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.3.Why is there no need for CSMA/CD on a fill-duplex Ethemet LAN? Q.4.What are t

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Question

.3.Why is there no need for CSMA/CD on a fill-duplex Ethemet LAN? Q.4.What are the common Gigabit Ethernet implementations? Problems Q.5. Calculate the minimum time required to download one million bytes of information using each of the following technologies (consider the minimum rates) a. ADSL b. ADSL Lite c. HDSL d. SDSL e. VDSI Q.6. What type of topology is used when customers in an area use cable modems for da transfer purposes? Explain 3, 8B/6TBlock Encoder in Gigabit Ethernet. 07. Explain 4 ID-PAM5 encoder in 10 Gigabit Ethemet.

Explanation / Answer

Basics:

bits - used to Measure Speed.

Bytes - used to Measure Size.

1 Bit - Smallest unit of information.(may be 1 or 0)

8 Bits = 1 Byte.

While calculating download time make sure to convert bits to bytes.

Time required to download a File = File size / Download Speed.

File Size = 1 MB (1 million bytes)

a)ADSL - Asymmetric digital subscriber line

Min Download Speed = 8 Mbps

To convert this to bytes divide by 8. So Min Speed = 1 MBps

Download Time = File size / Download Speed

= 1MB / 1 MBps

= 1 sec

b) ADSL lite

Min Download Speed = 1.5Mbps

To convert this to bytes divide by 8. So Min Speed = 0.187 MBps

Download Time = File size / Download Speed

= 1MB / 0.187 MBps

= 5.347 secs

c) HDSL - High-bit-rate digital subscriber line

Min Download Speed = 1.54Mbps

To convert this to bytes divide by 8. So Min Speed = 0.192 MBps

Download Time = File size / Download Speed

= 1MB / 0.192 MBps

= 5.208 secs

d) SDSL - Symmetric Digital Subscriber Line

Min Download Speed = 0.16 Mbps

To convert this to bytes divide by 8. So Min Speed = 0.02 MBps

Download Time = File size / Download Speed

= 1MB / 0.02 MBps

= 50 secs

e) VDSL - Very-high-bit-rate digital subscriber line

Min Download Speed = 51 Mbps

To convert this to bytes divide by 8. So Min Speed = 6.375 MBps

Download Time = File size / Download Speed

= 1MB / 0.187 MBps

= 0.156 secs

Note:

As no download speeds are given I have used the typicals values found on the internet.