Network

occupation 1:
1. Access shed light on: digital reader line (DSL)
[pic]
Use existing telephone line to commutation office DSLAM
-data everywhere DSL phone line goes to Internet
-voice all over DSL phone line goes to telephone net
-< 2.5 Mbps upstream transmission drift (typically < 1 Mbps)
-< 24 Mbps downstream transmission rate (typically < 10 Mbps)

2. Access net: electrify network
[pic]
-HFC: hybrid graphic symbol coax
? asymmetric: up to 30Mbps downstream transmission rate, 2 Mbps upstream transmission rate
-network of cable, fiber attaches homes to ISP router
? homes share access network to cable headend
? unlike DSL, which has dedicated access to central office
3. Access net: home network
[pic]

Problem 2:
Propagation delay= 2500000m/250000000
=0.01s
transmittal delay= 8000bits/2000000bps (since 1bytes=8 bits)
=0.004s

Because of this the transmission delay is 0.004s, is 2/5 of the propagation delay, the transmission delay cannot be ignored and so that the delay is depends on both propagation and the transmission delay.

Problem 3:
a. packetization time = 48x8bits/64000bps
=0.006s
b. transmission delay = 64000bps x 0.006s / 1000000bps
=0.384ms
c. sum total time = 6ms + 0.384ms + 2ms
=8.384ms

Problem 4:
a. 3Mbps / 150kbps
= 20 users can be supported and 150kbps dedicated.
b.



Because each user can only transmits 10% of the time
So, probability = 0.1
c. Probability = Cn120 x 0.1n x 0.9120-n

Problem 5:
a.
[pic]
2 traceroutes with their appropriate averages and standard deviations.

b. The paths may be changed over the hours.
c. The largest delays are likely to occur between adjacent ISPs.
d.
[pic]
By comparing the intra-continent and inter-continent results, to connect to other countries outside HK need more(prenominal) traceroutes.

Problem 6:
a. 8 x 106 / 2 x 106 = 4s
Total time = 4 x 3 = 12s
b. measure to move the beginning packet from host A to the first switch = 10000 / 2 x 106
= 0.005s
Time for the flake packet be estimabley...If you want to get a full essay, order it on our website: Ordercustompaper.com



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