Final Internship Report-ashish.docx

INTERNSHIP AT POWERGRID CORPORATION OF INDIA LIMITED (POWERTEL)

Ashish Pant B.Tech 4th semester JIMS Engineering Management technical Campus Aff. To Guru Gobind Singh Indraprastha University New Delhi Mr. Parijat S.M. Tripathi Chief Manager (Telecom)

ACKNOWLEDGEMENT I take immense pleasure in thanking Mr. A.K.Arora (COO, Telecom Deptt. New Delhi) for having permitted me to carry out this project work. I wish to express my deep sense of gratitude to my project in-charge Mr. Parijat S.M. Tripathi (Ch.Manager (telecom)) for his encouragement and cooperation in carrying out the project work. I would also like to thank Mr. Ashu Kr Mishra for their guidance and help through the course of training.

Telecommunication is the transmission of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio , optical or electromagnetic systems .Telecommunication occurs when the exchange of information between communication participants includes the use of Technology. It is transmitted either electrically over physical media, such as cable, or via electromagnetic radiation. Optical communication is a form of telecommunication that uses optical fibers, by use fiber we can send lots of information at very high speed and eventually will change our society and make our lives more comfortable. POWERGRID, the Central Transmission Utility (CTU) of the country, is engaged in power transmission business. With the vision to bridge the digital divide in the country, POWERGRID has diversified into telecom to utilize spare telecommunication capacity of its Unified Load Dispatch Centre (ULDC) schemes, with its brand name as POWERTEL. Among the telecom players, POWERGRID is the only utility in the country having overhead optic fibre network using OPGW (Optical Ground Wire) on power transmission lines, OPGW is a dual functioning cube performing the duties of a ground wire and also providing a patch for the transmission of voice, video or data signals.

   

Owns and operates ≍ 43,450 km of Telecom Network Points of Presence in 662 locations Intra City network in 105 cities across India Backbone Telecom Network Availability > 99.5%

CONTENTS

1. Introduction 2. Optical Fibres 3. Types of optical fibres 4. Multiplexing 5. Synchronous Digital Hierarchy(SDH) 6. PDH vs SDH 7. Dense Wavelength Digital Multiplexing 8. Transceivers Vs Transponders 9. Network management system 10. IPv4 11. TCP/IP 12. MPLS Network 13. Powergrid’s MPLS network 14. Traffic Engineering 15. Technical specifications for shelters 16. Type testing 17. Installation of underground fibre optic cable system

INTRODUCTION POWER GRID CORPORATION OF INDIA LIMITED POWER GRID CORPORATION OF INDIA LIMITED (POWERGRID), the Centre Transmission Utility (CTU) of the country under Ministry of Power, is engaged in power transmission business with the responsibility for planning, coordination, supervision and control over inter-State transmission system and operation of National & Regional Power Grids. As on March 31, 2012, the Company owns and operates about 92,950 circuit km’s of transmission lines at 800/765kV, 400kV, 220kV & 132kV EHVAC & +500kV HVDC levels and 150 sub-stations with transformation capacity of about 1, 24,525 MVA. This gigantic transmission network, spread over length and breadth of the country, is consistently maintained at an availability of over 99%. The mission of the corporation is establishment and operation of regional and national power grids to facilitate transfer of electric power within and across the regions with reliability, security and economy, on sound commercial principles. POWERGRID is committed to: a) Establish and maintain an efficient and effective "national grid" with due regard to time, cost, technology, and value additions. b) Sustainable development through conservation of natural resources and adopting environment friendly technology on principle of avoidance, minimization and mitigation. c) Ensure safe, occupational hazard free and healthy work environment, to the satisfaction of stake holders in all areas of its activities and shall endeavor to continually improve its management systems and practices in conformity to legal and regulatory provisions. POWERGRID is in the business of Bulk power transmission, Telecom and providing consultancy services to Power Utilities (both domestic and International)

Telecom Business of POWERGRID With the vision to bridge the digital divide in the country and ensure that benefits of information revolution reach the entire length and breadth of the country, POWERGRID has diversified into Telecom utilizing right of way on its Extra High Voltage Power Transmission Network infrastructure in the country with its brand name as POWERTEL. Among the telecom players, POWERGRID is the only utility in the country having overhead fibre optics network using OPGW (Optical Ground Wire) on power transmission lines. POWERGRID has an all India Broad Band Telecom Network of about 25000Kms which is likely to be doubled in 2-3 years with multiple selfresilient rings for backbone as well as intra city access networks connecting more than 200 cities and town across the country and ensuring a reliability of more than 99.9%.

Salient features Most of the POWERGRID’s optic fibre backbone network is laid overhead on the extra high voltage Power transmission lines .The Telecom network on the Transmission lines has proved to be sturdy and secure, rodent menace free, vandalism proof which offers it distinct advantage over the underground optic fiber. The other advantages of leasing bandwidth capacity on POWERGRID’s Telecom route are: •Instant bandwidth allocation on POWERGRID’s Telecom route •End to end connectivity •Instant upgradation to higher capacity •Better Service Level •Services catering to the specific needs of the customers •High reliability, high quality service in a cost effective manner.

Something about POWERTEL: Services offered: • End to End bandwidth • Ethernet private leased line • Internet services • MPLS-VPN services • Telecom Tower Infrastructure To provide total solution to customers through state-of-the-art Broadband Telecom Network and contribute in bridging the digital divide by accelerating the process of Convergence in urban and rural areas and enable the common man living in remotest and uneconomical areas become a part of the global village. The inherent Communication infrastructure coupled with right of way along its extensive Power Transmission network have made it possible to leverage these characteristics in creating convergence of technologies. POWERGRID’s telecom network of 50,000kms, connecting about 60 major cities/ Metros is nearing completion. POWERGRID’s telecom network provides a robust telecom highway at affordable cost with ultra-modern and eco-friendly implementation techniques. POWERGRID is one of the few telecom players with a marked presence in remote areas viz. North Eastern Region, Jammu and Kashmir, Himachal Pradesh, etc.

POWERGRID has a 24X7 Real time monitoring of the telecom network through National Level Control Centre (NTCC): Delhi Regional Level Control Centres (RTCC): Kolkata, Banglore, Mumbai, Delhi.

POWERGRID’S Network Spreading in all over India

OPTICAL FIBERS An optical fibre is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fibre-optic communication, where they permit transmission over longer distances and at higher bandwidths (data rates) than electrical cables. The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Fibers are also used for illumination and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers. Optical fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection. This causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those that only support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter, and are used for short-distance communication links and for applications where high power must be transmitted. Singlemode fibers are used for most communication links longer than 1,050 meters.

Joining lengths of optical fiber is more complex than joining electrical wire or cable. The ends of the fibers must be carefully cleaved, and then spliced together, either mechanically or by fusing them with heat. Special optical fiber connectors for removal connections are also available.

FUNCTIONING AND CONSTRUCTION A main purpose of a fibre optic cable is to protect the fibre core inside the cable that carries the light signal transmission. The following diagram shows the construction of a fibre optic cable.

Core The fibre core is made of silica glass and is the central part of the fibre optic cable that carries the light signal. They are hair-thin in size and the diameter of the fibre core is typically 8 µm for single mode fibre, and 50 µm or 62.5 µm for multi-mode fibre.

Cladding The cladding is also made of glass, and is the layer that surrounds the fibre core. Together, they form a single solid fibre of glass that is used for the light transmission. The diameter of the cladding is typically 125 µm.

Primary Coating After the cladding, there is the primary coating that is also known as the primary buffer. This layer provides protection to the fibre core and cladding. They are made of plastic and only provide mechanical protection. They do not interfere with the light transmission of the core and the cladding.

Strength Members The next layer is strength members. They are strands of agamid yarn, or better known as Kevlar. They are added to the fibre optic cable to prevent the breakage of the fibre glass during installation. When fibre is pulled through a duct, the outer cover would stretch and the pulling load would be rested on the fibre. The strength members prevent this as their material is designed to take the strain.

Cable Jacket The last layer is the cable jacket, which are comprised of different materials depending on the choice of the end user and the application in use. Like the primary coating, they serve only as a mechanical protection to the fibre core and cladding inside

Types of Optical fiber Fiber with a core diameter less than about ten times the wavelength of the propagating light cannot be modeled using geometric optics. Instead, it must be analyzed as an electromagnetic structure, by solution of Maxwell's equations as reduced to the electromagnetic. The electromagnetic analysis may also be required to understand behaviors such as speckle that occur when coherent light propagates in multi-mode fiber. As an optical waveguide, the fiber supports one or more confined transverse modes by which light can propagate along the fiber.

Single Mode Fibre: Fiber supporting only one mode is called single-mode or mono-mode fiber In this type of fibres the dimension of core are so reduced as to support one ray of transmission or one mode of propagation. In terms of electromagnetic theory, only one mode of transmission is supported. The main advantage of single mode fibre turns out to be the larger bandwidth of information that can be transmitted by it with low loss of transmission. The most common type of single-mode fiber has a core diameter of 8–10 micrometers and is designed for use in the near infrared. The mode structure depends on the wavelength of the light used, so that this fiber actually supports a small number of additional modes at visible wavelengths.

The structure of a typical single-mode fiber. 1. Core: 8 µm diameter 2. Cladding: 125 µm dia. 3. Buffer: 250 µm dia. 4. Jacket: 400 µm dia

The waveguide analysis shows that the light energy in the fiber is not completely confined in the core. Instead, especially in single-mode fibers, a significant fraction of the energy in the bound mode travels in the cladding as an evanescent wave.

Multi Mode Fibre: It has a definite core/cladding dimension and refractive index profile, which allows a number of rays to be transmitted through the core. In terms of optical wave guiding, the refractive indices permit number of modes to be supported by the fibre as the name indicates. Modes can be “seen” when ultra-thin beams (Laser) enter multimode fibres at different angles. multi-mode fiber can also be modeled using the wave equation, which shows that such fiber supports more than one mode of propagation (hence the name). Multi-mode fiber is manufactured with core diameters as small as 50 micrometers and as large as hundreds of micrometers. The normalized frequency V for this fiber should be less than the first zero of the Bessel function J0 (approximately 2.405).

MULTIPLEXING When two devices are connected by a point-to-point link they usually do not use the full capacity of the transmission medium. For efficiency, it should be possible to share that capacity. A generic term for such sharing is multiplexing. The network element that accomplishes this function is called a multiplexer (MUX). Different technologies are used for multiplexing signals. They are frequency division multiplexing (FDM), time division multiplexing (TDM) and (dense) wavelength division multiplexing (WDM). Radio and television broadcasts use FDM. WDM is related to the transport of different signals through an optical fiber by using different wavelengths. TDM is commonly used for multiplexing digitized voice streams and data streams.

There are basically two types of multiplexing

Multiplexer Naming Conventions

tributaries

TM m/n

aggregate

aggregate

ADM m/n

aggregate

tributaries

•

Terminal Multiplexer (TM) • • •

All traffic is terminated here. m: aggregate level n: lowest tributary level

•

Add-Drop Multiplexer (ADM) • •

Part of the traffic is terminated. Part of the traffic goes transparently through.

The terminal multiplexer (TM) combines (multiplexes) data from n input lines and transmits over a higher-capacity data link. The inputs are called tributaries. The TM combines many tributaries into one aggregate signal. The second alternative is an Add-Drop Multiplexer (ADM) which has tributaries, but has two, instead of one, aggregate. In an ADM we can drop traffic or we can add traffic or traffic can simply go through it - that is called transparency. This configuration is often used in ADM rings. In an ADM ring we can in each node terminate traffic (TP, termination point) or it can go through transparently or traffic can be added (TP). If we compare ADM to TM, we notice that in TM we always have to terminate all traffic, but in ADM we can let some of the traffic through it transparently.

DIGITAL CROSS CONNECT A digital cross-connect is a piece of equipment that is a combination of a cross-connection matrix and a multiplexer. The mux takes the aggregate signals and de multiplexes those into tributary signals. These signals go into the cross-connector. The cross-connection matrix is just a matrix in which any incoming signal can be connected /switched to any outgoing signal, if the cross-connection matrix is fully non-blocking. If the cross-connection matrix is blocking, some connections are impossible. The cross-connection matrix can consist of two different types of matrices. A matrix can be either time division or space division or, as it usually is, a combination of those.

SYNCHRONOUS DIGITAL HIERARCHY (SDH) SDH is an international standard for high speed telecommunication over optical/electrical networks which can transport digital signals to variable capacities. It is a synchronous system which tends to provide a more flexible, yet simple network infrastructure. Synchronous digital hierarchy(SDH) are standardized multiplexing protocol that transfer multiple digital bit streams over optical fiber using lasers or LED’s. The method was developed to replace Plesiochronou Digital Hierarchy(PDH) system for transporting larger amounts of telephone calls and data traffic over the same phone call without the problem of synchronization. It originated from Synchronous Optical Network(SONET) in the US. SDH is based on direct synchronous multiplexing (done at byte level). This means that tributary signals may be multiplexed directly into a higher rate SDH signal without intermediate stages of multiplexing, and, as a result, NEs can be interconnected directly with cost and equipment savings. SDH provides numerous facilities built into the signal overhead for embedded operations, administration and maintenance (OAM) purposes. The whole becomes an integrated network management and maintenance system. SDH provides flexible signal transportation capabilities. The SDH signal easily integrates new services, such as Asynchronous Transfer Mode (ATM), Fiber Distributed Data Interface (FDDI) and Distributed Queue Dual Bus (DQDB), along with existing European 2, 34, and 140 Mbps PDH signals, and North American 1.5, 6.3 and 45 Mbps signals, all the common tributary signals found in telecommunication networks. Other advantages are that SDH takes advantage of the bandwidth provided by optical technology (an optical fiber is a medium capable of conducting an optical ray, which is using wavelength in the order of micrometers, so the bandwidth is immense). It is also standardized which means that equipment from different manufacturers are able to work together. This also applies to protection, which is standardized in SDH. Reduced networking cost due to the transversal compatibility. Synchronous structure is flexible.

IMPORTANCE OF SDH To cope with the demand for ever-higher bit rates, a multiplex hierarchy or plesiosynchronous digital hierarchy (PDH) evolved. The bit rates start with the basic multiplex rate of 2 Mbps with further stages of 8, 34, and 140 Mbps. In North America and Japan, however the primary rate is 1.5 Mbps with additional stages of 6 and 44 Mbps. This fundamental difference in developments made the set up of gateways between the networks both difficult and expensive.

ADVANTAGE OF SDH In response to the demand for increased bandwidth, reliability, and high quality service, SDH developed steadily during the 1980s eliminating many of the disadvantages inherent in PDH. In turn, network providers began to benefit from the many technological and economic advantages this new technology introduced including:  HIGH TRANSMISSION RATES Transmission rates of up to 10 gbps can be achieved in modern SDH systems making it the most suitable technology in today's telecommunications networks. 

SIMPLIFIED ADD AND DROP FUNCTION

Compared to the older PDH system, low bit rate channels can be easily extracted from and inserted into the high-speed bit streams in SDH. It is now no longer necessary to apply the complex and costly procedure of de multiplexing then re multiplexing the plesiosynchronous structure.  RELIABILITY Modern SDH networks include various automatic back-up circuit and repair mechanisms which are designed to cope with system faults and are monitored by management. As a result, failure of a link or an NE does not lead to failure of the entire network.  FUTURE PROFF PLATFORM FOR NEW SERVICESA SDH is the ideal platform for a wide range of services including POTS, ISDN, mobile radio, and data communications (LAN, WAN, etc.). It is also able to handle more recent services such as video on demand and digital video broadcasting via ATM.

THE SYNCHRONOUS DIGITAL HIERARCHY IN TERMS OF LAYERS Telecommunications technologies are generally explained using so called layer models. SDH can also be depicted in the same way. SDH networks are subdivided into various layers directly related to the network topology. I. The lowest layer is the physical layer, which represents the transmission medium. This is usually a glass fiber or possibly radio or satellite link. II. The regenerator section is the path between regenerators. Part of the regenerator section overhead (RSOH) is available for the signalling required within this layer. The remainder of the overhead, the multiplex section overhead (MSOH) is used for multiplex section needs. The multiplex section covers the part of the SDH link between multiplexers. III. The carriers or virtual containers (VC) are available as payload at the two ends of this section. The two VC layers represent a part of the mapping process. IV. Mapping is the procedure whereby the tributary signals, such as PDH and ATM are packed into SDH transport modules. VC-4 mapping is used for 140-Mbps or ATM signals and VC-12 mapping is used for 2Mbps signals.

REGENRATORS A digital signal can be transmitted only a limited distance before attenuation endangers the integrity of the data. To achieve greater distances, repeaters are used. The term used in SDH is regenerator. The repeater takes the signal, interprets and reproduces it. So if the distance between two repeaters is optimal, we will have a close-to-original signal after the repeater.

Plesiochronous Digital Hierarchy(PDH) PDH is a popular technology that is widely used in network of communication in order to transport huge amounts of data over digital equipment for transportation like optic system. PDH works in a state when the various different parts of a network are clearly synchronized. But with the change in technology, the PDH is now being replaced by the SDH. The SDH is useful equipment that is used in most of the telecommunication networks.

PDH Vs SDH As the technology has improved with the passing of time, now the telecommunication companies have replaced the PDH equipment with that of SDH equipment, which has the capability of transmitting the data at much higher rates as compared to the PDH system. The SDH is an international standard that is highly popular and used for its high speed data transfer of telecommunication and digital signals. The SDH is designed in order to design simple and flexible network infrastructure. This system has bought a considerable amount of change in the telecommunication networks that were based on the optical fibres as far as performance and cost were concerned. The main weaknesses of PDH were: I. Had asynchronous structure. II. Restricted management capacity III. No optical interface And SDH system has a large number of advantages over PDH: I. II. III. IV. V.

Optical interface Capability of powerful management Synchronous structure was flexible Cost effective World standard digital format

DWDM (Dense wavelength division multiplexing) Brief With today’s seemingly limitless demand for transmission capacity, service providers often cope with extreme fiber usage and exhaust across significant portions of their networks. An enormous amount of bandwidth capacity is therefore needed to provide the services required by customers. The expansion of existing links calls for simple, cost effective solutions that cause minimum disruption to working systems. The telecommunications industry has so far met these needs by using dense wavelength division multiplexing (DWDM) systems. In allowing both new and existing fiber optic links to carry several channels simultaneously, DWDM can optimize the use of current facilities whilst offering greater capacities for the future. Some examples of DWDM includes voice transmission, e-mail, video and multimedia which can be simultaneously transmitted in DWDM systems, regardless of their transmission formats which include synchronous optical network(SONET), synchronous digital hierarchy (SDH), asynchronous transfer mode (ATM), internet protocol (IP), packet over SONET/SDH (PoS) or gigabit ethernet (GigE). Unlike previous systems however, the planning, installation, and maintenance of DWDM networks demands that much closer attention be paid to a number of performance limiting parameters.

WHI IS IT NEEDED? A DWDM system can be described as a parallel set of optical channels, each using a slightly different wavelength, but all sharing a single transmission medium or fiber. The figure illustrates the functionality of a multichannel DWDM transmission system when various 10 gbps signals are fed to optical transmission modules. The optical output signals are converted to defined wavelengths in the 1550 nm window via wavelength transponders. An optical DWDM coupler (multiplexer) then ‘bunches’ these optical signals

together on one fiber and forwards them as a multiplexed signal to an optical fiber amplifier (OFA). Depending on path length and type of fiber used, one or more OFAs can be used to boost the optical signal for long fiber spans. At termination on the receiving end, the optical signals are pre-amplified, then separated using optical filters (de-multiplexer) before being converted into electrical signals in the receiver modules. Recent innovations in DWDM transport systems include pluggable and software-tunable transceiver modules capable of operating on 40 or 80 channels. This dramatically reduces the need for discrete spare pluggable modules, when a handful of pluggable devices can handle the full range of wavelengths.

Some characteristics of DWDM:    

Increase Network Capacity Working on Existing Fibre Infrastructure Low Initial Cost Quick Capacity Upgrade Later

HISTORY

The laying of new fiber was once the only way to cope with fiber exhaust in telecommunication networks. A cost and labor intensive process, the main drawback of this solution was its inability to enable network operators to provide new services. At the beginning of the 1980s, time domain multiplexing (TDM) made it possible to increase the bit-rate. With TDM, the capacity of a single fiber could be increased by slicing time into smaller intervals and thereby multiplexing the different signals. In TDM systems, each telecommunication fiber is able to transport an optical signal from a single laser (figure 1). This optical signal is converted into an electrical signal, regenerated (electrically reshaped, retimed and reamplified) and finally transformed back into an optical signal again encountering losses. High bitrate transmissions via TDM however proved to be challenging. Wavelength division multiplexing (WDM), the simultaneous transmission of multiple signals at different wavelengths over a single fiber proved to be a more reliable alternative. The first networks deploying WDM technology at the end of the 1980s, multiplexed signals from the lasers of two very different wavelength

(a technology now referred to as Coarse WDM). The disadvantage of this technique was that the multiplexed signal had to be separated each time before being electrically regenerated .Today’s modern CWDM system (such as those with over 20 nanometers (nm) channel spacing), are used for short range transmissions where no regeneration is required. They transmit up to 16 channels between 1310 and 1610 nm, thus making CWDM a cost effective solution. During the 1990s, networks were designed to send up to four different signals over one fiber at different wavelengths within the same optical window (Broadband WDM). This is an application however necessitating the use of narrow lasers. In order to increase the number of services (bandwidth), the channel spaces can be moved closer together (for example with a space of just 0.8 nm between two channels), creating Dense WDM or DWDM as it is commonly known. This technology economically increases transport capacity through the utilization of existing fiber routes and terminal equipment. While debate continues as to whether WDM or TDM is best suited for the expansion of existing fiber networks, it has become clear that only solutions incorporating both technologies will give service providers the flexibility and capacity for future requirements. A DWDM system can be described as a parallel set of optical channels, each using a slightly different wavelength, but all sharing a single transmission medium or fiber. The figure illustrates the functionality of a multichannel DWDM transmission system when various 10 gbps signals are fed to optical transmission modules. The optical output signals are converted to defined wavelengths in the 1550 nm window via wavelength transponders. An optical DWDM coupler (multiplexer) then ‘bunches’ these optical signals together on one fiber and forwards them as a multiplexed signal to an optical fiber amplifier (OFA).

COMPONENTS OF DWDM: 1. Terminal multiplexer-> The terminal multiplexer contains a 'wavelength converting transponder' for each data signal, an optical multiplexer and where necessary an optical amplifier (EDFA). Each 'wavelength converting transponder' receives an optical data signal from the client-layer, such as Synchronous optical networking [SONET /SDH] or another type of data signal, converts this signal into the electrical domain and re-transmits the signal at a specific wavelength using a 1550 nm band laser. These data signals are then combined together into a 'multi-wavelength optical signal' using an optical multiplexer, for transmission over a single fiber (e.g. SMF-28 fiber). The terminal multiplexer may or may not also include a local transmit EDFA for power amplification of the 'multi-wavelength optical signal'. (Early DWDM systems contained 4 or 8 'wavelength converting transponders' in the mid 1990s. By 2000 or so, commercial systems capable of carrying 128 signals were available 2. Intermediate line repeater -> It is placed approximately every 80 – 100 km to compensate for the loss of optical power as the signal travels along the fiber. The 'multi-wavelength optical signal' is amplified by an EDFA, which usually consists of several amplifier stages 3. Intermediate optical terminal/ optical add-drop multiplexer> This is a remote amplification site that amplifies the multi-wavelength signal that may have traversed up to 140 km or more before reaching the remote site. Optical diagnostics and telemetry are often extracted or inserted at such a site, to allow for localization of any fiber breaks or signal impairments. In more sophisticated systems (which are no longer point-to-point), several signals out of the 'multi-wavelength optical signal' may be removed and dropped locally. 4. Terminal de-multiplexer-> At the remote site, the terminal demultiplexer consisting of an optical de-multiplexer and one or more 'wavelength converting transponders' separates the 'multi-wavelength optical signal' back into individual data signals and outputs them on separate fibers for client-layer systems (such as SONET/SDH). Originally,

this de-multiplexing was performed entirely passively, except for some telemetry, as most SONET systems can receive 1550nm signals. 5. Optical Supervisory Channel (OSC)-> This is data channel which uses an additional wavelength usually outside the EDFA amplification band (at 1510 nm, 1620 nm, 1310 nm or another proprietary wavelength). The OSC carries information about the multi-wavelength optical signal as well as remote conditions at the optical terminal or EDFA site. It is also normally used for remote software upgrades and user (i.e., network operator) Network Management information.

DWDM systems have to maintain more stable wavelength or frequency than those needed for CWDM because of the closer spacing of the wavelengths. Precision temperature control of laser transmitter is required in DWDM systems to prevent "drift" off a very narrow frequency window of the order of a few GHz. In addition, since DWDM provides greater maximum capacity it tends to be used at a higher level in the communications hierarchy than CWDM, for example on the Internet backbone and is therefore associated with higher modulation rates, thus creating a smaller market for DWDM devices with very high performance levels. These factors of smaller volume and higher performance result in DWDM systems typically being more expensive than CWDM.

Wavelength converting transponders wavelength converting transponders served originally to translate the transmit wavelength of a client-layer signal into one of the DWDM system's internal wavelengths in the 1550 nm band. In the mid-1990s, wavelength converting transponders rapidly took on the additional function of signal regeneration. Signal regeneration in transponders quickly evolved through 1R to 2R to 3R and into overhead-

1R- Retransmission. Basically, early transponders were "garbage in garbage out" in that their output was nearly an analogue 'copy' of the received optical signal, with little signal cleanup occurring. This limited the reach of early DWDM systems because the signal had to be handed off to a clientlayer receiver (likely from a different vendor) before the signal deteriorated

too far. Signal monitoring was basically confined to optical domain parameters such as received power. 2R- Re-time and re-transmit. Transponders of this type were not very common and utilized a quasi-digital Schmitt triggering method for signal clean-up. Some rudimentary signal quality monitoring was done by such transmitters that basically looked at analogue parameters. 3R-Re-time, re-transmit, re-shape. 3R Transponders were fully digital and normally able to view SONET/SDH section layer overhead bytes such as A1 and A2 to determine signal quality health. Many systems will offer 2.5 Gbit/s transponders, which will normally mean the transponder is able to perform 3R regeneration on OC-3/12/48 signals, and possibly gigabit Ethernet, and reporting on signal health by monitoring SONET/SDH section layer overhead bytes. Many transponders will be able to perform full multi-rate 3R in both directions. Some vendors offer 10 Gbit/s transponders, which will perform Section layer overhead monitoring to all rates up to and including OC-192.

Muxponder The muxponder (from multiplexed transponder) has different names depending on vendor. It essentially performs some relatively simple time division multiplexing of lower rate signals into a higher rate carrier within the system. More recent muxponder designs have absorbed more and more TDM functionality.

Transceivers versus Transponders Transceivers – Since communication over a single wavelength is one-way and most practical communication systems require two-way communication, two wavelengths will be required (which might or might not be on the same fiber, but typically they will be each on a separate fiber in a socalled fiber pair). As a result, at each end both a transmitter (to send a signal over a first wavelength) and a receiver (to receive a signal over a second wavelength) will be required. A combination of a transmitter and a receiver is called a transceiver; it converts an electrical signal to and from an optical signal. There is usually types transceiver based on WDM technology Transponders – In practice, the signal inputs and outputs will not be electrical but optical instead (typically at 1550 nm). This means that in effect we need wavelength converters instead, which is exactly what a transponder is. A transponder can be made up of two transceivers placed after each other: the first transceiver converting the 1550 nm optical signal to/from an electrical signal, and the second transceiver converting the electrical signal to/from an optical signal at the required wavelength. Transponders that don't use an intermediate electrical signal (all-optical transponders) are in development.

Network Management System (NMS) A Network Management System (NMS) is a combination of hardware and software used to monitor and administer a network. Individual network elements (NEs) in a network are managed by an element management system.

Planning for a Network Management System Effective planning for a network management system requires that a number of network management tasks be folded in a single software solution. The network management system should discover the network inventory, monitor the health and status of devices and provide alerts to conditions that impact system performance. NMS systems make use of various protocols for the purpose they serve. For example, SNMP protocol allows them to simply gather the information from the various devices down the network hierarchy. NMS software is responsible for identification of the problem, the exact source of the problem and solving them. The NMS systems not only are responsible for the detection of faults but also for collecting the statistics of the devices over a period of time. They may include a library where the previous network statistical data over a period of time is stored along with the problems and the solutions that worked in the past. This library can come useful in case a fault is found. NMS software can consult the library and search for the best possible method to resolve the problem.

Network management Network management refers to the activities, methods, procedures, and tools that pertain to the operation, administration, maintenance, and provisioning of networked systems.  Operation deals with keeping the network (and the services that the network provides) up and running smoothly. It includes monitoring the network to spot problems as soon as possible, ideally before users are affected.  Administration deals with keeping track of resources in the network and how they are assigned. It includes all the "housekeeping" that is necessary to keep the network under control.





Maintenance is concerned with performing repairs and upgrades—for example, when equipment must be replaced, when a router needs a patch for an operating system image, when a new switch is added to a network. Maintenance also involves corrective and preventive measures to make the managed network run "better", such as adjusting device configuration parameters. Provisioning is concerned with configuring resources in the network to support a given service. For example, this might include setting up the network so that a new customer can receive voice service.



A common way of characterizing network management functions is FCAPS—Fault, Configuration, Accounting, Performance and Security. Functions that are performed as part of network management accordingly include controlling, planning, allocating, deploying, coordinating, and monitoring the resources of a network, network planning, frequency allocation, predetermined traffic routing to support load balancing, cryptographic key distribution authorization, configuration management, fault management, security management, performance management, bandwidth management, Route analytics and accounting management. Data for network management is collected through several mechanisms, including agents installed on infrastructure, synthetic monitoring that simulates transactions, logs of activity, sniffers and real user monitoring. In the past network management mainly consisted of monitoring whether devices were up or down; today performance management has become a crucial part of the IT team's role which brings about a host of challenges—especially for global organizations.

Network Architecture Network architecture is the design of a communications network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation. In computing, the network architecture is a characteristics of a computer network. The most prominent architecture today is evident in the framework of the Internet, which is based on the Internet Protocol Suite. In telecommunication, the specification of a network architecture may also include a detailed description of products and services delivered via a

communications network, as well as detailed rate and billing structures under which services are compensated. In distinct usage in distributed computing, network architecture is also sometimes used as a synonym for the structure and classification of distributed application architecture, as the participating nodes in a distributed application are often referred to as a network. For example, the applications architecture of the public switched telephone network (PSTN) has been termed the Advanced Intelligent Network. There are any number of specific classifications but all lie on a continuum between the dumb network (e.g., Internet) and the intelligent computer network (e.g., the telephone network). Other networks contain various elements of these two classical types to make them suitable for various types of applications. Recently the context aware network, which is a synthesis of the two, has gained much interest with its ability to combine the best elements of both.

Network Monitoring The term network monitoring describes the use of a system that constantly monitors a computer network for slow or failing components and that notifies the network administrator in case of outages via email, pager or other alarms. It is a subset of the functions involved in network management. While an intrusion detection system monitors a network for threats from the outside, a network monitoring system monitors the network for problems caused by overloaded and/or crashed servers, network connections or other devices. For example, to determine the status of a web server, monitoring software may periodically send an HTTP request to fetch a page; for email servers, a test message might be sent through SMTP and retrieved by IMAP or POP3. Commonly measured metrics are response time and availability (or uptime), although both consistency and reliability metrics are starting to gain popularity. The widespread addition of WAN optimization devices is having an adverse effect on most network monitoring tools -- especially when it comes to measuring accurate end to end response time because they limit round trip visibility. Status request failures, such as when a connection cannot be established, it times-out, or the document or message cannot be retrieved, usually produce an action from the monitoring system. These actions vary: an alarm may be sent out to the resident (SMS, email...) sysadmin, automatic failover systems may be activated to remove the troubled server from duty until it can be repaired, etcetera.

Monitoring the performance of a network uplink is also known as network traffic measurement, and more software is listed there.

Network Tomography Network tomography is an important area of network measurement, which deals with monitoring the health of various links in a network using end-to-end probes sent by agents located at vantage points in the network/Internet.

Route Analytics Route analytics is another important area of network measurement. It includes the methods, systems, algorithms and tools to monitor the routing posture of networks. Incorrect routing or routing issues cause undesirable performance degradation or downtime.

IPv4(internet protocol version 4 ) Internet protocol version 4 is the fourth version of the internet protocol(IP). It is one of the core protocols of standards-based internetworking methods in the internet. It still routes most internet traffic today. IPv4 is a connectionless protocol for use on pocket-switched networks. It operates on a best effort delivery model, in that it does not gurantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol, such as the transmission control protocol(TCP). It defines an IP address as 2 bit numbers. IP addresses are usually written and displayed in human readable notations.

Classless Inter Domain Routing(CIDR) It is a method for allocating IP addresses And IP routing.

Routing It is a process of selecting a path for trafficin a network, or between or across multiple networks.

OSI Model Open System interconnection model is a conceptual model that characterizes and standardizes the communication function of a telecommunication or computing system without regard to its underlying internal structure and technology. The model partitions a communication system into abstraction layers. The original version of the model defined seven layers. OSI has two major components, an abstract model of networking, called the Basic reference Model or seven layer model, and a set of specific protocols.

ABSTRACTION LAYER: In computing, a layer is a way of hiding the implementation details of a particular set of functionality. A layer is considered to be on top of another if it depends on it. A layer serves the layer above it and is served by the layer below it. For Example, a layer that provides error free communication across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that comprise the contents of the path. Every layer can exist without the layers above it, and requires the layer below it to function. Frequently abstraction layers can be composed into a hierarchy of abstraction levels. The OSI model comprises seven abstraction layers. Each layer of the model encapsulates and addresses a different part of the needs of digital communications, thereby reducing the complexity of the associated engineering solutions. The concept of a seven-layer model was provided by the work of Charles Bachman at Honeywell information services. Various aspects of OSI design evolved from experiences with the APARNET, NPLNET, EIN, CYCLADES network and the work in IFIP WG6.1. The new Design was documented in ISO 7498 and its various addenda. In this model, a networking system was divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacted directly only with the layer immediately beneath it, and provided facilities for use by the layer above it.

OSI layers Layer

PDU

1. Physical

2. Data link

3. Network

4. Transport

Symbol

Frame

packet

segment

6. Session

data

7. presentation

Data

8. Application

data

Function Transmission and reception of raw bit streams over a physical medium. Reliable transmission of data frames between two nodes connected by a physical layer. Structuring and managing a multimode network including addressing, routing, traffic control. Reliable transmission of data segments between points on a network including segmentation and multiplexing. Continuous exchange of info in the form of multiple back and forth transmission between nodes. Translation of data between a network services and an application High level API

Layer 1: Physical Layer The physical layer is responsible for the transmission and reception of unstructured raw data between a device and a physical transmission medium. It converts the digital bits into electrical, radio, or optical signals. The components of a physical layer can be described in terms of a network topology. Examples of protocols using the physical layer include bluetooth, ethernet and USB

Layer 2: Data Link Layer The data link layer provides node-to-node data transfer—a link between two directly connected nodes. It detects and possibly corrects errors that may occur in the physical layer. It defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them.

Layer 3: Network Layer The network layer provides the functional and procedural means of transferring variable length data sequences (called packets) from one node to another connected in "different networks". A network is a medium to which many nodes can be connected, on which every node has an address and which permits nodes connected to it to transfer messages to other nodes connected to it by merely providing the content of a message and the address of the destination node and letting the network find the way to deliver the message to the destination node. Message delivery at the network layer is not necessarily guaranteed to be reliable; a network layer protocol may provide reliable message delivery, but it need not do so.

Layer 4: Transport Layer The transport layer provides the functional and procedural means of transferring variable-length data sequences from a source to a destination host, while maintaining the quality of service functions. The transport layer controls the reliability of a given link through flow control, segmentation/de-segmentation, and error control. This means that the transport layer can keep track of the segments and re-transmit those that fail delivery. The transport layer also provides the acknowledgement of the successful data transmission and sends the next data if no errors occurred. The transport layer creates segments out of the message received from the application layer. Segmentation is the process of dividing a long message into smaller messages.

Layer 6: Presentation Layer The presentation layer establishes context between application-layer entities, in which the application-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. If a mapping is available, presentation protocol data units are encapsulated into session protocol data units and passed down the protocol stack. This layer provides independence from data representation by translating between application and network formats. The presentation layer transforms data into the form that the application accepts. This layer formats data to be sent across a network. It is sometimes called the syntax layer. The presentation layer can include compression functions. The Presentation Layer negotiates the Transfer Syntax.

Layer 7: Application Layer The application layer is the OSI layer closest to the end user, which means both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. Such application programs fall outside the scope of the OSI model. Application-layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication. When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. The most important distinction in the application layer is the distinction between the application-entity and the application.

PDU(Protocol Data Unit)-> It is the information that is transmitted as asingle unit among peer entities of a computer network. A PDU may contain user data or networking address.

TCP/IP The Internet protocol suite is the conceptual model and set of communication protocols used on the Internet and similar computer networks. It is commonly known as TCP/IP because the foundational protocols in the suite are the Transmission control protocol (TCP) and the Internet Protocol (IP). The Internet protocol suite provides end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers, which classify all related protocols according to the scope of networking involved. From lowest to highest, the layers are: The link layer containing communication methods for data that remains within a single network segment (link). The internet layer, providing internetworking between independent networks. The transport layer, providing end-to-end communication services for applications. The application layer, providing services to users and system functions. In March 1982, the US Department of Defense declared TCP/IP as the standard for all military computer networking. IBM, AT&T and DEC were the first major corporations to adopt TCP/IP The two main protocols in the internet protocol suite serve specific functions. TCP defines how applications can create channels of communication across a network. It also manages how a message is assembled into smaller ackets before they are then transmitted over the internet and reassembled in the right order at the destination address. IP defines how to address and route each packet to make sure it reaches the right destination. Each gateway computer on the network checks this IP address to determine where to forward the message.

1) LINK LAYER: It is the lowest layer in internet protocol suite. The link layer defines the networking methods within the scope of the local network link on which hosts communicate without intervening routers. This layer includes the protocols used to describe the local network topology and the interfaces needed to effect transmission of Internet layer datagrams to next-neighbor hosts. The link layer is used to move packets between the Internet layer interfaces of two different hosts on the same link. The processes of transmitting and receiving packets on a given link can be controlled both in the software device driver. This is also the layer where packets may be selected to be sent over a virtual private network or other networking tunnel.

2) INTERNET LAYER: The internet layer exchanges datagrams across network boundaries. It provides a uniform networking interface that hides the actual topology (layout) of the underlying network connections. It is therefore also referred to as the layer that establishes internetworking. Indeed, it defines and establishes the Internet. It provides internetworking between two networks. It is used to transport network packets from the host to the destination specified by the IP address. The most notable example of internetworking is the Internet, a network of networks based on many underlying hardware technologies. For the Internet, the Internet Protocol defines a unified, global address format and provides rules for format and handling of packets, and routers are the components interconnecting networks. The Internet Protocol performs two basic functions:  

Host addressing and identification: This is accomplished with a hierarchical IP addressing system. Packet routing: This is the basic task of sending packets of data (datagrams) from source to destination by forwarding them to the next network router closer to the final destination.

3) TRANSPORT LAYER: The transport layer establishes basic data channels that applications use for task-specific data exchange. The layer establishes host-to-host connectivity, meaning it provides end-to-end message transfer services that are independent of the structure of user data. The protocols in this layer may provide error control, segmentation, flow control, congestion control, multiplexing and application addressing. It provides a channel for the communication needs of applications. UDP is the basic transport layer protocol.

4) APPLICATION LAYER: The application layer is the top layer of the Internet protocol suite."[21] The application layer includes the protocols used by most applications for providing user services or exchanging application data over the network connections established by the lower level protocols. This may include some basic network support services such as protocols for routing and host configuration. Examples of application layer protocols include the Hypertext transfer Protocol (HTTP), the File Transfer Protocol (FTP), the Simple Mail Transfer Protocol (SMTP)It is the scope within which applications create user data and communicate this data to other applications on another or the same host. The TCP/IP model does not consider the specifics of formatting and presenting data, and does not define additional layers between the application and transport layers as in the OSI model (presentation and session layers). Such functions are the realm of libraries and application programming interfaces.

MPLS NETWORK: MPLS stands for Multi Protocol Label Switching; ‘multi protocol’ because its techniques are applicable to ANY network layer protocol, of which IP is the most popular. MPLS (multi-protocol label switching) is a relatively new technology that can improve network performance for select traffic. In the typical network without MPLS, packet paths are determined in real time as routers decide each packet’s appropriate next hop. However, conventional IP routing requires time and eliminates opportunity to influence packets’ paths. With MPLS, you predefine explicit paths for specific types of traffic, identified by path labels put in each packet. MPLS is a scalable, protocol-independent transport. In an MPLS network, data packets are assigned labels. Packet-forwarding decisions are made solely on the contents of this label, without the need to examine the packet itself. This allows one to create end-to-end circuits across any type of transport medium, using any protocol. The primary benefit is to eliminate dependence on a particular OSI Model data link layer (layer 2) technology, such as Asynchronous transfer mode(ATM), Frame Relay, Synchronous Optical networking (SONET) or Ethernet, and eliminate the need for multiple layer-2 networks to satisfy different types of traffic. Important advantages:    



Classification of packets based on the source of the packets (FEC assignment). Packets can be assigned a priority label, making quality-of-service guarantees possible. Packet payloads are not examined by the forwarding routers, allowing for different levels of traffic encryption and the transport of multiple protocols. A packet can be forced to follow an explicit route rather than the route chosen by normal dynamic algorithm as the packet travels through the network. This may be done to support traffic engineering, as a matter of policy or to support a given QoS MPLS is independent of the layer 2 and layer 3 technologies and hence allows integration of networks with different layer 2 and layer 3 protocols and hence different services.

MPLS network

The MPLS cloud: MPLS network built by a service provider is generally termed as MPLS cloud of that service provider. The term cloud represents a network which is capable of taking customer traffic from one location to another without dedicated hard wire connections or it is a shared network, in other terms.

Difference between Edge location and Core location in MPLS network: Generally MPLS routers are categorized as CORE routers and EDGE routers. Major difference between these two routers is the way they are used in the network. CORE routers form backbone of MPLS cloud and perform traffic switching in the network, whereas EDGE routers have access ports and interface with customer’s network. Therefore Core and Edge locations in an MPLS cloud have typically the following equipment/components.

Routers that perform routing based only on the label are called label switch routers (LSRs). The entry and exit points of an MPLS network are called label edge routers (LERs), which, respectively, push an MPLS label onto an incoming packet and pop it off the outgoing packet. Alternatively, under penultimate hop popping this function may instead be performed by the LSR directly connected to the LER. Labels are distributed between LERs and LSRs using the Label Distribution Protocol (LDP). LSRs in an MPLS network regularly exchange label and reachability information with each other using standardized procedures in order to build a complete picture of the network they can then use to forward packets. Label-switched paths (LSPs) are established by the network operator for a variety of purposes, such as to create network-based IP virtual private networks or to route traffic along specified paths through the network. In many respects, LSPs are not different from permanent virtual circuits (PVCs) in ATM or Frame Relay networks, except that they are not dependent on a particular layer-2 technology. In the specific context of an MPLS-based virtual private network (VPN), LERs that function as ingress and/or egress routers to the VPN are often called PE (Provider Edge) routers. Devices that function only as transit routers are similarly called P (Provider) routers. See RFC 4364. The job of a P router is significantly easier than that of a PE router, so they can be less complex and may be more dependable because of this.

When an unlabeled packet enters the ingress router and needs to be passed on to an MPLS tunnel, the router first determines the forwarding equivalence class (FEC) the packet should be in, and then inserts one or more labels in the packet's newly created MPLS header. The packet is then passed on to the next hop router for this tunnel. When a labeled packet is received by an MPLS router, the topmost label is examined. Based on the contents of the label a swap, push (impose) or pop (dispose) operation can be performed on the packet's label stack. Routers can have prebuilt lookup tables that tell them which kind of operation to do based on the topmost label of the incoming packet so they can process the packet very quickly. In a swap operation the label is swapped with a new label, and the packet is forwarded along the path associated with the new label. In a push operation a new label is pushed on top of the existing label, effectively "encapsulating" the packet in another layer of MPLS. This allows hierarchical routing of MPLS packets. Notably, this is used by MPLS VPNs. In a pop operation the label is removed from the packet, which may reveal an inner label below. This process is called "de-capsulation". If the popped label was the last on the label stack, the packet "leaves" the MPLS tunnel. During these operations, the contents of the packet below the MPLS Label stack are not examined. Indeed transit routers typically need only to examine the topmost label on the stack. The forwarding of the packet is done based on the contents of the labels, which allows "protocolindependent packet forwarding" that does not need to look at a protocoldependent routing table and avoids the expensive IP longest prefix match at each hop.

HOW MPLS NETWORK WORKS  An Ethernet frame (IP packet) enters the PE router.  Layer-2 header is stripped off and IP packet is taken out.  MPLS label is placed over IP packet and the packet is forwarded using Layer-2 (Ethernet) frame.  Layer-2 (Ethernet) header is stripped off, MPLS packet is taken out and MPLS label is replaced as per Label Information Base.  The packet is forwarded using Layer-2 (Ethernet) frame.  Layer-2 (Ethernet) header as well as MPLS label is stripped off and IP packet is taken out.  Data in Ethernet frame exits the PE router and handed over to CPE device.

POWERGRID’S MPLS NETWORK



8 core locations, 26 edge locations and 74 Access locations covering 108 location with all major cities on the network with highest redundancy.



State-of-the-art NOC design with fully redundant servers at DR site.



Core layer at 10 gbps and Edge layer at 2.5 gbps makes highest of capacities possible at any instant and at any location.



Layer 3/layer 2 VPN technologies to serve all type of connectivity requirements and different Class of Services, QoS and any-to-any connectivity

Salient Features of Powergrid’s MPLS network: 

Highly reliable.



Sturdy and secure.



Free from cuts, rodent menace and vandalism

 

All India Broadband Telecom network of 25,000 kms.



Expansion in progress for another 33,000Kms



Coverage over 200 cities & towns



Reliability of 99.99%



Multiple self resilient rings of complete redundancy in backbone as well as intra-city access networks.

Advantages of MPLS: Data Security and Performance :



Port based VPNs: o The VPN is configured on logical interface for each port. The corresponding VRF (Virtual Routing and Forwarding Table) is not shared other ports/VPNs and the data is forwarded in dedicated tunnels.



Label based Forwarding: o Packets are forwarded switched based on Labels and Label Information Base in all MPLS routers except PE routers. This is in contrast with general routing based on IP address .



Fast Switching: o The Switching is done at Layer 2.5, thereby taking less time as compared to IP based routing which involves Layer-3 processing and corresponding routing Tables.

Quality Of Service

MPLS SERVICE CLASSES OFFERED Service Class

Recommended Purpose for

CRITICAL

Critical Application traffic

This class for Low Delay, Low Jitter, Low Packet loss applications e.g. Tele-protection Signaling etc

REAL TIME

Voice, Signaling

This class is intended for delay and Jitter sensitive applications like VOIP, Video conferencing etc

Network This class is for Customer /Business Enterprise Data and MANAGEMENT Management, application access. This class is intended for low delay Critical Data network management and OAM protocols etc BUSINESS

Business Data, This class is intended for network non-real time traffic Enterprise which is not delay and Jitter sensitive e.g. Video Applications recordings etc

STANDARD

The Bulk Data class is intended for background, nonBulk Data/ interactive traffic flows, such as large file transfers, Transactional content distribution, database synchronization, backup Data operations, and email.

BEST EFFORT

Default The Best Effort class is also the default class. Generally Data/Internet used for non critical internet traffic

Traffic Engineering : Multiprotocol Label Switching (MPLS) traffic engineering software enables an MPLS backbone to replicate and expand upon the traffic engineering capabilities of Layer 2 ATM and Frame Relay networks. Traffic engineering is essential for service provider and Internet service provider (ISP) backbones. Such backbones must support a high use of transmission capacity, and the networks must be very resilient, so that they can withstand link or node failures. MPLS traffic engineering provides an integrated approach to traffic engineering. With MPLS, traffic engineering capabilities are integrated into Layer 3, which optimizes the routing of IP traffic, given the constraints imposed by backbone capacity and topology. MPLS traffic engineering routes traffic flows across a network based on the resources the traffic flow requires and the resources available in the network. MPLS traffic engineering employs "constraint-based routing," in which the path for a traffic flow is the shortest path that meets the resource requirements (constraints) of the traffic flow. In MPLS traffic engineering, the flow has bandwidth requirements, media requirements, a priority versus otherflows, and so on. MPLS traffic engineering gracefully recovers to link or node failures that change the topology of the backbone by adapting to the new set of constraints.

How MPLS Traffic Engineering Works : MPLS is an integration of Layer 2 and Layer 3 technologies. By making traditional Layer 2 features available to Layer 3, MPLS enables traffic engineering. Thus, you can offer in a one-tier network what now can be achieved only by overlaying a Layer 3 network on a Layer 2 network. MPLS traffic engineering automatically establishes and maintains the tunnel across the backbone, using RSVP. The path used by a given tunnel at any point in time is determined based on the tunnel resource requirements and network resources, such as bandwidth. Available resources are flooded via extensions to a link-state based Interior Protocol Gateway (IPG). Tunnel paths are calculated at the tunnel head based on a fit between required and available resources (constraint-based routing). The IGP automatically routes the traffic into these tunnels. Typically, a packet crossing the MPLS traffic engineering backbone travels on a single tunnel that connects the ingress point to the egress point. MPLS traffic engineering is built on the following IOS mechanisms: • Label-switched path (LSP) tunnels, which are signalled through RSVP, with traffic engineering extensions. LSP tunnels are represented as IOS tunnel interfaces, have a configured destination, and are unidirectional. • A link-state IGP (such as IS-IS) with extensions for the global flooding of resource information, and extensions for the automatic routing of traffic onto LSP tunnels as appropriate. • An MPLS traffic engineering path calculation module that determines paths to use for LSP tunnels.

• An MPLS traffic engineering link management module that does link admission and Book keeping of the resource information to be flooded. • Label switching forwarding, which provides routers with a Layer 2-like ability to direct traffic across multiple hops as directed by the resourcebased routing algorithm.

One approach to engineer a backbone is to define a mesh of tunnels from every ingress device to every egress device. The IGP, operating at an ingress device, determines which traffic should go to which egress device, and steers that traffic into the tunnel from ingress to egress. The MPLS traffic engineering path calculation and signalling modules determine the path taken by the LSP tunnel, subject to resource availability and the dynamic state of the network. For each tunnel, counts of packets and bytes sent are kept. Sometimes, a flow is so large that it cannot fit over a single link, so it cannot be carried by a single tunnel. In this case multiple tunnels between a given ingress and egress can be configured, and the flow is load shared among them.

MPLS SERVICES: The Major Services, as per present market trend, are classified as under:  VPWS (Virtual Private Wired Service e.g. CPIPE) : o VPWS is a Point-to-Point link between to PE routers generally required for critical applications. A VPWS for TDM requirement is termed as CPIPE.  Layer-2 VPN (VPLS) : o In Layer-2 VPN, the whole MPLS network acts as a Layer-2 Switch a switches the traffic based on the MAC address of CPE devices. The MPLS network in this case remains unaware of customer side IP addresses and customer network, therefore.  Layer-3 VPN (VPRN) : o In Layer-3 VPN, the customers IP addresses are advertised to the MPLS network PE does the routing based on the IP addresses. The VPRN (Virtual Private Routed Network) is the most commonly used VPN in the MPLS networks.

Technical Specifications for Shelters Introduction This section describes the functional requirement, major technical parameters and all the testing requirements for telecom shelter system including its sub-systems. shelters are used to amplify data , stabilize electricity and to give back up to optical fibre cable and to distribute or underground cable wires Shelter Dimensions The minimum internal and external dimensions of the shelters shall be as per Table 2.1 as specified below:

SNo.

Table 2.1 External/Intern al

Length (L)

External

4500

2700

3160

Internal

4340

2540

3000

External

2360

2700

3160

Internal

2200

2540

3000

External

2360

2160

3160

Internal

2200

2000

3000

1

2

3

All dimensions are in mm Width (W) Height (H)

The Bill of Quantity has been defined in the appendices. Requirements General The shelters shall be protected and insulated to achieve sound proof, thermal resistance and impact withstand capabilities. The shelters shall be 100% leak and water proof with IP 55 protection. The shelters shall be maintenance free having minimum life of 15 years. These shelters shall be suitable for outdoor and may be mounted at any location including ground and rooftop and in any climatic conditions throughout India. The shelters

shall be easily assembled and installed at site. The shelters shall be relocatable as and when required. The steel shelter shall be installed at most of the locations, however, at costal areas or high pollution area, aluminium shelters shall be installed. Shelter Panels The shelter shall be made of “sandwich insulated panels” 80 mm thick with Poly Urethane Foam (PUF) as filler material between polyester pre-coated cold rolled steel or aluminium sheets. Floor The floor shall consist of standard PUF sandwich panels suitably reinforced to support the minimum load capacity of 2000 kg/m2 and having at least 19 mm Marine plywood covered with anti static PVC flooring. In case of floor panel, 19 mm Marine plywood shall be provided on top of the panel and no steel or aluminium sheet shall be provided inside the panel. The anti static flooring shall be provided with pacific blue anti static vinyl robust rolls of at least 2 mm thickness. The floor shall be even surfaced, scratch proof having long life The installation of various proposed equipment shall be possible either by direct placement on the floor or by grouting to the floor or through C rails. The Contractor shall submit the reinforcement and other details calculations in support of the meeting the load capacity. Roof Roofs shall be made of the panels same as specified for walls. A secondary slanting roof of suitable material shall be provided to protect the primary roof from direct sunlight and rainwater. A minimum down slant of 1:50 shall be maintained from front to back. The secondary roof shall have minimum projections and shall be hidden by angular profiles on the rooftop to decrease the aerodynamic effect and improve on aesthetics. The secondary roof shall be suitably clamped/ bolted to the shelter panels to withstand the specified wind load. The details of the secondary roof and its attachment arrangement shall be enclosed with the Bid. The cable tray shall be attached suitably from the roof and the roof shall have sufficient strength to support the load of cable trays and the cables installed on the cable tray. The detailed load calculation shall be submitted for Employer’s approval during detail engineering.

Door The Shelters shall have one door for main entrance. The door dimensions shall be 1000 mm (W) X 2200 mm (H). Main door opening outwards shall be provided with external and internal handles/knobs respectively. A reputed make lock shall be provided in door handle. The make of the lock shall be got approved during detail engineering. The door can be opened from inside when locked. Door, when locked cannot be removed even if the hinges are removed. The door shall generally be hinged at right, however, other option may be also required at some sites to meet the actual site condition. The door shall have aluminium biddings extrusions in door/jamb profile, replaceable and suitable neoprene rubber gaskets around its border for proper weather proofing. The door shall also be equipped with a hydraulic auto closure and the door latch / stopper shall be provided to keep the door in open position. The door shall have a limit switch to indicate intrusion and switch on one light provided inside the shelter. A canopy of minimum size 1200 mm X 500 mm shall also be fixed up above the external light / door for protection from direct sun/rain. The canopy shall suitable slope and shall be covered from both sides. Jointing All panel to panel connections shall be made with eccentric cam locks. The wall to floor and wall to roof jointing shall be made with angular frames of suitable size. The panel to panel jointing at the corners shall either be suitably angular frames of suitable size or a single corner panel may be provided. All internal corners shall be jointed suitable angles. All the joints shall be suitable sealed with PU or silicon sealant to provide 100 % leakage and water proofing. The Contractor shall submit the drawing indicating details of all joints in support of meeting the specified requirement. Opening The shelter shall have provision for openings for required air-conditioners, piping and all electrical and optical cablings on the wall panels. The details of openings required for different applications and the locations of the openings shall be decided during detail engineering. All openings shall be custom built based upon the actual application required at each site. The

Contractor shall provide the required cut outs for above purpose. Any sealed cut outs required for future use may also be provided and the size of this cut out shall be finalised during detail engineering. All the openings shall be sealed for water and leak proof with suitable flexible sealing arrangement for the proposed cable connections and also for addition and deletion of cables/pipes in future. The sealing arrangement shall be fire retardant and type/make/details shall be got approved by the Employer.

The Contractor shall submit the earlier carried out type tests reports for PUF material. In case the contractor does not submit the reports or the submitted reports are not meeting the requirements, the contractor shall carry out the type tests on PUF material for the following: Thickness, Density, Compressive strength, Tensile Strength, Dimensional Stability, Thermal Conductivity and Fire resistance.

Colour The shelter panels shall be factory coated with good quality and long life paints. The thickness, quality, make and the process of colouring of panels shall be got approved by the Employer before manufacturing. The finished panels shall be provided with suitably protection to avoid scratches during transportation, handling and installation. The colour shall be stabilised grey on all external sides and off white on all internal sides. The colour of the slanting roof shall also be stabilised grey. However, the actual colouring scheme shall be finalised during detail engineering.

Fire and Smoke Detection System Suitable fire & smoke detection system shall be provided in each of the shelters. The offered fire & smoke detection system shall work on DC supply (-48V) being provided by the Contractor under this contract. In case, the smoke detector and fire alarm system requires other voltage than the above stipulated voltage (-48V DC) for operations, suitable converter & hardware shall also be provided by the Contractor. The Contractor shall provide all required cabling & accessories for full functioning of the offered system with both power supplies. At least two ionisation type smoke detectors along with fire detection panel shall be provided below the roof panel in strategic locations inside the shelter. The alarm should activate only if both fire detectors are actuated to avoid any false alarm.

Lighting system Normal and emergency lighting shall be provided inside the shelters. The normal lights shall consist of two nos. (36 Watts) of reputed make fluorescent lights along with requisite fittings and shall be powered with ac supply from ACDB. Two nos. emergency light with requisite fittings shall also be provided which shall be powered with dc supply available (-48 V DC) for telecom equipment from DCDB. Additionally, at least one of the normal lights inside the shelter shall be lit up with the opening of the shelter door.

Energy Meter Box weatherproof box of size 600 mm X 600 mm X 250 mm of IP 55 compliant shall be provided for housing the energy meter along with MCBs and fuse units. The energy meter box shall have two different doors and compartments, one for accessing/housing energy meter and another for accessing/housing MCBs and fuses. The energy meter box shall have glass for view of meter reading from outside. The energy meter box shall be of Fibreglass Reinforced Polymer (FRP) material. The alternate material, if required, shall be with specific approval of the Employer. The box shall be provided with pad lock arrangement and shall be installed on external shelter panels with suitable fittings. Proper sealing shall also be done to A

avoid any water leakage into the panel. The locations of meter installation shall be finalised during detail engineering. Loading Capacity Minimum roof loading capacity : 250 kg/m2 Minimum floor load capacity : 2000 kg/m2 Minimum wall load capacity : 300 kg/m2 The above load capacities have been identified as minimum requirement.

Structural Stability   

Resistant to various volumes of rain, dust & sand impinging from various directions over different durations and different speeds. Resistant to corrosion against water, industrial air and saline air. Resistant to decomposing vegetation, rodents, termites and microorganisms.

Survival wind speed The shelter shall be designed to withstand a wind load of 200 kmph.

Earthing For satisfactory operation of the equipment inside the shelter, good and proper earthing is required at each site. The earthing resistance generally varies depending on soil resistivity. The earthing system at each site shall be provided by the Contractor with earthing resistance not exceeding the five (5) ohms. The Contractor shall provide the chemical earthing along with the necessary hardware and accessories required. The chemical earthing shall be free from periodic rejuvenation requirements. In case of pipe type earthing, two earth pits shall be made at each location.

Installation The shelter shall be installed on the foundation system as specified above and to meet the actual requirement as per actual site/soil conditions. The installation of shelters shall be carried out in such a way that it shall meet all specified requirement. The installed shelters shall be suitable for both transporting in assembled condition to another location and dismantling, transporting to another site and reassembling there.

Environmental Conditions As indicated in the appendices, the shelters shall be installed all over India. The environmental conditions required are as under: Normal Internal Temperature

:

+24 ± 1 oC

Maximum Outside Temperature

:

+50 oC

Minimum Outside Temperature

:

0 oC

Maximum Inside Temperature

:

+55 oC

Humidity

:

Up to 100 %.

Type testing Factory Acceptance Testing (FAT) The following tests shall be carried out during Factory Acceptance testing (FAT): a. Dimensional and checks as per approved DRS/drawings b.Quality checks as per approved MQP c. BOQ verification as per approved drawings/documents a. Test certificates from the Original Equipment Manufacturer. b.Density test, Compression test and Thermal Conductivity test on the PUF material. FAT on other items shall be carried out as specified in this specifications and relevant standards.

Site Acceptance Testing (SAT) The site acceptance testing shall be carried out for each site. The installed system shall be powered up and all the equipment shall be tested and commissioned. The various installed system shall be tested for the specified functional requirements and shall be as per approved drawings. The SAT shall be carried in an integrated way and not individual equipment basis to demonstrate the integrated functioning of the installed system. The tests shall be carried out on following minimum items during SAT: i. ii. iii. iv. v. vi. vii. viii. ix. x.

Site preparedness, PCC and RCC. Civil Pedestals and Steel structure for Base of Shelter System Shelter (including water proof test) Air-Conditioning System Cable Tray Lighting System Fire and Smoke Detector System C-Rails Earthing System Wire Mess Fencing

The detailed SAT procedure shall be submitted for Employer’s approval.

INSTALLATION OF UNDERGROUND FIBRE OPTIC CABLE SYSTEM This section describes the installation procedures and methods including survey, clearances, excavation of trenches and pits, trench less digging, installation of PLB HDPE pipes, installation of RCC hume pipes and GI Pipes, marking, backfilling, installation of underground cable, construction of manholes, splicing, termination and site acceptance testing requirements of the underground fibre optic cabling system. This specification is applicable for underground optical fibre installation work and some miscellaneous works to be executed inside city/town. The quantities indicated in the BoQ are indicative only and the final quantities against individual items will be approved by the Owner after detailed survey and depending upon the site conditions.

Identification of underground fibre cable route The Contractor shall propose preferably most suitable route for each link keeping in views the following broad criteria: a. b. c. d. e. f. g. h. i.

The route shall be as straight and as short as possible. The route shall have minimum obstacles in order to minimise reinstatement cost. Clearances required from other authorities/bodies are minimum and that the clearances can be obtained expeditiously. Wet or unstable ground shall be avoided to the extent possible. The route for the pipes shall be away from the carriage-way of the road to the extent possible. The route shall be suitable for placing manholes wherever required. Future expansion of roads shall be taken into consideration. Road, rail, river, nallah crossings, horizontal direction drilling shall be minimum. As far as possible underground fibre optic cable route shall be on the opposite side of the existing cables laid by DOT/BSNL or other utilities. Wherever both routes fall on the same side of the road, a spacing of about 2.0 m be maintained, to the extent possible subjected to ROW clearance.

Underground Fibre Optic Cable Installation The cable shall be installed inside one of the 40mm diameter PLB HDPE pipes along the route(s). Generally the cable shall be installed by compressed air blowing technique. However, for short spans, the Contractor can use pulling method for installation of OFC in HDPE pipe. If any temporary manhole or hand hole is required for installation of OFC, the same will be done by the Contractor without any additional cost implication, subject to approval of the Engineer-in-charge/Project. Contractor shall take into consideration the following guidelines, for installation of OFC. a. The Optical Fibre Cable Drums shall be handled with utmost care. The drum shall not be subjected to shocks by dropping etc. They shall not be normally rolled along the ground for long distance and when rolled, shall in the direction indicated by the arrow. The battens shall be removed only at the time of actual laying. b. A blowing machine in association with an appropriate compressor shall be used for blowing. c. Temporary blowing chambers (if required) shall be constructed and then backfilled after blowing operation is completed. d. Locations along the route, which provide easy access points for blowing machine and compressor, shall be determined. e. Before starting the cable blowing, both PLB HDPE pipes shall be checked for obstacles or damage. f. Always blow downhill wherever possible. While installing the cable, excess length of min 10 meters shall be stored at each joint location for each side.

Underground Fibre Optic Cable SAT for optical fibre cable shall be carried out link by link from FODPs/FMS/FDMS to FODPs/FMS/FDMS for fibers spliced in the FMS/FODPs as per Table – A, B & C.

All the issuance of OFC by POWERGRID, the contractor shall carry out OTDR testing of the cable to ensure its healthiness. Subsequently, any damage during handling/laying or otherwise shall be to the contractors account.

Table –A Fibre Optic Cable Pre-Installation Testing Item Description:

Acceptance Criteria

1.

Physical Inspection of the cable No Damage for damage

2.

Optical fiber Continuity and fiber attenuation with OTDR at 1310 Attenuation ≤ 0.35 db per nm (applicable for cable length > KM 1 Km) Table – B Fibre Optic Cable Splice Testing

Item Description:

Acceptance Criteria

1.

Physical inspection of Joint Box As per para 11.2 for proper fibre routing techniques

2.

Physical inspection of sealing As per para 11.2 techniques, weatherproofing, etc

Table – C Fibre Optic Cable Splice Testing Item Description: 1.

2.

Acceptance Criteria

Fibre continuity and link attenuation (bi-directional) between FODP connectors at two ends for each fibre at 1310 nm by OTDR where ever feasible.

Attenuation ≤ 0.35 db per KM

Fibre continuity and link attenuation (bi-directional) between FODP connectors at two ends for each fibre at 1310 nm by Power Meter & Laser Source where ever feasible.

Attenuation ≤ 0.35 db per KM

No testing of fibre under SAT shall be required in case total route length for the specific connectivity is less than 500 meters. Allowable Wastage The Owners will provide the underground optical fibre cable to the Contractor for installation. The Contractor is expected to make no wastage of the same provided by the Owner, however in order to take care of exigencies, wastage upto 2% of the material provided may be allowed during installation. However for re-conciliation, OFC lengths of less than 50 meters shall be treated in the allowable wastage and shall not be taken over by the owner.