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TS 25.432
UTRAN – Iub Interface –
Signalling Transport

V18.0.0 (PDF)  2024/03  11 p.
V17.0.0  2022/03  11 p.
V16.0.0  2020/06  11 p.
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V7.1.0  2007/03  10 p.
V6.0.0  2004/01  10 p.
V5.1.0  2002/10  10 p.
V4.0.0  2001/04  9 p.
V3.1.0  1999/10  9 p.
Mr. Wilson, Mick

Content for  TS 25.432  Word version:  18.0.0

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1  Scopep. 5

The present document specifies the signalling transport related to NBAP signalling to be used across the Iub Interface. The Iub interface is a logical interface for the interconnection of Node B and Radio Network Controller (RNC) components of the UMTS Terrestrial Radio Access Network (UTRAN) for the UMTS system. The radio network control signalling between these nodes is based on the Node B application part (NBAP).

2  Referencesp. 5

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
ITU-T Recommendation Q.2100 (1994-07): "B-ISDN signalling ATM adaptation layer (SAAL) overview description".
ITU-T Recommendation Q.2130 (1994-07): "B-ISDN signalling ATM adaptation layer - Service specific coordination function for support of signalling at the user network interface (SSCF-UNI)".
ITU-T Recommendation Q.2110 (1994-07): "B-ISDN ATM adaptation layer - Service specific connection oriented protocol (SSCOP)".
ITU-T Recommendation I.363.5 (1996-08): "B-ISDN ATM Adaptation LayerSpecification : Type 5 AAL".
ITU-T Recommendation I.361 (1995-11): "B-ISDN ATM layer specification".
ITU-T Recommendation I.630 (1999-02): "ATM protection switching".
RFC 2960  (2000-10): "Stream Control Transmission Protocol".
RFC 2460  (1998-12): "Internet Protocol, Version 6 (IPv6) Specification".
RFC 791  (1981-09): "Internet Protocol".
RFC 2474  (1998-12): "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers".
RFC 1661  (1994-07): "The Point-to-Point Protocol (PPP)".
RFC 1662  (1994-07): "PPP in HDLC-like Framing".
RFC 2507  (1999-02): "IP header compression".
RFC 1990  (1996-08): "The PPP Multilink Protocol (MP)".
RFC 2686  (1999-09): "The Multi-Class Extension to Multi-Link PPP".
RFC 2509  (1999-02): "IP Header Compression over PPP".
RFC 3153  (2001-08): "PPP Multiplexing".
RFC 2364  (1998-07): "PPP over AAL5".
RFC 3031  (2001-01): "Multiprotocol Label Switching Architecture".
RFC 3309  (2002-09): "Stream Control Transmission Protocol (SCTP) Checksum Change".
TS 25.433: "UTRAN Iub interface Node B Application Part (NBAP) signalling".

3  Definitions, symbols and abbreviationsp. 6

3.1  Definitionsp. 6

For the purposes of the present document, the following terms and definitions apply:
IP UTRAN node:
An UTRAN Node supporting the IP Transport Option

3.2  Symbolsp. 6


3.3  Abbreviationsp. 6

ATM Adaptation Layer
Asynchronous Transfer Mode
High-level Data Link Control
Internet Protocol
Node B Application Part
Point-to-Point Protocol
Radio Network Controller
Signalling ATM Adaptation Layer
Stream Control Transmission Protocol
Service Specific Coordination Function
Service Specific Connection Oriented Protocol
User-Network Interface

4  Data Link Layerp. 6

4.1  ATM Transport Optionp. 6

ATM shall be used in the radio network control plane according to ITU-T Rec. I.361 [5].

4.1.1  Protection switching at ATM Layerp. 6

If redundancy of pathways at ATM layer between RNC and Node B is supported, it shall be implemented using ATM Protection Switching according to ITU-T Rec. I.630 [6].

4.2  Data Link Layer for IP Transport Optionp. 6

A RNC or Node B supporting IP Transport Option shall support the PPP protocol with HDLC framing (IETF RFC 1661 [11], IETF RFC 1662 [12]).
A RNC or Node B supporting IP transport option and having interfaces connected via slow bandwidth PPP links like E1/T1/J1 shall also support IP Header Compression (IETF RFC 2507 [13]) and the PPP extensions ML/MC-PPP (IETF RFC 1990 [14], IETF RFC 2686 [15]). In this case, negotiation of header compression (IETF RFC 2507 [13]) over PPP shall be performed via (IETF RFC 2509 [16]).

5  NBAP signalling bearerp. 7

5.1  Introductionp. 7

The Signalling Bearer for NBAP (TS 25.433) is a point-to-point protocol. There may be multiple point-to-point links between an RNC and a Node B. As shown in Figure 1, the standard allows operators to choose one out of two protocol suites for transporting the NBAP messages.
Copy of original 3GPP image for 3GPP TS 25.432, Fig. 1: Iub NBAP Signalling Transport
Figure 1: Iub NBAP Signalling Transport
(⇒ copy of original 3GPP image)

5.2  Signalling bearer in case of ATM Transport Optionp. 7

The signalling bearer in the Radio Network Control Plane is SAAL-UNI (ITU-T Rec. Q.2100 [1]) over ATM. The protocols to be used to support NBAP signalling are SSCF-UNI (ITU-T Rec. Q.2130 [2]) on top of SSCOP (ITU-T Rec. Q.2110 [3]) and AAL Type 5 (ITU-T Rec. I.363.5 [4]).

5.3  Signalling bearer in case of IP Transport Optionp. 7

SCTP (IETF RFC 2960 [7]) over IP shall be supported as the transport for NBAP signalling bearer on Iub Interface. A RNC equipped with the SCTP stack option shall initiate the INIT procedure for establishing association. The data link layer is as specified in chapter 4.2.
The checksum method specified in IETF RFC 3309 [20] shall be used instead of the method specified in IETF RFC 2960 ([7]).
An IP UTRAN node shall support IPv6 (IETF RFC 2460 [8]). The support of IPv4 (IETF RFC 791 [9]) is optional.
IP dual stack is recommended for the potential transition period from IPv4 to IPv6 in the transport network.
Each signalling bearer between the RNC and Node B shall correspond to one single SCTP stream in UL and one single SCTP stream in DL direction, both streams belonging to the same SCTP association.
IP Differentiated Services code point marking (IETF RFC 2474 [10]) shall be supported. The Diffserv code point may be determined from the application parameters.

$  Change Historyp. 9

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