Tanenbaum- Q30(Network layer)

Question

The CPU in a router can process 2 million packets/sec. The load offered to it is 1.5
million packets/sec. If a route from source to destination contains 10 routers, how
much time is spent being queued and serviced by the CPUs?

Answer 1

only processing  delay =10*(1/2M)=5 us

Answer 2

Here μ is 2 million and λ is 1.5 million,

                    so ρ=λ/μ is 0.75,

and from queueing theory, each packet experiences a delay four times what it would in an idle system.

The time in an idle system is 500 nsec, here it is 2 μsec.

With 10 routers along a path, the queueing plus service time 20 μsec. 

 

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