Tutorial 8

# Tutorial 8 - IERG4020 Tutorial 8 FENG Shen 1 QUIZ 3...

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Unformatted text preview: IERG4020 Tutorial 8 FENG Shen 1 QUIZ 3 DISCUSSION 2 Quiz 3 statistics Quiz 1 Quiz 2 Quiz 3 MEAN 3.02 4.77 6.79 SD 2.07 2.56 2.67 MAX 8.50 10.00 10.00 MIN 1.00 0.00 1.00 MEDIAN 2.00 5.00 6.75 3 DEFLECTION ROUTING 4 Introduction  Deflection Routing is a way to solve packet contention problem without having to buffer the losing packets.  The basic idea is to route (deflect) the losing packets to “wrong” outgoing links rather than drop them.  Redundancy is built into the switch design so that deflected packets can be routed in later switching stages in a way that corrects for the earlier mistakes. 5 Tandem-Banyan Network  Basic idea: Consists of K Banyan networks connected in series, so each packet can have K attempts to reach its destination.   k-1 =  k +  c k 6 1st Banyan Network 2nd Banyan Network Kth Banyan Network   1  c 1  2  K  c 2  c K Tandem-Banyan Network   k is the offered load to the input of the ( k +1)-th Banyan network – losing packets (if k > 0).   c k is the carried load on the output of the k-th Banyan network – winning packets. 7 1st Banyan Network 2nd Banyan Network Kth Banyan Network   1  c 1  2  K  c 2  c K 2 1 1 1 1 1 1 4 4 4 c k k k k k k k k n n n                      Tandem-Banyan Network  State Transition Diagram:  j = # of remaining stages to go in Banyan network(s). n = # of stages in each Banyan network.  e.g. a packet is deflected in the 2nd stage of a 8 × 8 Banyan network ( n = 3), it has 1 more stage to go in the current Banyan network and 3 more stages to go in the next Banyan network. 8 Note that packets can only be deflected within here Tandem-Banyan Network  A tandem-Banyan network example: 9 111 101 110 100 101 111 100 110 Shuffle-exchange Network  In tandem-Banyan switch, the deflection distance is n - 1. The penalty is high....
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## This note was uploaded on 12/08/2010 for the course IEG IEG4020 taught by Professor Fengshen during the Spring '10 term at CUHK.

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Tutorial 8 - IERG4020 Tutorial 8 FENG Shen 1 QUIZ 3...

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