Problem 3 : 10 points A factor in the delay of a store-and-forward packet-switch

Question

Problem 3 : 10 points A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and forward a packet through a switch. If switching time is 8msec, is this likely to be a major factor in the response of a client-server system where the client is in New York and the server is in California? Assume propagation speed in copper and fiber to be 9/10 the speed of light in vacuum. Now consider 15 switches between the client and server, how does this affect the calculation?

Explanation / Answer

The speed of propagation is 200,000 km/sec
=200 meters/sec.
  
In 8 milli seconds the signal travels 8000*200= 1600000m = 1600 km.
Hence each switch needs 1600 km of extra cable.
For 15 switches we need 1600*15= 24000 km to the total path.

If distance between New York and California is 5,000 km, the percentage of the equivalent
added distance is =24000/5000
= 4.8%
switching delay is not a major factor

Thus, switching delay is not a major factor under these circumstances.

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.