Interview Questions.

Question 1. What Is Ftth?

Answer :

Fiber to the Home (FTTH) is the closing fiber get admission to solution wherein each subscriber is connected to an optical fiber. The deployment alternatives discussed on this tutorial are based totally on a complete optical fiber path from the OLT proper through to the subscriber premises. This choice permits for the availability of high bandwidth services and content to every customer and ensures maximum bandwidth for the destiny demands of the brand new offerings. Therefore, Hybrid options regarding ‘part’ fiber and ‘part’ copper infrastructure networks aren't included.

Question 2. What Do You Mean By Differential Fiber Distance?

Answer :

The differential fiber distance is the difference inside the distance among the closest and furthest ONU/ONT from the OLT.

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Question 3. What Is The Maximum Differential Fiber Distance In Gpon?

Answer :

In GPON, the most differential fiber distance is 20 kms. This influences the dimensions of the ranging window and provides compliance with [ITU-T G.983.1].

Question four. What Do You Understand By Logical Reach?

Answer :

Logical attain is described because the maximum distance that can be done for a specific transmission device, no matter the optical price range. Logical reach is the most distance between ONU/ONT and OLT besides for the challenge of the physical layer.

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Question 5. What Is The Maximum Logical Reach In Gpon?

Answer :

In GPON, the maximum logical attain is defined as 60 kms.

Geographic Information System (GIS) Interview Questions
Question 6. What Do You Understand By Mean Signal Transfer Delay?

Answer :

The mean sign transfer put off is the common of the upstream and downstream postpone values among reference points. This fee is decided by way of measuring round-ride put off after which dividing by means of 2.

GPON ought to accommodate services that require a maximum mean signal transfer postpone of one.5 ms. A GPON system must have a most suggest Signal Transfer Delay Time of much less than1.5 ms between TV reference factors.

Question 7. What Do You Understand By Optical Access Network (oan)?

Answer :

The OAN is the set of get right of entry to hyperlinks sharing the identical community-aspect interfaces and supported via optical get entry to transmission structures. The OAN may additionally consist of some of ODNs connected to the identical OLT.

Hardware and Networking Interview Questions
Question 8. What Do You Understand By Optical Distribution Network (odn)?

Answer :

In the PON context, a tree of optical fibers in the get admission to community, supplemented with power or wavelength splitters, filters or other passive optical devices.

Question nine. What Do You Understand By Optical Line Termination (olt)?

Answer :

A tool that terminates the commonplace (root) endpoint of an ODN. Then implements a PON protocol inclusive of that defined by means of [ITU-T G.984]; after which adapts PONPDUs for uplink communications over the issuer carrier interface.

The OLT provides control and upkeep capabilities for the subtended ODN and ONUs.

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Question 10. What Do You Understand By Optical Network Termination (ont)?

Answer :

A single subscriber tool that terminates any person of the dispensed (leaf) endpoints of an ODN, implements a PON protocol, and adapts PON PDUs to subscriber service interfaces. An ONT is a unique case of an ONU.

Question 11. What Do You Understand By Optical Network Unit (onu)?

Answer :

A general time period denoting a tool that terminates any person of the disbursed (leaf) endpoints of an ODN, implements a PON protocol, and adapts PON PDU.

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Question 12. What Is The Mean Of Physical Reach In Ftth Technology?

Answer :

Physical reach is defined because the maximum physical distance that can be done for a selected transmission system. Since, ‘Physical Reach’ is the most bodily distance between the ONU/ONT and the OLT. However, in GPON, two alternatives are defined for the bodily reach: 10 kms, and 20 kms. It is thought that 10 km is the most distance over which FP-LD can be used in the ONU for excessive bit prices consisting of 1.25 Gbit/s or above.

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Question 13. What You Understand By The Services In Ftth Scenario?

Answer :

Services in FTTH are described as a community carrier required by using operators. Service is described by using a call this is genuinely diagnosed via absolutely everyone, no matter whether it is a frame structure name or a standard call.

Question 14. What Are The Bit Rates Defined In Gpon?

Answer :

GPON targets at transmission speeds more than or same to at least one.2 Gbit/s. Accordingly, GPON identifies  transmission velocity combos as follows:

1.2 Gbps up, 2.Four Gbps down
2.Four Gbps up, 2.4 Gbps down
The most crucial bit fee is 1.2 Gbps up, 2.Four Gbps down, constituting nearly all of the deployed and deliberate deployment of the GPON structures.

Question 15. What Do You Understand By The Term “cut up Ratio”? Explain?

Answer :

The large the cut up ratio is for GPON, the more reasonably-priced it is from cost perspective. However, a larger break up ratio implies greater optical strength and bandwidth splitting, which creates the want for an increased power price range to help the bodily attain. Split ratios of up to one:sixty four are realistic for the physical layer, given current generation. However, looking ahead to the continuing evolution of optical modules, the TC layer have to consider cut up ratios up to at least one:128.

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Question 16. What Are The Benefits Of Optical Fiber In Ftth?

Answer :

Benefits of optical fiber:

Very lengthy distances
Strong, flexible, and dependable
Allows small diameter and light weight cables
Safe and at ease
Immune to electromagnetic interference (EMI)
Lower cost
Question 17. What Are The Passive Modules/additives In Pon Technology?

Answer :

Various modules / components in PON technology are:

WDM Coupler
1×N Splitter
Optical fiber and cable
Connector
ODF/Cabinet/Subrack
FOC (Fiber Optic Route Checker) Interview Questions
Question 18. What Are The Active Modules/components In Pon Technology?

Answer :

The lively modules / additives in PON technology are:

In OLT:

Laser transmitter (1490-nm) and
Laser receivers (1310-nm)
For CATV utility:

Laser amplifier (1550-nm ) and
EDFA for amplifying video signal
In ONU:

Power/ Battery for ONU
Laser transmitter (1310-nm)
Laser receivers (1490-nm)
Receivers for CATV signal (1550-nm)
Geographic Information System (GIS) Interview Questions
Question 19. What Is The Full Form Of Gpon?

Answer :

The full form of GPON is – Gigabit Passive Optical Network

Question 20. What Is Gpon? Explain.

Answer :

GPON is an Optical System for the Access Networks, primarily based on ITU-T specifications G.984 collection. It can offer a 20 km attain with a 28dB optical finances via the usage of elegance B+ optics with 1:32 break up ratio.

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Question 21. Explain The Features Of The Gpon?

Answer :

The most generally known capabilities of GPON are as listed beneath.

Downstream transmission:

2.4Gbps
BW for one ONT is sufficient to deliver more than one HDTV indicators
QOS allows for put off sensitive site visitors (voice)
Upstream transmission:

1 24Gbps
Minimum BW may be guaranteed
Unused timeslots may be assigned to heavy customers
QOS permits for put off touchy traffic (voice)
Question 22. What Are The Standards That Defines Gpon Technology?

Answer :

GPON requirements construct on the previous BPON specifications. These specs are all listed beneath:

G.984.1:This record describes the Gigabit-Capable Passive Optical Network trendy characteristics.
G.984.2:This record describes the Gigabit-Capable Passive Optical Network Physical media-Dependent layer specification.
G.984.3:This report describes the Gigabit-Capable Passive Optical Network Transmission convergence layer specification.
Question 23. Explain The Gpon Architecture?

Answer :

GPON systems have essentially the identical bodily components which might be configured inside the equal way as in different PON networks. Of path, the products developed for GPON structures are mainly designed for GPON and are not interchangeable with the EPON or BPON gear.

GPON systems also have many of the equal simple capabilities as other PON systems have. The main differences within the structure are GPON in statistics throughput. The Gigabit GPON encapsulation techniques allow wearing an expansion of offerings including ATM, TDM voice, and Ethernet.

Fiber Optics Interview Questions
Question 24. What Is The Optical Power Sensitivity For Gpon?

Answer :

One of the primary requirements of an optical gadget is to provide additives with sufficient capability to extend the optical sign to the anticipated variety. There are three categories or lessons of additives are primarily based on electricity and sensitivity.

The instructions of components are:

Class A optics: five to 20dB
Class B optics: 10 to 25dB
Class C optics: 15 to 30dB
Hardware and Networking Interview Questions
Question 25. What Is The Full Form Of Epon?

Answer :

The complete form of EPON is – Ethernet Passive Optical Network.

Question 26. Explain The Epon Technology.

Answer :

Ethernet Passive Optical Network (EPON) is a PON encapsulate data with Ethernet and may offer 1 Gbps to ten Gbps ability. EPON follows the authentic structure of a PON. Here, the DTE related to the trunk of the tree and known as as Optical Line Terminal (OLT).

It is normally located at the carrier company, and the related the DTE branches of the tree are called Optical Network Unit (ONU), located inside the premises of the subscriber. The signals from the OLT pass via a passive splitter to gain the ONU and vice versa.

Fiber Channel over Ethernet (FCoE) Interview Questions
Question 27. Explain The Qos In Epon?

Answer :

Many PON applications require excessive QoS (e.G. IPTV).

EPON leaves QoS to higher layers −

VLAN tags
P bits or DiffServ DSCP
In addition, there is a important distinction between LLID and Port-ID −
There is always 1 LLID consistent with ONU
There is 1 Port-ID in keeping with enter port - there may be many consistent with ONU
This makes port-based QoS simple to implement at PON layer
Network Engineer Interview Questions
Question 28. What Do You Understand By Dba?

Answer :

An set of rules carried out in the OLT, using Report and Gate messages to build a transmission application and skip the ONUs is referred to as a dynamic bandwidth allocation (DBA) algorithm.

Question 29. Explain The Epon Frame Format?

Answer :

EPON operation is primarily based on the Ethernet MAC and EPON frames (based on GbE frames), but extensions are needed :

MultiPoint Control Protocol PDUs :This is the manage protocol implementing the specified logic.

Point-to-point emulation (reconciliation):This makes the EPON looks like a point-to-factor hyperlink and EPON MACs have some unique constraints.

Instead of CSMA/CD, they transmit whilst granted.

Time thru MAC stack need to be steady (± sixteen bit periods).

Accurate nearby time ought to be maintained.

Question 30. Explain The Epon Header?

Answer :

Standard Ethernet begins with an basically content-loose 8B preamble:

7B of alternating ones and zeros 10101010

1B of SFD 10101011

In order to cover the new PON header, EPON overwrites a number of the preamble bytes.

Question 31. Explain The Security Feature In Epon?

Answer :

DS traffic is broadcast to all ONUs, so the encryption is basically smooth for a malicious person to reprogram ONU and capture favored frames. US site visitors no longer visible by way of other ONUs, so the encryption isn't always wished.

Do not take into account fiber-tappers because EPON does not provide any trendy encryption approach, however

Can supplement with IPsec or MACsec.
Many carriers have added proprietary AES-based mechanisms.
BPON used a mechanism known as churning − Churning became a low fee hardware solution (24b key) with numerous protection flaws

Engine become linear - easy regarded-textual content attack
24b key became out to be derivable in 512 attempts
Therefore, G.983.Three brought AES assist - now used in GPON.
Question 32. What Is Xpon?

Answer :

XPON is the following era PON, that may support data price up to 10G. XPON may be divided in two categories, i.E., XG-PON1 and XG-PON2. XG-PON1 is backward well suited with GPON, whereas XG-PON2 is completely new improvement.

Question 33. What Is A Full Form Of Wdm-pon?

Answer :

The complete form of WDM-PON is – Wavelength Division Multiplex PON.

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Question 34. Explain Wdm-pon?

Answer :

In WDM-PON, one of a kind wavelength is needed for exceptional ONT; every ONT receives an one of a kind wavelength and enjoys the bandwidth resources of wavelength. In other words, WDM-PON works on a logical Point to Multi Point (P2MP) topology.

Question 35. Explain Odsm-pon?

Answer :

The full form of ODSM-PON is – Opportunistic Spectrum and Dynamic PON. In ODSM-PON, the network remains unchanged from CO to user premises except one trade, which is energetic WDM splitter. A WDM splitter will be there among OLT and ONT changing passive splitter. In ODSM-PON, the downstream adopts WDM, approach facts in the direction of ONT use special wavelength for one-of-a-kind ONT and in upstream and ODSN-PON adopts dynamic TDMA + WDMA era.

Question 36. What Do You Understand By Optical Signal Splitting? Explain?

Answer :

The single fiber starting from OLT is split via passive optical splitters to serve 64 patron premise ONTs. The equal fiber incorporates each the down-stream (OLT toward ONT) and the upstream (ONT toward OLT) bit streams viz., 2.488 Mbps/1490 nm (1480 - 1500nm window) and 1.244 Mbps/1310 nm (1260-1360nm window) via WDM (Wavelength Division Multiplexing) for duplex (bi-directional) operation.

The equal single fiber downstream transmission from the OLT to the ONTs is broadcast with an ONT accepting best the visitors addressed to it. Upstream transmission is Time Division Multiple Access (TDMA) with the every ONT transmitting in flip.

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Question 37. What Do You Understand By Rf Overlay For Tv Services? Explain?

Answer :

The TV signals (derived from a satellite Head End) are optionally broadcasted on a 3rd optical wavelength of 1550 nm on identical (or additional) fiber brought into the FTTx machine via an RF Overlay sub-gadget. CATV Signal can be coupled with GPON signal after amplification by EDFA.

The RF CATV indicators modulated onto the 1550 nm wavelength. It is extracted via a Demux characteristic constructed interior ONT and routed to again plane carrier connection for the STB/TV.

Question 38. Explain The Split Ratios, Maximum Reach & Traffic Management As Per Classes Defined By Itu?

Answer :

The maximum permissible optical energy attenuation among OLT optical port to ONT input is 28 dB utilising so referred to as Class B optical network factors. ODN Class A, B, and C are differentiated in particular on the ‘optical transmitter strength output’ and ‘bit-charge optical receiver sensitivity. Class A gives the least-optical finances and Class C offers the highest, even as fee wise both are in the equal order. For maximum 1:64 cut up ratio, Class B optics are generally deployed on industrial basis.

Question 39. Explain Ngpon1?

Answer :

The following points explain NGPON1:

G.987/G.988 XGPON trendy have been released in 2011.
It standardized the XGPON with 2.5Gbps upstream /10Gbps downstream.
GPON and XGPON use different wavelength for coexisting in a single network.
Question 40. Explain Ngpon2?

Answer :

The following factors explain NGPON2:

Does no longer recall being like minded with current ODN network, a more open preferred of PON technology.
Focuses to WDM PON and 40G PON.
FOC (Fiber Optic Route Checker) Interview Questions