draft-ietf-sigtran-signalling-over-sctp-applic-06.txt   draft-ietf-sigtran-signalling-over-sctp-applic-07.txt 
INTERNET-DRAFT L. Coene(Ed) INTERNET-DRAFT L. Coene(Ed)
Internet Engineering Task Force Siemens Internet Engineering Task Force Siemens
Issued: November 2002 J. Pastor Issued: January 2003 J. Pastor
Expires: May 2003 Ericsson Expires: July 2003 Ericsson
Telephony Signalling Transport over SCTP applicability statement Telephony Signalling Transport over SCTP applicability statement
draft-ietf-sigtran-signalling-over-sctp-applic-06.txt < draft-ietf-sigtran-signalling-over-sctp-applic-07.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
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Abstract Abstract
This document describes the applicability of the new protocols This document describes the applicability of the new protocols
developed under the signalling transport framework[RFC2719]. A developed under the signalling transport framework[RFC2719]. A
description of the main issues regarding the use of the Stream description of the main issues regarding the use of the Stream
Control Transmission Protocol (SCTP)[RFC2960] and each adaptation Control Transmission Protocol (SCTP)[RFC2960] and each adaptation
layer for transport of telephony signalling information over IP layer for transport of telephony signalling information over IP
infrastructure is explained. infrastructure is explained.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
Table of contents Table of contents
Telephony signalling over SCTP Applicability statement ......... ii Telephony signalling over SCTP Applicability statement ......... ii
Chapter 1: Introduction ........................................ 2 Chapter 1: Introduction ........................................ 2
Chapter 1.1: Scope ..... ....................................... 3 Chapter 1.1: Scope ..... ....................................... 3
Chapter 1.2: Terminology ....................................... 3 Chapter 1.2: Terminology ....................................... 3
Chapter 1.3: Contributors ...................................... 3 Chapter 1.3: Contributors ...................................... 3
Chapter 2: SIGTRAN architecture ................................ 4 Chapter 2: SIGTRAN architecture ................................ 4
Chapter 2.1: Overview ......................................... 4 Chapter 2.1: Overview ......................................... 4
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Chapter 4.2.1.3: Main difference between M2PA and M2UA ......... 16 Chapter 4.2.1.3: Main difference between M2PA and M2UA ......... 16
Chapter 4.2.2: M3UA (SS7 MTP3 User Adaptation) Layer ........... 17 Chapter 4.2.2: M3UA (SS7 MTP3 User Adaptation) Layer ........... 17
Chapter 4.2.3: SUA (SS7 SCCP User Adaptation) Layer ............ 18 Chapter 4.2.3: SUA (SS7 SCCP User Adaptation) Layer ............ 18
Chapter 5: Security considerations ............................. 20 Chapter 5: Security considerations ............................. 20
Chapter 6: References and related work ......................... 20 Chapter 6: References and related work ......................... 20
Chapter 7: Acknowledgments ..................................... 21 Chapter 7: Acknowledgments ..................................... 21
Chapter 8: Author's address .................................... 22 Chapter 8: Author's address .................................... 22
1 INTRODUCTION 1 INTRODUCTION
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
This document intends to inform how to transport telephony This document intends to inform how to transport telephony
signalling protocols, used in classic telephony systems, over IP signalling protocols, used in classic telephony systems, over IP
networks. The whole architecture is called SIGTRAN (Signalling networks. The whole architecture is called SIGTRAN (Signalling
Transport) as described in RFC2719 and is composed of a transport Transport) as described in RFC2719 and is composed of a transport
protocol(SCTP) and several User Adaptation layers(UAL). The protocol(SCTP) and several User Adaptation layers(UAL). The
transport protocol SCTP has been been developed to fulfill the transport protocol SCTP has been been developed to fulfill the
stringent requirements that telephony signalling networks have. The stringent requirements that telephony signalling networks have. The
set of User Adaptation layers have also been introduced to make it set of User Adaptation layers have also been introduced to make it
possible that different signalling protocols can use the SCTP layer. possible that different signalling protocols can use the SCTP layer.
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layer telephony signalling protocols that are to be transported over layer telephony signalling protocols that are to be transported over
SCTP/IP. SCTP/IP.
ISEP: IP signalling endpoint: a IP node that implements SCTP and a ISEP: IP signalling endpoint: a IP node that implements SCTP and a
User adapatation layer. User adapatation layer.
SP: signalling point SP: signalling point
1.3 Contributors 1.3 Contributors
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
The following people contributed to the document: L. Coene(Editor), The following people contributed to the document: L. Coene(Editor),
M. Tuexen, G. Verwimp, J. Loughney, R.R. Stewart, Qiaobing Xie, M. Tuexen, G. Verwimp, J. Loughney, R.R. Stewart, Qiaobing Xie,
M. Holdrege, M.C. Belinchon, A. Jungmaier, J. Pastor and L. Ong. M. Holdrege, M.C. Belinchon, A. Jungmaier, J. Pastor and L. Ong.
2 SIGTRAN architecture 2 SIGTRAN architecture
The SIGTRAN architecture describes the transport of signalling The SIGTRAN architecture describes the transport of signalling
information over IP infrastructure. information over IP infrastructure.
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(3) The standard Internet Protocol. (3) The standard Internet Protocol.
The telephony signalling protocols to be transported can be: The telephony signalling protocols to be transported can be:
- SS7 MTP3 users: SCCP, ISUP, TUP... - SS7 MTP3 users: SCCP, ISUP, TUP...
- SS7 MTP2 users: MTP3 - SS7 MTP2 users: MTP3
- SS7 SCCP users: RANAP, MAP(+TCAP), INAP(+TCAP)... - SS7 SCCP users: RANAP, MAP(+TCAP), INAP(+TCAP)...
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
- ISDN Q.921 users: Q.931 - ISDN Q.921 users: Q.931
- V5.2/DSS1 - V5.2/DSS1
- .... - ....
Every classic telephony protocol can have a corresponding UAL Every classic telephony protocol can have a corresponding UAL
developed. developed.
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- Protection against blind masquerade attacks - Protection against blind masquerade attacks
SCTP is used as the transport protocol for telephony signalling SCTP is used as the transport protocol for telephony signalling
applications. Message boundaries are preserved during data applications. Message boundaries are preserved during data
transport by SCTP and so each UAL can specify its own message transport by SCTP and so each UAL can specify its own message
structure withing the SCTP user data. The SCTP user data can be structure withing the SCTP user data. The SCTP user data can be
delivered by the order of transmission within a stream(in sequence delivered by the order of transmission within a stream(in sequence
delivery) or unordered. delivery) or unordered.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
SCTP can be used to provide redundancy at the SCTP can be used to provide redundancy at the
transport layer and below. Telephony applications needing this level transport layer and below. Telephony applications needing this level
of redundancy can make use of SCTP's multi-homing support. of redundancy can make use of SCTP's multi-homing support.
SCTP can be used for telephony applications where head-of-line SCTP can be used for telephony applications where head-of-line
blocking is a concern. Such an application should use multiple blocking is a concern. Such an application should use multiple
streams to provide independent ordering of telephony signalling streams to provide independent ordering of telephony signalling
messages. messages.
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with the congestion control procedures in SCTP. with the congestion control procedures in SCTP.
3.2 Detection of failures 3.2 Detection of failures
Telephony systems often must have no single point of failure in Telephony systems often must have no single point of failure in
operation. operation.
The UAL must meet certain service availability and performance The UAL must meet certain service availability and performance
requirements according to the classical signalling layers they are requirements according to the classical signalling layers they are
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
replacing. Those requirements may be specific for each UAL. replacing. Those requirements may be specific for each UAL.
For example, telephony systems are often required to be able to For example, telephony systems are often required to be able to
preserve stable calls during a component failure. Therefore error preserve stable calls during a component failure. Therefore error
situations at the transport layer and below must be detected quickly situations at the transport layer and below must be detected quickly
so that the UAL can take approriate steps to recover and preserve the so that the UAL can take approriate steps to recover and preserve the
calls. This poses special requirements on SCTP to discover calls. This poses special requirements on SCTP to discover
unreachablility of a destination address or a peer. unreachablility of a destination address or a peer.
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HB.interval. It should be noted this might result in a higher traffic HB.interval. It should be noted this might result in a higher traffic
load. load.
3.2.3 Maximum number of retransmissions 3.2.3 Maximum number of retransmissions
Setting Path.Max.Retrans and Association.Max.Retrans SCTP parameters Setting Path.Max.Retrans and Association.Max.Retrans SCTP parameters
to lower values will speed up both destination address and peer to lower values will speed up both destination address and peer
failure detection. However, if these values are set too low, the failure detection. However, if these values are set too low, the
probability of false fault detections might increase. probability of false fault detections might increase.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
3.3 Shorten end-to-end message delay 3.3 Shorten end-to-end message delay
Telephony applications often require short end-to-end message Telephony applications often require short end-to-end message
delays. The method described in section 3.2.1 on lowering RTO may delays. The method described in section 3.2.1 on lowering RTO may
be considered. The different paths within a single association will be considered. The different paths within a single association will
have a different RTO, so using the path with the lowest RTO will have a different RTO, so using the path with the lowest RTO will
lead to a shorter end-to-end message delay for the application lead to a shorter end-to-end message delay for the application
running on top of the UAL's. running on top of the UAL's.
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next sub-sections. next sub-sections.
The delivery mechanism in the several UALs The delivery mechanism in the several UALs
- Supports seamless operation of UALs user peers over an IP - Supports seamless operation of UALs user peers over an IP
network connection. network connection.
- Supports the interface boundary that the UAL user had with the - Supports the interface boundary that the UAL user had with the
traditional lower layer. traditional lower layer.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
- Supports management of SCTP transport associations and traffic - Supports management of SCTP transport associations and traffic
between SGs and ISEPs or two ISEPs between SGs and ISEPs or two ISEPs
- Supports asynchronous reporting of status changes to management. - Supports asynchronous reporting of status changes to management.
Signalling User Adaptation Layers have been developed for both: Signalling User Adaptation Layers have been developed for both:
Access and Trunk Telephony Signalling. They are defined as follows. Access and Trunk Telephony Signalling. They are defined as follows.
Access Signalling: This is the signalling that is needed between and Access Signalling: This is the signalling that is needed between and
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- ISDN Q.921 Users: Q.931 - ISDN Q.921 Users: Q.931
- V5.2/DSS1 - V5.2/DSS1
- DPNSS/DASS2 - DPNSS/DASS2
- SS7 MTP3 Users: SCCP, ISUP, TUP - SS7 MTP3 Users: SCCP, ISUP, TUP
- SS7 MTP2 Users: MTP3 - SS7 MTP2 Users: MTP3
- SS7 SCCP Users: TCAP, RANAP, BSSAP, ... - SS7 SCCP Users: TCAP, RANAP, BSSAP, ...
Two main scenarios have been developed to use the different UALS for Two main scenarios have been developed to use the different UALS for
IP Signalling Transport: IP Signalling Transport:
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
(1) Intercommunication of traditional Signalling transport nodes and (1) Intercommunication of traditional Signalling transport nodes and
IP based nodes. IP based nodes.
Traditional Telephony Traditional Telephony
Telephony Signalling Telephony Signalling
********* Signalling ********** over IP ******** ********* Signalling ********** over IP ********
* SEP *----------------* SG *--------------* ISEP * * SEP *----------------* SG *--------------* ISEP *
********* ********** ******** ********* ********** ********
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+-------+ +-------+ +-------+ +-------+
| UAL | | UAL | | UAL | | UAL |
+-------+ +-------+ +-------+ +-------+
| SCTP | | SCTP | | SCTP | | SCTP |
+-------+ +-------+ +-------+ +-------+
| IP | | IP | | IP | | IP |
+-------+ +-------+ +-------+ +-------+
This is also referred to as IPSP communication. IPSP is the name This is also referred to as IPSP communication. IPSP is the name
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
of the role that an UAL plays on an IP-based node. It stands for of the role that an UAL plays on an IP-based node. It stands for
IP Signalling Point. IP Signalling Point.
The first scenario is applied for both types of signalling (access The first scenario is applied for both types of signalling (access
and trunk signalling). On the other hand the peer to peer basis can and trunk signalling). On the other hand the peer to peer basis can
only be used for trunk signalling. only be used for trunk signalling.
4.1 Access Signalling 4.1 Access Signalling
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+-----+ +-----+ +-----+ +-----+
|Q.931| (NIF) |Q.931| |Q.931| (NIF) |Q.931|
+-----+ +----------+ +-----+ +-----+ +----------+ +-----+
| | | | IUA| | IUA | | | | | IUA| | IUA |
| | | +----+ +-----+ | | | +----+ +-----+
|Q.921| |Q.921|SCTP| |SCTP | |Q.921| |Q.921|SCTP| |SCTP |
| | | +----+ +-----+ | | | +----+ +-----+
| | | | IP | | IP | | | | | IP | | IP |
+-----+ +-----+----+ +-----+ +-----+ +-----+----+ +-----+
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
NIF - Nodal Interworking Function NIF - Nodal Interworking Function
PBX - Private Branch Exchange PBX - Private Branch Exchange
SCTP - Stream Control Transmission Protocol SCTP - Stream Control Transmission Protocol
IUA - ISDN User Adaptation Layer Protocol IUA - ISDN User Adaptation Layer Protocol
The SCTP (and UDP/TCP) Registered User Port Number Assignment for IUA The SCTP (and UDP/TCP) Registered User Port Number Assignment for IUA
is 9900. is 9900.
The value assigned by IANA for the Payload Protocol Identifier in the The value assigned by IANA for the Payload Protocol Identifier in the
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+-----+ +-----+----+ +-----+ +-----+ +-----+----+ +-----+
AN Access Network AN Access Network
NIF Nodal Interworking Function NIF Nodal Interworking Function
LAPV5 Link Access Protocol for the V5 channel LAPV5 Link Access Protocol for the V5 channel
SCTP - Stream Control Transmission Protocol SCTP - Stream Control Transmission Protocol
The SCTP (and UDP/TCP) Registered User Port Number Assignment for The SCTP (and UDP/TCP) Registered User Port Number Assignment for
V5UA is 5675. V5UA is 5675.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
The value assigned by IANA for the Payload Protocol Identifier in the The value assigned by IANA for the Payload Protocol Identifier in the
SCTP Payload Data chunk is "6". SCTP Payload Data chunk is "6".
4.1.3 DPNSS/DASS2 over IP 4.1.3 DPNSS/DASS2 over IP
UAL: DUA (DPNSS/DASS2 User Adaptation) UAL: DUA (DPNSS/DASS2 User Adaptation)
The DUA is built on top of IUA defining the necessary extensions to The DUA is built on top of IUA defining the necessary extensions to
IUA for a DPNSS/DASS2 transport. DPNSS stands for Digital Private IUA for a DPNSS/DASS2 transport. DPNSS stands for Digital Private
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The SIGTRAN WG have developed UALs to transport the following SS7 The SIGTRAN WG have developed UALs to transport the following SS7
protocols: protocols:
- MTP2 Users: MTP3 - MTP2 Users: MTP3
- MTP3 Users: ISUP, TUP, SCCP - MTP3 Users: ISUP, TUP, SCCP
- SCCP Users: TCAP, RNSAP, RANAP, BSSAP, ... - SCCP Users: TCAP, RNSAP, RANAP, BSSAP, ...
4.2.1 MTP lvl3 over IP 4.2.1 MTP lvl3 over IP
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
UALs: UALs:
- M2UA (SS7 MTP2 User Adaptation) - M2UA (SS7 MTP2 User Adaptation)
- M2PA (SS7 MTP2-User Peer-to-Peer Adaptation) - M2PA (SS7 MTP2-User Peer-to-Peer Adaptation)
4.2.1.1 M2UA (SS7 MTP2 User Adaptation) 4.2.1.1 M2UA (SS7 MTP2 User Adaptation)
M2UA protocol is mainly used between a Signalling Gateway (SG) and M2UA protocol is mainly used between a Signalling Gateway (SG) and
Media Gateway Controller (MGC). The SG will terminate up to MTP Level Media Gateway Controller (MGC). The SG will terminate up to MTP Level
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MGC - Media Gateway Controler MGC - Media Gateway Controler
SG - Signalling Gateway SG - Signalling Gateway
SEP - SS7 Signalling Endpoint SEP - SS7 Signalling Endpoint
NIF - Nodal Interworking Function NIF - Nodal Interworking Function
IP - Internet Protocol IP - Internet Protocol
SCTP - Stream Control Transmission Protocol SCTP - Stream Control Transmission Protocol
The SCTP (and UDP/TCP) Registered User Port Number Assignment for The SCTP (and UDP/TCP) Registered User Port Number Assignment for
M2UA is 2904. M2UA is 2904.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
The value assigned by IANA for the Payload Protocol Identifier in the The value assigned by IANA for the Payload Protocol Identifier in the
SCTP Payload Data chunk is "2" SCTP Payload Data chunk is "2"
4.2.1.2 M2PA (SS7 MTP2-User Peer-to-Peer Adaptation) Layer 4.2.1.2 M2PA (SS7 MTP2-User Peer-to-Peer Adaptation) Layer
M2PA protocol is used between SS7 Signalling Points employing the MTP M2PA protocol is used between SS7 Signalling Points employing the MTP
Level 3 protocol. The SS7 Signalling Points may also employ standard Level 3 protocol. The SS7 Signalling Points may also employ standard
SS7 links using the SS7 MTP Layer 2 to provide transport of MTP Layer SS7 links using the SS7 MTP Layer 2 to provide transport of MTP Layer
3 signalling messages. 3 signalling messages.
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+------+ +------+ +------+ +------+
| IP | | IP | | IP | | IP |
+------+ +------+ +------+ +------+
IP - Internet Protocol IP - Internet Protocol
IPSP - IP Signalling Point IPSP - IP Signalling Point
SCTP - Stream Control Transmission Protocol SCTP - Stream Control Transmission Protocol
Interconnection of SS7 and IP nodes: Interconnection of SS7 and IP nodes:
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
******** SS7 *************** IP ******** ******** SS7 *************** IP ********
* SEP *--------* SG *--------* IPSP * * SEP *--------* SG *--------* IPSP *
******** *************** ******** ******** *************** ********
+------+ +------+ +------+ +------+
| TCAP | | TCAP | | TCAP | | TCAP |
+------+ +------+ +------+ +------+
| SCCP | | SCCP | | SCCP | | SCCP |
+------+ +-------------+ +------+ +------+ +-------------+ +------+
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b. M2PA: SG-IPSP connection is an SS7 link. b. M2PA: SG-IPSP connection is an SS7 link.
M2UA: SG-MGC connection is not an SS7 link. It is an M2UA: SG-MGC connection is not an SS7 link. It is an
extension of MTP to a remote entity. extension of MTP to a remote entity.
c. M2PA: SG is an SS7 node with a point code. c. M2PA: SG is an SS7 node with a point code.
M2UA: SG is not an SS7 node and has no point code. M2UA: SG is not an SS7 node and has no point code.
d. M2PA: SG can have upper SS7 layers, e.g., SCCP. d. M2PA: SG can have upper SS7 layers, e.g., SCCP.
M2UA: SG does not have upper SS7 layers since it has no MTP3. M2UA: SG does not have upper SS7 layers since it has no MTP3.
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
e. M2PA: relies on MTP3 for management procedures. e. M2PA: relies on MTP3 for management procedures.
M2UA: uses M2UA management procedures. M2UA: uses M2UA management procedures.
4.3 MTP lvl3-Users (ISUP, TUP, SCCP) over IP 4.3 MTP lvl3-Users (ISUP, TUP, SCCP) over IP
UAL: M3UA (SS7 MTP3 User Adaptation) UAL: M3UA (SS7 MTP3 User Adaptation)
M3UA protocol supports the transport of any SS7 MTP3-User signalling M3UA protocol supports the transport of any SS7 MTP3-User signalling
such as TUP, ISUP and SCCP over IP using the services of SCTP. such as TUP, ISUP and SCCP over IP using the services of SCTP.
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+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| L1 | | L1 | | IP | | IP | | L1 | | L1 | | IP | | IP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
SEP - SS7 Signalling End Point SEP - SS7 Signalling End Point
SCTP - Stream Control Transmission Protocol SCTP - Stream Control Transmission Protocol
NIF - Nodal Interworking Function NIF - Nodal Interworking Function
Communication between two IP nodes: Communication between two IP nodes:
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
******** IP ******** ******** IP ********
* IPSP *----------* IPSP * * IPSP *----------* IPSP *
******** ******** ******** ********
+------+ +------+ +------+ +------+
|SCCP- | |SCCP- | |SCCP- | |SCCP- |
| User | | User | | User | | User |
+------+ +------+ +------+ +------+
| SCCP | | SCCP | | SCCP | | SCCP |
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SUA does not pose stringent timing constraints on SCTP due to the SUA does not pose stringent timing constraints on SCTP due to the
fact that SUA applications have broad timing requirement (from 10 of fact that SUA applications have broad timing requirement (from 10 of
seconds to hours) which the applications guard themselves and the seconds to hours) which the applications guard themselves and the
timing supervision of the application is end-to-end, not hop-by- timing supervision of the application is end-to-end, not hop-by-
hop(as with ISUP). hop(as with ISUP).
Possible configurations are showed in the pictures below. Possible configurations are showed in the pictures below.
- Interconnection of SS7 and IP: - Interconnection of SS7 and IP:
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
******** *************** ******** ******** *************** ********
* SEP * IP * * IP * * * SEP * IP * * IP * *
* or *---------* SG *--------* ASP * * or *---------* SG *--------* ASP *
* STP * * * * * * STP * * * * *
******** *************** ******** ******** *************** ********
+------ +------+ +------ +------+
| SUAP | | SUAP | | SUAP | | SUAP |
+------+ +------+------+ +------+ +------+ +------+------+ +------+
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| SCTP | | SCTP | | SCTP | | SCTP |
+------+ +------+ +------+ +------+
| IP | | IP | | IP | | IP |
+------+ +------+ +------+ +------+
IANA has registered SCTP Port Number 14001 for SUA. It is IANA has registered SCTP Port Number 14001 for SUA. It is
recommended that SGs use this SCTP port number for listening for new recommended that SGs use this SCTP port number for listening for new
connections. The payload protocol identifier for the SCTP DATA chunks connections. The payload protocol identifier for the SCTP DATA chunks
is "4". is "4".
Draft Telephony Signalling AS October 2002 Draft Telephony signalling over SCTP AS January 2003
5 Security considerations 5 Security considerations
UALs are designated to carry signalling messages for telephony UALs are designated to carry signalling messages for telephony
services. As such, UALs must involve the security needs of several services. As such, UALs must involve the security needs of several
parties: the end users of the services; the network providers and parties: the end users of the services; the network providers and
the applications involved. Additional requirements may come from the applications involved. Additional requirements may come from
local regulation. While having some overlapping security needs, any local regulation. While having some overlapping security needs, any
security solution should fulfill all of the different parties' security solution should fulfill all of the different parties'
needs. See specific Security considerations in each UAL technical needs. See specific Security considerations in each UAL technical
specification. specification.
SCTP only tries to increase the availability of a network. SCTP does SCTP only tries to increase the availability of a network. SCTP does
not contain any protocol mechanisms which are directly related to not contain any protocol mechanisms which are directly related to
user message authentication, integrity and confidentiality communication security, i.e. user message authentication, integrity
functions. For such features, it depends on the IPSEC protocols and or confidentiality functions. For such features, it depends on
architecture and/or on security features of its user protocols. security protocols. In the field of system security, SCTP includes
mechanisms for reducing the risk of blind denial-of-service attacks
Mechanisms for reducing the risk of blind denial-of-service attacks as it is described in section 11 in RFC2960.
and masquerade attacks are built into SCTP protocol. See RFC2960,
section 11 for detailed information.
Currently the IPSEC working group is investigating the support of This document does not add any new components to the protocols
multihoming by IPSEC protocols. At the present time to use IPSEC, included in the discussion. For secure use of the SIGTRAN protocols
one must use 2 * N * M security associations if one endpoint uses N the readers should go through the "Security Considerations for
addresses and the other M addresses. SIGTRAN protocols" [RFCSIGSEC]). According to that document, the use
of the IPsec is the main recommendation to secure SIGTRAN protocols
in the Internet, but TLS is also considered as a perfectly valid
option to be used in certain scenarios. Recomendations of usage are
also included.
6 References and related work 6 References and related work
[RFC2960] Stewart, R. R., Xie, Q., Morneault, K., Sharp, C. , , [RFC2960] Stewart, R. R., Xie, Q., Morneault, K., Sharp, C. , ,
Schwarzbauer, H. J., Taylor, T., Rytina, I., Kalla, M., Zhang, Schwarzbauer, H. J., Taylor, T., Rytina, I., Kalla, M., Zhang,
L. and Paxson, V, "Stream Control Transmission Protocol", RFC2960, L. and Paxson, V, "Stream Control Transmission Protocol", RFC2960,
October 2000. October 2000.
[RF3257] Coene, L., Tuexen, M., Verwimp, G., Loughney, J., Stewart, [RF3257] Coene, L., Tuexen, M., Verwimp, G., Loughney, J., Stewart,
R. R., Xie, Q., Holdrege, M., Belinchon, M.C., and Jungmayer, A., R. R., Xie, Q., Holdrege, M., Belinchon, M.C., and Jungmayer, A.,
"Stream Control Transmission Protocol Applicability statement", "Stream Control Transmission Protocol Applicability statement",
RFC3257, April 2002. RFC3257, April 2002.
[RFC2719] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene, [RFC2719] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene,
L., Lin, H., Juhasz, I., Holdrege, M., Sharp, C., "Framework L., Lin, H., Juhasz, I., Holdrege, M., Sharp, C., "Framework
Architecture for Signalling Transport", RFC2719, October 1999. Architecture for Signalling Transport", RFC2719, October 1999.
[RFC3057] Morneault, K., Rengasami, S., Kalla, M., Sidebottom, G., Draft Telephony signalling over SCTP AS January 2003
Draft Telephony Signalling AS October 2002
[RFC3057] Morneault, K., Rengasami, S., Kalla, M., Sidebottom, G.,
"ISDN Q.921-User Adaptation Layer", RFC3057, February 2001. "ISDN Q.921-User Adaptation Layer", RFC3057, February 2001.
[RFC3331] Morneault, K., Dantu, R., Sidebottom, G., George, T., [RFC3331] Morneault, K., Dantu, R., Sidebottom, G., George, T.,
Bidulock, B., Heitz , J., "Signaling System 7 (SS7) Message Transfer Bidulock, B., Heitz , J., "Signaling System 7 (SS7) Message Transfer
Part (MTP) 2 - User Adaptation Layer", RFC3331, September 2002. Part (MTP) 2 - User Adaptation Layer", RFC3331, September 2002.
[RFC3332] Sidebottom, G., Pastor-Balbas, J., Rytina, I., Mousseau, [RFC3332] Sidebottom, G., Pastor-Balbas, J., Rytina, I., Mousseau,
G., Ong, L., Schwarzbauer, H.J., Gradischnig, K., Morneault, K., G., Ong, L., Schwarzbauer, H.J., Gradischnig, K., Morneault, K.,
Kalla, M., Glaude, N., Bidulock, B., Loughney, J., "SS7 MTP3-User Kalla, M., Glaude, N., Bidulock, B., Loughney, J., "SS7 MTP3-User
Adaptation Layer (M3UA)", RFC3332, September 2002. Adaptation Layer (M3UA)", RFC3332, September 2002.
skipping to change at page 21, line 37 skipping to change at page 21, line 38
[RFCqqqq] Weilandt, E., Khanchandani, N., Rao, S.,"V5.2-User [RFCqqqq] Weilandt, E., Khanchandani, N., Rao, S.,"V5.2-User
Adaptation Layer (V5UA)", RFCqqqq, June 2002 Adaptation Layer (V5UA)", RFCqqqq, June 2002
[RFCtttt] Vydyam, A., Mukundan, R., Mangalpally, N., Morneault, [RFCtttt] Vydyam, A., Mukundan, R., Mangalpally, N., Morneault,
K.,"DPNSS/DASS 2 extensions to the IUA protocol", RFCtttt, August K.,"DPNSS/DASS 2 extensions to the IUA protocol", RFCtttt, August
2002. 2002.
[ALLMAN99] Allman, M. and Paxson, V., "On Estimating End-to-End [ALLMAN99] Allman, M. and Paxson, V., "On Estimating End-to-End
Network Path Properties", Proc. SIGCOMM'99, 1999. Network Path Properties", Proc. SIGCOMM'99, 1999.
[RFCSIGSEC] Loughney, J., Tuexen, M. and Pastor-Balbas, J.,"Security
Considerations for SIGTRAN Protocols",
draft-ietf-sigtran-security-00.txt, work in progress
7 Acknowledgments 7 Acknowledgments
This document was initially developed by a design team consisting of This document was initially developed by a design team consisting of
Lode Coene, John Loughney, Michel Tuexen, Randall R. Stewart, Lode Coene, John Loughney, Michel Tuexen, Randall R. Stewart,
Qiaobing Xie, Matt Holdrege, Maria-Carmen Belinchon, Andreas Qiaobing Xie, Matt Holdrege, Maria-Carmen Belinchon, Andreas
Jungmaier, Gery Verwimp and Lyndon Ong. Jungmaier, Gery Verwimp and Lyndon Ong.
Draft Telephony signalling over SCTP AS January 2003
The authors wish to thank Renee Revis, H.J. Schwarzbauer, T. Taylor, The authors wish to thank Renee Revis, H.J. Schwarzbauer, T. Taylor,
G. Sidebottom, K. Morneault, T. George, M. Stillman and many others G. Sidebottom, K. Morneault, T. George, M. Stillman and many others
for their invaluable comments. for their invaluable comments.
8 Author's Address 8 Author's Address
Draft Telephony Signalling AS October 2002
Lode Coene Phone: +32-14-252081 Lode Coene Phone: +32-14-252081
Siemens Atea EMail: lode.coene@siemens.atea.be Siemens Atea EMail: lode.coene@siemens.com
Atealaan 34 Atealaan 34
B-2200 Herentals B-2200 Herentals
Belgium Belgium
Javier Pastor-Balbas Phone: Javier Pastor-Balbas Phone: +34-91-3393819
Ericsson Espana S.A. Email: j.javier.pastor@ericsson.com Ericsson Espana S.A. Email: j.javier.pastor@ericsson.com-
C/ Retama 1 C/ Retama 1
28045 Madrid 28045 Madrid
Spain Spain
Expires: August 2002
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished This document and translations of it may be copied and furnished
to others, and derivative works that comment on or otherwise to others, and derivative works that comment on or otherwise
explain it or assist in its implementation may be prepared, explain it or assist in its implementation may be prepared,
copied, published and distributed, in whole or in part, without copied, published and distributed, in whole or in part, without
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and this paragraph are included on all such copies and derivative and this paragraph are included on all such copies and derivative
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skipping to change at page 22, line 47 skipping to change at page 23, line 4
languages other than English. languages other than English.
The limited permissions granted above are perpetual and will not The limited permissions granted above are perpetual and will not
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ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
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THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
Draft Telephony signalling over SCTP AS January 2003
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Draft Telephony Signalling AS October 2002 -
 End of changes. 

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