ETSI TS 148 016 V17.0.0 (2022-05)

Digital cellular telecommunications system (Phase 2+) (GSM); General Packet Radio Service (GPRS); Base Station System (BSS) - Serving GPRS Support Node (SGSN) interface; Network service (3GPP TS 48.016 version 17.0.0 Release 17)

RTS/TSGR-0048016vh00

General Information

• Status: Not Published
• Technical Committee: 3GPP RAN - Technical Specification Group Radio Access Network
• Current Stage: 12 - Completion
• Completion Date: 05-May-2022

Standards Content (Sample)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
General Packet Radio Service (GPRS);
Base Station System (BSS)
- Serving GPRS Support Node (SGSN) interface;
Network service
(3GPP TS 48.016 version 17.0.0 Release 17)

R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
3GPP TS 48.016 version 17.0.0 Release 17 1 ETSI TS 148 016 V17.0.0 (2022-05)

Reference
RTS/TSGR-0048016vh00
Keywords
GSM
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - APE 7112B
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° w061004871

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
If you find a security vulnerability in the present document, please report it through our
Coordinated Vulnerability Disclosure Program:
https://www.etsi.org/standards/coordinated-vulnerability-disclosure
Notice of disclaimer & limitation of liability
The information provided in the present deliverable is directed solely to professionals who have the appropriate degree of
experience to understand and interpret its content in accordance with generally accepted engineering or
other professional standard and applicable regulations.
No recommendation as to products and services or vendors is made or should be implied.
No representation or warranty is made that this deliverable is technically accurate or sufficient or conforms to any law
rule and/or regulation and further, no representation or warranty is made of merchantability or fitness
and/or governmental
for any particular purpose or against infringement of intellectual property rights.
In no event shall ETSI be held liable for loss of profits or any other incidental or consequential damages.

Any software contained in this deliverable is provided "AS IS" with no warranties, express or implied, including but not
limited to, the warranties of merchantability, fitness for a particular purpose and non-infringement of intellectual property
rights and ETSI shall not be held liable in any event for any damages whatsoever (including, without limitation, damages
for loss of profits, business interruption, loss of information, or any other pecuniary loss) arising out of or related to the use
of or inability to use the software.
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2022.
All rights reserved.
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 2 ETSI TS 148 016 V17.0.0 (2022-05)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to
ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (https://ipr.etsi.org/).
Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not
referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,
essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the ®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Legal Notice
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities. These shall be
interpreted as being references to the corresponding ETSI deliverables.
The cross reference between 3GPP and ETSI identities can be found under http://webapp.etsi.org/key/queryform.asp.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 3 ETSI TS 148 016 V17.0.0 (2022-05)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 6
1 Scope . 7
2 References . 7
3 Definitions, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Symbols . 9
3.3 Abbreviations . 9
4 Network Service general description . 10
4.1 Overview . 10
4.2 Addressing . 11
4.2.1 Network Service Virtual Link (NS-VL) . 11
4.2.2 Network Service Virtual Connection (NS-VC) . 12
4.2.3 Network Service Virtual Connection Group . 13
4.2.4 BSSGP Virtual Connection (BVC) . 13
4.2.5 Use of Concepts on the Gb Interface when Intra Domain Connection of RAN Nodes to Multiple CN
Nodes applies in the BSS . 14
4.3 Sub-Network Service functions . 14
4.4 Load sharing function . 15
4.4.1 Load Sharing function for the Frame Relay Sub-Network . 15
4.4.1.1 Overview . 15
4.4.1.2 Requirements on load sharing function . 15
4.4.2 Load sharing function for the IP Sub-Network . 15
4.4.2.1 Overview . 15
4.4.2.2 Selection of the local IP endpoint . 16
4.4.2.3 Selection of the remote IP endpoint . 16
4.4.2.3.1 Selection of remote IP endpoint for data traffic . 16
4.4.2.3.2 Selection of remote IP endpoint for signalling traffic . 17
4.4a Resource distribution function . 17
4.4a.1 Requirements on resource distribution function . 17
4.5 NS-VC management function . 18
4.5.1 Blocking / unblocking of an NS-VC . 18
4.5.2 Reset of an NS-VC . 18
4.5.3 Test of an NS-VC . 19
5 Elements for layer-to-layer communication . 19
5.1 Service primitive model . 19
5.2 Service primitives and parameters . 19
5.2.1 Primitives . 20
5.2.1.1 NS-UNITDATA-Request . 20
5.2.1.2 NS-UNITDATA-Indication . 20
5.2.1.3 NS-CONGESTION-Indication . 20
5.2.1.4 NS-STATUS-Indication . 20
5.2.2 Parameters. 20
5.2.2.1 NS SDU . 20
5.2.2.2 Link Selector Parameter . 21
5.2.2.3 BVCI I and NSEI . 21
5.2.2.4 Congestion cause . 21
5.2.2.5 Transfer capability . 21
5.2.2.6 NS affecting cause. 21
5.2.2.7 NS change IP endpoint . 21
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 4 ETSI TS 148 016 V17.0.0 (2022-05)
6 Sub-Network Service protocol . 22
6.1 Frame Relay support of the Sub-Network Service protocol . 22
6.1.1 Overview . 22
6.1.2 Network configuration . 22
6.1.3 Services expected from layer 1 . 23
6.1.4 Options selected from FRF 1.1 . 23
6.1.4.1 Support of DL-CONTROL sub-layer. 23
6.1.4.2 Frame length . 23
6.1.4.3 Congestion control procedures . 23
6.1.4.3.1 DE bit usage . 23
6.1.4.3.2 FECN and BECN bit usage . 23
6.1.4.4 Signalling procedures . 24
6.1.4.5 C/R bit usage . 24
6.1.5 Abnormal conditions. 24
6.2 IP Support of the Sub-Network Service Protocol . 24
6.2.1 Overview . 24
6.2.1a Abnormal Conditions . 25
6.2.2 IP Fragmentation . 25
6.2.3 Services expected from layer 1 and layer 2 . 25
6.2.4 Size Procedure . 25
6.2.4.1 Abnormal Conditions . 26
6.2.5 Configuration Procedure . 26
6.2.5.1 Abnormal Conditions . 27
6.2.6 Add Procedure . 28
6.2.6.1 Abnormal Conditions . 28
6.2.7 Delete Procedure . 29
6.2.7.1 Abnormal Conditions . 29
6.2.8 ChangeWeight Procedure . 29
6.2.8.1 Abnormal Conditions . 30
7 Network Service Control protocol . 30
7.1 Procedures for the transmission of NS SDUs . 30
7.1.1 Abnormal Conditions . 30
7.2 Blocking / unblocking procedures . 30
7.2.1 Abnormal Conditions . 32
7.3 Reset procedure . 32
7.3.1 Abnormal conditions. 33
7.4 Test procedure for a Frame Relay Sub-network . 33
7.4.1 Abnormal conditions. 34
7.4b Test Procedure for an IP Sub-network . 34
7.4b.1 Abnormal Conditions . 34
7.4b.1.1 Abnormal Conditions for signalling endpoints . 34
7.4b.1.2 Abnormal Conditions for data endpoints . 35
7.5 Procedure for error reporting . 35
7.5.1 Abnormal conditions. 35
7.6 Resource Distribution Procedure . 35
7.6.1 Abnormal Conditions . 36
8 General protocol error handling . 36
8.1 General case . 36
8.1.1 Presence requirements of Information Elements . 36
8.1.2 Erroneous events . 37
8.1.3 Non-erroneous events . 37
8.1.4 Other events . 38
8.2 Special cases . 38
8.2.1 Deviations from the "General case" sub-clause . 38
8.2.2 Error reporting . 38
9 General PDU definitions and contents . 38
9.1 General structure of a PDU . 38
9.2 Network Service Control PDUs . 39
9.2.1 NS-ALIVE . 39
9.2.2 NS-ALIVE-ACK . 40
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 5 ETSI TS 148 016 V17.0.0 (2022-05)
9.2.3 NS-BLOCK . 40
9.2.4 NS-BLOCK-ACK . 40
9.2.5 NS-RESET . 41
9.2.6 NS-RESET-ACK . 41
9.2.7 NS-STATUS . 41
9.2.7.1 Static conditions for NS-VCI . 42
9.2.7.2 Static conditions for NS PDU . 42
9.2.7.3 Static conditions for BVCI . 42
9.2.7.4 Static conditions for List of IP4 Elements. 42
9.2.7.5 Static conditions for List of IP6 Elements. 42
9.2.8 NS-UNBLOCK . 43
9.2.9 NS-UNBLOCK-ACK . 43
9.2.10 NS-UNITDATA . 43
9.3 Sub-Network Service Control PDUs . 43
9.3.1 SNS-ACK . 43
9.3.2 SNS-ADD . 44
9.3.3 SNS-CHANGEWEIGHT . 44
9.3.4 SNS-CONFIG . 44
9.3.5 SNS-CONFIG-ACK . 45
9.3.6 SNS-DELETE . 45
9.3.7 SNS-SIZE . 45
9.3.8 SNS-SIZE-ACK . 46
10 General information elements coding . 46
10.1 General structure of the information elements . 46
10.1.1 Information Element Identifier . 47
10.1.2 Length indicator . 47
10.2 Information element description . 47
10.3 Information elements . 48
10.3.1 BVCI . 48
10.3.2 Cause . 48
10.3.2a End Flag . 49
10.3.2b IP Address . 49
10.3.2c List of IP4 Elements . 50
10.3.2d List of IP6 Elements . 50
10.3.2e Maximum Number of NS-VCs . 50
10.3.2f Number of IP4 Endpoints . 51
10.3.2g Number of IP6 Endpoints . 51
10.3.3 NS PDU . 51
10.3.4 NS SDU . 51
10.3.5 NS-VCI . 52
10.3.6 NSEI . 52
10.3.7 PDU type . 52
10.3.7a Reset Flag . 52
10.3.8 (void) . 53
10.3.9 NS SDU Control Bits . 53
10.3.10 Transaction ID . 53
11 List of system variables . 53
Annex A (informative): Recommended usage of BVCI and NSEI. 55
Annex B (informative): Recommended usage of Resource Distribution for IP . 56
Annex C (informative): Change History . 59
History . 60

ETSI
3GPP TS 48.016 version 17.0.0 Release 17 6 ETSI TS 148 016 V17.0.0 (2022-05)
Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 7 ETSI TS 148 016 V17.0.0 (2022-05)
1 Scope
The present document specifies the Network Service used on the Base Station System (BSS) to Serving GPRS Support
Node (SGSN) interface (Gb interface).
The protocol stack on the Gb interface is defined in the stage 2 Technical Specification 3GPP TS 43.060.
The Network Service entity provides network services to the BSSGP entity specified in 3GPP TS 48.018.
The layer 1 of the Gb interface is specified in 3GPP TS 48.014.
In the present document, the communication between adjacent layers and the services provided by the layers are
distributed by use of abstract service primitives. But only externally observable behaviour resulting from the description
is normatively prescribed by the present document.
The service primitive model used in the present document is based on the concepts developed in ITU-T
Recommendation X.200.
2 References
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.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 22.060: "General Packet Radio Service (GPRS); Service description; Stage 1".
[3] 3GPP TS 23.060: "General Packet Radio Service (GPRS); Service description; Stage 2".
[4] 3GPP TS 48.014: "General Packet Radio Service (GPRS); Base Station System (BSS) - Serving
GPRS Support Node (SGSN) interface; Gb interface Layer 1".
[5] 3GPP TS 48.018: "General Packet Radio Service (GPRS); Base Station System (BSS) - Serving
GPRS Support Node (SGSN); BSS GPRS Protocol (BSSGP)".
[6] FRF 1.1 (1996): "User-to-Network Implementation Agreement (UNI)".
[7] (void).
[8] ITU-T Recommendation Q.921 (1997): "ISDN user-network interface - Data link layer
specification".
[9] ITU-T Recommendation Q.922 (1992): "ISDN data link layer specification for frame mode bearer
services".
[10] ITU-T Recommendation Q.931 (1998): "ISDN user-network interface layer 3 specification for
Basic Call Control".
[11] ITU-T Recommendation Q.933 (1995): "Digital Subscriber Signalling System No. 1
(DSS 1) - Signalling specifications for frame mode switched and permanent virtual connection
control and status monitoring".
[12] ITU-T Recommendation I.370 (1991): "Congestion management for the ISDN Frame Relaying
Bearer Service".
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 8 ETSI TS 148 016 V17.0.0 (2022-05)
[13] ITU-T Recommendation X.200 (White Book): "Information technology - Open Systems
Interconnection - Basic Reference Model: The basic model".
[14] ANSI T1.602: "ISDN - Data Link Layer Signalling Specification for Application at the
User-Network Interface".
[15] ANSI T1.606 (1990): "Frame Relaying Bearer Service Architectural Framework and Service
description (R 1996)".
[16] ANSI T1.617 (1991): "Digital Subscriber System No. 1 (DSS1) Signaling Specification for Frame
Relay Bearer Service (R1997)".
[17] ANSI T1.618 (1991): "Digital Subscriber System No. 1 (DSS1) Core Aspects of Frame Relay
Protocol for Use with Frame Relay Bearer Service (R1997)".
[18] IETF RFC 768 (1980): "User Datagram Protocol" (STD 6).
[19] IETF RFC 791 (1981): "Internet Protocol" (STD 5).
[20] IETF RFC 2460 (1998): "Internet Protocol, Version 6 (IPv6) Specification".
[21] 3GPP TS 23.236: "Intra-domain connection of Radio Access Network (RAN) nodes to multiple
Core Network (CN) nodes".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TS 22.060 and the following in
apply:
BSSGP Virtual Connection (BVC): end-to-end virtual communication path between remote Network Service user
entities
BSSGP Virtual Connection Identifier (BVCI): identifier of a BVC, having end-to-end significance across the Gb
interface
IP endpoint: an endpoint defined by its IP address and UDP port. An IP endpoint can be a data endpoint and/or a
signalling endpoint
Data IP endpoint: an IP endpoint used for Data traffic
Signalling IP endpoint: an IP endpoint used for Signalling traffic
Data traffic: data traffic for an IP Sub-Network is defined as NS SDUs for PTP and PTM functional entities (BVCI≥1)
Signalling traffic: signalling traffic for an IP Sub-Network is defined as NS SDUs for Signalling functional entities
(BVCI=0) and all PDUs for IP Sub-Network Service Control
Full Mesh Connectivity: any IPv4 endpoint in an NSE is capable of communications with any IPv4 endpoint in its
peer NSE. Also any IPv6 endpoint in an NSE is capable of communications with any IPv6 endpoint in its peer NSE
Network Service Entity Identifier (NSEI): identifier of an NS Entity having end-to-end significance across the Gb
interface, i.e. the peer NSEs on the BSS side and the SGSN side are identified by the same NSEI value
Network Service Virtual Connection (NS-VC): end-to-end virtual communication path between Network Service
peer entities
Network Service Virtual Connection Identifier (NS-VCI): identifier of an NS-VC having end-to-end significance
across the Gb interface
Network Service Virtual Link (NS-VL): virtual communication path between the BSS or the SGSN and the
intermediate network, or between the BSS and the SGSN in case of direct point-to-point configuration
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 9 ETSI TS 148 016 V17.0.0 (2022-05)
Network Service Virtual Link Identifier (NS-VLI): identifier of an NS-VL, having local significance at the BSS or
SGSN
Network Service Virtual Connection Group: groups all NS-VCs together which provide communication between the
same peer NS entities. This grouping has local significance at the BSS or SGSN
Blocked / unblocked: when an NS-VC can not be used for NS user traffic, it is blocked. When an NS-VC can be used
for NS user traffic, it is unblocked
Dead / alive: when an NS-VC is able to provide communication between remote NS entities, it is alive. When it is not
able, it is dead. These states are supervised by means of a test procedure, as further described in the present document
Pool area: an area within which an MS may roam without need to change the serving SGSN. A pool area is served by
one or more SGSNs in parallel. All the cells controlled by a BSC belong to the same one (or more) pool area(s).
3.2 Symbols
For the purposes of the present document, the symbols given in 3GPP TS 23.060 apply.
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TS 21.905 and the following apply:
BECN Backward Explicit Congestion Notification
BSSGP Base Station System GPRS Protocol
BVC BSSGP Virtual Connection
BVCI BSSGP Virtual Connection Identifier
CLLM Consolidated Link Layer Management
DE Discard Eligibility
FECN Forward Explicit Congestion Notification
FR Frame Relay
FRF Frame Relay Forum
IP Internet Protocol
IPv4 Internet Protocol version 4
IPv6 Internet Protocol version 6
LLC Logical Link Control
LSP Link Selector Parameter
MAC Medium Access Control
NS Network Service
NSEI Network Service Entity Identifier
NS-SAP Network Service Service Access Point
NS-VC Network Service Virtual Connection
NS-VCI Network Service Virtual Connection Identifier
NS-VL Network Service Virtual Link
NS-VLI Network Service Virtual Link Identifier
PDU Protocol Data Unit
PTM Point-To-Multipoint
PTP Point-To-Point
PVC Permanent Virtual Connection
RLC Radio Link Control
SGSN Serving GPRS Support Node
SNS Sub-Network Service
UDP User Datagram Protocol
UNI User-to-Network Interface
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 10 ETSI TS 148 016 V17.0.0 (2022-05)
4 Network Service general description
4.1 Overview
The position of the Network Service within the protocol stack of the Gb interface is shown in figure 4.1.1.

LLC
RELAY
BSSGP
RLC BSSGP
MAC
NS NS
L1 L1
Gb
BSS SGSN
NOTE: BSSGP, L1, LLC, MAC, RELAY, RLC are outside the scope of the present document, refer to
3GPP TS 43.060 for further details.

Figure 4.1.1: Position of the NS within the Gb interface protocol stack
The Network Service performs the transport of NS SDUs between the SGSN and BSS. The services provided to the NS
user shall be:
- Network Service SDU transfer. The Network Service entity shall provide network service primitives allowing
for transmission and reception of upper layer protocol data units between the BSS and SGSN. The NS SDUs are
transferred in order by the Network Service, but under exceptional circumstances order may not be maintained.
- Network congestion indication. Congestion recovery control actions may be performed by the Sub-Network
Service (e.g. Frame Relay). Congestion reporting mechanisms available in the Sub-Network Service
implementation shall be used by the Network Service to report congestion.
- Status indication. Status indication shall be used to inform the NS user of the NS affecting events e.g. change in
the available transmission capabilities.
The Network Service entity is composed of an entity dependent on the intermediate transmission network used on the
Gb interface, the Sub-Network Service, and of a control entity independent from that network, the Network Service
Control. There is a hierarchical relationship between both entities. This is reflected in figure 4.1.2. The detailed
communication mechanisms between both entities is an internal matter for the Network Service and is not further
standardized.
Network Service
Network Service Control /
Network Service Control protocol
Sub-Network Service /
Sub-Network Service protocol
Figure 4.1.2: Internal architecture of the Network Service
ETSI
3GPP TS 48.016 version 17.0.0 Release 17 11 ETSI TS 148 016 V17.0.0 (2022-05)
The Sub-Network Service entity provides a communication service to Network Service Control peer entities. The
Network Service Control peer entities use the Sub-Network Service for communication with each other. The peer-to-
peer communication accross the Gb interface between remote Network Service Control entities is performed over
Network Service Virtual Connections (NS-VCs). An NS-VC is a virtual communication path between Network Service
Control peer entities.
The Network Service entity provides a communication service to NS user peer entities: the peer-to-peer communication
between remote NS user entities is performed over BSSGP Virtual Connections (BVCs). A BVC is a virtual
communication path between Network Service user peer entities. A Network Service Entity comm
...