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Auteur(s) Bonaventure Olivier
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Se connecter

Se connecter

Traffic pattern through a FIFO queue

As in the previous exercise, we consider that packets enter our router at a rate of 10 Mbps and that they must be forwarded over a 1 Mbps link. Our router has a buffer which can hold up to p packets. On this router, a packet remains inside the buffer until the transmission of the last bit of the packet on the downstream link.

For simplicity, we consider that all packets have a length of 10000 bits.

We consider different traffic patterns that arrive on our router. These patterns will be represented as a sequence of P and .. Each character corresponds to a delay of one millisecond. A P indicates the transmission of a 10000 bits long packet while . indicates no transmission. Each pattern repeats itself forever.

Question 1: Traffic pattern
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Our router has a buffer which can hold up to three packets. This buffer is empty when it receives the following traffic pattern :

..PP..PP..PP..PP..PP..PP

If the first packet is packet number 0, what is the number of the first packet that will be dropped by our router (-1 if packets are never dropped).

Question 2: Packet loss ratio
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Over a long period of time, what is the percentage of the incoming packets that will be discarded by our router because its buffer is full ?

Question 3: Traffic pattern
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Our router has a buffer which can hold up to three packets. This buffer is empty when it receives the following traffic pattern :

....P....P....P....P

If the first packet is packet number 0, what is the number of the first packet that will be dropped by our router (-1 if packets are never dropped).

Question 4: Packet loss ratio
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Over a long period of time, what is the percentage of the incoming packets that will be discarded by our router because its buffer is full ?

Question 5: Traffic pattern
Add answer

Our router has a buffer which can hold up to three packets. This buffer is empty when it receives the following traffic pattern :

PPPPP.....PPPPP.....PPPPP

If the first packet is packet number 0, what is the number of the first packet that will be dropped by our router (-1 if packets are never dropped).

Question 6: Packet loss ratio
Add answer

Over a long period of time, what is the percentage of the incoming packets that will be discarded by our router because its buffer is full ?