Question
In Section 4.3, we noted that the maximum queuing delay is (n–1)D if the switching fabric is n times faster than the input line rates. Suppose that all packets are of the same length, n packets arrive at the same time to the n input ports, and all n packets want to be forwarded to different output ports. What is the maximum delay for a packet for the (a) memory, (b) bus, and (c) crossbar switching fabrics?
Answer
Consider the given data:
Assume packet length=n
Maximum queuing delay= (n–1)D
All packets are of the same length, n packets arrive at the same time to the n input ports, and all n packets want to be forwarded to different output ports.
a)
The maximum delay for a packet for the memory = (n-1)D
b)
The maximum delay for a packet for the bus = (n-1)D
c)
The maximum delay for a packet for the crossbar switching fabrics= 0