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Unformatted text preview: a link model,
the other factor that comes into the picture is the size of the packet that has arrived. Here is where we make
^
another assumption : the packet length is exponentially distributed with mean length 1= bits. Now if we
denote the speed of a link by C bps; then, the average service rate of packets is = C
^
which is exponentially distributed. Thus, we can use the M/M/1 model for exponentially distributed packet
size for studying a network link.
Example # 2:
If link speed is 1.5 Mbps (i.e., a T1link), and the average packet size is 1 Kbits, then the average
service rate is 1.5 Mbps/1Kbits = 1500 packets per sec (pps). 10. A view on Statistical Multiplexing
The next thing to realize is that all the packets that arrive to a data network link is statistically
multiplexed. This is a key behavior of packetswitched networks. This also results in queueing of packets
if all the capacity of a link is used up at a certain time – this points to the average packet delay we discussed
earlier.
Cons...
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 Fall '08
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 Computer Networks

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