اسئلة عامة عن الشبكات والبنق تحديدا

**hatema** · 29-12-2010, 00:12

السلام عليكم

احد اصدقائى يدرس فى كلية الهندسه وقابلته بعض الاسئلة فى مادة الشبكات والحمدلله انهينا معظمها وتبقى لنا سؤالين هما

1 . Use ping to determine the propagation delay. Specifically, send 10 very small packets (these will be 24 bytes) to a particular destination and recod the average round-trip time (RTT). Then use ping to send 10 packets with larger payload (type "ping" then press enter for help with ping) and compute the average RTT. Compare the difference in the RTTs and determine the transmission time. You might need to try this with various sized packets.
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2 . Do links have time-varying delay? To answer this questions run trace route and ping at different times of the day (e.g., the middle of the night, morning, afternoon, etc., or maybe just run ping for an entire day) and compare the delay times. (Make sure to include destinations not in the US. Also, use IP addresses instead of names. Use nslookup to translate between names an IP addresses.) Use packet sizes less than 1450. One way to do this is use "ping XXXX.com -t > PingData.txt." Then open the file in a text editor to remove the first few lines and last few lines and remove the letters "ms" (use the replace function for this). So, when you are done, the file has many lines of
...
Reply from 66.218.71.198: bytes=32 time=79 TTL=243
Reply from 66.218.71.198: bytes=32 time=80 TTL=243
...
Then open this file in excel (or matlab) and make a plot of RTT.

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ارجوا منكم المساعدة

تحياتى

**mezomora123** · 29-12-2010, 09:16

المشاركة الأصلية كتبت بواسطة hatema

السلام عليكم

احد اصدقائى يدرس فى كلية الهندسه وقابلته بعض الاسئلة فى مادة الشبكات والحمدلله انهينا معظمها وتبقى لنا سؤالين هما

1 . Use ping to determine the propagation delay. Specifically, send 10 very small packets (these will be 24 bytes) to a particular destination and recod the average round-trip time (RTT). Then use ping to send 10 packets with larger payload (type "ping" then press enter for help with ping) and compute the average RTT. Compare the difference in the RTTs and determine the transmission time. You might need to try this with various sized packets.
-------------------------------------------------------------
2 . Do links have time-varying delay? To answer this questions run trace route and ping at different times of the day (e.g., the middle of the night, morning, afternoon, etc., or maybe just run ping for an entire day) and compare the delay times. (Make sure to include destinations not in the US. Also, use IP addresses instead of names. Use nslookup to translate between names an IP addresses.) Use packet sizes less than 1450. One way to do this is use "ping XXXX.com -t > PingData.txt." Then open the file in a text editor to remove the first few lines and last few lines and remove the letters "ms" (use the replace function for this). So, when you are done, the file has many lines of
...
Reply from 66.218.71.198: bytes=32 time=79 TTL=243
Reply from 66.218.71.198: bytes=32 time=80 TTL=243
...
Then open this file in excel (or matlab) and make a plot of RTT.

-------------------------

ارجوا منكم المساعدة

تحياتى

================================================== =============
السلام عليكم أخى.......
تابع معايا كده....وربنا يسهل ان شاء الله.
أول حاجة.....
Use ping to determine the propagation delay. Specifically, send 10 very small packets (these will be 24 bytes) to a particular destination and recod the average round-trip time (RTT)
ولنفترض ان احنا هنعمل Ping على Yahoo ......يبقى هنكتب الاتى.
ping yahoo.com -n 10 -l 24
-n دى عشان تحدد ال 10 Packet......و -l عشان تحدد ال Size بتاع كل Packet
وهيكون النتاج مثلاً كده.....
Ping statistics for 209.191.122.70:
Packets: Sent = 10, Received = 10, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 213ms, Maximum = 229ms, Average = 221ms
وهنسجل ال RTT .....
Minimum = 213ms, Maximum = 229ms, Average = 221ms
وبعد كده السؤال بيقول
Then use ping to send 10 packets with larger payload (type "ping" then press enter for help with ping) and compute the average RTT
وهنعمل Ping تانى بس مع تغيير ال Size بس ونخليه أكبر.
Ping yahoo.com -n 10 - l 300
وهيكون الناتج كده.....

Ping statistics for 209.191.122.70:
Packets: Sent = 10, Received = 10, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 224ms, Maximum = 237ms, Average = 230ms
والسؤال بيقول and compute the average RTT
يبقى Average = 230ms
وأخيراً........
Compare the difference in the RTTs and determine the transmission time
أعتقد النسب والارقام موجودة فوق عندك......تقدر تحسب منها اللى انت عايزه.......

**hatema** · 29-12-2010, 13:33

الف شكر اخى الكريم

ياريت توضحلى هذه النقطة

determine the transmission time

**mezomora123** · 29-12-2010, 15:22

المشاركة الأصلية كتبت بواسطة hatema

الف شكر اخى الكريم

ياريت توضحلى هذه النقطة

determine the transmission time

================================================== ==============

Pinging yahoo.com [209.191.122.70] with 32 bytes of data:

Reply from 209.191.122.70: bytes=32 time=668ms TTL=54
Reply from 209.191.122.70: bytes=32 time=713ms TTL=54
Reply from 209.191.122.70: bytes=32 time=701ms TTL=54
Reply from 209.191.122.70: bytes=32 time=661ms TTL=54

Ping statistics for 209.191.122.70:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 661ms, Maximum = 713ms, Average = 685ms
================================================== ==========
ودا مثال......
admin@localhost# ping en.wikipedia.org
PING rr.pmtpa.wikimedia.org (66.230.200.100) 56(84) bytes of data.
64 bytes from rr.pmtpa.wikimedia.org (66.230.200.100): icmp_seq=1 ttl=52 time=87.7 ms
64 bytes from rr.pmtpa.wikimedia.org (66.230.200.100): icmp_seq=2 ttl=52 time=95.6 ms
64 bytes from rr.pmtpa.wikimedia.org (66.230.200.100): icmp_seq=3 ttl=52 time=85.4 ms
64 bytes from rr.pmtpa.wikimedia.org (66.230.200.100): icmp_seq=4 ttl=52 time=95.8 ms
64 bytes from rr.pmtpa.wikimedia.org (66.230.200.100): icmp_seq=5 ttl=52 time=87.0 ms
64 bytes from rr.pmtpa.wikimedia.org (66.230.200.100): icmp_seq=6 ttl=52 time=97.6 ms
--- rr.pmtpa.wikimedia.org ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 8998ms
rtt min/avg/max/mdev = 78.162/89.213/97.695/6.836 ms
وهنا التوضيح......
The output shows the results of 10 pings to 66.230.200.100 with the results summarized at the end. The program is stopped by pressing Ctrl-C.
shortest round trip time was 78.162 milliseconds
average round trip time was 89.213 milliseconds
maximum round trip time was 97.695 milliseconds
Standard deviation of the round-trip time was 6.836 milliseconds
=========================================
يارب تكون وضحت الفكرة كده........
وشوف الموضوع دا هيفيدك.....
https://en.wikipedia.org/wiki/Ping
وشكراً