Internet Access; V5.2 controlled Internet access in the Access Network (AN), phase 1; Part 1: Interface Specification

(Draft scope, which will be refined in the March 98 SPS3 meeting.) To define the V5 functionality in LE and AN to support routing of internet (dial-up) traffic in  the AN to an internet acces interface. For phase 1 the functionality is limited to a routeing  without signaling between LE and the internet access interface. The specification of the  internet access interface is not part of this work item, although some requirements for this  interface may evolve from this activity. Supporting members: Siemens, Ericsson, Kycebtm, Alcatel (ES)

Internetni dostop – Prek V5.2 krmiljen internetni dostop v dostopovnem omrežju (AN), faza 1 – 1. del: Specifikacija vmesnika

General Information

Status
Published
Publication Date
31-Dec-2004
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jan-2005
Due Date
01-Jan-2005
Completion Date
01-Jan-2005

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SLOVENSKI STANDARD
SIST-TP ETSI/TR 101 662-1 V1.1.2:2005
01-januar-2005
Internetni dostop – Prek V5.2 krmiljen internetni dostop v dostopovnem omrežju
(AN), faza 1 – 1. del: Specifikacija vmesnika

Internet Access; V5.2 controlled Internet access in the Access Network (AN), phase 1;

Part 1: Interface Specification
Ta slovenski standard je istoveten z: TR 101 662-1 Version 1.1.2
ICS:
33.020 Telekomunikacije na splošno Telecommunications in
general
SIST-TP ETSI/TR 101 662-1 V1.1.2:2005 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP ETSI/TR 101 662-1 V1.1.2:2005
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SIST-TP ETSI/TR 101 662-1 V1.1.2:2005
ETSI TR 101 662-1 V1.1.2 (1999-07)
Technical Report
Internet Access;
V5.2 controlled Internet access in the Access Network (AN),
phase 1;
Part 1: Interface Specification
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SIST-TP ETSI/TR 101 662-1 V1.1.2:2005
2 ETSI TR 101 662-1 V1.1.2 (1999-07)
Reference
DTR/SPS-09062-1 (fe090idg.PDF)
Keywords
AN, Internet, LE, V5 interface
ETSI
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Individual copies of this ETSI deliverable
can be downloaded from
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If you find errors in the present document, send your
comment to: editor@etsi.fr
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 1999.
All rights reserved.
ETSI
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SIST-TP ETSI/TR 101 662-1 V1.1.2:2005
3 ETSI TR 101 662-1 V1.1.2 (1999-07)
Contents

Intellectual Property Rights................................................................................................................................4

Foreword ............................................................................................................................................................4

Introduction ........................................................................................................................................................4

1 Scope........................................................................................................................................................6

2 References................................................................................................................................................6

3 Abbreviations...........................................................................................................................................6

4 Basic functionality of the LE Bypass mechanism ...................................................................................7

5 Progress of standardization work.............................................................................................................7

5.1 First results......................................................................................................................................................... 7

5.2 Open items ......................................................................................................................................................... 8

5.2.1 General architecture ..................................................................................................................................... 8

5.2.2 AS interface.................................................................................................................................................. 9

5.2.3 Signalling between LE and AS................................................................................................................... 12

5.3 NAS/NAS Controller architecture ................................................................................................................... 13

5.3.1 Network architecture .................................................................................................................................. 13

5.3.1.1 NAS Controller..................................................................................................................................... 13

5.3.1.2 Network Access Server......................................................................................................................... 14

5.3.2 Internet traffic grooming within the Access Network................................................................................. 14

History..............................................................................................................................................................16

ETSI
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SIST-TP ETSI/TR 101 662-1 V1.1.2:2005
4 ETSI TR 101 662-1 V1.1.2 (1999-07)
Intellectual Property Rights

IPRs essential or potentially essential to the present document may have been declared to ETSI. The information

pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect

of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the

ETSI Web server (http://www.etsi.org/ipr).

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee

can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)

which are, or may be, or may become, essential to the present document.
Foreword

This Technical Report (TR) has been produced by ETSI Technical Committee Services and Protocol for Advanced

Networks (SPAN).
Introduction

Telephone calls to the Internet differ greatly from normal telephone calls; in particular, the holding time is much longer

than for voice or fax calls. Therefore traffic models as used for normal telephone service are not applicable for Internet

calls. With an increasing amount of traffic to the Internet the classic PSTN/ISDN designed with traffic models based on

different rules lack the necessary performance. The present document describes a method of extending the V5.2

interface to allow decoupling of the telephone traffic to the Internet already in the AN or to bypass the LE; the Internet

traffic is routed directly from the AN to the Access Server (AS) under control of the LE. Whether the AS offers direct

access to the Internet or transports the user data to an ISP which is the gateway to the Internet is not relevant to the

present document.
POTS
V5.2
AN LE
ISDN BA
ISDN PRA
Internet
Figure 1: Internet access via AN and AS
ETSI
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5 ETSI TR 101 662-1 V1.1.2 (1999-07)

The reason for decoupling Internet traffic is that the users allocate bandwidth for the whole time they are online although

much less bandwidth is really needed due to the bursty nature of the packet data which is exchanged between user and

the ISP (Internet). The basic idea for decoupling the Internet traffic in the AN is that the circuit-switched traffic be taken

from the PSTN/ISDN and enter the better suited packet data world as soon as possible. In this scenario the AS, which is

probably (but does not have to be) physically located quite close to the AN has the task of terminating the analogue

modem traffic and sending the user data to the target ISP using IP protocol. The actual functionality of the AS is not

seen to be part of the ETSI work item for V5.2 extension; nevertheless the following tasks can be seen as possible

functions of the AS:

• transforming the user data from circuit-switched traffic to packet-oriented traffic;

• forwarding the user data to the addressed ISP, possibly using IP protocols and a tunnelling protocol, e.g. L2TP,

to separate the IP addresses of the ISP and the transporting network;
• other packet mode transport from AS to ISP is possible;

• offering direct access to the Internet; in this case, the operator of the AS is an ISP.

Comparable solutions with a decoupling of Internet traffic behind the ingress switch are already available on the market.

A solution with a decoupling in the AN would save additional equipment, i.e. interfaces between AN and LE, and

switching capacity in the ingress switch. To make such a solution work, efficient use of equipment (i.e. interfaces

between AN and AS) would need to be made.
Ingress
Egress
Switch
Switch a)
Internet
POTS,
ISDN
ISP
Figure 2: Connection from user to ISP

Figure 2 shows different possibilities of connecting a user with an ISP. Today, the user data reaches the ISP via the

ingress switch and maybe an egress switch using a circuit-switched connection, path c), b) and a). Blocking (or at least

excessive use of bandwidth) can occur in the PSTN/ISDN network in different places:

a) on the egress of the switch the ISP is connected to. Due to the extremely high traffic on ISP lines, the egress

switch has to be designed to be able to carry the traffic;
b) on trunk lines between switches;
c) on the V5.2 interface between the AN and the ingress switch.

Bandwidth is wasted because the data is transported circuit-switched up to the ISP. Better use of the bandwidth is made

if the AS, located as close as possible to the user, transforms the datastream into the packet mode and transports it then

to the ISP. A connection of the AS to the ingress switch (path 1) is already available on the market and can also be used

for users connected via a V5.2 interface. The scope of the present document is the direct connection of the AS to the AN

(path 2) and therefore, the saving of bandwidth in the ingress switch.
ETSI
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1 Scope

The present document describes scenarios whereby Internet traffic could bypass the local exchange by being routed in

the Access Network directly to the Internet access services.
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.

• A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same

number.

[1] ITU-T Recommendation E.164 (1997): "The international public telecommunication numbering

plan".

[2] Bellcore: GR-303-CORE Issue 2: "IDLC Generic Requirements, Objectives, and Interface",

December 1998; associated: Issues List Report: GR-303-ILR Issue 2A, December 1998.

[3] ETS 300 347-1: "Signalling Protocols and Switching (SPS); V interfaces at the digital Local

Exchange (LE); V5.2 interface for the support of Access Network (AN); Part 1: V5.2 interface

specification" (also ITU-T Recommendation G.964).
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AN Access Network
AS Access Server
BCC Bearer Channel Connection
CPE Customer Premises Equipment
DSP Digital Signal Processor
IAC Internet Access Control
IP Internet Protocol
ISDN Integrated Services Digital Network
ISDN-BA ISDN Basic Access
ISDN-PRA ISDN Primary Rate Access
ISDN-PRI ISDN Primary Rate Interface
ISP Internet Service provider
LE Local Exchange
LL Leased Lines
L2TP Layer 2 Tunnelling Protocol
NAS Network Access Server
POTS Plain Old Telephone Service
PSTN Public Switched Telephony Network
RAS Remote Access Server
VoIP Voice over IP
VPN Virtual Private Networking
ETSI
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4 Basic functionality of the LE Bypass mechanism

When an end customer, whose line is terminated on an AN with the Internet Bypass feature, goes off-hook, dial tone is

provided by the ingress LE via the V5.2 interface just as it is done today. If the customer (or CPE) dials the destination

E.164 address of a contracted ISP, the LE will re-route the Bearer channel from the V5.2 interface to the AS, so that the

end-customer has a direct bearer channel connection to the AS and the resource on the V5.2 interface is freed. The

signalling path from the end customer to the LE is still kept active as long as the call is ongoing. As the LE knows about

this re-routed call, billing and usual call processing (e.g. call waiting, call forwarding) are still possible.

New signalling has to be introduced for communication from LE to the AS port, as this is the b-leg of the call; signalling

with the AS is necessary to inform the LE about the AS accepting the call (begin of charging) and a possible release of

the call by the AS.

Although Internet traffic is mentioned to be rerouted in the present document, it shall not be excluded to use the Internet

Bypass functionality to e.g. reroute voice traffic to an AS which serves as a VoIP Gateway.

5 Progress of standardization work

At the outset, it was intended that the standardization should start with a simple first phase without signalling from the

LE towards the AS interface. A second phase was planned for the introduction of a signalling protocol. The simple first

phase was abandoned after realising that, without a signalling protocol, proper billing in the LE for re-routed calls would

not be possible. It was agreed that signalling between LE and AN at the AS interface is a necessity from the start. At the

time of writing, the details of this signalling remain undetermined, as does the definition of the interface between AN

and AS. Another open item is whether the AS port is located on the subscriber or network side of the AN. The open

items are discussed in more detail below.
5.1 First results
The following basic requirements have been identified:
• "The aim of the activity is to bypass the LE".

• The V5 standard is to provide connection capabilities in the AN such that Internet traffic is directly connected

from the user to the AS.

• The capability should not impact on existing services; service as seen by the user should be as for the non-bypass

case.
• The capability is to be available to PSTN (POTS), ISDN-BA and ISDN-PRA users.

• The solution is to be generic, with no knowledge in the LE about the services other than to handle the connection;

LE does not interact with the contents of the bearer channel.

• The "Always On/Dynamic ISDN" service is not to be affected by the Internet Bypass capability.

• The AN will not have any subscriber provisioning data that belongs to the LE, only connection data.

• The solution should be simple; minimum complexity; easily manageable (particularly provisioning); minimum

development and deployment costs.

• Support of current AN architectures which (can) handle V5.2; (as a good objective) AN equipment which is

currently being deployed or under development should be (software) upgradable to support Internet Bypass.

• The solution for Internet Bypass is to allow for correct (i.e. accurate/reliable) billing.

• The subscriber is not to notice any difference whether the connection to the RAS goes via the Internet Bypass

function or not; nor should there be any difference between a direct connection which uses V5 and the Internet

Bypass function.
ETSI
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• The physical AS interface will not be defined in the extended V5.2 standard.

• It is to be possible to use the same physical AS interface for all ports on different V5.2 interfaces on the same

AN.
• The LE need have no knowledge of the AN architecture.
5.2 Open items
5.2.1 General architecture

In the current V5 standard [3], the AN supports user-side to network-side connections. Signalling from the LE to the

subscriber ports is passed transparently through the AN or mapped from messages to line signals. Regarding the AS

interface this could be seen as a network side interface or a user port. There are advantages for both viewpoints.

In favour of the network-side interface:

In general, ANs currently only support user-side to network-side connections. This has major architectural benefits,

particularly in the simplification and minimization of
...

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