bsnl 2016 industrial training report

Industrial Training Report 2016

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Sagar Institute of Research and Technology

Bhopal (M.P.)

The First ISO-9001-2000 Certified e-Governed Engineering College in M.P.

Department of

Electronics & Communication

Session [2016-2017]

Major Training Completed at BSNL, Bhopal

Report on

Basic Telecommunication

From 08 July 2016 to 21 July 2016

Submitted By:

Niharika Sharma


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Bharat Sanchar Nigam Limited

Bharat Sanchar Nigam Limited (BSNL), a Public Sector Undertaking of Government of India, is the largest Telecom Service Provider in India having countrywide presence with over 120 million customers. It is also the largest ISP and presently offering Broadband Service on wireline, fiber & wireless to its customers. The Broadband network of BSNL is currently operating across the nation except in Delhi and Mumbai.

Its responsibilities include improvement of quality of already installed telecom services, expansion of telecom services in rural areas and acquiring confidence among its customers.

It provides comprehensive range of services in India, which include wireless connections, CDMA mobiles, GSM lines, internet, broadband, MPLS-VPN (Multi Protocol Level Switching-Virtual Private Network), VSAT (Very Small Aperture Terminal), WIMAX, FTTH and VOIP (Voice Over Internet Protocol).

Within this short span of time, it has also become one of the largest public sector companies in India.


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BSNL Mobile is the major service provider of GSM cellular mobile services under the brand name Cellone. BSNL provides complete telecom services solution to enterprise customers including MPLS, P2P and internet leased lines. It provides fixedline services and landline using CDMA technology and its extensive optical fiber network. BSNL provides internet access services through dial-up connection as prepaid, Netone as postpaid and Dataone as BSNL Broadband.

BSNL offers value-added services, such as Free Phone Services (FPH), Account Call Calling (ACC), Virtual Private Network (VPN), Tele-voting, Premium Rate Service (PRM), Universal Access Number (UAN).

BSNL also offers IPTV which enables customers to watch television through internet and Voice and Video Over Internet Protocol (VVoIP).

In 2007, BSNL announced plans for providing 5 million broadband connectivity and secured 80% of the INR 25 billion rural telephony project of Government of India.

On 20 March 2009, BSNL launched blackberry services across India. BSNL paid 101.87 billion for 3G spectrum in 2010. As of 2011, BSNL offers coverage in over 800 cities across India.

BSNL launched in 2012 3G wireless pocket router named Winknet Mf50. BSNL 3G provides HSPA+ service with highest speed of 21.1 Mbit/s downlink and 5.76 Mbit/s uplink.

BSNL announced the discontinuation of its telegram services from 15 July 2013, after 160 years in service. It was upgraded to a web-based messaging system in 2010, through 182 telegraph office across India.


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BSNL is fourth largest department of Telecommunication Company in Asia and 7th in World today. This is one of the most earning revenue in India. Above more than 3 laces employees, officer and engineers working in BSNL at present. Previously electro mechanically exchanges for use in India namely Strowger type exchange, cross bar exchanges were there. These manual telephone exchanges suffered from some disadvantages. To overcome these an automatic exchange was introduced in this system. In 1980’s PITHROTHA LTD. introduced “ C-DOT ” exchange in India. These exchanges replaced by electro mechanical exchange. These exchange which has wide range of capacity replaced electro mechanical exchange, C-DOT-128, C-DOT-256, C-DOT-512, C-DOT- 1024(SBM) exchange, C-DOT-2048(MBM) exchange and so on. Besides C-DOT exchange ILT exchange, E-10B exchange also proved of mild stone in Telecommunication Sector to replace electromechanical exchanges, which were most sophisticated and modern latest techniques electronics exchanges. There after it was OCB-283 exchange which proved very important exchange in this series to replace electro mechanical exchanges. Now it is “WLL” & “GSM” mobiles which is also proved a mild stone in Telecommunication sector. It was 31st march 2002 when BSNL started these GSM mobile and today it has provided almost 35 lacks mobiles in all over country. WLL system which is also a mobile with limited mobility in city & can have Tele communication facility in that area almost. While GSM can cover all cities of the country.


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DOT provides the following facilities: • Telegraph services • Telephone services such as Local calls, Trunk calls, Overseas calls etc. • Wireless services including mobile wireless services for police, defense, metrological departments, etc. • Renting of Broadcast & TV channels • Telecom Bureau Services • Data Services • FAX Services • I.T.I. Bangalore for the manufacturing for the carriers, VFT, Coaxial and microwave equipment. • I.T.I. Gonda for the manufacturing of E-10B electronic exchange equipment. • Hindustan Cables LTD. Hyderabad for manufacturing underground cables. • Hindustan Teleprinters LTD Chennai for manufacturing teleprinters. Local telecom network at the metropolitan cities of Mumbai and Delhi are under the MTNL (Mahanagar Telephone Nigam Limited). Its corporate office is at Delhi. Hence Telecommunication sector has changed our life style today entirely and today it seems that world has become very small.


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Telecommunication

Telecommunication encompasses the electrical communication at a distance of voice, data, and image information (e.g., TV and facsimile). These media, therefore, will be major topics of this book. The word media (medium, singular) also is used to describe what is transporting telecommunication signals. This is termed transmission media. An overall telecommunications network (i.e., the PSTN) consists of local networks interconnected by a long-distance network. Local Network Local Network

Long Distance Network

Local Network Local Network PSTN consists of local networks interconnected by a long distance network

This is the PSTN, which is open to public correspondence. It is usually regulated by a government authority or may be a government monopoly, although there is a notable trend toward privatization.

End Users, Nodes, Connectivity End-users provide the inputs to the network and are recipients of network outputs. The end-user employs an I/ O, standing for input/ output (device). An I/O may be a PC, computer, telephone


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instrument, cellular/ PCS telephone or combined device, facsimile, or conference TV equipment. End-users usually connect to nodes. A node is a point or junction in a transmission system where lines and trunks meet. A node usually carries out a switching function. In the case of the local area network (LAN), a network interface unit is used, through which one or more end-users may be connected. Connectivity connects an end-user to a node, and from there possibly through other nodes to some final end-user destination with which the initiating end-user wants to communicate.

Functions of End Users, Nodes and Connectivity

Stages of Telephone Call

There are three sequential stages to a telephone call:

1. Call setup

2. Information exchange and

3. Call take down.

Call setup is the stage where a circuit is established and activated. The setup is facilitated by signaling. It is initiated by the calling subscriber (user) going off-hook. It means “the action of taking the telephone instrument out of its cradle.” Two little knobs in the cradle pop up, pushed by a spring action, causing an electrical closure.


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If we turn a light on, we have an electrical closure allowing electrical current to pass. The same thing happens with our telephone set; it now passes current. The current source is a “battery” that resides at the local serving switch. It is connected by the subscriber loop. This is just a pair of copper wires connecting the battery and switch out to the subscriber premises and then to the subscriber instrument.

The action of current flow alerts the serving exchange that the subscriber requests service. When the current starts to flow, the exchange returns a dial tone, which is audible in the headset (of the subscriber instrument). The calling subscriber (user) now knows that she/ he may start dialing digits or pushing buttons on the subscriber instrument. Each button is associated with a digit. There are 10 digits, 0 through 9.

A subscriber set is connected to a telephone exchange by a subscriber loop If the called subscriber and the calling subscriber are in the same local area, only seven digits need be dialed. These seven digits represent the telephone number of the called subscriber (user). This type of signaling, the dialing of the digits, is called address signaling. The digits actuate control circuits in the local switch, allowing a connectivity to be set up.

If the calling and called subscribers reside in the serving area of that local switch, no further action need be taken. A connection is made to the called subscriber line and the switch sends a special ringing signal down that loop to the called subscriber, and her/ his telephone rings, telling her/ him that someone wishes to talk to her/ him on the telephone. This audible ringing is called alerting, another form of signaling.


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Once the called subscriber goes off-hook (i.e., takes the telephone out of its cradle), there is activated connectivity, and the call enters the information-passing phase, or phase 2 of the telephone call. When the call is completed, the telephones at each end are returned to their cradles, breaking the circuit of each subscriber loop. This is analogous to turning off a light; the current stops flowing. Phase 3 of the telephone call begins. It terminates the call, and the connecting circuit in the switch is taken down and freed-up for another user. Both subscriber loops are now idle. If a third user tries to call either subscriber during stages 2 and 3, she/ he is returned a busy-back by the exchange (serving switch).This is the familiar “busy signal,” a tone with a particular cadence. The return of the busy-back is a form of signaling called call-progress signaling.

How Line reaches from Subscriber to Exchange

Telephone Subscriber

Distribution Point

Pillor

Cabinet

Main Distribution Frame

Telephone Exchange


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Parts of Telecommunication Network

The main parts of Telecommunication network are:

1) Telephone Exchange (TAX) 2) Main Distribution Frame (MDF) 3) Power Plant

Telephone Exchange

Equipment which effects the interconnection of telephones is known as Switching Equipment. The switching centre, which houses the terminating and switching equipment, is called Telephone Exchange. A Telephone Exchange is a telecommunication system used in the Public Switch Telephone Network or in large enterprises. An exchange consists of electronic components that interconnect (switch) telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between the subscribers. All telephone subscribers are served by automatic exchanges. Today’s automatic exchanges use pair of computers. One running the program that provides the services second is monitoring the operation of the first, ready to take over in few seconds in the event of equipment failure.


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Telephone Exchange

Various exchanges present in BSNL are: 1) C-DOT 2) OCB (Organe De Commande B2 Version) 3) EWSD

C-DOT

It works on telecom technology, product and services. It provides solutions for current and future requirements of telecommunication and converged networks including those required for rural application. It provides market orientation to R&D activities and sustains C-DOT as center of excellence.


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OCB

OCB-283 is digital switching system which supports a variety of communication needs like basic telephony, ISDN, etc. This system has been developed by CIT ALCATEL of France and therefore has many similarities to its predecessor E-10B (also known as OCB-181 in France). Salient features of the system: 1) It is a digital switching with single ‘T’ stage switch. A maximum of 2048 PCM’s can be connected. 2) It supports both analog and digital subscribers. 3) It supports all the existing signaling systems, like decadic, MF (R2), CAS and also CCITT#7 signaling system. 4) It provides telephony, ISDN, Data communication, cellular radio, and other value added services. 5) The system has ‘automatic’ recovery feature. When a serious fault occurs in a control unit, it gives a message to SMM. The SMM puts this unit out of service, loads the software of this unit in a back up unit and brings it into service. Diagnostic programmes are run on the faulty unit and the diagnostics is printed on a terminal. 6) It has a double remoting facility. Subscribers access unit can be placed at a remote place and connected to the main exchange through PCM links. Further, line concentrators can also be placed at a remote location and connected to the CSNL or CSND through PCMs.


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7) Various units of OCB 283 system are connected over token rings. This enables fast exchange of information and avoids complicated links and wiring between various units. 8) The charge accounts of subscribers are automatically saved in the disc, once in a day. This avoids loss of revenue in case of battery failure. 9) The traffic handling capacity of the system is huge. 10) The exchange can be managed either locally or from an NMC through 64 kb/s link. 11) All the control units are implemented on the same type of hardware. This is called a station. 12) The system is made up of only 35 types of cards. This excludes the cards required for CSN. Due to this, the number of spare cards to be kept for maintenance is drastically reduced. 13) The system has modular structure. The expansion can be very easily carried out by adding necessary hardware and software. 14) The SMMs are duplicated with one active other standby. In case of faults, switch over takes place automatically. 15) The hard disc is very small in size, compact and maintenance free. It has a very huge memory capacity of 1.2 Giga bytes. 16) The space requirement is very small. 17) There is no fixed or rigid rack and suite configuration in the system.


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EWSD The EWSD Digital Switching System offers a wide range of telephony feature and supplementary services. Further capabilities can be developed to meet specific customer needs. EWSD is widely installed telephonic switch system developed by Siemens. Siemens says that EWSD performs switching for over 160 million lines in more than 100 countries. EWSD is a modularsystem in which some switches in the system can be installed in Telephone Company’s centrexfacility and other switches can be located at the costumer.

Important Features of EWSD include the following: Advanced Intelligent Network (AIN) 0.1and 0.2 capabilities allow switching services to be added at Services Control Points, meaning that new services can be added and performed by switching system without the customer having to by new equipment. In addition to AIN capabilities, EWSD provide ISDN, CLASS, SS7, and centrex services. Digital and analog lines can be combined in


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same line groups, allowing full interoperability between digital and analog terminals. Carriers using EWSD can provide Automatic Call Distributor services for customers with call centers

EWSD provides both Bellcore AIN 0.2 and Global System for Mobile (GSM) Communications for personal communication services.

Architecture of EWSD Switching System

EWSD System Description Digital Line Unit (DLU) :-

Analog or Digital subscribers, PBX lines are terminated on DLU. DLUs can be used locally within the exchange or remotely as remote switch unit.


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Line/ Trunk Group (LTG) :- The line/trunk groups (LTG) is the sub system in EWSD exchange which forms the interface between the digital environment of an EWSD exchange and the switching network (SN). Here line as ISDN PRI, V5.2 and trunks are connected.

Switching Network (SN) :- Switching network performs the switching function for speech as well as for messages in EWSD exchange.

Co-ordination Processor (CP) :- The coordination processors (CP) does the main call processing and other functions like routing, Zoning, safeguarding etc.

Message Buffer (MB):- Message Buffer is the module for coordinating internal message traffic between the CP, the SN, the LTGs and the CCNC in an exchange.

Common Channel Signaling Network Control(CCNC):- The MTP function of CCS#7 are handled by the common channel signaling network control (CCNC).The UP is incorporated in the software of relevant LTG.

System panel Display (SYPD):- It is to display system internal alarms and the CP load. The SYPD also displays external alarms such as fire and air - conditioning system failure.

Central Clock Generator (CCG): It is for the synchronization of the exchange and for the network.


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Main Distribution Frame

MDF is a media between switching network and subscriber’s line. It is the termination point within the local telephone exchange where exchange equipment and termination of local loops are connected by jumper wires

The switching equipment, common to all the subscribers of the area is located in an exchange. To make possible for a subscriber to communicate with remaining subscribers, telephone of each and every subscriber must be connected to the exchange. The function of MDF is to provide a means for connecting side is terminated at OCB where the switching takes place. From OCB, through PCM connected to various sections like WLL, TAX etc. A line from the subscriber’s telephone set involves: • Subscribers House wiring • Overhead wires • Cable Distribution Point


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• Underground cables • Exchange Main Distribution Frame

From the subscriber’s house wiring, the line is brought on overhead wires to a point called distribution point (DP). From the DP, the pairs are extended to the exchange through underground distribution cables, secondary cables and primary cables. At the exchange are brought through underground cables to cable chamber. In the cable chambers, they are jointed to PVC cables for terminating at MDF. This frame incorporates protecting devices and provides for a flexible arrangement for connecting subscriber’s lines to exchange equipments. Subscribers house wiring: PVC aluminum twin wire 1or1.12 mm is used for wiring at subscriber’s house. Protective devices are not necessary at the subscriber’s premises as per present standards. Underground cables: The underground cables laid at a depth to 2.5 feet below the ground level connect the DP post to the exchange MDF. The cabinets and pillars included in the cable network provide flexible arrangement of interconnection between various sizes of cables.

Functions of MDF:

1) All cable copper wires supplying services through user telephone lines are terminated and distributed through MDF. 2) The most common kind of large MDF is long steel rack accessible from both sides. Each jumper is a twisted wire. 3) It consists of local connection and broadband connection frames for the main exchange area.


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4) The MDF usually holds central office protective devices including heat coils and functions as a test point between the line and the office. 5) It provides testing of calls.

6) It checks whether the fault is indoor or external.

7) All lines terminate individually.

Organization of MDF

Vertical Side

Horizontal Side

Vertical Side Rack: On the rack, the tags are situated. One rack is having eight

tags. The counting is done from Up (0) to Down (7).

Tags: Each rack consists of eight tags. 1 tag = 4 core 1 core = 4 bunch 1 bunch = 2 line

N.E.: N.E. stands for “Number of Equipment”. It is used for testing number.

Wedge: Wedge is used as a device for checking the ring. Wedge is placed in jack strips, which is connected to telephone for checking.

Horizontal Side


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The Horizontal side is connected to the underground cable. This cable is having 100 pairs. This pair is distributed when the company allots the telephone number to the subscriber.

Horizontal Side is again subdivided into two parts. One side is connected with vertical side. Another with the subscriber line using 100 pair underground cable


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Power Plant

Power is the main source of any organization. It is the case of E-10B exchange. The first requirement of any organization is the input. The main source of this exchange is AC Supply. 1) Batteries for providing 48V supply 2) UPS (Uninterruptable Power Supply) 3) Charging – Discharging Unit 4) Inverter – Converter Unit

Power Plant

The power system is intended primarily to provide uninterrupted DC power to Telecom equipments and current for charging the batteries in the presence of AC Mains. The system works from commercial AC mains which is rectified and regulated to –50V DC and is fed to the equipment (exchange).


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Telecommunication systems require electrical energy for transmission of signals energization of subscriber’s telephone transmitters and for many miscellaneous functions. A telephone exchange requires a considerable large amount of energy, as the common exchange power plants required to feed currents for the subscriber’s transmitters, for signaling and for control and operation of exchanges switches. It is therefore, necessary that a power source should not be only economical but adequate to meet the needs of a particular type of the installation.

Failure of power supply system in any installation renders the communication facilities offered by it to be instantly paralyzed.

SMPS (SWITCHED MODE POWER SUPPLY) POWER PLANT The power plant is used to rectify the ac input supply to desired output dc (-48v). The conventional power plants which were in use earlier were based on SCRs or Ferro-resonant techniques. These conventional types of power plants were having following problems:

Very large size

Large weight

Lower efficiency

No scope for modular expansion. To get rid of all these problems now SMPS (Switched Mode Power System) power plants are used.

BATTERY These days, most of the Battery used in mobile network is VRLA (Valve Regulated Lead Acid Battery) type. Various capacities of batteries are 120 AH, 400 AH, 600 AH, 1000AH, 1500 AH, 2000 AH, 2500 AH, 3000 AH, 4000 AH & 5000 AH.


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INVERTER In most of the telecom installations, inverters are installed to provide uninterrupted AC supply to OMC terminals. Capacity of invertors used varies from 1KVA to 10KVA depending on the connected AC load. The basic precautions for installation is that inverter should be installed as close to battery room as possible so as to reduce DC voltage loss due to cabling. The inverters may not be loaded beyond 80%of its rated capacity and initial start up load also needs to be taken into account. Only essential equipment may be connected to inverter output.

EARTHING Earthing plays a vital role in the protection of equipments and the personnel. Apart from protection from hazardous stray currents in electrical equipment in Telecommunication circuits and equipments, Earthing is provided for the following purposes:

Reduction of Crosstalk and Noise.

Protection of costly apparatus and persons against foreign voltages and leakage currents from power wirings touching the metallic frame of the equipment.

Protection of buildings and equipments from lightning strikes.

Earthing of power supply systems is used to ensure reliability of power as it helps to provide stability of voltage conditions preventing excess fluctuations and providing a measure of protection against lightning.


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National Internet Backbone

The BSNL NIB2 network is primarily designed to be a high speed IP/MPLS network. The network is intended to be used for convergent services, integrating data, voice and video. It will provide services like Internet bandwidth for ISPs, Corporate, Institutions, Government bodies and retail users. The BSNL network is designed to be capable of meeting a wide range of customer requirements, including security, Quality of Service (QoS), and any-to-any connectivity. It is designed to be able to offer fully managed services to customers and allow BSNL to introduce additional services such as bandwidth on demand, etc. over the same network. The backbone infrastructure consists of an MPLS core with Internet services and VPN services edge networks. Cisco 12416 GSR & Cisco 12410 GSR routers are used to build the core network with the edge network consisting of Cisco 7613 routers. Cisco 7613 Routers serve also as the miscellaneous routers like Router Reflectors, International Data Center Routers, Internet Exchange Point Routers, IP Tax Routers, and International Gateway Routers. Below are the services, which the network is designed to offer: i) L3 MPLS VPN services 1) Intranet -Managed & Unmanaged 2) Extranet – Managed & Unmanaged 3) Internet Access services ii) Layer 2 MPLS VPN Services 1) Ethernet over MPLS 2) Frame relay over MPLS 3) PPP over MPLS 4) VPLS (Virtual Private LAN Service) 5) Layer 2 Any-to-Any Interworking (except ATM)


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iii) Encryption services iv) Firewall Services v) NAT Services vi) Multicast Service

The BSNL NIB2 network is primarily designed to be a Carrier Grade high speed IP/MPLS network. The backbone infrastructure consists of an MPLS core with Internet services and VPN services edge networks. Cisco 12416 GSR & Cisco 12410 GSR routers are used to build the core network with the edge network consisting of Cisco 7613 routers.


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The NIB-2 Layer-1 core network (A1, A2 and A3) constitutes high speed Backbone (STM-16) that comprise of fully or partially meshed Core routers with built-in redundancies supporting MPLS protocol with link capacities in accordance with the traffic justification. Its function is primarily limited to high-speed packet forwarding between the core nodes. The five major nodes of Mumbai, Bangalore, Noida, Kolkata and Chennai are the A1 nodes and are configured in full mesh with link bandwidths of STM-16. The Core routers at A2, A3 and A4 cities are dual homed to the nearest A core routers. The 9 nodes of Pune, Hyderabad Ahmedabad, Lucknow, Jallander, Jaipur, Indore, Ernakulum and Patna are the A2 and A3 nodes and are configured in dual mesh with link bandwidths of STM-16. The Juniper based MPLS infrastructure at Chandigarh, Allahabad, Ranchi, Guwahati, Bhubaneswar, Raipur, Vijayawada, Coimbatore, Mangalore, and Nagpur classify as A4 cities, which are dual homed to nearest A locations with link bandwidth of STM-1. The Layer-2 Edge network constitutes the second layer of the IP backbone network comprising of 71 cities consisting of MPLS “Provider Edge” routers (or “PE” routers) connected to the Core layer either locally through the Gigabit Ethernet switch or remotely through STM-1 links. The Edge network architecture provides for dual homing links from the Edge router to be terminated one each on the dual redundant Core routers to which the Edge router is parented. The NIB-II Edge nodes are classified into five categories according to their respective sizes. The A1 node represents the 5 core nodes of Noida, Mumbai, Bangalore, Chennai and Kolkatta. A2 represents nodes in the 3 cities of Pune, Hyderabad and Ahmedabad. A3 represents the 6 nodes in Ernakulum, Lucknow, Jaipur, Jallander, Indore and Patna. The B nodes (47 in total) are classified into 21 * B1 nodes dual homed to the core with STM-1 links and 26 * B2 nodes dual homed to the core with STM-1 links.


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The function of this Edge layer is aggregation of customer traffic. This layer enforces QoS and other administrative policies. This layer provides customer access through three mechanisms, a) Dialup b) Dedicated Access and c) Broadband Access. This layer provides connectivity to secure VPNs as well as to Internet Data Centers. The Interior gateway protocol used is OSPF and is based on a single Area model, which would offer a scalable, reliable, & redundant architecture, increasing efficiencies in the dynamics of the carrier grade IP Network of BSNL.


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bsnl 2016 industrial training report

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