INTERNET BROADBANDINTERNET BROADBAND

ITTM, Delhi ITTM, Delhi Definition of Broadband

An ‘always-on' data connection that is able to support interactive services including Internet access.According to Broadband policy 2004,has the capability of the minimum download speed of 256 kilo bits per second (kbps) to an individual subscriber from the Point Of Presence (POP) of the service provider. According to New Telecom policy 2011, minimum download speed should be 512 kbps.It provides Internet, IPTV and VoIP simultaneously along with basic telephone service.

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ITTM, Delhi ITTM, Delhi What is ADSL ?

Asymmetrical digital subscriber line (ADSL) is emerging as the optimal solution to high-speed Internet access technology. ADSL matches the asymmetric pattern of Internet traffic with speeds of up to 8 Mb/s downstream from the network to the end user, and up to 640 kb/s upstream from the end user to the network. Because ADSL can transmit both voice and data simultaneously over an existing, single copper pair up to 5.5 KM long, it is the perfect solution for service providers to meet the increasing customer demand for faster Internet access. With its amazing speed and economical use of the installed base of copper cable, ADSL keeps the service cost low for both service providers and end users.

An ADSL system consists of the following components:• ADSL transceiver unit-central office (ATU-C), also referred to as DSLAM

• ADSL transceiver unit-remote (ATU-R), also referred to as an ADSL modem

• Splitter – low pass filter for separating POTS from ADSL

• Digital subscriber line access multiplexer (DSLAM) – Multiplexes many ADSL copper lines into one Ethernet uplink fiber and include the splitter in ATU-C Frame.

Splitter- a low pass filter.Splitter- a low pass filter.

ITTM, Delhi ITTM, Delhi Freq. spectrum used in Broadband

4 KHz 26 KHz 138 KHz 1 . 1 MHz

UPSTREAM DOWNSTREAM

ADSL Bandwidth

ITTM, Delhi ITTM, Delhi Traditional plain old telephone service (POTS) uses a narrow 4-kHz baseband

frequency to transmit analog voice signals. This means that even with sophisticated modulation techniques, current modem technology can only achieve throughput of up to 56 kb/s. To attain a much higher throughput of up to 8 Mb/s, ADSL increases the usable frequency range from 4 kHz to 1.1 MHz. Frequency division multiplexing (FDM) then allows ADSL to create multiple frequency bands to carry upstream and downstream data simultaneously with the POTS signal over the same copper pair. The lower 4-kHz frequency range is reserved for POTS, the middle frequency band is used to transmit upstream data, and the larger, higher frequency band is used for downstream data.

Modulation Techniques

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xDSL, is a family of technologies that provides digital data transmission over the wires of a local telephone networkDSL (Digital Subscriber Line) exploits the unused analogue bandwidth that is potentially available in the wires that run from the user premises to the local exchangeThe phone system nominally passes audio between 0.3 KHz and 3.4 KHz, which is regarded as the range required for human speech to be clearly intelligible. This is known as voiceband or commercial bandwidthThe local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit of POTS.DSL takes advantage of this unused bandwidth of the local loop for carrying data.

XDSL

ITTM, Delhi ITTM, Delhi HOW XDSL WORKSThese technologies provide high rate, bi-directional data communications by using elaborate modulation and error correction schemes which send and receive frequencies above 20 kHz - and therefore above the hearing range of humans. With appropriate filtering at each end of the twisted pair, many of these approaches also allow an ordinary analogue Plain Old Telephone System (POTS) telephone service to continue to operate on the same line. If this filtering can be achieved without the need for external power at the customer site, this preserves existing life-line telephone services, while providing a bi-directional multi-megabit-per-second digital communication path to each home or office.

ITTM, Delhi ITTM, Delhi Advantages of DSL Technology

DSL is more cost-effective because it eliminates the need for extensive and expensive infrastructure upgrades.

Increased Bandwidth capacity in the existing infrastructure.

The speed is much higher than a regular voice band modem.

Voice and data can be transmitted at the same time.

Very Secure and reliable.

ITTM, Delhi ITTM, Delhi Symmetric bandwidth corresponds to the situation when the maximum rate of transfer is the same in both directions i.e. upload and download speed.

Asymmetric bandwidth corresponds to the situation when the maximum rate of transfer is different in each direction. A typical case might be a DSL line with 768 kbps upload and 2 Mbps download.

Asymmetric DSL Standards======================

•ADSL: (Full Rate asymmetrical DSL) •G.lite ADSL (or simply G.lite)•RADSL: (rate adaptive DSL)•VDSL (Very high bit rate DSL)

Symmetric DSL Standards====================

•SDSL: (Symmetric DSL) •SHDSL (Single-pair high-speed DSL) •HDSL: (High bit rate DSL) •HDSL2: (2nd generation HDSL) •IDSL: (Integrated services digital network DSL)

Symmetric Vs Asymmetric

ITTM, Delhi ITTM, Delhi ASYMMETRIC DIGITAL SUBSCRIBER LINE

SplitterSplitter

EXCHANGE

ADSL

LT

ISP

Exchange

Eqpt .

Existing

Copper Lines

ADSL MODEM

Telephone Exchange

Telephone Line

Telephone

MTNL Broadband N/W

Internet Gateway( Broadband)

PC

DSL Modem

VoIP

SOFT SWITCH

Telephone

Analog Telephone Adaptor

HEAD ENDEQUIPMENT

(ENCODERS)

DVD

TV Channel

Set Top Box

TV

IPTV And VOIP (Triple Play Service)

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IPTV (Internet Protocol Television) delivers television programming to households via a broadband connection using Internet protocols. It requires a IPTV set-top box, and offers key advantages over existing TV cable and satellite technologies. IPTV is typically bundled with other services like Video on Demand (VOD), voice over IP (VOIP) or digital phone, and Web access, collectively referred to as Triple Play.

IPTV : Brief Definition

ITTM, Delhi ITTM, Delhi DSLAM - INTRODUCTION

Digital Subscriber Line Access Multiplexer (DSLAM) is a network device, located in the telephone exchanges of the service providers, that connects multiple customer Digital Subscriber Lines (DSLs) to a high-speed Internet backbone line using multiplexing techniques.

• In terms of the OSI 7 Layer Model, the DSLAM acts like a massive network switch, since its functionality is purely Layer 2.

• The aggregated signal then loads onto backbone switching equipment, travelling through an access network (AN) — also known as a Network Service Provider (NSP) — at speeds of up to 10 Gbit/s and connecting to the Internet-backbone.

• The DSLAM, functioning as a switch, collects the ADSL modem data (connected to it via twisted or non-twisted pair copper wire) and multiplexes this data via the gigabit link that physically plugs into the DSLAM itself, into the Telco's backbone.

ITTM, Delhi ITTM, Delhi TYPES OF DSLAMS IN MTNL

A DSLAM delivers exceptionally high-speed data transmission over existing copper telephone lines. A DSLAM separates the voice-frequency signals from the high-speed data traffic and controls and routes digital subscriber line (xDSL) traffic between the subscriber's end-user equipment (CPE) and Broadband Access Server or BBRAS, but it may not be a direct connection;  the BBRAS can be located anywhere.

DSLAMs of following make are installed in MTNL:•ERICSSON (Ethernet DSL Access)•HUAWEI (SMARTAX MA 5600)•ALCATEL (7302 ISAM)

ITTM, Delhi ITTM, Delhi DSLAM PORT NAMING

PORT TYPE PORT NAMING TYPE OF DSLAM

ERICSSON XYYZTTTT

X: DSLAM TYPEYY: DSLAM NO. (01, 02 ETC)Z: SUBRACK NO.(1, 2, 3, 4)TTTT: PORT NO. (0001 TO 1152)

A– 1152 PORTSB – 576 PORTSC – 288 PORTS

HUAWEI XYYZTTTT

X: DSLAM TYPE (I, J, K)YY: DSLAM NO. (01, 02 ETC)Z: SUBRACK NO. TTTT: PORT NO. (0001 TO 0960)

I – 960 PORTSJ – 480 PORTSK – 240 PORTS

ITTM, Delhi ITTM, Delhi PHYSICAL CONNECTIONS

20

LocalExchange

MTNLLine MDF

MTNLExch MDF

MTNL Copper< 5Km

DSLAMExch MDF DSLAM

Line MDF

IPDSLAM

MTNL Fiber Network

2x GigEfiber

Tier 2Switch

MDF

EthernetOr USB

RJ-11

2-wire

2-wire

2-wire

Exchange RSU/MSUCustomer home

Spiltter

DSL Modem

DSL OVERVIEW-DSL CONNECTIVITY

ITTM, Delhi ITTM, Delhi

ATM is a switched, connection-oriented networking technology that provides dedicated, high-speed connections to virtually an unlimited number of users. It operates on a cell-based fast-packet communication method that supports transfer rates from 1.544 Mbps to 10 Gbps.Dedicated media connections running in parallel allow an ATM switch to simultaneously support multiple conversations.When Data is transferred in an ATM network, a switched virtual circuit (SVC) is established between the sender and receiver. The information is converted into fixed-length cells, which are transmitted through the network and reassembled into data packets at the destination.

ATM Technology

ITTM, Delhi ITTM, Delhi ATM networks are fundamentally connection oriented. This means that a virtual connection needs to be established across the ATM network prior to any data transfer. ATM virtual connections are of two general types: • Virtual path connections (VPCs), identified by a VPI. • Virtual channel connections (VCCs), identified by the combination of a VPI and a VCI. A virtual path is a bundle of virtual channels, all of which are switched transparently across the ATM network on the basis of the common VPI. A VPC can be thought of as a bundle of VCCs with the same VPI value.VPI identifies the virtual path to be used by the cell during transmission and VCI identifies the channel to be used. PTI tells the content of the data portion. It tells the priority of the cell.

ITTM, Delhi ITTM, Delhi ATM Virtual Path And Virtual Channel Connections

ITTM, Delhi ITTM, Delhi

Within the block identified as 'Service provider', there are three important components:DSLAM - DSL Access Multiplexer A Digital Subscriber Line Access Multiplexer (DSLAM) is a network device, usually at a telephone company central office, that receives signals from multiple customer Digital Subscriber Line (DSL) connections and puts the signals on a high-speed backbone line using multiplexing techniques. BBRAS - Broadband Remote Access Server The BBRAS is the piece of equipment that sits between the DSLAM at the telephone exchange and the ISP that connects to the Internet. ISP - Internet Service ProviderThe Broadband Access Servers are connected to an Internet Service Provider or ISP. This is the place where the connection to the Internet is made.

DSLAMDSLAM ( (DSLDSL AAccess ccess MMultiplexer) ultiplexer)

LOCAL LOOP

OFD

S

L

A

M

BRAS

ISP

INTERNET

Ericsson networkEricsson network Element Element        BBRAS           6        T1              7              T2              42 (Working as on

date)        DSLAM           445        Radius  1 (From M/s Oracle

Product name Portal)

ConnectivityConnectivity to to GatewaysGateways.  All the internet traffic is coming from

DSLAM to T2, the  from T2 to T1, from T1 to BBRAS as layer 2 traffic. All the BBRAS's are connected to Two switches (known as Aggregation A and Aggregation B) using fiber cable. And these switches are connected to two gateways routers (4th floor and 9th floor) with six pairs of fibers. That is from Agg-A Three pairs of fibers are going to gateway 1 and Three pairs of fibers are going to gateway 2. Same is the case with Agg - B switch.

Network Elements in Network Elements in HuaweiHuawei systemsystem

Network Elements in Huawei system

NETWORK ELEMENTSNETWORK ELEMENTS

Huawei Product Model

TotalNumber ofElements

BRAS MA5200G-88

Tier-I NE80E8

Tier-II S650664

DSLAM MA5600 629EMS Client iManagerN2000 30

ITTM, Delhi ITTM, Delhi Network Overview

ITTM, Delhi ITTM, Delhi Ericsson Broadband Network

RADIUSRADIUSRemote Authentication Dial In

User ServiceConcept of AAAAuthenticationAuthorizationAccounting

ITTM, Delhi ITTM, Delhi How Broadband Service Works?

3 、 Authentication system checks

account &password ；BRAS allocates valid

IP BBRAS

Radius Server

Lan switch

Core

R

5 、 Billing server start accounting

2 、 PPPoE session

ends here and session

ID is allocated

1 、 PPPoE is

initiated by

subscriber

4 、 Subscriber gets IP and visit Internet

ITTM, Delhi ITTM, Delhi BB Service Flow

PC CPE DSLAM T2 T1 BRAS

Service flow begins from Client BRAS which terminated PPP sessions.The process for user connection to internet is:

1. Client starts pppoe session by using pppoe software.2. ADSL modem translates IP packets into ATM cell.3. DSLAM recovers ATM cells to IP packets.4. DSLAM uses Q-in-Q protocol/VMAC, which adds a new vlan

/vmac tag to the recovered IP packets. Each user has a respective vlan/vmac.

5. T2 forwards IP packet to T1 & T1 transfers the IP packets to BRAS.

6. BRAS also supports Q-in-Q protocol /vmac according to different outer vlan and inner vlan to identify Different users.

ITTM, Delhi ITTM, Delhi LAN Switches

Important features of LAN Switch:Supports multiple service VLANsAggregates links towards T1 switch or BRASSupports multicastingControls flow of Ethernet framesEnsures QoS for different types of trafficAllows management through CLI, Console, Telnet,

SNMP and System log

ITTM, Delhi ITTM, Delhi T1/T2/Aggregation/NOC Switches

Definition: They are LAN switches used for aggregating and cross-connecting clients, servers and other network devices.

Devices used in MTNL: 3COM 7700 LAN Switches (ERICSSON) and NE80E T-1 Switch, S6506 T-2 Switch (HUAWEI)

ITTM, Delhi ITTM, Delhi Broadband Remote Access Server (BRAS)

Definition: BRAS is a network device used to route traffic to and from broadband remote access devices such as DSLAM on an ISP network. It aggregates users sessions from access network and plays major role policy management and QoS.

Devices used in MTNL: Juniper ERX 1440 (ERICSSON) &

MA5200G-8 (HUAWEI)

ITTM, Delhi ITTM, Delhi BRAS

Important Features:Aggregates the circuits from access devices such as DSLAMsProvides layer 2 connectivity through either transparent bridging or PPP sessions over EthernetEnforces quality of service (QoS) policiesProvides layer 3 connectivity and routes IP traffic through Internet service provider’s backbone network to the Internet

ThanksThanks

…..Broadband Faculty, ITTM