ETSI ETS 300 211 ed.1 (1992-12)

SLOVENSKI STANDARD
01-december-2003
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Network Aspects (NA); Metropolitan Area Network (MAN); Principles and architecture
Ta slovenski standard je istoveten z: ETS 300 211 Edition 1
ICS:
35.110 Omreževanje Networking
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 211
TELECOMMUNICATION December 1992
STANDARD
Source: ETSI TC-NA Reference: DE/NA-053020
ICS: 33.040
Key words: Network, MAN, principles
Network Aspects (NA);
Metropolitan Area Network (MAN)
Principles and architecture
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1992. All rights reserved.

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ETS 300 211: December 1992
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 211: December 1992
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .9
3.1 Definitions .9
3.1.1 Interfaces.9
3.1.2 Network elements.9
3.1.3 Functions.10
3.1.4 Services.10
3.2 Alphabetical list of terms.11
3.3 Abbreviations .11
4 Basic principles .14
5 Functional architecture.16
5.1 General architecture .16
5.2 Reference configuration and functions .19
5.2.1 Reference points .19
5.2.2 List of functional groups .19
5.2.3 List of functions .21
5.3 Access Facilities (AFs) .23
5.3.1 Access facility 1 (AF1).23
5.3.2 Access Facility 2 (AF2).24
5.3.2.1 User Specific Interfaces (USIs) .25
5.3.2.1.1 USI based on ISO/IEC 8802-3 (CSMA/CD) .25
5.3.2.1.2 USI based on ISO/IEC 8802-5 (Token Ring).26
6 Protocol reference model for MANs.34
6.1 Generic reference model .34
6.2 Protocol reference model.34
6.3 Extension of the MAN PRM to accommodate encapsulation of MAC-PDUs containing
48 bit addresses.35
6.4 Application of the PRM for Access Facility 1 .36
6.5 Application of the PRM for Access Facility 2 .36
6.5.1 Application of the PRM for Access Facility 2a.36
6.5.2 Application of the PRM for Access Facility 2b.37
7 Addressing principles .43
7.1 Individual addresses .43
7.2 Group addresses .43
8 MAN management .43
8.1 MAN management framework.43
8.2 Generic MAN management functional architecture.44
Annex A (informative): MAN Switching System (MSS) .45
A.1 MSS management functions.45
A.2 Control & switching functions .45
A.3 DQDB access termination.45

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ETS 300 211: December 1992
A.4 Transit access termination. 45
A.5 DQDB access termination configurations. 46
Annex B (informative): Bibliography . 49
History. 50

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ETS 300 211: December 1992
Foreword
This European Telecommunication Standard (ETS) has been prepared by the Network Aspects (NA)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS describes the basic principles of the European Metropolitan Area Network (MAN) concept and is
elaborated, taking into account the following:
- the emerging demand for multi-megabit communication services, especially for business users;
- the availability of new network technology based on distributed access over a shared broadband
medium;
- the strategic need that the development and introduction of MAN products in Europe be driven by
adequate ETSI standards;
- the requirement that MAN standardisation takes into account ongoing standardisation work on
Broadband Integrated Services Digital Network (B-ISDN) and generate the necessary output so as
to influence B-ISDN development.
MANs will promote B-ISDN by enabling network operators to timely offer a subset of B-ISDN services; in
this way, user demand and provision of MANs should provide a graceful evolution towards B-ISDN by
facilitating the access to this network.
The description of interworking aspects between the MAN and the transit network will be provided in the
relevant ETSI documents.
General aspects of MAN management are defined in this ETS. More detailed information will be provided
in the relevant ETSI documents.

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ETS 300 211: December 1992
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ETS 300 211: December 1992
1 Scope
This European Telecommunication Standard (ETS) describes the basic principles and network
architecture for an European Metropolitan Area Network (MAN).
This ETS defines and describes the MAN reference configuration and the functional blocks between the
Customer Network (CN) and the MAN Switching System (MSS), which is described in Annex A
(informative).
In addition, this ETS defines the protocol reference model for MANs, and is the basis for the development
of companion ETSs related to MAN protocols (ETS 300 212 to ETS 300 216, [19] to [23], inclusive).
General aspects of MAN management are also defined in this ETS.
The MAN definition takes into account the final goal of providing an easy integration with Broadband
Integrated Services Digital Network (B-ISDN).
The protocol chosen as the basis for this ETS is the IEEE Standard 802.6 [1].
The specification of performance figures is outside the scope of this ETS.
2 Normative references
This ETS incorporates, by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to, or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] IEEE Standard 802.6 (1990): "Distributed Queue Dual Bus (DQDB) Subnetwork
of a metropolitan area network (MAN)".
[2] CCITT Recommendation I.431 (1988): "Primary rate user-network interface -
Layer 1 specification".
[3] CCITT Recommendation M.30 (1989): "Principles for a telecommunications
management network".
[4] CCITT Recommendation X.200 (1988): "Reference model of open systems
interconnection for CCITT applications".
[5] CCITT Recommendation I.113 (1991): "Vocabulary of terms for broadband
aspects of ISDN".
[6] CCITT Recommendation I.121 (1991): "Broadband aspects of ISDN".
[7] CCITT Recommendation I.150 (1991): "B-ISDN asynchronous transfer mode
functional characteristics".
[8] CCITT Recommendation I.211 (1991): "B-ISDN service aspects".
[9] CCITT Recommendation I.311 (1991): "B-ISDN general network aspects".
[10] CCITT Recommendation I.321 (1991): "B-ISDN protocol reference model and
its application".
[11] CCITT Recommendation I.327 (1991): "B-ISDN functional architecture".
[12] CCITT Recommendation I.361 (1991): "B-ISDN ATM layer specification".
[13] CCITT Recommendation I.362 (1991): "B-ISDN ATM adaptation layer (AAL)
functional description".
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ETS 300 211: December 1992
[14] CCITT Recommendation I.363 (1991): "B-ISDN ATM adaptation layer (AAL)
specification".
[15] CCITT Recommendation I.413 (1991): "B-ISDN user network interface".
[16] CCITT Recommendation I.432 (1991): "B-ISDN user network interface Physical
layer specification".
[17] CCITT Recommendation I.610 (1991): "OAM principles of the B-ISDN access".
[18] ISO/IEC 10038: "Information technology - Telecommunications and information
exchange between systems - Local area network - Media access control (MAC)
bridges".
[19] ETS 300 212 (1992): "Network Aspects (NA); Metropolitan Area Network (MAN)
Media access control layer and physical layer specification".
[20] ETS 300 213 (1992): "Network Aspects (NA); Metropolitan Area Network (MAN)
Physical layer convergence procedure for 2,048 Mbit/s".
[21] ETS 300 214 (1992): "Network Aspects (NA); Metropolitan Area Network (MAN)
Physical layer convergence procedure for 34,368 Mbit/s".
[22] ETS 300 215 (1992): "Network Aspects (NA); Metropolitan Area Network (MAN)
Physical layer convergence procedure for 139,264 Mbit/s".
[23] ETS 300 216 (1992): "Network Aspects (NA); Metropolitan Area Network (MAN)
Physical layer convergence procedure for 155,520 Mbit/s".
[24] ETS 300 217, Parts 1 to 4 (1992): "Network Aspects (NA); Connectionless
Broadband Data Service (CBDS)".
[25] ISO/IEC 8802-3 (1990): "Information processing systems - Local area networks
- Part 3: Carrier sense multiple access with collision detection (CSMA/CD)
access method and physical layer specifications".
[26] ISO/IEC 8802-5 (1992): "Information processing systems - Local and
metropolitan area networks - Part 5: Token ring access method and physical
layer specifications".
[27] IEEE Standard 802.3b (1988): "Broadband Medium Attachment Unit and
Broadband Medium Specifications, Type 10 BROAD36".
[28] IEEE Standard 802.3i (1990) (supplement to 802.3, (1990) edition): "System
Considerations for Multi-Segment 10MB/S Baseband Networks (Section 13) and
Medium Attachment Unit and Baseband Medium specification, Type 10 Base-T
(Section 14)".
[29] IEEE Standard 802.1 (1990): "Local Area Network and Metropolitan Area
Network - Overview and architecture".
[30] CCITT Recommendation E.164 (1991): "Numbering plan for the ISDN era".
[31] CCITT X.700 Recommendation Series (1988) on System management.
[32] CCITT Recommendation I.411 (1988): "ISDN user-network interfaces -
Reference configurations".
[33] CCITT Recommendation I.320 (1988): "ISDN protocol reference model".
[34] ISO 9314 (1989): "Information processing systems - Fiber Distributed Data
Interface (FDDI)".
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ETS 300 211: December 1992
[35] prETS 300 273: "Network Aspects (NA); Metropolitan Area Network (MAN)
Medium Access Control (MAC) layer management".
[36] prETS 300 275: "Network Aspects (NA); Metropolitan Area Network (MAN)
Interconnection of MANs".
[37] prETS 300 276: "Network Aspects (NA); Metropolitan Area Network (MAN)
Physical layer convergence procedure for 622,080 Mbit/s CCITT
Recommendations G.707, G.708 and G.709 SHD based systems".
[38] prETS 300 268: "Network Aspects (NA); Metropolitan Area Network (MAN)
Protocol Implementation Conformance Statement (PICS)".
[39] ISO/IEC TR 9575 (1990): "Information technology - Telecommunications and
information exchange between systems - OSI Routing Framework".
[40] CCITT Recommendation G.773 (1990): "Protocol suites for Q-interfaces for
management of transmission systems".
3 Definitions and abbreviations
This Clause consists primarily of those terms and definitions that are considered essential to the
understanding and application of the principles of MANs.
3.1 Definitions
For the purposes of this ETS, the following definitions apply.
3.1.1 Interfaces
101 Inter MAN Systems Interface (IMSI) : IMSI is a generic term that correspond to a family of
interfaces. These interfaces apply between two MSSs or between the MSS and the Transit
Network. As far as the direct interconnection between MSSs is concern, corresponding
interfaces are described in ETS 300 275 [36], the specification of the interconnection via
Asynchronous Transfer Mode (ATM) links will be provided in another ETSI document.
102 User MAN Interface (UMI): interface between the CN and the Access Facility 1 (AF1).
103 User Specific Interface (USI): interface based on a user specific protocol.
3.1.2 Network elements
201 Shared medium: transmission facility whose capacity is shared among several users.
202 Access Node (AN): the network element located in the Customer EQuipment (CEQ) which
performs the interfacing of various customer related protocols with the Distributed Queue
Dual Bus (DQDB) protocol.
203 Terminal Equipment (TE): user terminals. The term "terminal" is used in a broad sense with
different levels of complexity and functionality.
204 Customer Network (CN): the CN is defined between the T and S reference points.
M M
205 Customer EQuipment (CEQ): the concatenation of equipment on the user side of the T
M
reference point. In the case of multiple access, the CEQ includes all the equipment on the
user side of all those accesses comprising the multiple access.
206 Access Facility (AF): the network segment that connects the CN to the MAN Switching
System (MSS). The functionality of the AF may vary.
207 Access Facility 1 (AF1): an AF which only consists of a DQDB link between the CEQ and
the MSS.
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ETS 300 211: December 1992
208 Access Facility 2 (AF2): an AF which consists of a gathering network.
209 Gathering network: a network which consists of several interconnected public MAN nodes.
210 Metropolitan Area Network (MAN): digital network based on a shared access broadband
medium. A MAN covers an urban or metropolitan area (typically in the range of 50 km in
diameter). A MAN is composed of one MSS and one or more AFs connected to the MSS.
Remote MANs can be interconnected in order to cover a larger area by means of public
Transit Network (TN) facilities. A MAN is a means to provide the support of narrowband and
broadband services integrated in the same network.
211 MAN Switching System (MSS): a collection of functions that provides high-speed switching
in the public network. It can be implemented through distributed or centralised switching.
212 MAN Node (MN): a network element, located in the public domain, performing the interfacing
between the CEQ and the IEEE Standard 802.6 [1] DQDB protocol.
213 Transit Network (TN) : a network which provides transmission, switching and management
functions to allow MSS interconnection. It can be implemented through point-to-point links,
digital cross-connect, B-ISDN transit node, etc.
3.1.3 Functions
301 DQDB Access Functions (DAF): protocol functions required to receive and transmit
information over the shared medium between different nodes. Functions for the management
of the DQDB subnetwork are also contained in DAF.
302 DQDB Access Termination (DAT): functions within the MSS which consist of the DAF and
Service Specific Function (SSF) functional blocks.
303 Service Specific Functions (SSF): those functions required for the provision of the
connectionless, connection-oriented isochronous and connection-oriented non-isochronous
services.
304 User Access Functions (UAF): the functionality to access a user specific network or a
directly attached terminal.
3.1.4 Services
401 Connectionless service: a service, supporting the transfer of variable length data units that
can tolerate variable delay but require error detection functions and without the establishment
of an end to end connection. This service is described in ETS 300 217 [24] and is
comparable to the "packet-oriented" Medium Access Control (MAC) service of ISO/IEC 8802
[25], Local Area Networks (LANs).
402 Connection-oriented isochronous service: a service which is oriented to the transport of
isochronous data (e.g. conventional digitised voice); "isochronous" means that the time
characteristic of an event or signal is recurring at known, periodic time intervals (as defined in
IEEE Standard 802.6 [1]). The precise definition of this service is outside the scope of this
ETS and is for further study.
403 Connection-oriented non-isochronous service: a service supporting the transfer, over a
virtual channel, of information flows segmented into fixed-length cells having no specified
inter-arrival time. The precise definition of this service is outside the scope of this document
and is for further study.
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ETS 300 211: December 1992
3.2 Alphabetical list of terms
206 Access Facility (AF)
207 Access Facility 1 (AF1)
208 Access Facility 2 (AF2)
202 Access Node (AN)
402 Connection-oriented isochronous service
403 Connection-oriented non-isochronous service
401 Connectionless service
205 Customer EQuipment (CEQ)
204 Customer Network (CN)
301 DQDB Access Functions (DAF)
302 DQDB Access Termination (DAT)
209 Gathering network
101 Inter MAN systems Interface (IMSI)
210 Metropolitan Area Network (MAN)
212 MAN Node (MN)
211 MAN Switching System (MSS)
303 Service Specific Functions (SSF)
201 Shared medium
304 User Access Functions (UAF)
102 User MAN Interface (UMI)
103 User Specific Interface (USI)
203 Terminal Equipment (TE)
213 Transit Network (TN)
3.3 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
ACF Access Control Field
AF Access Facility
AN Access Node
ATM Asynchronous Transfer Mode
AUI Attachment Unit Interface
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ETS 300 211: December 1992
B-ISDN Broadband Integrated Services Digital Network
BT BiT sublayer
C&S Control & Switching functions
CEQ Customer EQuipment
CN Customer Network
CNMS Customer Network Management Services
CSMA/CD Carrier Sense Multiple Access with Collision Detection
DAF DQDB Access Functions
DAT DQDB Access Termination
DDI Direct Dialling In
DLSAP Data Link Service Access Point
DM Derived MAC sublayer
DM-PDU Derived MAC Protocol Data Unit
DQDB Distributed Queue Dual Bus
DTE Data Terminal Equipment
DXC Digital Cross-Connect
E-LAN Extended LAN
EOB End Of Bus
FDDI Fibre Distributed Data Interface
HL Higher Layers
HOB Head Of Bus
IM Initial MAC sublayer
IM-PDU Initial MAC-Protocol Data Unit
IMSI Inter MAN Systems Interface
ISPBX Integrated Services Private Branch eXchange
LAN Local Area Network
LCRF Local Connection Related Function
LLC Logical Link Control
LT Line Termination
M-LT MAN-Line Termination
M-NT MAN-Network Termination
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ETS 300 211: December 1992
MAC Media Access Control
MAN Metropolitan Area Network
MAU Medium Attachment Unit
MDI Medium Dependent Interface
MIC Medium Interface Connector
MID Message IDentifier
MMF MSS Management Function
MN MAN Node
MS Management Services
MSAP MAC Service Access Point
MSS MAN Switching System
NMF Node Management Function
NT Network Termination
OSI Open Systems Intercommunication
OUI Organisationally Unique Identifier
PA Pre-Arbitrated
PID Protocol IDentifier
PHY PHYsical layer
PLS PhysicaL Signalling
PMA Physical Medium Attachment
PRM Protocol Reference Model
QA Queued Arbitrated
QOS Quality Of Service
SLT SLoT sublayer
SLT-PDU SLot Protocol Data Unit
SM SegMent sublayer
SM-PDU SegMent Protocol Data Unit
SNAP Sub-Network Access Protocol
SSF Service Specific Functions
SV SerVice sublayer
TAT Transit Access Termination

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TC Transmission Convergence sublayer
TCRF Transit Connection Related Function
TCU Trunk Coupling Unit
TE Terminal Equipment
TL Transit Link
TM TransMission sublayer
TMN Telecommunication Management Network
TN Transit Network
UAF User Access Functions
UMI User MAN Interface
USI User Specific Interface
4 Basic principles
A MAN is defined as a digital network that:
- is oriented to public domain network applications;
- is based on a shared access broadband medium;
- covers an urban or metropolitan area (typically in the range of 50 km in diameter);
- can be interconnected with other remote MANs in order to cover a larger area by means of public
transit network facilities, whose specification is outside the scope of this ETS;
and is a means to provide integrated support of narrowband and broadband services (data, voice, video)
as supported by bearer services e.g.:
- connectionless service;
a service, supporting the transfer of variable length data units that can tolerate variable delay but
require error detection functions and without the establishment of an end-to-end connection. This
service is described in ETS 300 217 [24] and is comparable to the "packet oriented" MAC service of
ISO/IEC 8802 [25], Local Area Networks (LANs);
- connection-oriented isochronous service;
a service which is oriented to the transport of isochronous data; "isochronous" means that the time
characteristic of an event or signal is recurring at known, periodic time intervals (as defined in IEEE
Standard 802.6 [1]). The precise definition and description of this service and the way to support it
are outside the scope of this ETS and are for further study;
- connection-oriented non-isochronous service;
a service, supporting the transfer, over a virtual channel, of information flows segmented into fixed-
length cells that have no specified inter-arrival time. The precise definition and description of this
service and the way to support it in a MAN are outside the scope of this ETS and are for further
study.
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ETS 300 211: December 1992
A MAN is oriented to public domain network applications, and is devoted to a multi-user environment. The
same basic technologies and architectures can be used in a private environment, as CNs that are
identified with the term "Extended LANs" (E-LANs), but the differences in operational and management
attributes are substantial.
The field of application of MANs is primarily directed towards large business users.
MAN solutions are intended, in a first phase, mainly for carrying data services, in particular for the
interconnection of LANs with resulting service characteristics comparable with those available within a
single LAN, mainly in terms of throughput and delay.
As far as the isochronous services are concerned, the provision of primary rate access (CCITT
Recommendation I.431 [2]), suitable e.g. for the interconnection of Integrated Services Private Branch
eXchanges (ISPBXs), is considered to be of primary interest.
MANs are digital networks based on a shared access broadband medium: a broadband transmission
medium (e.g. optical fibre) is shared by network nodes under the control of a distributed multiple access
protocol.
MANs play the role of public access/gathering networks to provide multi-megabit communication services
to heterogeneous users, in particular to business customers.
With reference to the B-ISDN, the MAN concept is based on "distributed Local Connection Related
Functions (LCRF)": customers have access to the network using a shared medium.
The specificity of MANs may require, in some cases, the adoption of concepts and terminology other than
those up to now defined by B-ISDN. Additional concepts, terminology, reference configurations, functional
groups and reference points are required for MANs.
The IEEE Standard 802.6 [1] DQDB is the distributed multiple access protocol identified as the basis for
ETSI MANs, at least for connectionless services. This multiple access protocol is specified in ETS
300 212 [19].
However, where only two DQDB nodes are connected to a dual bus (simple point-to-point configuration) a
subset of the full IEEE Standard 802.6 [1] protocol may be implemented.
Simplifications applying in the special case are indicated in ETS 300 268 [38].
Enhancements to the IEEE Standard 802.6 [1] DQDB access method for the support of services with
guaranteed constant bit rate and specified transfer delay is defined in ETS 300 276 [37].
The MAN concept includes not only the transmission infrastructure and the access protocol but also the
necessary additional functions such as principles for network management and other operational issues,
as required in a multi-user environment.
MAN architecture is described in functional terms, and it is recognised that MANs may be implemented in
a variety of configurations according to specific situations.

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ETS 300 211: December 1992
5 Functional architecture
5.1 General architecture
A MAN is composed of one MSS and one or more AFs connected to the MSS. The general architecture
for MANs is depicted in figure 1. The CNs are connected to AFs that terminate on MSSs. Several MSSs
are interconnected, through the TN, through Inter MAN Systems Interfaces (IMSIs).
At least two options are envisaged for the AFs, as shown in figure 2:
- the first, (AF1), is based on a distributed multiple access protocol with shared medium; the CEQ is
connected to this link through the UMI;
- the second one, (AF2), is based on a set of MNs, forming a gathering network; they communicate
through a distributed multiple access protocol.
The MSS is a multi-megabit switching system. It may be implemented through distributed or centralised
switching technology. The MSS shall provide the following functions:
- provision of AF termination;
- routing of the subscriber communication to the destination AF;
- routing of communication towards other MSSs.
The IMSI links remote MSSs either directly or through the transit network; in this way, larger (e.g.
nationwide) networks can be formed. Several options are envisaged for the IMSI, also depending on the
time frame, e.g. dedicated links on wide area network carriers, Digital Cross-Connects (DXCs), B-ISDN,
etc.
For MAN management, a set of management interfaces Q*, carrying management information to the
Telecommunications Management Network (TMN) system, is identified.
The MSS and AFs exchange management information with the TMN management system through Q*
interfaces.
General MAN management principles are based on the TMN model of CCITT Recommendation M.30 [3]
and are described in Clause 8 of this ETS.
More detailed information will be provided in the relevant ETSI documents (e.g. ETS 300 273 [35]).

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ETS 300 211: December 1992
CN
CN
*
TMN Q
*
Q
UMI
T
M
CN *
Q
GATHERING
T
AF1
M
NETWORK
AF2
MSS
MSS
GATHERING UMI
IM SI
NETW ORK
IM SI
CN
AF2
TRANSIT
T
T
M
M
NETWORK
CN
CN
AF : Access Facility.
CN : Customer Network.
IMSI : Inter MAN systems Interface.
MSS : MAN Switching System.
Q* : Management Interfaces.
TMN : Telecommunications Management Network.
UMI : User MAN Interface.
TM : T reference point for MANs.
NOTE: For the interfaces of AF2 see subclause 5.3.2.1.
Figure 1: General architectural model for MANs

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ETS 300 211: December 1992
AF1
MSS
e.g. : C&A
T  = IEEE 802.6
M
AF2
T  = IEEE 802.6, (ATM)
M
MSS
e.g. : C& A
T  = ISO 8802.3, 8802-5
M
B/R, C&A
T  = IEEE 802.6
M
CUSTO M ER PROTO COL
DQDB PROTOCOL
MSS PROTOCOL
AF : Access Facility.
B/R : Bridging/Routing.
C&A : Charging & Access control.
MSS : MAN Switching System.
Figure 2: Simplified illustration of the access facilities

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ETS 300 211: December 1992
5.2 Reference configuration and functions
Figure 3 shows the reference configuration for MANs considered general enough to be applicable for all
specific cases of MANs.
Reference points, functional groups and associated functions are described hereafter.
5.2.1 Reference points
The following reference points are identified:
-T:
M
T , the T reference point for MAN, represents the boundary between the public network and the
M
CN. It is at the conjunction of the MAN-Network Termination 2 (M-NT2) and the AF.
In the MAN architecture several interfaces are foreseen at this reference point.
-Y:
M
Y , the Y reference point for MAN, is set between the AF and the LCRF functional groups. At this
M
reference point a DQDB-based access interface is implemented.
-Z:
M
Z , the Z reference point for MAN, is set between the LCRF and the Transit Link (TL). The interface
M
to be implemented at this reference point is an IMSI type interface.
-S:
M
S , the S reference point for MAN, represents the boundary between the TE and the M-NT2.
M
5.2.2 List of functional groups
In the MAN reference configuration the following functional groups are identified:
- Terminal Equipment (TE):
this functional group, according to CCITT Recommendation I.411 [32], includes functions broadly
belonging to layer 1 and higher layers of the reference model of CCITT Recommendation X.200 [4].
Examples of TE functions are:
- user/user and user/machine dialogue and protocol;
- interface termination;
- protocol handling for signalling;
- connection handling to other equipment;
- management functions.
- MAN-Network Termination 2 (M-NT2):
this functional group, according to CCITT Recommendation I.411 [32], includes functions broadly
equivalent to layer 1 and higher layers of the reference model of CCITT Recommendation X.200
[4].
M-NT2 is null in the case of coincidence between S and T .
M M
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ETS 300 211: December 1992
Examples of M-NT2 functions are:
- adaptation of functions for different media and topologies;
- functions of distributed M-NT2;
- slot delineation;
- concentration;
- buffering;
- multiplexing and demultiplexing;
- resource allocation;
- management functions;
- signalling protocol handling.
M-NT2 implementations may be concentrated or distributed. In a specific access arrangement the M-NT2
may consist of only physical connections. When present, implementations of the M-NT2 shall be locally
powered.
1)
Similar to the CCITT B-ISDN Recommendations , the CN is defined between the T and S reference
M M
points. The CEQ consists of the TE and an optional CN. The CEQ includes the user end-systems (e.g.
ISO LANs, Fibre Distributed Data Interface (FDDI) LANs, data, voice or video equipment, IEEE Standard
802.6 [1] DQDB private networks, etc.).
- Access Facility (AF):
the AF connects the CEQ to the LCRF. It is based on a IEEE Standard 802.6 [1] DQDB distributed
multiple access protocol on a shared broadband medium. Different cases can be identified, namely:
AF1: AF is a simple IEEE Standard 802.6 [1] DQDB link between the CEQ and the LCRF;
AF2: AF includes a set of nodes communicating with each other and with the LCRF through
the IEEE Standard 802.6 [1] DQDB protocol.
- Local Connection Related Function (LCRF):
the LCRF corresponds to the MSS of figure 1 and includes the following functions: AF termination,
switching, connection to the transit network and maintenance. The implementation of the MSS is
not subject to standardisation but it is of interest to describe some examples of possible
implementations. In particular, the MSS can be implemented as a centralised switching node, or as
a set of nodes communicating with each other (see Annex A).
In the TN the following functional groups are identified:
- Transit Link (TL):
the TL includes the transmission functions required to interconnect the LCRF and the Transit
Connection Related Functions (TCRFs).

1)
CCITT Recommendations I.113, I.121, I.150, I.211, I.311, I.321, I.327, I.361, I.362, I.363, I.413, I.432 and I.610: normative
references [5] to [17].
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ETS 300 211: December 1992
- Transit Connected Related Function (TCRF):
the TCRF covers the functions of the TN of figure 1. It is in charge of the interconnection of different
LCRFs. It includes switching and maintenance functions. TCRF can be implemented through point-
to-point links, DXC, B-ISDN transit nodes, etc.;
the configuration of the TN shown in figure 3 is one of the different possibilities described in CCITT
Recommendation I.327 [11].
5.2.3 List of functions
The following functions are found in the identified functional groups. The functions which are relevant to
the MSS only, are described in Annex A.
- User Access Functions (UAF):
UAF contain the functions of accessing a user specific network or a directly attached terminal. In
the case of the connectionless service the UAF performs the functionality of the physical and MAC
layer of the user network protocol, for example, the ISO/IEC 8802-3 [25], 8802-5 [26] or ISO 9314
[34] Fiber Distributed Data Interface (FDDI) protocol.
- Service Specific Functions (SSF):
the SSF contain all functions required for the provision of the services supported by MANs.
In the case of the connectionless service the SSF may perform one or more of the following
functions:
- address validation (see ETS 300 217 [24]);
- address screening (see ETS 300 217 [24]);
- access class enforcement (see ETS 300 217 [24]);
- charging support (see ETS 300 217 [24]);
- multiplexing and demultiplexing;
- encapsulation (see subclause 6.3);
- bridging (see ISO/IEC 10038 [18]);
- routing (see ISO/IEC TR 9575 [39]).
In essence, those functions that are related with network integrity issues are denoted by SSF1 and
include: address validation, address screening, access class enforcement, multiplexing and
demultiplexing, filtering and forwarding. In addition, other functions like charging support may be
included.
Those functions that are related with relaying issues are denoted by SSF2 and include:
encapsulation, bridging and routing. Other functions may be included.
- DQDB Access Functions (DAF):
The DAF contain the functions required to receive and transmit information over a shared medium.
In the case of the IEEE Standard 802.6 [1] DQDB protocol, the block performs the functionality of
the PHYsical layer (PHY) and DQDB layer as described in subclause 6.2, as well as the functions
for management of the DQDB subnetwork.

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ETS 300 211: December 1992
- M-NT1 and MAN-Line Termination (M-LT):
these terminate the transmission line between the public network and the subscriber: they are
required to provide functions broadly equivalent to the physical layer of the ISO Open Systems
Interconnection (OSI) reference model including:
- line transmission termination;
- transmission interface handling;
- management functions.
In addition, the M-NT1 is the physical termination of the public network.
Whether or not the functionalities of the M-NT1 and M-LT are identical to the ones specified in
CCITT Recommendation I.411 [32] is for further study.
CUSTOMER METROPOLITAN
TRAN SIT
EQUIPMENT AREA NETW O RK
NETW ORK
CU STOM ER
NETW ORK
AF TCRF
TE M-NT2 TL
LC RF
(M SS)
T Y
S
Z
M
M M
M
AF : Access Facility.
LCRF : Local Connection Related Functions.
MSS : MAN Switching System.
M-NT2 : MAN Network Termination 2.
TCRF : Transit Connection Related Function.
TE : Terminal Equipment.
TL : Transit Link.
Figure 3: MAN reference configuration

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ETS 300 211: December 1992
5.3 Access Facilities (AFs)
The AF connects the CEQ to the MSS. The AF is delimited by two reference points, T and Y , as
M M
depicted in figure 3.
The functionality of the AF may vary from case to case and at least two cases have been identified.
The DQDB protocol mentioned hereafter is described in IEEE Standard 802.6 [1] and is specified in ETS
300 212 [19]:
- AF1 is based on the IEEE Standard 802.6 [1] DQDB protocol, which is a distributed, multiple access
protocol. The interface at the T reference point is referred to as the UMI, and the CEQ may
M
consist of one or more nodes connected to the dual bus. The AF1 contains the M-NT1 and the
MAN-Line Termination (M-LT). The M-NT1 clearly demarcates the boundary between the public
network and the CN. This case is further described in subclause 5.3.1;
- AF2 is based on a set of nodes interconnected together forming a gathering network. The nodes
are interconnected using the same IEEE Standard 802.6 [1] DQDB based protocol used in AF1
above. Each node can serve one or more CEQs. The nodes of the AF2 are under the control and
supervision of the network operator. This case is further described in subclause 5.3.2.
The IEEE Standard 802.6 [1] DQDB protocol can be applied to two different subnetwork topologies:
- the open bus topology;
- the looped bus topology.
The applicability of these two topologies to AF configurations is described in Annex A.
5.3.1 Access facility 1 (AF1)
Figure 4 shows the functional configuration of AF1. The model is not intended to require or exclude any
specific implementation, but to provide a guide for the specification of AF functions and their distribution
and allocation.
The functions identified in figure 4 are described in subclause 5.2.3.
The CEQ is connected to the public MSS via an access link. The interface between the CEQ and the AF
is referred to as the UMI and is located at the T reference point.
M
An M-NT1 located within AF1 demarcates the area of responsibility between the network operator and the
customer.
The CEQ communicates with the MSS via a protocol based on the IEEE Standard 802.6 [1], DQDB
protocol.
The CEQ may include more than one AN communicating by means of the IEEE Standard 802.6 [1] DQDB
protocol.
The AN performs the interfacing in the CEQ between various customer related protocols and the IEEE
Standard 802.6 [1] DQDB protocol.
A single AN may be shared by several LANs, terminals, workstations or host computers.
A functional description of the MSS is provided in Annex A.
The MSS has to reflect a subset of AN functionalities.
In particular, the SSF1 functions should be implemented in the MSS to safeguard the network integrity.

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ETS 300 211: December 1992
CEQ
TE TE TE TE
S S
M M
LCRF (M SS)
LAN LAN
MEDIUM MEDIUM
DATn
TM N
*
UAF Q
SSF2
C& S
DAF DAT1
AN1 AN1
T Y
M M
AF1
SSF1
TR ANSIT
M-LT
M-NT1 TA T
M-NT2
DAF
LIN KS
(U M I)
Z
M
AF : Access Facility. M-LT : MAN-Line Termination.
AN : Access Node. M-NT : MAN-Network Termination.
C&S : Charging & Access control. MSS : MAN Switching System.
CEQ : Customer Equipment. NT : Network Termination.
DAF : DQDB Access Functions. SSF1 : Service Specific Functions
DAT : DQDB Access Termination. (e.g. charging and screening).
LAN : Local Area Network. SSF2 : Service Specific Functions
LCRF : Local Connection Related Functions. (e.g. relaying and routing).
LT : Line Termination. TAT : Transit Access Termination.
TE : Terminal Equipment.
UAF : User Access Functions.
UMI : User MAN Interface.
Figure 4: Functional configuration of AF1
5.3.2 Access Facility 2 (AF2)
The main goal of this architecture is supplying services to many customers by means of a shared medium
access.
This topology exploits very well the MAN characteristics as each customer shares the access medium
with other customers.
The MN, located in the public network domain, performs the interfacing between the CEQ and the IEEE
Standard 802.6 [1] DQDB protocol.
The MSS and the MNs share a broadband medium and perform distributed switching as they are
interconnected by means of the IEEE Standard 802.6 [1] DQDB protocol.
Moreover a single MN can serve more than one CEQ and can provide different services.
This solution is targeted primarily towards users which do not require the full capacity of the broadband
medium.
The functions relevant to MSS are described in Annex A.
The main functions identified are depicted in figure 5.

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ETS 300 211: December 1992
Two functional configurations have been derived from figure 5, depending on the implementation of the
bridging/routing functions in the MN and the M-NT2:
- AF2a, wher
...