draft-ietf-spirits-architecture-03.txt   rfc3136.txt 
Network Working Group L. Slutsman (Ed.)
Internet Draft AT&T Labs
<draft-ietf-spirits-architecture-03.txt> I. Faynberg
Expires October 2001 H. Lu
M. Weissman
Lucent Technologies
The SPIRITS Architecture Network Working Group L. Slutsman, Editor
Request for Comments: 3136 AT&T Labs
Category: Informational I. Faynberg
H. Lu
M. Weissman
Lucent Technologies
June 2001
Status of this Memo The SPIRITS Architecture
This document is an Internet-Draft and is in full conformance wit all Status of this Memo
provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task This memo provides information for the Internet community. It does
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may also distribute working documents as Internet-Drafts. memo is unlimited.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at Copyright Notice
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at Copyright (C) The Internet Society (2001). All Rights Reserved.
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Abstract Abstract
This document describes the architecture for supporting SPIRITS This document describes the architecture for supporting SPIRITS
services, which are those originating in the PSTN and necessitating the services, which are those originating in the PSTN (Public Switched
interactions between the PSTN and the Internet. (Internet Call Waiting, Telephone Network)and necessitating the interactions between the PSTN
Internet Caller-ID Delivery, and Internet Call Forwarding are examples and the Internet. (Internet Call Waiting, Internet Caller-ID
of SPIRIT services.) Specifically, it defines the components Delivery, and Internet Call Forwarding are examples of SPIRIT
constituting the architecture and the interfaces between the components. services.) Specifically, it defines the components constituting the
architecture and the interfaces between the components.
1. Introduction 1. Introduction
This document describes the architecture for supporting SPIRITS This document describes the architecture for supporting SPIRITS
services, which are those originating in the PSTN and necessitating the services, which are those originating in the PSTN (Public Switched
interactions between the PSTN and the Internet. (Internet Call Waiting, Telephone Network) and necessitating the interactions between the
Internet Caller-ID Delivery, and Internet Call Forwarding are examples PSTN and the Internet. (Internet Call Waiting, Internet Caller-ID
of SPIRIT services.) Specifically, it defines the components Delivery, and Internet Call Forwarding are examples of SPIRIT
constituting the architecture and the interfaces between the services.) Specifically, it defines the components constituting the
components. architecture and the interfaces between the components.
The rest of the document is organized as follows: The rest of the document is organized as follows:
+ Section 2 describes example SPIRITS services from the end-user point
of view;
+ Section 3 describes the SPIRITS architecture;
<draft-ietf-spirits-architecture-03.txt> November 2001 + Section 2 describes example SPIRITS services from the end-user
point of view;
+ Section 4 contains security consideration; + Section 3 describes the SPIRITS architecture;
+ Section 5 contains acknowledgments; + Section 4 contains security considerations;
+ Section 6 contains references; and
+ Appendix contains the figure. + Section 5 contains acknowledgments;
+ Section 6 contains references; and
+ Appendix contains the figure.
2. Brief Description of Example SPIRITS Services 2. Brief Description of Example SPIRITS Services
To illustrate the motivation for the overall SPIRIT architecture, To illustrate the motivation for the overall SPIRIT architecture,
this section provides a brief description of the example SPIRITS this section provides a brief description of the example SPIRITS
services: services:
+ Internet Call Waiting (ICW),
+ Internet Caller-ID Delivery, and + Internet Call Waiting (ICW),
+ Internet Call Forwarding.
+ Internet Caller-ID Delivery, and
+ Internet Call Forwarding.
These services are considered from the end-user point of view under These services are considered from the end-user point of view under
the assumptions below: the assumptions below:
+ Service subscription (or cancellation) is a separate process and + Service subscription (or cancellation) is a separate process and
may be done over the telephone, via postal mail, or over the Web. may be done over the telephone, via postal mail, or over the Web.
+ The subscriber's IP host (e.g., a PC) is loaded with the necessary + The subscriber's IP host (e.g., a PC) is loaded with the necessary
software [including a Personal Identification Number (PIN) and the IP software [including a Personal Identification Number (PIN) and the
addresses of the SPIRITS servers] for realizing the SPIRITS services. IP addresses of the SPIRITS servers] for realizing the SPIRITS
The software may be sent by postal mail or downloaded from the Web. services. The software may be sent by postal mail or downloaded
from the Web.
+ The subscriber activates a SPIRITS service by an act of service + The subscriber activates a SPIRITS service by an act of service
session registration, which can take place anytime after he (or she) session registration, which can take place anytime after he (or
is connected to the Internet. The subscriber may specify the life she) is connected to the Internet. The subscriber may specify the
span of the session. As soon as the session ends, the SPIRITS service life span of the session. As soon as the session ends, the
is deactivated. Naturally, the subscriber should also be able to SPIRITS service is deactivated. Naturally, the subscriber should
deactivate a SPIRITS service anytime during the service session. also be able to deactivate a SPIRITS service anytime during the
service session.
For certain services (such as ICW or Caller-ID Delivery) the For certain services (such as ICW or Caller-ID Delivery) the
assumption is that the service subscriber has a single telephone line assumption is that the service subscriber has a single telephone line
and a PC, which is connected to the Internet via this telephone. and a PC, which is connected to the Internet via this telephone.
(Only under this assumption these services make sense.) Nevertheless, (Only under this assumption these services make sense.)
in other services (such as Web-based Call Center, in which a call Nevertheless, in other services (such as Web-based Call Center, in
center assistant could re-direct or reject a call presented in a which a call center assistant could re-direct or reject a call
pop-up window) this assumption may be unnecessary or even presented in a pop-up window) this assumption may be unnecessary or
inapplicable. even inapplicable.
2.1 Internet Call Waiting (ICW) 2.1 Internet Call Waiting (ICW)
The Internet call waiting service enables a subscriber engaged in an The Internet call waiting service enables a subscriber engaged in an
Internet dial-up session to Internet dial-up session to
o be notified of an incoming call to the very same telephone line o be notified of an incoming call to the very same telephone line
that is being used for the Internet connection; that is being used for the Internet connection;
o specify the desirable treatment of the call; and
o have the call handled as specified. o specify the desirable treatment of the call; and
<draft-ietf-spirits-architecture-03.txt> November 2001 o have the call handled as specified.
The details of the ICW service lie in the ways that a waiting call The details of the ICW service lie in the ways that a waiting call
can be treated [1]. Typical ways for handling a call include: can be treated [1]. Typical ways for handling a call include:
+ Accept the incoming call over the PSTN by terminating the Internet + Accept the incoming call over the PSTN by terminating the Internet
connection. (As switching cannot be done immediately, the caller may connection. (As switching cannot be done immediately, the caller
hear an opening announcement followed by the "ringing" tone.) may hear an opening announcement followed by the "ringing" tone.)
+ Forward the incoming call to another telephone number. The + Forward the incoming call to another telephone number. The
subscriber will remain connected to the Internet, while the caller subscriber will remain connected to the Internet, while the caller
will hear an announcement indicating the call is being forwarded and will hear an announcement indicating the call is being forwarded
eventually be connected to the new destination number. and eventually be connected to the new destination number.
+ Accept the incoming call by voice over IP. The subscriber will + Accept the incoming call by voice over IP. The subscriber will
answer the incoming call via the already established Internet answer the incoming call via the already established Internet
connection. (The proposed SPIRITS architecture, however, does not connection. (The proposed SPIRITS architecture, however, does not
reflect this feature.) reflect this feature.)
+ Redirect the incoming call to voice mail. The subscriber will + Redirect the incoming call to voice mail. The subscriber will
remain connected to the Internet, while the caller will hear an remain connected to the Internet, while the caller will hear an
announcement inviting him (or her) to leave a message. announcement inviting him (or her) to leave a message.
+ Play a pre-recorded message to the calling party and disconnect the + Play a pre-recorded message to the calling party and disconnect
call. The subscriber will remain connected to the Internet. the call. The subscriber will remain connected to the Internet.
+ Reject the incoming call. The subscriber will remain connected to + Reject the incoming call. The subscriber will remain connected to
the Internet, while the caller will hear an announcement rejecting the Internet, while the caller will hear an announcement rejecting
the call. the call.
The subscriber may specify the call treatment on the fly when The subscriber may specify the call treatment on the fly when
notified of an incoming call. Alternatively, the subscriber may notified of an incoming call. Alternatively, the subscriber may
specify a priori a general treatment for all calls (e.g., re-directed specify a priori a general treatment for all calls (e.g., re-directed
to voice mail) or call treatments tailored to the origination to voice mail) or call treatments tailored to the origination
numbers. As a result, when a call comes in, the subscriber won't be numbers. As a result, when a call comes in, the subscriber won't be
presented the call but can examine afterwards the treatment and presented the call but can examine afterwards the treatment and
outcome of the call from the log that is kept for all the calls outcome of the call from the log that is kept for all the calls
processed during the ICW service. Typical information recorded in the processed during the ICW service. Typical information recorded in
log includes the incoming call date and time, calling party number, the log includes the incoming call date and time, calling party
calling party name, and call disposition. number, calling party name, and call disposition.
2.2 Internet Caller-ID Delivery 2.2 Internet Caller-ID Delivery
This service allows the subscriber to see the caller's number or name This service allows the subscriber to see the caller's number or name
or both while being connected to the Internet. If the subscriber has or both while being connected to the Internet. If the subscriber has
only one telephone line and is using the very line for the Internet only one telephone line and is using the very line for the Internet
connection, the service is a subset of the ICW service and follows connection, the service is a subset of the ICW service and follows
the relevant description in Section 2.1. Otherwise, the subscriber's the relevant description in Section 2.1. Otherwise, the subscriber's
IP host serves as an auxiliary device of the telephone to which the IP host serves as an auxiliary device of the telephone to which the
call is first sent. call is first sent.
2.3 Internet Call Forwarding 2.3 Internet Call Forwarding
The Internet call forwarding service allows a service subscriber to The Internet call forwarding service allows a service subscriber to
forward an incoming call to another telephone number while being forward an incoming call to another telephone number while being
connected to the Internet. If the subscriber has only one telephone connected to the Internet. If the subscriber has only one telephone
<draft-ietf-spirits-architecture-03.txt> November 2001
line and is using the very line for the Internet connection, the line and is using the very line for the Internet connection, the
service is a subset of the ICW service and follows the relevant service is a subset of the ICW service and follows the relevant
description in Section 2.1. Otherwise, the subscriber's IP host description in Section 2.1. Otherwise, the subscriber's IP host
serves as an auxiliary device of the telephone to which the call is serves as an auxiliary device of the telephone to which the call is
first sent. first sent.
3. SPIRITS Architecture 3. SPIRITS Architecture
Figure 1 of the Appendix depicts the SPIRITS architecture, which Figure 1 of the Appendix depicts the SPIRITS architecture, which
includes the following entities: includes the following entities:
1. Service Control Function (SCF) [2], which executes service logic, 1. Service Control Function (SCF) [2], which executes service logic,
interacts with the entities in the IP domain (e.g., the SPIRITS interacts with the entities in the IP domain (e.g., the SPIRITS
Gateway and PINT Server) through the SPIRITS Client, and instructs Gateway and PINT Server) through the SPIRITS Client, and instructs
the switches on how to complete a call. Physically, the SCF may be the switches on how to complete a call. Physically, the SCF may
located in either stand-alone general-purpose computers called be located in either stand-alone general-purpose computers called
Service Control Points (SCPs) or specialized pieces of equipment Service Control Points (SCPs) or specialized pieces of equipment
called Service Nodes (SNs) [2]. called Service Nodes (SNs) [2].
2. Service Switching Function (SSF) [2], which normally resides in a 2. Service Switching Function (SSF) [2], which normally resides in a
switch and is responsible for the recognition of Intelligent Network switch and is responsible for the recognition of Intelligent
(IN) triggers and interactions with the SCF. Network (IN) triggers and interactions with the SCF.
3. SPIRITS Client, which is responsible for receiving PSTN requests 3. SPIRITS Client, which is responsible for receiving PSTN requests
from the SCF as well as sending responses back. It may be co-located from the SCF as well as sending responses back. It may be co-
with the SCF. If not, it communicates with the SCF over the D located with the SCF. If not, it communicates with the SCF over
interface. the D interface.
4. PINT Server, which receives PINT requests from the PINT Client and 4. PINT Server, which receives PINT requests from the PINT Client and
relays them to the PSTN for execution over the E interface. relays them to the PSTN for execution over the E interface.
5. SPIRITS Gateway, which is co-located with the PINT Server or 5. SPIRITS Gateway, which is co-located with the PINT Server or PINT
PINT Gateway (or both when they are co-located as assumed here Gateway (or both when they are co-located as assumed here for
for simplicity) and serves as an intermediary between the SPIRITS simplicity) and serves as an intermediary between the SPIRITS
Server and SPRITS Client via the B and C interfaces, respectively. Server and SPRITS Client via the B and C interfaces, respectively.
6. PINT Client, which resides in the subscriber's IP host and is 6. PINT Client, which resides in the subscriber's IP host and is
responsible for initiating PINT requests, which are sent to the PINT responsible for initiating PINT requests, which are sent to the
server over the A interface. PINT server over the A interface.
7. SPIRITS Server, which terminates PSTN requests and is responsible 7. SPIRITS Server, which terminates PSTN requests and is responsible
for all interactions (e.g., incoming call notification and relaying for all interactions (e.g., incoming call notification and
the call treatment) between the subscriber and the SPIRITS Gateway. relaying the call treatment) between the subscriber and the
SPIRITS Gateway.
The rest of the Section describes the interfaces between the entities The rest of the Section describes the interfaces between the entities
in detail. in detail.
3.1 Interface A 3.1 Interface A
This interface is used for sending PINT requests to PINT Server. Its This interface is used for sending PINT requests to PINT Server. Its
principal use is for service session registration and as a result principal use is for service session registration and as a result
activation of a SPIRITS service (see Section 2). In addition, this activation of a SPIRITS service (see Section 2). In addition, this
interface may be used for service subscription. interface may be used for service subscription.
<draft-ietf-spirits-architecture-03.txt> November 2001
3.2 Interface B 3.2 Interface B
This interface serves two main purposes: 1) to notify the subscriber This interface serves two main purposes: 1) to notify the subscriber
of incoming calls together with the calling number and name, if of incoming calls together with the calling number and name, if
available; and 2) to send to the SPRITS Gateway the subscriber's available; and 2) to send to the SPRITS Gateway the subscriber's
choice of call disposition specified on the fly. choice of call disposition specified on the fly.
3.3 Interface C 3.3 Interface C
This interface is used for communications between the SPIRITS Client This interface is used for communications between the SPIRITS Client
and SPIRITS Gateway. The SPIRITS Gateway may in turn communicate and SPIRITS Gateway. The SPIRITS Gateway may in turn communicate
with the SPIRITS Server, or may act as a virtual server, terminating with the SPIRITS Server, or may act as a virtual server, terminating
the requests without sending them down to the SPIRITS Server. the requests without sending them down to the SPIRITS Server.
3.4 Interface D 3.4 Interface D
This interface is for communications between the SPIRITS Client and This interface is for communications between the SPIRITS Client and
the SCF. Specifically, from the SCF to the SPIRITS Client, the the SCF. Specifically, from the SCF to the SPIRITS Client, the
parameters associated with the applicable IN triggers are sent. From parameters associated with the applicable IN triggers are sent. From
the SPIRITS Client to SCF, the subscriber's call disposition is sent. the SPIRITS Client to SCF, the subscriber's call disposition is sent.
The SCF "transforms" the user's disposition into appropriate actions, The SCF "transforms" the user's disposition into appropriate actions,
such as playing an announcement to the caller, and resuming the such as playing an announcement to the caller, and resuming the
suspended call processing in the SSP. suspended call processing in the SSP.
3.5 Interface E 3.5 Interface E
This interface is for sending PINT requests to the SCF for execution. This interface is for sending PINT requests to the SCF for execution.
4. Security Considerations 4. Security Considerations
skipping to change at page 6, line 36 skipping to change at page 6, line 16
such as playing an announcement to the caller, and resuming the such as playing an announcement to the caller, and resuming the
suspended call processing in the SSP. suspended call processing in the SSP.
3.5 Interface E 3.5 Interface E
This interface is for sending PINT requests to the SCF for execution. This interface is for sending PINT requests to the SCF for execution.
4. Security Considerations 4. Security Considerations
As Figure 1 demonstrates, there are two distinct communications As Figure 1 demonstrates, there are two distinct communications
interfaces, B and C. The B interface is, in general, across the interfaces, B and C. The B interface is, in general, across the
public Internet and is thus most vulnerable to security attacks public Internet and is thus most vulnerable to security attacks
resulting in theft or denial of service. The C interface, on the resulting in theft or denial of service. The C interface, on the
other hand is likely to be implemented across a service provider's other hand is likely to be implemented across a service provider's
intranet, where the security measures should be applied at the intranet, where the security measures should be applied at the
discretion of the service provider. Even then, because at least on discretion of the service provider. Even then, because at least one
IP host (the PINT gateway) is connected to the Internet, special IP host (the PINT gateway) is connected to the Internet, special
measures (e.g., installation of firewalls, although this particular measures (e.g., installation of firewalls, although this particular
measure alone may be insufficient) need to be taken to protect the measure alone may be insufficient) need to be taken to protect the
interface C and the rest of the network from security attacks. interface C and the rest of the network from security attacks.
The assumption that the PINT Client and SPIRITSs server are co- The assumption that the PINT Client and SPIRITS server are co-
located, dictates that the security considerations for the A and B located, dictates that the security considerations for the A and B
interfaces are exactly same. Detailed security requirements and interfaces are exactly the same. Detailed security requirements and
solutions for interface A (and, consequently, B) can be found in RFC solutions for interface A (and, consequently, B) can be found in RFC
2848 [3]. In addition, security requirements are listed in the 2848 [3]. In addition, security requirements are listed in the
companion SPIRITS Protocol Requirements RFC. companion SPIRITS Protocol Requirements RFC.
5. Acknowledgments 5. Acknowledgments
We would like to thank Alec Brusilovsky, Jorgen Bjorkner, Scott We would like to thank Alec Brusilovsky, Jorgen Bjorkner, Scott
Bradner, Jim Buller, Lawrence Conroy, Jorge Gato, Dave Hewins, Naoto Bradner, Jim Buller, Lawrence Conroy, Jorge Gato, Dave Hewins, Naoto
<draft-slutsman-spirits-architecture-03.txt> May 2001
Makinae, and Dave Shrader for their comments and input. Makinae, and Dave Shrader for their comments and input.
6. References 6. References
[1] Lu, H. (Editor), I. Faynberg, J. Voelker, M. Weissman, W. Zhang, [1] Lu, H., Editor, Faynberg, I., Voelker, J., Weissman, M., Zhang,
S. Rhim, J. Hwang, S. Ago, S. Moeenuddin, S. Hadvani, S. Nyckelgard, W., Rhim, S., Hwang, J., Ago, S., Moeenuddin, S., Hadvani, S.,
J. Yoakum, and L. Robart, "Pre-SPIRITS Implementations of PSTN- Nyckelgard, S., Yoakum, J. and L. Robart, "Pre-SPIRITS
Initiated Services ", RFC 2995. Implementations of PSTN-Initiated Services", RFC 2995, November
2000.
[2] Faynberg, I., L. Gabuzda, M. Kaplan, and N.Shah, "The Intelligent [2] Faynberg, I., L. Gabuzda, M. Kaplan, and N.Shah, "The Intelligent
Network Standards: Their Application to Services", McGraw-Hill, 1997. Network Standards: Their Application to Services", McGraw-Hill,
1997.
[3] S. Petrack, and L. Conroy, The PINT Service Protocol: Extensions [3] Petrack, S. and L. Conroy, "The PINT Service Protocol: Extensions
to SIP and SDP for IP Access to Telephone Call Services, Proposed to SIP and SDP for IP Access to Telephone Call Services", RFC
Standard. RFC 2848, June 2000. 2848, June 2000.
Appendix Appendix
...................... ......................
+----------------+ . . +----------------+ . .
| +------------+ | . +------------+ . | +------------+ | . +------------+ .
| | | | A . | | . | | | | A . | | .
| | PINT Client|********************|PINT Server/|******** | | PINT Client|********************|PINT Server/|********
| | | | . Gateway | * | | | | . Gateway | *
| +------------+ | . +------------+ . * | +------------+ | . +------------+ . *
| | . . * | | . . *
| Subscriber's | . . * | Subscriber's | . . *
| | . . * | | . . *
| IP Host | . . * | IP Host | . . *
| | . +------------+ . * | | . +------------+ . *
| +------------+ | . | SPIRITS | . * | +------------+ | . | SPIRITS | . *
| | SPIRITS | | B . | Gateway | . * | | SPIRITS | | B . | Gateway | . *
| | Server |********************| | . * E | | Server |********************| | . * E
| | | | . +------------+ . * | | | | . +------------+ . *
| +------------+ | . * . * | +------------+ | . * . *
+----------------+ . * . * +----------------+ . * . *
...........*.......... * ...........*.......... *
//-------\\ * * //-------\\ * *
/// \\\ * * /// \\\ * *
| Subscriber's | * C * | Subscriber's | * C *
| Telephone | * * | Telephone | * *
\\\ /// * * \\\ /// * *
\\ -------// * * \\ -------// * *
* * * * * *
* * * * * *
++++++++++++++++++++++++++ PSTN ++++++++++++++++++++++++++ ++++++++++++++++++++++++++ PSTN ++++++++++++++++++++++++++
* * * * * *
* * * * * *
* +------------------+ * * +------------------+ *
* Line | SPIRITS Client | * * Line | SPIRITS Client | *
* | | * * | | *
+--------------------+ +---+----- D ---------+-*+ +--------------------+ +---+----- D ---------+-*+
| | INAP/SS7 | | | | INAP/SS7 | |
|Service Switching ************Service Control Function | |Service Switching ************Service Control Function |
| Function | | | | Function | | |
| | +-------------------------+ | | +-------------------------+
| | | |
| | | |
+--------------------+ +--------------------+
Figure 1: SPIRITS Architecture Figure 1: SPIRITS Architecture
Author's Addresses Authors' Addresses
Igor Faynberg Igor Faynberg
Lucent Technologies Lucent Technologies
Room 4D-601A Room 4D-601A
101 Crawfords Corner Road 101 Crawfords Corner Road
Holmdel, NJ 07733-3030 US Holmdel, NJ 07733-3030 US
E-mail: faynberg@lucent.com
<draft-ietf-spirits-architecture-03.txt> November 2001 Phone: +1 732 949 0137
EMail: faynberg@lucent.com
Telephone: +1 732 949 0137 Hui-Lan Lu
Lucent Technologies Room 4C-607A
101 Crawfords Corner Road
Holmdel, NJ 07733-3030 US
Hui-Lan Lu Phone: +1 732 949 0321
Lucent Technologies Room 4C-607A EMail: huilanlu@lucent.com
101 Crawfords Corner Road
Holmdel, NJ 07733-3030 US
E-mail: huilanlu@lucent.com
Telephone: +1 732 949 0321
Mark Weissman Mark Weissman
Lucent Technologies Lucent Technologies
Room NE406B Room NE406B
200 Lucent Lane 200 Lucent Lane
Cary, NC 27511 Cary, NC 27511
E-mail: maw1@lucent.com
Telephone: +1 919 463 3258
Lev Slutsman Phone: +1 919 463 3258
AT&T Labs EMail: maw1@lucent.com
Room D5-3D26
200 Laurel Avenue Lev Slutsman
Middletown, NJ 07748 AT&T Labs
E-mail: slutsman@att.com Room D5-3D26
Telephone: 732-420-3756 200 Laurel Avenue
Middletown, NJ 07748
Phone: 732-420-3756
EMail: lslutsman@att.com
Full Copyright Statement Full Copyright Statement
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<draft-ietf-spirits-architecture-03.txt> November 2001 The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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