16 4.7. OC-Reduction-Percentage AVP . . . . . . . . . . . . . . . 18
4.8. Attribute Value Pair flag rules . . . . . . . . . . . . . 17 4.8. Attribute Value Pair flag rules . . . . . . . . . . . . . 19
5. Overload Control Operation . . . . . . . . . . . . . . . . . . 18 5. Overload Control Operation . . . . . . . . . . . . . . . . . 19
5.1. Overload Control Endpoints . . . . . . . . . . . . . . . . 18 5.1. Overload Control Endpoints . . . . . . . . . . . . . . . 19
5.2. Piggybacking Principle . . . . . . . . . . . . . . . . . . 21 5.2. Piggybacking Principle . . . . . . . . . . . . . . . . . 23
5.3. Capability Announcement . . . . . . . . . . . . . . . . . 22 5.3. Capability Announcement . . . . . . . . . . . . . . . . . 24
5.3.1. Reacting Node Endpoint Considerations . . . . . . . . 22 5.3.1. Reacting Node Endpoint Considerations . . . . . . . . 24
5.3.2. Reporting Node Endpoint Considerations . . . . . . . . 23 5.3.2. Reporting Node Endpoint Considerations . . . . . . . 24
5.4. Protocol Extensibility . . . . . . . . . . . . . . . . . . 23 5.3.3. Agent Considerations . . . . . . . . . . . . . . . . 25
5.5. Overload Report Processing . . . . . . . . . . . . . . . . 24 5.4. Protocol Extensibility . . . . . . . . . . . . . . . . . 25
5.5.1. Overload Control State . . . . . . . . . . . . . . . . 24 5.5. Overload Report Processing . . . . . . . . . . . . . . . 26
5.5.2. Reacting Node Considerations . . . . . . . . . . . . . 24 5.5.1. Overload Control State . . . . . . . . . . . . . . . 26
5.5.3. Reporting Node Considerations . . . . . . . . . . . . 27 5.5.2. Reacting Node Considerations . . . . . . . . . . . . 28
6. Transport Considerations . . . . . . . . . . . . . . . . . . . 27 5.5.3. Reporting Node Considerations . . . . . . . . . . . . 30
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 5.5.4. Agent Considerations . . . . . . . . . . . . . . . . 31
7.1. AVP codes . . . . . . . . . . . . . . . . . . . . . . . . 28 6. Transport Considerations . . . . . . . . . . . . . . . . . . 31
7.2. New registries . . . . . . . . . . . . . . . . . . . . . . 28 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
7.1. AVP codes . . . . . . . . . . . . . . . . . . . . . . . . 31
8. Security Considerations . . . . . . . . . . . . . . . . . . . 28 7.2. New registries . . . . . . . . . . . . . . . . . . . . . 31
8.1. Potential Threat Modes . . . . . . . . . . . . . . . . . . 28 8. Security Considerations . . . . . . . . . . . . . . . . . . . 32
8.2. Denial of Service Attacks . . . . . . . . . . . . . . . . 30 8.1. Potential Threat Modes . . . . . . . . . . . . . . . . . 32
8.3. Non-Compliant Nodes . . . . . . . . . . . . . . . . . . . 30 8.2. Denial of Service Attacks . . . . . . . . . . . . . . . . 33
8.4. End-to End-Security Issues . . . . . . . . . . . . . . . . 30 8.3. Non-Compliant Nodes . . . . . . . . . . . . . . . . . . . 33
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 31 8.4. End-to End-Security Issues . . . . . . . . . . . . . . . 34
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 35
10.1. Normative References . . . . . . . . . . . . . . . . . . . 32 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.2. Informative References . . . . . . . . . . . . . . . . . . 32 10.1. Normative References . . . . . . . . . . . . . . . . . . 35
Appendix A. Issues left for future specifications . . . . . . . . 33 10.2. Informative References . . . . . . . . . . . . . . . . . 35
A.1. Additional traffic abatement algorithms . . . . . . . . . 33 Appendix A. Issues left for future specifications . . . . . . . 36
A.2. Agent Overload . . . . . . . . . . . . . . . . . . . . . . 33 A.1. Additional traffic abatement algorithms . . . . . . . . . 36
A.3. DIAMETER_TOO_BUSY clarifications . . . . . . . . . . . . . 33 A.2. Agent Overload . . . . . . . . . . . . . . . . . . . . . 36
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 33 A.3. DIAMETER_TOO_BUSY clarifications . . . . . . . . . . . . 36
B.1. Mix of Destination-Realm routed requests and Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 37
Destination-Host routed requests . . . . . . . . . . . . . 33 B.1. Mix of Destination-Realm routed requests and Destination-
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 37 Host routed requests . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction 1. Introduction
This specification defines a base solution for Diameter Overload This specification defines a base solution for Diameter Overload
Control (DOC). The requirements for the solution are described and Control (DOC). The requirements for the solution are described and
discussed in the corresponding design requirements document discussed in the corresponding design requirements document
[RFC7068]. Note that the overload control solution defined in this [RFC7068]. Note that the overload control solution defined in this
specification does not address all the requirements listed in specification does not address all the requirements listed in
[RFC7068]. A number of overload control related features are left [RFC7068]. A number of overload control related features are left
for the future specifications. for the future specifications.
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The solution defined in this specification addresses the Diameter The solution defined in this specification addresses the Diameter
overload control between two endpoints (see Section 5.1). overload control between two endpoints (see Section 5.1).
Furthermore, the solution is designed to apply to existing and future Furthermore, the solution is designed to apply to existing and future
Diameter applications, requires no changes to the Diameter base Diameter applications, requires no changes to the Diameter base
protocol [RFC6733] and is deployable in environments where some protocol [RFC6733] and is deployable in environments where some
Diameter nodes do not implement the Diameter overload control Diameter nodes do not implement the Diameter overload control
solution defined in this specification. solution defined in this specification.
2. Terminology and Abbreviations 2. Terminology and Abbreviations
Server Farm Abatement Algorithm
A set of Diameter servers that can handle any request for a given
set of Diameter applications. While these servers support the
same set of applications, they do not necessarily all have the
same capacity. An individual server farm might also support a
subset of the users for a Diameter Realm. A server farm may host
a single or multiple realms.
Diameter Routing:
Diameter Routing between non-adjacent nodes relies on the
Destination-Realm AVP to determine the Diameter realm in which the
request needs to be processed. A Destination-Host AVP may also be
present in the request to address a specific server inside the
Diameter realm. This function is defined in [RFC6733]. However,
it is possible to enhance the routing decisions with application
level knowledge as it done in 3GPP PCC [3GPP.23.203] and NAI-based
source routing [RFC5729].
Diameter layer Load Balancing:
Diameter layer load balancing allows Diameter requests to be
distributed across the set of servers. Definition of this
function is outside the scope of this document.
Topology Hiding:
Topology Hiding is loosely defined as ensuring that no Diameter An algorithm requested by reporting nodes and used by reacting
topology information about a Diameter network can be discovered nodes to reduce the amount of traffic sent to the reporting node
from Diameter messages sent outside a predefined boundary during an occurrence of overload control.
(typically an administrative domain). This includes obfuscating
identifiers and address information of Diameter entities in the
Diameter network. It can also include hiding the number of
various Diameter entities in the Diameter network. Identifying
information can occur in many Diameter Attribute-Value Pairs
(AVPs), including Origin-Host, Destination-Host, Route-Record,
Proxy-Info, Session-ID and other AVPs.
Throttling: Throttling:
Throttling is the reduction of the number of requests sent to an Throttling is the reduction of the number of requests sent to an
entity. Throttling can include a client dropping requests, or an entity. Throttling can include a client dropping requests, or an
agent rejecting requests with appropriate error responses. agent rejecting requests with appropriate error responses.
Clients and agents can also choose to redirect throttled requests Clients and agents can also choose to redirect throttled requests
to some other entity or entities capable of handling them. to some other entity or entities capable of handling them.
Reporting Node Reporting Node
A Diameter node that generates an overload report. (This may or A Diameter node that generates an overload report. (This may or
may not be the actually overloaded node.) may not be the overloaded node.)
Reacting Node Reacting Node
A Diameter node that consumes and acts upon a report. Note that A Diameter node that consumes and acts upon a report. Note that
"act upon" does not necessarily mean the reacting node applies an "act upon" does not necessarily mean the reacting node applies an
abatement algorithm; it might decide to delegate that downstream, abatement algorithm; it might decide to delegate that downstream,
in which case it also becomes a "reporting node". in which case it also becomes a "reporting node".
OLR Overload Report. Overload Control State (OCS)
State describing an occurrence of overload control maintained by
reporting and reacting nodes.
Overload Report (OLR)
A set of AVPs sent by a reporting node indicating the start or
continuation of an occurrence of overload control.
3. Solution Overview 3. Solution Overview
The Diameter Overload Information Conveyance (DOIC) mechanism allows
Diameter nodes to request other nodes to perform overload abatement
actions, that is, actions to reduce the load offered to the
overloaded node or realm.
A Diameter node that supports DOIC is known as a "DOIC endpoint".
Any Diameter node can act as a DOIC endpoint, including clients,
servers, and agents. DOIC endpoints are further divided into
"Reporting Nodes" and "Reacting Nodes." A reporting node requests
overload abatement by sending an Overload Report (OLR) to one or more
reacting nodes.
A reacting node consumes OLRs, and performs whatever actions are
needed to fulfill the abatement requests included in the OLRs. A
Reporting node may report overload on its own behalf, or on behalf of
other (typically upstream) nodes. Likewise, a reacting node may
perform overload abatement on its own behalf, or on behalf of other
(typically downstream) nodes.
A node's role as a DOIC endpoint is independent of its Diameter role.
For example, Diameter relay and proxy agents may act as DOIC
endpoints, even though they are not endpoints in the Diameter sense.
Since Diameter enables bi-directional applications, where Diameter
servers can send requests towards Diameter clients, a given Diameter
node can simultaneously act as a reporting node and reacting node.
Likewise, a relay or proxy agent may act as a reacting node from the
perspective of upstream nodes, and a reporting node from the
perspective of downstream nodes.
DOIC endpoints do not generate new messages to carry DOIC related
information. Rather, they "piggyback" DOIC information over existing
Diameter messages by inserting new AVPs into existing Diameter
requests and responses. Nodes indicate support for DOIC, and any
needed DOIC parameters by inserting an OC_Supported_Features AVP
(Section 4.1) into existing requests and responses. Reporting nodes
send OLRs by inserting OC-OLR AVPs. (Section 4.3)
A given OLR applies to the Diameter realm and application of the
Diameter message that carries it. If a reporting node supports more
than one realm and/or application, it reports independently for each
combination of realm and application. Similarly, OC-Feature-Vector
AVPs apply to the realm and application of the enclosing message.
This implies that a node may support DOIC for one application and/or
realm, but not another, and may indicate different DOIC parameters
for each application and realm for which it supports DOIC.
Reacting nodes perform overload abatement according to an agreed-upon
abatement algorithm. An abatement algorithm defines the meaning of
the parameters of an OLR, and the procedures required for overload
abatement. This document specifies a single must-support algorithm,
namely the "loss" algorithm [ref?]. Future specifications may
introduce new algorithms.
Editor's note: The need to restructure the document to contain a
section that describes the loss algorithm. This likely means
separating the description of the mechanisms for reporting the need
for overload control from the description of the loss algorithm.
Overload conditions may vary in scope. For example, a single
Diameter node may be overloaded, in which case reacting nodes may
reasonably attempt to send throttled requests to other destinations
or via other agents. On the other hand, an entire Diameter realm may
be overloaded, in which case such attempts would do harm. DOIC OLRs
have a concept of "report type" (Section 4.6), where the type defines
such behaviors. Report types are extensible. This document defines
report types for overload of a specific server, and for overload of
an entire realm.
While a reporting node sends OLRs to "adjacent" reacting nodes, nodes
that are "adjacent" for DOIC purposes may not be adjacent from a
Diameter, or transport, perspective. For example, one or more
Diameter agents that do not support DOIC may exist between a given
pair of reporting and reacting nodes, as long as those agents pass
unknown AVPs through unmolested. The report types described in this
document can safely pass through non-supporting agents. This may not
be true for report types defined in future specifications. Documents
that introduce new report types MUST describe any limitations on
their use across non-supporting agents.
3.1. Architectural Assumptions 3.1. Architectural Assumptions
This section describes the high-level architectural and semantic This section describes the high-level architectural and semantic
assumptions that underlie the Diameter Overload Control Mechanism. assumptions that underlie the Diameter Overload Control Mechanism.
3.1.1. Application Classification 3.1.1. Application Classification
The following is a classification of Diameter applications and The following is a classification of Diameter applications and
requests. This discussion is meant to document factors that play requests. This discussion is meant to document factors that play
into decisions made by the Diameter identity responsible for handling into decisions made by the Diameter identity responsible for handling
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terminated after a single Diameter transaction and a new Session-Id terminated after a single Diameter transaction and a new Session-Id
is generated for each Diameter request. is generated for each Diameter request.
For the purposes of this discussion, session-less applications are For the purposes of this discussion, session-less applications are
further divided into two types of applications: further divided into two types of applications:
Stateless applications: Stateless applications:
Requests within a stateless application have no relationship to Requests within a stateless application have no relationship to
each other. The 3GPP defined S13 application is an example of a each other. The 3GPP defined S13 application is an example of a
stateless application [3GPP.29.272], where only a Diameter command stateless application [S13], --> where only a Diameter command is
is defined between a client and a server and no state is defined between a client and a server and no state is maintained
maintained between two consecutive transactions. between two consecutive transactions.
Pseudo-session applications: Pseudo-session applications:
Applications that do not rely on the Session-Id AVP for Applications that do not rely on the Session-Id AVP for
correlation of application messages related to the same session correlation of application messages related to the same session
but use other session-related information in the Diameter requests but use other session-related information in the Diameter requests
for this purpose. The 3GPP defined Cx application [3GPP.29.229] for this purpose. The 3GPP defined Cx application [Cx] is an
is an example of a pseudo-session application. example of a pseudo-session application.
The Credit-Control application defined in [RFC4006] is an example of The Credit-Control application defined in [RFC4006] is an example of
a Diameter session-based application. a Diameter session-based application.
The handling of overload reports must take the type of application The handling of overload reports must take the type of application
into consideration, as discussed in Section 3.1.2. into consideration, as discussed in Section 3.1.2.
3.1.2. Application Type Overload Implications 3.1.2. Application Type Overload Implications
This section discusses considerations for mitigating overload This section discusses considerations for mitigating overload
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Session-Initiating Request: Session-Initiating Request:
A session-initiating request is the initial message that A session-initiating request is the initial message that
establishes a Diameter session. The ACR message defined in establishes a Diameter session. The ACR message defined in
[RFC6733] is an example of a session-initiating request. [RFC6733] is an example of a session-initiating request.
Correlated Session-Initiating Request: Correlated Session-Initiating Request:
There are cases when multiple session-initiated requests must be There are cases when multiple session-initiated requests must be
correlated and managed by the same Diameter server. It is notably correlated and managed by the same Diameter server. It is notably
the case in the 3GPP PCC architecture [3GPP.23.203], where the case in the 3GPP PCC architecture [PCC], where multiple
multiple apparently independent Diameter application sessions are apparently independent Diameter application sessions are actually
actually correlated and must be handled by the same Diameter correlated and must be handled by the same Diameter server.
server.
Intra-Session Request: Intra-Session Request:
An intra session request is a request that uses the same An intra session request is a request that uses the same Session-
Session-Id than the one used in a previous request. An intra Id than the one used in a previous request. An intra session
session request generally needs to be delivered to the server that request generally needs to be delivered to the server that handled
handled the session creating request for the session. The STR the session creating request for the session. The STR message
message defined in [RFC6733] is an example of an intra-session defined in [RFC6733] is an example of an intra-session requests.
requests.
Pseudo-Session Requests: Pseudo-Session Requests:
Pseudo-session requests are independent requests and do not use Pseudo-session requests are independent requests and do not use
the same Session-Id but are correlated by other session-related the same Session-Id but are correlated by other session-related
information contained in the request. There exists Diameter information contained in the request. There exists Diameter
applications that define an expected ordering of transactions. applications that define an expected ordering of transactions.
This sequencing of independent transactions results in a pseudo This sequencing of independent transactions results in a pseudo
session. The AIR, MAR and SAR requests in the 3GPP defined Cx session. The AIR, MAR and SAR requests in the 3GPP defined Cx
application are examples of pseudo-session requests. [Cx] application are examples of pseudo-session requests.
3.1.4. Request Type Overload Implications 3.1.4. Request Type Overload Implications
The request classes identified in Section 3.1.3 have implications on The request classes identified in Section 3.1.3 have implications on
decisions about which requests should be throttled first. The decisions about which requests should be throttled first. The
following list of request treatment regarding throttling is provided following list of request treatment regarding throttling is provided
as guidelines for application designers when implementing the as guidelines for application designers when implementing the
Diameter overload control mechanism described in this document. Diameter overload control mechanism described in this document. The
Exact behavior regarding throttling must be defined per application. exact behavior regarding throttling is a matter of local policy,
unless specifically defined for the application.
Independent requests: Independent requests:
Independent requests can be given equal treatment when making Independent requests can be given equal treatment when making
throttling decisions. throttling decisions.
Session-initiating requests: Session-initiating requests:
Session-initiating requests represent more work than independent Session-initiating requests represent more work than independent
or intra-session requests. Moreover, session-initiating requests or intra-session requests. Moreover, session-initiating requests
are typically followed by other related session-related requests. are typically followed by other session-related requests. As
As such, as the main objective of the overload control is to such, as the main objective of the overload control is to reduce
reduce the total number of requests sent to the overloaded entity, the total number of requests sent to the overloaded entity,
throttling decisions might favor allowing intra-session requests throttling decisions might favor allowing intra-session requests
over session-initiating requests. Individual session-initiating over session-initiating requests. Individual session-initiating
requests can be given equal treatment when making throttling requests can be given equal treatment when making throttling
decisions. decisions.
Correlated session-initiating requests: Correlated session-initiating requests:
A Request that results in a new binding, where the binding is used A Request that results in a new binding, where the binding is used
for routing of subsequent session-initiating requests to the same for routing of subsequent session-initiating requests to the same
server, represents more work load than other requests. As such, server, represents more work load than other requests. As such,
skipping to change at page 10, line 13 skipping to change at page 10, line 36
and server to maintain the ongoing session state. Session and server to maintain the ongoing session state. Session
terminating requests should be throttled less aggressively in terminating requests should be throttled less aggressively in
order to gracefully terminate sessions, allow clean-up of the order to gracefully terminate sessions, allow clean-up of the
related resources (e.g. session state) and get rid of the need for related resources (e.g. session state) and get rid of the need for
other intra-session requests, reducing the session management other intra-session requests, reducing the session management
impact on the overloaded entity. The default handling of other impact on the overloaded entity. The default handling of other
intra-session requests might be to treat them equally when making intra-session requests might be to treat them equally when making
throttling decisions. There might also be application level throttling decisions. There might also be application level
considerations whether some request types are favored over others. considerations whether some request types are favored over others.
3.1.5. Diameter Agent Behaviour 3.1.5. Diameter Agent Behavior
Editor's note: This section needs to be revisited once definition of
DOIC endpoints is finalized.
In the context of the Diameter Overload Indication Conveyance (DOIC) In the context of the Diameter Overload Indication Conveyance (DOIC)
and reacting to the overload information, the functional behaviour of and reacting to the overload information, the functional behavior of
Diameter agents in front of servers, especially Diameter proxies, Diameter agents in front of servers, especially Diameter proxies,
needs to be common. This is important because agents may actively needs to be common. This is important because agents may actively
participate in the handling of an overload conditions. For example, participate in the handling of an overload conditions. For example,
they may make intelligent next hop selection decisions based on they may make intelligent next hop selection decisions based on
overload conditions, or aggregate overload information to be overload conditions, or aggregate overload information to be
disseminated downstream. Diameter agents may have other deployment disseminated downstream. Diameter agents may have other deployment
related tasks that are not defined in the Diameter base protocol related tasks that are not defined in the Diameter base protocol
[RFC6733]. These include, among other tasks, topology hiding, or [RFC6733]. These include, among other tasks, topology hiding, or
agent acting as a Server Front End (SFE) for a farm of Diameter agent acting as a Server Front End (SFE) for a farm of Diameter
servers. servers.
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3.1.6. Simplified Example Architecture 3.1.6. Simplified Example Architecture
Figure 1 illustrates the simplified architecture for Diameter Figure 1 illustrates the simplified architecture for Diameter
overload information conveyance. See Section 5.1 for more discussion overload information conveyance. See Section 5.1 for more discussion
and details how different Diameter nodes fit into the architecture and details how different Diameter nodes fit into the architecture
from the DOIC point of view. from the DOIC point of view.
Realm X Same or other Realms Realm X Same or other Realms
<--------------------------------------> <----------------------> <--------------------------------------> <---------------------->
+--^-----+ : (optional) : +--^-----+ : (optional) :
|Diameter| : : |Diameter| : :
|Server A|--+ .--. : +---^----+ : .--. |Server A|--+ .--. : +---^----+ : .--.
+--------+ | _( `. : |Diameter| : _( `. +---^----+ +--------+ | _( `. : |Diameter| : _( `. +---^----+
+--( )--:-| Agent |-:--( )--|Diameter| +--( )--:-| Agent |-:--( )--|Diameter|
+--------+ | ( ` . ) ) : +-----^--+ : ( ` . ) ) | Client | +--------+ | ( ` . ) ) : +-----^--+ : ( ` . ) ) | Client |
|Diameter|--+ `--(___.-' : : `--(___.-' +-----^--+ |Diameter|--+ `--(___.-' : : `--(___.-' +-----^--+
|Server B| : : |Server B| : :
+---^----+ : : +---^----+ : :
End-to-end Overload Indication End-to-end Overload Indication
1) <-----------------------------------------------> 1) <----------------------------------------------->
Diameter Application Y Diameter Application Y
Overload Indication A Overload Indication A' Overload Indication A Overload Indication A'
2) <----------------------> <----------------------> 2) <----------------------> <---------------------->
standard base protocol standard base protocol standard base protocol standard base protocol
Figure 1: Simplified architecture choices for overload indication Figure 1: Simplified architecture choices for overload indication
delivery delivery
In Figure 1, the Diameter overload indication can be conveyed (1) In Figure 1, the Diameter overload indication can be conveyed (1)
end-to-end between servers and clients or (2) between servers and end-to-end between servers and clients or (2) between servers and
Diameter agent inside the realm and then between the Diameter agent Diameter agent inside the realm and then between the Diameter agent
and the clients when the Diameter agent acting as back-to-back-agent and the clients when the Diameter agent acting as back-to-back-agent
for DOIC purposes. for DOIC purposes.
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features. features.
3.2.1. DOIC Capability Discovery 3.2.1. DOIC Capability Discovery
Support of DOIC may be specified as part of the functionality Support of DOIC may be specified as part of the functionality
supported by a new Diameter application. In this way, support of the supported by a new Diameter application. In this way, support of the
considered Diameter application (discovered during capabilities considered Diameter application (discovered during capabilities
exchange phase as defined in Diameter base protocol [RFC6733]) exchange phase as defined in Diameter base protocol [RFC6733])
indicates implicit support of the DOIC mechanism. indicates implicit support of the DOIC mechanism.
Editor's Note: This method does not work in general when agents are
part of the deployment.
When the DOIC mechanism is introduced in existing Diameter When the DOIC mechanism is introduced in existing Diameter
applications, a specific capability discovery mechanism is required. applications, a specific capability discovery mechanism is required.
The "DOIC capability discovery mechanism" is based on the presence of The "DOIC capability discovery mechanism" is based on the presence of
specific optional AVPs in the Diameter messages, such as the OC- specific optional AVPs in the Diameter messages, such as the OC-
Supported-Features AVP (see Section 4.1). Although the OC-Supported- Supported-Features AVP (see Section 4.1). Although the OC-Supported-
Features AVP can be used to advertise a certain set of new or Features AVP can be used to advertise a certain set of new or
existing Diameter overload control capabilities, it is not a existing Diameter overload control capabilities, it is not a
versioning solution per se, however, it can be used to achieve the versioning solution per se, however, it can be used to achieve the
same result. same result.
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4. Attribute Value Pairs 4. Attribute Value Pairs
This section describes the encoding and semantics of the Diameter This section describes the encoding and semantics of the Diameter
Overload Indication Attribute Value Pairs (AVPs) defined in this Overload Indication Attribute Value Pairs (AVPs) defined in this
document. document.
4.1. OC-Supported-Features AVP 4.1. OC-Supported-Features AVP
The OC-Supported-Features AVP (AVP code TBD1) is type of Grouped and The OC-Supported-Features AVP (AVP code TBD1) is type of Grouped and
serves for two purposes. First, it announces node's support for the serves for two purposes. First, it announces a node's support for
DOIC in general. Second, it contains the description of the the DOIC in general. Second, it contains the description of the
supported DOIC features of the sending node. The OC-Supported- supported DOIC features of the sending node. The OC-Supported-
Features AVP SHOULD be included into every Diameter message a DOIC Features AVP MUST be included in every Diameter message a DOIC
supporting node sends (and intends to use for DOIC purposes). supporting node sends.
OC-Supported-Features ::= < AVP Header: TBD1 >
< OC-Sequence-Number >
[ OC-Feature-Vector ]
* [ AVP ]
The OC-Sequence-Number AVP is used to indicate whether the contents OC-Supported-Features ::= < AVP Header: TBD1 >
of the OC-Supported-Features AVP has changed since last time the node [ OC-Feature-Vector ]
included the OC-Supported-Features AVP (see Section 4.4). Although * [ AVP ]
sending the OC-Sequence-Number AVP is mandatory in the OC-Supported-
Features AVP, the receiving node MAY always choose to ignore the
sequence number if it can determine the feature support changes
otherwise.
The OC-Feature-Vector sub-AVP is used to announced the DOIC features The OC-Feature-Vector sub-AVP is used to announce the DOIC features
supported by the endpoint, in the form of a flag bits field in which supported by the endpoint, in the form of a flag bits field in which
each bit announces one feature or capability supported by the node each bit announces one feature or capability supported by the node
(see Section 4.2). The absence of the OC-Feature-Vector AVP (see Section 4.2). The absence of the OC-Feature-Vector AVP
indicates that only the default traffic abatement algorithm described indicates that only the default traffic abatement algorithm described
in this specification is supported. in this specification is supported.
A reacting node includes this AVP to indicate its capabilities to a A reacting node includes this AVP to indicate its capabilities to a
reporting node. For example, the endpoint (reacting node) may reporting node. For example, the endpoint (reacting node) may
indicate which (future defined) traffic abatement algorithms it indicate which (future defined) traffic abatement algorithms it
supports in addition to the default. supports in addition to the default.
During the message exchange the overload control endpoints express During the message exchange the overload control endpoints express
their common set of supported capabilities. The reacting node their common set of supported capabilities. The reacting node
includes the OC-Supported-Features AVP that announces what it includes the OC-Supported-Features AVP that announces what it
supports. The reporting node that sends the answer also includes the supports. The reporting node that sends the answer also includes the
OC-Supported-Features AVP that describes the capabilities it OC-Supported-Features AVP that describes the capabilities it
supports. The set of capabilities advertised by the reporting node supports. The set of capabilities advertised by the reporting node
depends on local policies. At least one of the announced depends on local policies. At least one of the announced
capabilities MUST match mutually. If there is no single matching capabilities MUST match. If there is no single matching capability
capability the reacting node MUST act as if it does not implement the reacting node MUST act as if it does not implement DOIC and cease
DOIC and cease inserting any DOIC related AVPs into any Diameter inserting any DOIC related AVPs into any Diameter messages with this
messages with this specific reacting node. specific reacting node.
Editor's note: The last sentence conflicts with the last sentence two
paragraphs up. In reality, there will always be at least one
matching capability as all nodes supporting DOIC must support the
loss algorithm. Suggest removing the last sentence.
4.2. OC-Feature-Vector AVP 4.2. OC-Feature-Vector AVP
The OC-Feature-Vector AVP (AVP code TBD6) is type of Unsigned64 and The OC-Feature-Vector AVP (AVP code TBD6) is type of Unsigned64 and
contains a 64 bit flags field of announced capabilities of an contains a 64 bit flags field of announced capabilities of an
overload control endpoint. The value of zero (0) is reserved. overload control endpoint. The value of zero (0) is reserved.
The following capabilities are defined in this document: The following capabilities are defined in this document:
OLR_DEFAULT_ALGO (0x0000000000000001) OLR_DEFAULT_ALGO (0x0000000000000001)
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4.2. OC-Feature-Vector AVP 4.2. OC-Feature-Vector AVP
The OC-Feature-Vector AVP (AVP code TBD6) is type of Unsigned64 and The OC-Feature-Vector AVP (AVP code TBD6) is type of Unsigned64 and
contains a 64 bit flags field of announced capabilities of an contains a 64 bit flags field of announced capabilities of an
overload control endpoint. The value of zero (0) is reserved. overload control endpoint. The value of zero (0) is reserved.
The following capabilities are defined in this document: The following capabilities are defined in this document:
OLR_DEFAULT_ALGO (0x0000000000000001) OLR_DEFAULT_ALGO (0x0000000000000001)
When this flag is set by the overload control endpoint it means When this flag is set by the overload control endpoint it means
that the default traffic abatement (loss) algorithm is supported. that the default traffic abatement (loss) algorithm is supported.
4.3. OC-OLR AVP 4.3. OC-OLR AVP
The OC-OLR AVP (AVP code TBD2) is type of Grouped and contains the The OC-OLR AVP (AVP code TBD2) is type of Grouped and contains the
necessary information to convey an overload report. The OC-OLR AVP necessary information to convey an overload report. The OC-OLR AVP
does not contain explicit information to which application it applies does not explicitly contain all information needed by the reacting
to and who inserted the AVP or whom the specific OC-OLR AVP concerns node to decide whether a subsequent request must undergo a throttling
to. Both these information is implicitly learned from the process with the received reduction percentage. The value of the OC-
encapsulating Diameter message/command. The application the OC-OLR Report-Type AVP within the OC-OLR AVP indicates which implicit
AVP applies to is the same as the Application-Id found in the information is relevant for this decision (see Section 4.6). The
Diameter message header. The identity the OC-OLR AVP concerns is application the OC-OLR AVP applies to is the same as the Application-
determined from the Origin-Host AVP (and Origin-Realm AVP as well) Id found in the Diameter message header. The identity the OC-OLR AVP
found from the encapsulating Diameter command. The OC-OLR AVP is concerns is determined from the Origin-Host AVP (and Origin-Realm AVP
intended to be sent only by a reporting node. as well) found from the encapsulating Diameter command. The OC-OLR
AVP is intended to be sent only by a reporting node.
OC-OLR ::= < AVP Header: TBD2 > OC-OLR ::= < AVP Header: TBD2 >
< OC-Sequence-Number > < OC-Sequence-Number >
[ OC-Report-Type ] < OC-Report-Type >
[ OC-Reduction-Percentage ] [ OC-Reduction-Percentage ]
[ OC-Validity-Duration ] [ OC-Validity-Duration ]
* [ AVP ] * [ AVP ]
The Sequence-Number AVP indicates the "freshness" of the OC-OLR AVP. The OC-Validity-Duration AVP indicates the validity time of the
It is possible to replay the same OC-OLR AVP multiple times between overload report associated with a specific sequence number, measured
the overload control endpoints, however, when the OC-OLR AVP content after reception of the OC-OLR AVP. The validity time MUST NOT be
changes or sending endpoint otherwise wants the receiving endpoint to updated after reception of subsequent OC-OLR AVPs with the same
update its overload control information, then the OC-Sequence-Number sequence number. The default value for the OC-Validity-Duration AVP
AVP MUST contain a new greater value than the previously received. value is 5 (i.e., 5 seconds). When the OC-Validity-Duration AVP is
The receiver SHOULD discard an OC-OLR AVP with a sequence number that not present in the OC-OLR AVP, the default value applies.
is less than previously received one.
Note that if a Diameter command were to contain multiple OC-OLR AVPs Note that if a Diameter command were to contain multiple OC-OLR AVPs
they all MUST have different OC-Report-Type AVP value. OC-OLR AVPs they all MUST have different OC-Report-Type AVP value. OC-OLR AVPs
with unknown values SHOULD be silently discarded and the event SHOULD with unknown values SHOULD be silently discarded and the event SHOULD
be logged. be logged.
Editor's note: Need to specify what happens when two reports of the
same type are received.
The OC-OLR AVP can be expanded with optional sub-AVPs only if a The OC-OLR AVP can be expanded with optional sub-AVPs only if a
legacy implementation can safely ignore them without breaking legacy implementation can safely ignore them without breaking
backward compatibility for the given OC-Report-Type AVP value implied backward compatibility for the given OC-Report-Type AVP value implied
report handling semantics. If the new sub-AVPs imply new semantics report handling semantics. If the new sub-AVPs imply new semantics
for the report handling, then a new OC-Report-Type AVP value MUST be for the report handling, then a new OC-Report-Type AVP value MUST be
defined. defined.
4.4. OC-Sequence-Number AVP 4.4. OC-Sequence-Number AVP
The OC-Sequence-Number AVP (AVP code TBD3) is type of Time. Its The OC-Sequence-Number AVP (AVP code TBD3) is type of Unsigned64.
usage in the context of the overload control is described in Sections Its usage in the context of overload control is described in
4.1 and 4.3. Section 4.3.
From the functionality point of view, the OC-Sequence-Number AVP MUST From the functionality point of view, the OC-Sequence-Number AVP MUST
be used as a non-volatile increasing counter between two overload be used as a non-volatile increasing counter between two overload
control endpoints (neglecting the fact that the contents of the AVP control endpoints. The sequence number is only required to be unique
is a 64-bit NTP timestamp [RFC5905]). The sequence number is only between two overload control endpoints. Sequence numbers are treated
required to be unique between two overload control endpoints. in a uni-directional manner, i.e. two sequence numbers on each
Sequence numbers are treated in uni-directional manner, i.e. two direction between two endpoints are not related or correlated.
sequence numbers on each direction between two endpoints are not
related or correlated.
When generating sequence numbers, the new sequence number MUST be When generating sequence numbers, the new sequence number MUST be
greater than any sequence number previously seen between two greater than any sequence number in an active overload report
endpoints within a time window that tolerates the wraparound of the previously sent by the reporting node. This property MUST hold over
NTP timestamp (i.e. approximately 68 years). a reboot of the reporting node.
4.5. OC-Validity-Duration AVP 4.5. OC-Validity-Duration AVP
The OC-Validity-Duration AVP (AVP code TBD4) is type of Unsigned32 The OC-Validity-Duration AVP (AVP code TBD4) is type of Unsigned32
and describes the number of seconds the "new and fresh" OC-OLR AVP and indicates in seconds the validity time of the overload report.
and its content is valid since the reception of the new OC-OLR AVP. The number of seconds is measured after reception of the first OC-OLR
The default value for the OC-Validity-Duration AVP value is 5 (i.e., AVP with a given value of OC-Sequence-Number AVP. The default value
5 seconds). When the OC-Validity-Duration AVP is not present in the for the OC-Validity-Duration AVP is 5 (i.e., 5 seconds). When the
OC-OLR AVP, the default value applies. Validity duration values 0 OC-Validity-Duration AVP is not present in the OC-OLR AVP, the
(i.e., 0 seconds) and above 86400 (i.e., 24 hours) MUST NOT be used. default value applies. Validity duration with values above 86400
Invalid validity duration values are treated as if the OC-Validity- (i.e.; 24 hours) MUST NOT be used. Invalid duration values are
Duration AVP were not present. treated as if the OC-Validity-Duration AVP were not present and
result in the default value being used.
A timeout of the overload report has specific concerns that need to A timeout of the overload report has specific concerns that need to
be taken into account by the endpoint acting on the earlier received be taken into account by the endpoint acting on the earlier received
overload report(s). Section 4.7 discusses the impacts of timeout in overload report(s). Section 4.7 discusses the impacts of timeout in
the scope of the traffic abatement algorithms. the scope of the traffic abatement algorithms.
As a general guidance for implementations it is RECOMMENDED never to When a reporting node has recovered from overload, it SHOULD
let any overload report to timeout. Following to this rule, an invalidate any existing overload reports in a timely matter. This
overload endpoint should explicitly signal the end of overload can be achieved by sending an updated overload report (meaning the
condition and not rely on the expiration of the validity time of the OLR contains a new sequence number) with the OC-Validity-Duration AVP
overload report in the reacting node. This leaves no need for the value set to zero ("0"). If the overload report is about to expire
reacting node to reason or guess the overload condition of the naturally, the reporting node MAY choose to simply let it do so.
reporting node.
A reacting node MUST invalidate and remove an overload report that
expires without an explicit overload report containing an OC-
Validity-Duration value set to zero ("0").
4.6. OC-Report-Type AVP 4.6. OC-Report-Type AVP
The OC-Report-Type AVP (AVP code TBD5) is type of Enumerated. The The OC-Report-Type AVP (AVP code TBD5) is type of Enumerated. The
value of the AVP describes what the overload report concerns. The value of the AVP describes what the overload report concerns. The
following values are initially defined: following values are initially defined:
0 A host report. The overload treatment should apply to requests 0 A host report. The overload treatment should apply to requests
the reacting node knows that will reach the overloaded node. For for which all of the following conditions are true:
example, requests with a Destination-Host AVP indicating the
endpoint. The reacting node learns the "host" implicitly from the
Origin-Host AVP of the received message that contained the OC-OLR
AVP.
1 A realm report. The overload treatment should apply to all The Destination-Host AVP is present in the request and its value
requests bound for the overloaded realm. The reacting node learns matches the value of the Origin-Host AVP of the received message
the "realm" implicitly from the Origin-Realm AVP of the received that contained the OC-OLR AVP.
message that contained the OC-OLR AVP.
The value of the Destination-Realm AVP in the request matches the
value of the Origin-Realm AVP of the received message that
contained the OC-OLR AVP.
The value of the Application-ID in the Diameter Header of the
request matches the value of the Application-ID of the Diameter
Header of the received message that contained the OC-OLR AVP.
1 A realm report. The overload treatment should apply to requests
for which all of the following conditions are true:
The Destination-Host AVP is absent in the request.
The value of the Destination-Realm AVP in the request matches the
value of the Origin-Realm AVP of the received message that
contained the OC-OLR AVP.
The value of the Application-ID in the Diameter Header of the
request matches the value of the Application-ID of the Diameter
Header of the received message that contained the OC-OLR AVP.
Editor's note: There is still an open issue on the definition of
Realm reports and whether what report types should be supported.
There is consensus that host reports should be supported. There is
discussion on Realm reports and Realm-Routed-Request reports. The
above definition applies to Realm-Routed-Request reports where Realm
reports are defined to apply to all requests that match the realm,
independent of the presence, absence or value of the Destination-Host
AVP.
The default value of the OC-Report-Type AVP is 0 (i.e. the host The default value of the OC-Report-Type AVP is 0 (i.e. the host
report). report).
The OC-Report-Type AVP is envisioned to be useful for situations The OC-Report-Type AVP is envisioned to be useful for situations
where a reacting node needs to apply different overload treatments where a reacting node needs to apply different overload treatments
for different "types" of overload. For example, the reacting node(s) for different "types" of overload. For example, the reacting node(s)
might need to throttle differently requests sent to a specific server might need to throttle differently requests sent to a specific server
(identified by the Destination-Host AVP in the request) and requests (identified by the Destination-Host AVP in the request) and requests
that can be handled by any server in a realm. The example in that can be handled by any server in a realm. The example in
skipping to change at page 16, line 47 skipping to change at page 18, line 20
When defining new report type values, the corresponding specification When defining new report type values, the corresponding specification
MUST define the semantics of the new report types and how they affect MUST define the semantics of the new report types and how they affect
the OC-OLR AVP handling. The specification MUST also reserve a the OC-OLR AVP handling. The specification MUST also reserve a
corresponding new feature, see the OC-Supported-Features and OC- corresponding new feature, see the OC-Supported-Features and OC-
Feature-Vector AVPs. Feature-Vector AVPs.
4.7. OC-Reduction-Percentage AVP 4.7. OC-Reduction-Percentage AVP
The OC-Reduction-Percentage AVP (AVP code TBD8) is type of Unsigned32 The OC-Reduction-Percentage AVP (AVP code TBD8) is type of Unsigned32
and describes the percentage of the traffic that the sender is and describes the percentage of the traffic that the sender is
requested to reduce, compared to what it otherwise would have sent. requested to reduce, compared to what it otherwise would send. The
The OC-Reduction-Percentage AVP applies to the default (loss like) OC-Reduction-Percentage AVP applies to the default (loss) algorithm
algorithm specified in this specification. However, the AVP can be specified in this specification. However, the AVP can be reused for
reused for future abatement algorithms, if its semantics fit into the future abatement algorithms, if its semantics fit into the new
new algorithm. algorithm.
The value of the Reduction-Percentage AVP is between zero (0) and one The value of the Reduction-Percentage AVP is between zero (0) and one
hundred (100). Values greater than 100 are interpreted as 100. The hundred (100). Values greater than 100 are ignored. The value of
value of 100 means that no traffic is expected, i.e. the reporting 100 means that all traffic is to be throttled, i.e. the reporting
node is under a severe load and ceases to process any new messages. node is under a severe load and ceases to process any new messages.
The value of 0 means that the reporting node is in a stable state and The value of 0 means that the reporting node is in a stable state and
has no requests to the other endpoint to apply any traffic abatement. has no need for the other endpoint to apply any traffic abatement.
The default value of the OC-Reduction-Percentage AVP is 0. When the The default value of the OC-Reduction-Percentage AVP is 0. When the
OC-Reduction-Percentage AVP is not present in the overload report, OC-Reduction-Percentage AVP is not present in the overload report,
the default value applies. the default value applies.
If an overload control endpoint comes out of the 100 percent traffic If an overload control endpoint comes out of the 100 percent traffic
reduction as a result of the overload report timing out, the reduction as a result of the overload report timing out, the
following concerns are RECOMMENDED to be applied. The reacting node following concerns are RECOMMENDED to be applied. The reacting node
sending the traffic should be conservative and, for example, first sending the traffic should be conservative and, for example, first
send "probe" messages to learn the overload condition of the send "probe" messages to learn the overload condition of the
overloaded node before converging to any traffic amount/rate decided overloaded node before converging to any traffic amount/rate decided
by the sender. Similar concerns apply in all cases when the overload by the sender. Similar concerns apply in all cases when the overload
report times out unless the previous overload report stated 0 percent report times out unless the previous overload report stated 0 percent
reduction. reduction.
Editor's note: Need to add additional guidance to slowly increase the
rate of traffic sent to avoid a sudden spike in traffic, as the spike
in traffic could result in oscillation of the need for overload
control.
4.8. Attribute Value Pair flag rules 4.8. Attribute Value Pair flag rules
+---------+ +---------+
|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-Supported-Features TBD1 x.x Grouped | | V | |OC-Supported-Features TBD1 x.x Grouped | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-OLR TBD2 x.x Grouped | | V | |OC-OLR TBD2 x.x Grouped | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Sequence-Number TBD3 x.x Time | | V | |OC-Sequence-Number TBD3 x.x Unsigned64 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Validity-Duration TBD4 x.x Unsigned32 | | V | |OC-Validity-Duration TBD4 x.x Unsigned32 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Report-Type TBD5 x.x Enumerated | | V | |OC-Report-Type TBD5 x.x Enumerated | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Reduction | | | |OC-Reduction | | |
| -Percentage TBD8 x.x Unsigned32 | | V | | -Percentage TBD8 x.x Unsigned32 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Feature-Vector TBD6 x.x Unsigned64 | | V | |OC-Feature-Vector TBD6 x.x Unsigned64 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
As described in the Diameter base protocol [RFC6733], the M-bit As described in the Diameter base protocol [RFC6733], the M-bit
setting for a given AVP is relevant to an application and each setting for a given AVP is relevant to an application and each
command within that application that includes the AVP. command within that application that includes the AVP.
The Diameter overload control AVPs SHOULD always be sent with the The Diameter overload control AVPs SHOULD always be sent with the
M-bit cleared when used within existing Diameter applications to M-bit cleared when used within existing Diameter applications to
avoid backward compatibility issues. Otherwise, when reused in newly avoid backward compatibility issues. Otherwise, when reused in newly
defined Diameter applications, the DOC related AVPs SHOULD have the defined Diameter applications, the DOC related AVPs SHOULD have the
M-bit set. M-bit set.
5. Overload Control Operation 5. Overload Control Operation
Editor's note: The concept of endpoints requires additional thought
and specification.
5.1. Overload Control Endpoints 5.1. Overload Control Endpoints
The overload control solution can be considered as an overlay on top The overload control solution can be considered as an overlay on top
of an arbitrary Diameter network. The overload control information of an arbitrary Diameter network. The overload control information
is exchanged over on a "DOIC association" established between two is exchanged over on a "DOIC association" established between two
communication endpoints. The endpoints, namely the "reacting node" communication endpoints. The endpoints, namely the "reacting node"
and the "reporting node" do not need to be adjacent Diameter peer and the "reporting node" do not need to be adjacent Diameter peer
nodes, nor they need to be the end-to-end Diameter nodes in a typical nodes, nor they need to be the end-to-end Diameter nodes in a typical
"client-server" deployment with multiple intermediate Diameter agent "client-server" deployment with multiple intermediate Diameter agent
nodes in between. The overload control endpoints are the two nodes in between. The overload control endpoints are the two
skipping to change at page 19, line 9 skipping to change at page 20, line 38
Diameter Session A Diameter session as defined in [RFC6733]. Diameter Session A Diameter session as defined in [RFC6733].
DOIC Association A DOIC association exists between two Diameter DOIC Association A DOIC association exists between two Diameter
Overload End-Points. One of the end-points is the overload Overload End-Points. One of the end-points is the overload
reporter and the other is the overload reactor. reporter and the other is the overload reactor.
Figure 2 illustrates the most basic configuration where a client is Figure 2 illustrates the most basic configuration where a client is
connected directly to a server. In this case, the Diameter session connected directly to a server. In this case, the Diameter session
and the DOIC association are both between the client and server. and the DOIC association are both between the client and server.
+-----+ +-----+ +-----+ +-----+
| C | | S | | C | | S |
+-----+ +-----+ +-----+ +-----+
| DEP | | DEP | | DEP | | DEP |
+--+--+ +--+--+ +--+--+ +--+--+
| | | |
| | | |
|{Diameter Session}| |{Diameter Session}|
| | | |
|{DOIC Association}| |{DOIC Association}|
| | | |
Figure 2: Basic DOIC deployment Figure 2: Basic DOIC deployment
In Figure 3 there is an agent that is not participating directly in In Figure 3 there is an agent that is not participating directly in
the exchange of overload reports. As a result, the Diameter session the exchange of overload reports. As a result, the Diameter session
and the DOIC association are still established between the client and and the DOIC association are still established between the client and
the server. the server.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| C | | A | | S | | C | | A | | S |
+-----+ +--+--+ +-----+ +-----+ +--+--+ +-----+
| DEP | | | DEP | | DEP | | | DEP |
+--+--+ | +--+--+ +--+--+ | +--+--+
| | | | | |
| | | | | |
|----------{Diameter Session}---------| |----------{Diameter Session}---------|
| | | | | |
|----------{DOIC Association}---------| |----------{DOIC Association}---------|
| | | | | |
Figure 3: DOIC deployment with non participating agent Figure 3: DOIC deployment with non participating agent
Figure 4 illustrates the case where the client does not support Figure 4 illustrates the case where the client does not support
Diameter overload. In this case, the DOIC association is between the Diameter overload. In this case, the DOIC association is between the
agent and the server. The agent handles the role of the reactor for agent and the server. The agent handles the role of the reactor for
overload reports generated by the server. overload reports generated by the server.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| C | | A | | S | | C | | A | | S |
+--+--+ +-----+ +-----+ +--+--+ +-----+ +-----+
| | DEP | | DEP | | | DEP | | DEP |
| +--+--+ +--+--+ | +--+--+ +--+--+
| | | | | |
| | | | | |
|----------{Diameter Session}---------| |----------{Diameter Session}---------|
| | | | | |
| |{DOIC Association}| | |{DOIC Association}|
| | | | | |
Figure 4: DOIC deployment with non-DOIC client and DOIC enabled agent Figure 4: DOIC deployment with non-DOIC client and DOIC enabled agent
In Figure 5 there is a DOIC association between the client and the In Figure 5 there is a DOIC association between the client and the
agent and a second DOIC association between the agent and the server. agent and a second DOIC association between the agent and the server.
One use case requiring this configuration is when the agent is One use case requiring this configuration is when the agent is
serving as a SFE for a set of servers. serving as a SFE for a set of servers.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| C | | A | | S | | C | | A | | S |
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| DEP | | DEP | | DEP | | DEP | | DEP | | DEP |
+--+--+ +--+--+ +--+--+ +--+--+ +--+--+ +--+--+
| | | | | |
| | | | | |
|----------{Diameter Session}---------| |----------{Diameter Session}---------|
| | | | | |
|{DOIC Association}|{DOIC Association}| |{DOIC Association}|{DOIC Association}|
| | and/or | | and/or
|----------{DOIC Association}---------| |----------{DOIC Association}---------|
| | | | | |
Figure 5: A deployment where all nodes support DOIC Figure 5: A deployment where all nodes support DOIC
Figure 6 illustrates a deployment where some clients support Diameter Figure 6 illustrates a deployment where some clients support Diameter
overload control and some do not. In this case the agent must overload control and some do not. In this case the agent must
support Diameter overload control for the non supporting client. It support Diameter overload control for the non supporting client. It
might also need to have a DOIC association with the server, as shown might also need to have a DOIC association with the server, as shown
here, to handle overload for a server farm and/or for managing Realm here, to handle overload for a server farm and/or for managing Realm
overload. overload.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| C1 | | C2 | | A | | S | | C1 | | C2 | | A | | S |
+-----+ +--+--+ +-----+ +-----+ +-----+ +--+--+ +-----+ +-----+
| DEP | | | DEP | | DEP | | DEP | | | DEP | | DEP |
+--+--+ | +--+--+ +--+--+ +--+--+ | +--+--+ +--+--+
| | | | | | | |
| | | | | | | |
|-------------------{Diameter Session}-------------------| |-------------------{Diameter Session}-------------------|
| | | | | | | |
| |--------{Diameter Session}-----------| | |--------{Diameter Session}-----------|
| | | | | | | |
|---------{DOIC Association}----------|{DOIC Association}| |---------{DOIC Association}----------|{DOIC Association}|
| | | and/or | | | and/or
|-------------------{DOIC Association}-------------------| |-------------------{DOIC Association}-------------------|
| | | | | | | |
Figure 6: A deployment with DOIC and non-DOIC supporting clients Figure 6: A deployment with DOIC and non-DOIC supporting clients
Figure 7 illustrates a deployment where some agents support Diameter Figure 7 illustrates a deployment where some agents support Diameter
overload control and others do not. overload control and others do not.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| C | | A | | A | | S | | C | | A | | A | | S |
+-----+ +--+--+ +-----+ +-----+ +-----+ +--+--+ +-----+ +-----+
| DEP | | | DEP | | DEP | | DEP | | | DEP | | DEP |
+--+--+ | +--+--+ +--+--+ +--+--+ | +--+--+ +--+--+
| | | | | | | |
| | | | | | | |
|-------------------{Diameter Session}-------------------| |-------------------{Diameter Session}-------------------|
| | | | | | | |
| | | | | | | |
|---------{DOIC Association}----------|{DOIC Association}| |---------{DOIC Association}----------|{DOIC Association}|
| | | and/or | | | and/or
|-------------------{DOIC Association}-------------------| |-------------------{DOIC Association}-------------------|
| | | | | | | |
Figure 7: A deployment with DOIC and non-DOIC supporting agents Figure 7: A deployment with DOIC and non-DOIC supporting agents
5.2. Piggybacking Principle 5.2. Piggybacking Principle
The overload control AVPs defined in this specification have been The overload control AVPs defined in this specification have been
designed to be piggybacked on top of existing application message designed to be piggybacked on top of existing application message
exchanges. This is made possible by adding overload control top exchanges. This is made possible by adding overload control top
level AVPs, the OC-OLR AVP and the OC-Supported-Features AVP as level AVPs, the OC-OLR AVP and the OC-Supported-Features AVP as
optional AVPs into existing commands when the corresponding Command optional AVPs into existing commands when the corresponding Command
skipping to change at page 22, line 32 skipping to change at page 24, line 11
"reacting node") or an answer (i.e. send by a "reporting node"). "reacting node") or an answer (i.e. send by a "reporting node").
Therefore, in a typical "client-server" deployment, the "client" MAY Therefore, in a typical "client-server" deployment, the "client" MAY
report its overload condition to the "server" for any server report its overload condition to the "server" for any server
initiated message exchange. An example of such is the server initiated message exchange. An example of such is the server
requesting a re-authentication from a client. requesting a re-authentication from a client.
5.3. Capability Announcement 5.3. Capability Announcement
Since the overload control solution relies on the piggybacking Since the overload control solution relies on the piggybacking
principle for the overload reporting and the overload control principle for the overload reporting and the overload control
endpoint are likely not adjacent peers, finding out whether the other endpoint are not adjacent peers, finding out whether the other
endpoint supports the overload control or what is the common traffic endpoint supports overload control or the common traffic abatement
abatement algorithm to apply for the traffic. The approach defined algorithm to apply for the traffic. The approach defined in this
in this specification for the end-to-end capability announcement specification for end-to-end capability announcement relies on the
relies on the exchange of the OC-Supported-Features between the exchange of the OC-Supported-Features AVPs between the endpoints.
endpoints. The feature announcement solution also works when carried The feature announcement solution also works when carried out on
out on existing applications. For the newly defined application the existing applications. For the newly defined applications the
negotiation can be more exact based on the application specification. negotiation can be more exact based on the application specification.
The announced set of capabilities MUST NOT change during the life
time of the Diameter session (or transaction in case of non-session Editor's note: Suggest removing the reference to the feature
maintaining applications). announcement solution.
5.3.1. Reacting Node Endpoint Considerations 5.3.1. Reacting Node Endpoint Considerations
The basic principle is that the request message initiating endpoint The basic principle is that the request message initiating endpoint
(i.e. the "reacting node") announces its support for the overload (i.e. the "reacting node") announces its support for the overload
control mechanism by including in the request message the OC- control mechanism by including in the request message the OC-
Supported-Features AVP with those capabilities it supports and is Supported-Features AVP with the capabilities it supports and is
willing to use for this Diameter session (or transaction in a case of willing to use for this Diameter transaction. The lifetime of a
a non-session state maintaining applications, see Section 3.1.2 for capability announcement is limited to a single transaction. As a
more details on Diameter sessions). It is RECOMMENDED that the result, the reacting node MUST include the capability announcement in
request message initiating endpoint includes the capability all request messages.
announcement into every request regardless it has had prior message
exchanges with the give remote endpoint. In a case of a Diameter
session maintaining application, sending the OC-Supported-Features
AVP in every message is not really necessary after the initial
capability announcement or until there is a change in supported
features.
Once the endpoint that initiated the request message receives an Once the endpoint that initiated the request message receives an
answer message from the remote endpoint, it can detect from the answer message from the remote endpoint, it can detect from the
received answer message whether the remote endpoint supports the received answer message whether the remote endpoint supports the
overload control solution and in a case it does, what features are overload control solution and in a case it does, what features are
supported. The support for the overload control solution is based on supported. The support for the overload control solution is based on
the presence of the OC-Supported-Features AVP in the Diameter answer the presence of the OC-Supported-Features AVP in the Diameter answer.
for existing application.
5.3.2. Reporting Node Endpoint Considerations 5.3.2. Reporting Node Endpoint Considerations
When a remote endpoint (i.e. a "reporting node") receives a request When a remote endpoint (i.e. a "reporting node") receives a request
message, it can detect whether the request message initiating message, it can detect whether the request message initiating
endpoint supports the overload control solution based on the presence endpoint supports the overload control solution based on the presence
of the OC-Supported-Features AVP. For the newly defined applications of the OC-Supported-Features AVP. For the newly defined applications
the overload control solution support can be part of the application the overload control solution support can be part of the application
specification. Based on the content of the OC-Supported-Features AVP specification. Based on the content of the OC-Supported-Features AVP
the request message receiving endpoint knows what overload control the request message receiving endpoint knows what overload control
functionality the other endpoint supports and then act accordingly functionality the other endpoint supports and then acts accordingly
for the subsequent answer messages it initiates. The answer message for the subsequent answer messages it initiates. The reporting node
initiating endpoint MAY announce as many supported capabilities as it MUST include the OC-Supported-Features AVP in all response messages
has (the announced set is a subject to local policy and for transactions where the request message included the OC-Supported-
configuration). However, at least one of the announced capabilities Features AVP. The reporting node MUST announce support of the single
MUST be the same as received in the request message. algorithm that the reporting node will request the reacting node to
use to mitigate overload instances. The reporting node MUST NOT
change the selected algorithm during a period of time that it is in
an overload state and, as a result, is sending OC-OLR AVPs in answer
messages.
The answer message initiating endpoint MUST NOT include any overload Note: There will always be at least one algorithm supported by both
control solution defined AVPs into its answer messages if the request the reacting and reporting nodes as all nodes that support DOIC must
message initiating endpoint has not indicated support at the support the loss algorithm defined in this document.
beginning of the created session (or transaction in a case of non-
session state maintaining applications). The same also applies if The handling of feature bits in the OC-Feature-Vector AVP that are
none of the announced capabilities match between the two endpoints. not associated with overload abatement algorithms MUST be specified
by the extensions that define the features.
The reporting node MUST NOT include the OC-Supported-Features AVP,
OC-OLR AVP or any other overload control AVPs defined in extension
drafts in response messages for transactions where the request
message does not include the OC-Supported-Features AVP. Lack of the
OC-Supported-Features AVP in the request message indicates that the
sender of the request message does not support DOIC.
5.3.3. Agent Considerations
Editor's note -- Need to add this section.
5.4. Protocol Extensibility 5.4. Protocol Extensibility
The overload control solution can be extended, e.g. with new traffic The overload control solution can be extended, e.g. with new traffic
abatement algorithms or new functionality. The new features and abatement algorithms, new report types or other new functionality.
algorithms MUST be registered with the IANA and for the possible use The new features and algorithms MUST be registered with the IANA and
with the OC-Supported-Features for announcing the support for the new for use with the OC-Supported-Features for announcing the support for
features (see Section 7 for the required procedures). the new features (see Section 7 for the required procedures).
It should be noted that [RFC6733] defined Grouped AVP extension It should be noted that [RFC6733] defined Grouped AVP extension
mechanisms also apply. This allows, for example, defining a new mechanisms also apply. This allows, for example, defining a new
feature that is mandatory to understand even when piggybacked on an feature that is mandatory to understand even when piggybacked on an
existing applications. More specifically, the sub-AVPs inside the existing applications. More specifically, the sub-AVPs inside the
OC-OLR AVP MAY have the M-bit set. However, when overload control OC-OLR AVP MAY have the M-bit set. However, when overload control
AVPs are piggybacked on top of an existing applications, setting AVPs are piggybacked on top of an existing applications, setting
M-bit in sub-AVPs is NOT RECOMMENDED. M-bit in sub-AVPs is NOT RECOMMENDED.
5.5. Overload Report Processing 5.5. Overload Report Processing
5.5.1. Overload Control State 5.5.1. Overload Control State
Both reacting and reporting nodes maintain an overload condition Both reacting and reporting nodes maintain an overload control state
state for each endpoint (a host or a realm) they communicate with and (OCS) for each endpoint (a host or a realm) they communicate with and
both endpoints have announced support for DOIC. See Sections 4.1 and both endpoints have announced support for DOIC. See Sections 4.1 and
5.3 for discussion about how the support for DOIC is determined. The 5.3 for discussion about how the support for DOIC is determined.
overload condition state SHOULD be able to make a difference between
a realm and a specific host in that realm.
The overload condition state could include the following information 5.5.1.1. Overload Control State for Reacting Nodes
(per host or realm):
o The endpoint information (Diameter identity of the realm and/or A reacting node maintains the following OCS per supported Diameter
host, application identifier, etc) application:
o Reduction percentage o A host-type Overload Control State for each Destination-Host
towards which it sends host-type requests and
o Validity period timer o A realm-type Overload Control State for each Destination-Realm
towards which it sends realm-type requests.
A host-type Overload Control State may be identified by the pair of
Application-Id and Destination-Host. A realm-type Overload Control
State may be identified by the pair of Application-Id and
Destination-Realm. The host-type/realm-type Overload Control State
for a given pair of Application and Destination-Host / Destination-
Realm could include the following information:
o Sequence number (as received in OC-OLR)
o Time of expiry (deviated from validity duration as received in OC-
OLR and time of reception)
o Selected Abatement Algorithm (as received in OC-Supported-
Features)
o Algorithm specific input data (as received within OC-OLR, e.g.
Reduction Percentage for Loss)
5.5.1.2. Overload Control States for Reporting Nodes
A reporting node maintains per supported Diameter application and per
supported (and eventually selected) Abatement Algorithm an Overload
Control State.
An Overload Control State may be identified by the pair of
Application-Id and supported Abatement Algorithm.
The Overload Control State for a given pair of Application and
Abatement Algorithm could include the information:
o Sequence number o Sequence number
o Supported/selected traffic abatement algorithm o Validity Duration and Expiry Time
The overload control state information SHOULD be maintained as long o Algorithm specific input data (e.g. Reduction Percentage for Loss)
as the other endpoint is known to support DOIC (based on the presence
of the DOIC AVPs or by a future application specification). Overload Control States for reporting nodes containing a validity
duration of 0 sec. should not expire before any previously sent
(stale) OLR has timed out at any reacting node.
5.5.1.3. Maintaining Overload Control State
Reacting nodes create a host-type OCS identified by OCS-Id = (app-id
,host-id) when receiving an answer message of application app-id
containing an Orig-Host of host-id and a host-type OC-OLR AVP unless
such host-type OCS already exists.
Reacting nodes create a realm-type OCS identified by OCS-Id = (app-id
,realm-id) when receiving an answer message of application app-id
containing an Orig-Realm of realm-id and a realm-type OC-OLR AVP
unless such realm type OCS already exists.
Reacting nodes delete an OCS when it expires (i.e. when current time
minus reception time is greater than validity duration).
Reacting nodes update the host-type OCS identified by OCS-Id = (app-
id,host-id) when receiving an answer message of application app-id
containing an Orig-Host of host-id and a host-type OC-OLR AVP with a
sequence number higher than the stored sequence number.
Reacting nodes update the realm-type OCS identified by OCS-Id = (app-
id,realm-id) when receiving an answer message of application app-id
containing an Orig-Realm of realm-id and a realm-type OC-OLR AVP with
a sequence number higher than the stored sequence number.
Reacting nodes do not delete an OCS when receiving an answer message
that does not contain an OC-OLR AVP (i.e. absence of OLR means "no
change").
Reporting nodes create an OCS identified by OCS-Id = (app-id,Alg)
when receiving a request of application app-id containing an OC-
Supported-Features AVP indicating support of the Abatement Algorithm
Alg (which the reporting node selects) while being overloaded, unless
such OCS already exists.
Reporting nodes delete an OCS when it expires.
Reporting nodes update the OCS identified by OCS-Id = (app-id,Alg)
when they detect the need to modify the requested amount of
application app-id traffic reduction.
5.5.2. Reacting Node Considerations 5.5.2. Reacting Node Considerations
Once a reacting node receives an OC-OLR AVP from a reporting node, it Once a reacting node receives an OC-OLR AVP from a reporting node, it
applies the traffic abatement based on the commonly supported applies traffic abatement based on the selected algorithm with the
algorithm with the reporting node and the current overload condition. reporting node and the current overload condition. The reacting node
The reacting node learns the reporting node supported abatement learns the reporting node supported abatement algorithms directly
algorithms directly from the received answer message containing the from the received answer message containing the OC-Supported-Features
OC-Supported-Features AVP or indirectly remembering the previously AVP.
used traffic abatement algorithm with the given reporting node.
The received OC-Supported-Features AVP does not change the existing The received OC-Supported-Features AVP does not change the existing
overload condition and/or traffic abatement algorithm settings if the overload condition and/or traffic abatement algorithm settings if the
OC-Sequence-Number AVP contains a value that is equal to the OC-Sequence-Number AVP contains a value that is equal to the
previously received/recorded one. If the OC-Supported-Features AVP previously received/recorded value. If the OC-Supported-Features AVP
is received for the first time for the reporting node or the OC- is received for the first time for the reporting node or the OC-
Sequence-Number AVP value is less than the previously received/ Sequence-Number AVP value is less than the previously received/
recorded one (and is outside the valid overflow window), then either recorded value (and is outside the valid overflow window), then the
the sequence number is stale (e.g. an intentional or unintentional sequence number is stale (e.g. an intentional or unintentional
replay) and SHOULD be silently discarded. replay) and SHOULD be silently discarded.
The OC-OLR AVP contains the necessary information of the overload
condition on the reporting node. Similarly to the OC-Supported-
Features's sequence numbering, the OC-OLR AVP also has the OC-
Sequence-Number AVP and its handling is similar to the one in the OC-
Supported-Features AVP. The reacting node MUST update its overload
condition state whenever receiving the OC-OLR AVP for the first time
or the OC-Sequence-Number sub-AVP indicates a change in the OC-OLR
AVP.
As described in Section 4.3, the OC-OLR AVP contains the necessary As described in Section 4.3, the OC-OLR AVP contains the necessary
information of the overload condition on the reporting node. information for the overload condition on the reporting node.
From the OC-Report-Type AVP contained in the OC-OLR AVP, the reacting From the OC-Report-Type AVP contained in the OC-OLR AVP, the reacting
node learns whether the overload condition report concerns a specific node learns whether the overload condition report concerns a specific
host (as identified by the Origin-Host AVP of the answer message host (as identified by the Origin-Host AVP of the answer message
containing the OC-OLR AVP) or the entire realm (as identified by the containing the OC-OLR AVP) or the entire realm (as identified by the
Origin-Realm AVP of the answer message containing the OC-OLR AVP). Origin-Realm AVP of the answer message containing the OC-OLR AVP).
The reacting node learns the Diameter application to which the The reacting node learns the Diameter application to which the
overload report applies from the Application-ID of the answer message overload report applies from the Application-ID of the answer message
containing the OC-OLR AVP. The reacting node MUST use this containing the OC-OLR AVP. The reacting node MUST use this
information as an input for its traffic abatement algorithm. The information as an input for its traffic abatement algorithm. The
idea is that the reacting node applies different handling of the idea is that the reacting node applies different handling of the
traffic abatement, whether sent request messages are targeted to a traffic abatement, whether sent request messages are targeted to a
specific host (identified by the Diameter-Host AVP in the request) or specific host (identified by the Diameter-Host AVP in the request) or
to any host in a realm (when only the Destination-Realm AVP is to any host in a realm (when only the Destination-Realm AVP is
present in the request). Note that future specifications MAY define present in the request). Note that future specifications MAY define
new OC-Report-Type AVP values that imply different handling of the new OC-Report-Type AVP values that imply different handling of the
OC-OLR AVP. For example, in a form of new additional AVPs inside the OC-OLR AVP. For example, in a form of new additional AVPs inside the
Grouped OC-OLR AVP that would define report target in a finer Grouped OC-OLR AVP that would define report target in a finer
granularity than just a host. granularity than just a host.
Editor's note: The above behavior for Realm reports is inconsistent
with the definition of realm reports in section Section 4.6.
In the context of this specification and the default traffic In the context of this specification and the default traffic
abatement algorithm, the OC-Reduction-Percentage AVP value MUST be abatement algorithm, the OC-Reduction-Percentage AVP value MUST be
interpreted in the following way: interpreted in the following way:
value == 0 value == 0
Indicates explicitly the end of overload condition and the Indicates that no traffic reduction has been requested. As a
reacting node SHOULD NOT apply the traffic abatement algorithm result the overload state, including the sequence number, MUST NOT
procedures anymore for the given reporting node (or realm). be removed and future overload reports of the same type from the
same reporting node must follow the rules for new sequence
numbers.
value == 100 value == 100
Indicates that the reporting node (or realm) does not want to Indicates that the reporting node (or realm) does not want to
receive any traffic from the reacting node for the application the receive any traffic from the reacting node for the application the
report concerns. The reacting node MUST do all measure not to report concerns. The reacting node MUST not send traffic to the
send traffic to the reporting node (or realm) as long as the reporting node (or realm) as long as the overload condition
overload condition changes or expires. changes or expires.
0 < value < 100 0 < value < 100
Indicates that the reporting node urges the reacting node to Indicates that the reporting node urges the reacting node to
reduce its traffic by a given percentage. For example if the reduce its traffic by a given percentage. For example if an OC-
reacting node has been sending 100 packets per second to the Reduction-Percentage value of 10 has been received, the reacting
reporting node, then a reception of OC-Reduction-Percentage value node which would otherwise send 100 requests MUST only send 90
of 10 would mean that from now on the reacting node MUST only send requests to the reporting node. How the reacting node achieves
90 packets per second. How the reacting node achieves the "true the "true reduction" in transactions leading to the sent request
reduction" transactions leading to the sent request messages is up messages is up to the implementation. The reacting node MAY
to the implementation. The reacting node MAY simply drop every simply drop every 10th request from its output queue and let the
10th packet from its output queue and let the generic application generic application logic try to recover from it.
logic try to recover from it.
If the OC-OLR AVP is received for the first time, the reacting node If the OC-OLR AVP is received for the first time, the reacting node
MUST create an overload condition state associated with the related MUST create overload control state associated with the related realm
realm or a specific host in the realm identified in the message or a specific host in the realm identified in the message carrying
carrying the OC-OLR AVP, as described in Section 5.5.1. the OC-OLR AVP, as described in Section 5.5.1.
If the value of the OC-Sequence-Number AVP contained in the received If the value of the OC-Sequence-Number AVP contained in the received
OC-OLR AVP is equal to or less than the value stored in an existing OC-OLR AVP is equal to or less than the value stored in an existing
overload condition state, the received OC-OLR AVP SHOULD be silently overload control state, the received OC-OLR AVP SHOULD be silently
discarded. If the value of the OC-Sequence-Number AVP contained in discarded. If the value of the OC-Sequence-Number AVP contained in
the received OC-OLR AVP is greater than the value stored in an the received OC-OLR AVP is greater than the value stored in an
existing overload condition state or there is no previously recorded existing overload control state or there is no previously recorded
sequence number, the reacting node MUST update the overload condition sequence number, the reacting node MUST update the overload control
state associated with the realm or the specific node is the realm. state associated with the realm or the specific node in the realm.
When an overload condition state is created or updated, the reacting When an overload control state is created or updated, the reacting
node MUST apply the traffic abatement requested in the OC-OLR AVP node MUST apply the traffic abatement requested in the OC-OLR AVP
using the algorithm announced in the OC-Supported-Features AVP using the algorithm announced in the OC-Supported-Features AVP
contained in the received answer message along with the OC-OLR AVP. contained in the received answer message along with the OC-OLR AVP.
The validity duration of the overload information contained in the The validity duration of the overload information contained in the
OC-OLR AVP is either explicitly indicated in the OC-Validity-Duration OC-OLR AVP is either explicitly indicated in the OC-Validity-Duration
AVP or is implicitly equals to the default value (5 seconds) if the AVP or is implicitly equals to the default value (5 seconds) if the
OC-Validity-Duration AVP is absent of the OC-OLR AVP. The reacting OC-Validity-Duration AVP is absent. The reacting node MUST maintain
node MUST maintain the validity duration in the overload condition the validity duration in the overload control state. Once the
state. Once the validity duration times out, the reacting node MUST validity duration times out, the reacting node MUST assume the
assume the overload condition reported in a previous OC-OLR AVP has overload condition reported in a previous OC-OLR AVP has ended.
ended.
A value of zero ("0") received in the OC-Validity-Duration in an
updated overload report indicates that the overload condition has
ended and that the overload state is no longer valid.
In the case that the validity duration expires or is explicitly
signaled as being no longer valid the state associated with the
overload report MUST be removed and any abatement associated with the
overload report MUST be ended in a controlled fashion. After
removing the overload state the sequence number MUST NOT be used for
future comparisons of sequence numbers.
5.5.3. Reporting Node Considerations 5.5.3. Reporting Node Considerations
A reporting node is a Diameter node inserting an OC-OLR AVP in a A reporting node is a Diameter node inserting an OC-OLR AVP in a
Diameter message in order to inform a reacting node about an overload Diameter message in order to inform a reacting node about an overload
condition and request Diameter traffic abatement. condition and request Diameter traffic abatement.
The operation on the reporting node is rather straight forward. The The operation on the reporting node is straight forward. The
reporting node learns the capabilities of the reacting node when it reporting node learns the capabilities of the reacting node when it
receives the OC-Supported-Features AVP as part of any Diameter receives the OC-Supported-Features AVP as part of any Diameter
request message. If the reporting node shares at least one common request message. If the reporting node shares at least one common
feature with the reacting node, then the DOIC can be enabled between feature with the reacting node, then the DOIC can be enabled between
these two endpoints. See Section 5.3 for further discussion on the these two endpoints. See Section 5.3 for further discussion on the
capability and feature announcement between two endpoints. capability and feature announcement between two endpoints.
When a traffic reduction is required due to an overload condition and When a traffic reduction is required due to an overload condition and
the overload control solution is supported by the sender of the the overload control solution is supported by the sender of the
Diameter request, the reporting node MUST include an OC-Supported- Diameter request, the reporting node MUST include an OC-Supported-
Features AVP and an OC-OLR AVP in the corresponding Diameter answer. Features AVP and an OC-OLR AVP in the corresponding Diameter answer.
The OC-OLR AVP contains the required traffic reduction and the OC- The OC-OLR AVP contains the required traffic reduction and the OC-
Supported-Features AVP indicates the traffic abatement algorithm to Supported-Features AVP indicates the traffic abatement algorithm to
apply. This algorithm MUST be one of the algorithms advertised by apply. This algorithm MUST be one of the algorithms advertised by
the request sender. the request sender.
A reporting node MAY rely on the OC-Validity-Duration AVP values for A reporting node MAY rely on the OC-Validity-Duration AVP values for
the implicit overload condition state cleanup on the reacting node. the implicit overload control state cleanup on the reacting node.
However, it is RECOMMENDED that the reporting node always explicitly However, it is RECOMMENDED that the reporting node always explicitly
indicates the end of a overload condition. indicates the end of a overload condition.
The reporting node SHOULD indicate the end of an overload occurrence
by sending a new OLR with OC-Validity-Duration set to a value of zero
("0"). The reporting node SHOULD insure that all reacting nodes
receive the updated overload report.
5.5.4. Agent Considerations
Editor's note -- Need to add this section.
6. Transport Considerations 6. Transport Considerations
In order to reduce overload control introduced additional AVP and In order to reduce overload control introduced additional AVP and
message processing it might be desirable/beneficial to signal whether message processing it might be desirable/beneficial to signal whether
the Diameter command carries overload control information that should the Diameter command carries overload control information that should
be of interest of an overload aware Diameter node. be of interest of an overload aware Diameter node.
Should such indication be include is not part of this specification. Should such indication be include is not part of this specification.
It has not either been concluded at what layer such possible It has not either been concluded at what layer such possible
indication should be. Obvious candidates include transport layer indication should be. Obvious candidates include transport layer
skipping to change at page 32, line 22 skipping to change at page 35, line 46
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010. Specification", RFC 5905, June 2010.
[RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn, [RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", RFC 6733, October 2012. "Diameter Base Protocol", RFC 6733, October 2012.
10.2. Informative References 10.2. Informative References
[3GPP.23.203] [Cx] 3GPP, , "ETSI TS 129 229 V11.4.0", August 2013.
3GPP, "Policy and charging control architecture", 3GPP
TS 23.203 10.9.0, September 2013.
[3GPP.29.229]
3GPP, "Cx and Dx interfaces based on the Diameter
protocol; Protocol details", 3GPP TS 29.229 10.5.0,
March 2013.
[3GPP.29.272]
3GPP, "Evolved Packet System (EPS); Mobility Management
Entity (MME) and Serving GPRS Support Node (SGSN) related
interfaces based on Diameter protocol", 3GPP TS 29.272
10.8.0, June 2013.
[I-D.ietf-dime-e2e-sec-req] [I-D.ietf-dime-e2e-sec-req]
Tschofenig, H., Korhonen, J., Zorn, G., and K. Pillay, Tschofenig, H., Korhonen, J., Zorn, G., and K. Pillay,
"Diameter AVP Level Security: Scenarios and Requirements", "Diameter AVP Level Security: Scenarios and Requirements",
draft-ietf-dime-e2e-sec-req-00 (work in progress), draft-ietf-dime-e2e-sec-req-00 (work in progress),
September 2013. September 2013.
[PCC] 3GPP, , "ETSI TS 123 203 V11.12.0", December 2013.
[RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J. [RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J.
Loughney, "Diameter Credit-Control Application", RFC 4006, Loughney, "Diameter Credit-Control Application", RFC 4006,
August 2005. August 2005.
[RFC5729] Korhonen, J., Jones, M., Morand, L., and T. Tsou, [RFC5729] Korhonen, J., Jones, M., Morand, L., and T. Tsou,
"Clarifications on the Routing of Diameter Requests Based "Clarifications on the Routing of Diameter Requests Based
on the Username and the Realm", RFC 5729, December 2009. on the Username and the Realm", RFC 5729, December 2009.
[RFC7068] McMurry, E. and B. Campbell, "Diameter Overload Control [RFC7068] McMurry, E. and B. Campbell, "Diameter Overload Control
Requirements", RFC 7068, November 2013. Requirements", RFC 7068, November 2013.
[S13] 3GPP, , "ETSI TS 129 272 V11.9.0", December 2012.
Appendix A. Issues left for future specifications Appendix A. Issues left for future specifications
The base solution for the overload control does not cover all The base solution for the overload control does not cover all
possible use cases. A number of solution aspects were intentionally possible use cases. A number of solution aspects were intentionally
left for future specification and protocol work. left for future specification and protocol work.
A.1. Additional traffic abatement algorithms A.1. Additional traffic abatement algorithms
This specification describes only means for a simple loss based This specification describes only means for a simple loss based
algorithm. Future algorithms can be added using the designed algorithm. Future algorithms can be added using the designed
skipping to change at page 33, line 28 skipping to change at page 36, line 42
steps. steps.
A.2. Agent Overload A.2. Agent Overload
This specification focuses on Diameter end-point (server or client) This specification focuses on Diameter end-point (server or client)
overload. A separate extension will be required to outline the overload. A separate extension will be required to outline the
handling the case of agent overload. handling the case of agent overload.
A.3. DIAMETER_TOO_BUSY clarifications A.3. DIAMETER_TOO_BUSY clarifications
The current [RFC6733] behaviour in a case of DIAMETER_TOO_BUSY is The current [RFC6733] behavior in a case of DIAMETER_TOO_BUSY is
somewhat under specified. For example, there is no information how somewhat under specified. For example, there is no information how
long the specific Diameter node is willing to be unavailable. A long the specific Diameter node is willing to be unavailable. A
specification updating [RFC6733] should clarify the handling of specification updating [RFC6733] should clarify the handling of
DIAMETER_TOO_BUSY from the error answer initiating Diameter node DIAMETER_TOO_BUSY from the error answer initiating Diameter node
point of view and from the original request initiating Diameter node point of view and from the original request initiating Diameter node
point of view. Further, the inclusion of possible additional point of view. Further, the inclusion of possible additional
information providing AVPs should be discussed and possible be information providing AVPs should be discussed and possible be
recommended to be used. recommended to be used.
Appendix B. Examples Appendix B. Examples
skipping to change at page 34, line 48 skipping to change at page 38, line 13
any specific server. Therefore, an agent may need to forward, or any specific server. Therefore, an agent may need to forward, or
originate, multiple overload reports with differing ReportType and originate, multiple overload reports with differing ReportType and
Reduction-Percentage values. Reduction-Percentage values.
Figure 8 illustrates such a mixed-routing scenario. In this example, Figure 8 illustrates such a mixed-routing scenario. In this example,
the servers S1, S2, and S3 handle requests for the realm "realm". the servers S1, S2, and S3 handle requests for the realm "realm".
Any of the three can handle requests that are not part of a user Any of the three can handle requests that are not part of a user
session (i.e. routed by Destination-Realm). But once a session is session (i.e. routed by Destination-Realm). But once a session is
established, all requests in that session must go to the same server. established, all requests in that session must go to the same server.
Client Agent S1 S2 S3 Client Agent S1 S2 S3
| | | | | | | | | |
|(1) Request (DR:realm) | | |(1) Request (DR:realm) | |
|-------->| | | | |-------->| | | |
| | | | | | | | | |
| | | | | | | | | |
| |Agent selects S1 | | | |Agent selects S1 | |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| |(2) Request (DR:realm) | | |(2) Request (DR:realm) |
| |-------->| | | | |-------->| | |
| | | | | | | | | |
| | | | | | | | | |
| | |S1 overloaded, returns OLR | | |S1 overloaded, returns OLR
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| |(3) Answer (OR:realm,OH:S1,OLR:RT=DH) | |(3) Answer (OR:realm,OH:S1,OLR:RT=DH)
| |<--------| | | | |<--------| | |
| | | | | | | | | |
| | | | | | | | | |
| |sees OLR,routes DR traffic to S2&S3 | |sees OLR,routes DR traffic to S2&S3
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
|(4) Answer (OR:realm,OH:S1, OLR:RT=DH) | |(4) Answer (OR:realm,OH:S1, OLR:RT=DH) |
|<--------| | | | |<--------| | | |
| | | | | | | | | |
| | | | | | | | | |
|Client throttles requests with DH:S1 | |Client throttles requests with DH:S1 |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
|(5) Request (DR:realm) | | |(5) Request (DR:realm) | |
|-------->| | | | |-------->| | | |
| | | | | | | | | |
| | | | | | | | | |
| |Agent selects S2 | | | |Agent selects S2 | |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| |(6) Request (DR:realm) | | |(6) Request (DR:realm) |
| |------------------>| | | |------------------>| |
| | | | | | | | | |
| | | | | | | | | |
| | | |S2 is overloaded... | | | |S2 is overloaded...
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| |(7) Answer (OH:S2, OLR:RT=DH)| | |(7) Answer (OH:S2, OLR:RT=DH)|
| |<------------------| | | |<------------------| |
| | | | | | | | | |
| | | | | | | | | |
| |Agent sees OLR, realm now overloaded | |Agent sees OLR, realm now overloaded
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
|(8) Answer (OR:realm,OH:S2, OLR:RT=DH, OLR: RT=R) |(8) Answer (OR:realm,OH:S2, OLR:RT=DH, OLR: RT=R)
|<--------| | | | |<--------| | | |
| | | | | | | | | |
| | | | | | | | | |
|Client throttles DH:S1, DH:S2, and DR:realm |Client throttles DH:S1, DH:S2, and DR:realm
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
Figure 8: Mix of Destination-Host and Destination-Realm Routed Figure 8: Mix of Destination-Host and Destination-Realm Routed
Requests Requests
1. The client sends a request with no Destination-Host AVP (that is, 1. The client sends a request with no Destination-Host AVP (that is,
a Destination-Realm routed request.) a Destination-Realm routed request.)
2. The agent follows local policy to select a server from its peer 2. The agent follows local policy to select a server from its peer
table. In this case, the agent selects S2 and forwards the table. In this case, the agent selects S2 and forwards the
request. request.
skipping to change at page 37, line 31 skipping to change at page 41, line 4
Authors' Addresses Authors' Addresses
Jouni Korhonen (editor) Jouni Korhonen (editor)
Broadcom Broadcom
Porkkalankatu 24 Porkkalankatu 24
Helsinki FIN-00180 Helsinki FIN-00180
Finland Finland
Email: jouni.nospam@gmail.com Email: jouni.nospam@gmail.com
Steve Donovan (editor)
Steve Donovan
Oracle Oracle
17210 Campbell Road 7460 Warren Parkway
Dallas, Texas 75254 Frisco, Texas 75034
United States United States
Email: srdonovan@usdonovans.com Email: srdonovan@usdonovans.com
Ben Campbell Ben Campbell
Oracle Oracle
17210 Campbell Road 7460 Warren Parkway
Dallas, Texas 75254 Frisco, Texas 75034
United States United States
Email: ben@nostrum.com Email: ben@nostrum.com
Lionel Morand Lionel Morand
Orange Labs Orange Labs
38/40 rue du General Leclerc 38/40 rue du General Leclerc
Issy-Les-Moulineaux Cedex 9 92794 Issy-Les-Moulineaux Cedex 9 92794
France France
Phone: +33145296257 Phone: +33145296257
Email: lionel.morand@orange.com Email: lionel.morand@orange.com
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