Introduction to computer networking
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Introduction to Introduction to computer computer networking networking Distributed Algorithms Distributed Algorithms Class Recitation Class Recitation
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Introduction to computer networking. Distributed Algorithms Class Recitation. Ex. 1 - PIF Revisited. Given the PIF algorithm: Init: l N ( l )0; m 0; p 0 Upon receipt of MSG s ( l ) N ( l )1 if m =0 then p1 send MSG s to all l N -{ l } m 1 - PowerPoint PPT Presentation
Transcript of Introduction to computer networking
Introduction to Introduction to computer computer
networkingnetworkingDistributed Algorithms Class Distributed Algorithms Class
RecitationRecitation
Ex. 1 - PIF RevisitedEx. 1 - PIF Revisited• Given the PIF algorithm:
Init: l N(l)0; m0; p0Upon receipt of MSGs(l)
N(l)1if m=0 then
p1send MSGs to all lN-{l}
m1if l’ holds N(l’)=1 then
send MSGs to p m0 l’ N(l’)0
• Is it possible that a node i will send messages to all itsneighbors except its parent, p, before node p has?
• Is it possible for node i to send a message to its parent p before node j has finished sending messages to its neighbors?
T=0T=0
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
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T=3T=3
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 1
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
T=4T=4
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 14 (2,4) 1 1 1
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
T=5T=5
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 14 (2,4) 1 1 15 (2,3) 1 1 25 (4,3) 1
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
T=6T=6
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 14 (2,4) 1 1 15 (2,3) 1 1 25 (4,3) 16 (1,3) 0 1/0 /0 /06 (3,4) 0 /0 1/0
QuickTime™ and aTIFF (LZW) decompressor
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T=7T=7
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 14 (2,4) 1 1 15 (2,3) 1 1 25 (4,3) 16 (1,3) 0 1/0 /0 /06 (3,4) 0 /0 1/07 (4,2) 1
QuickTime™ and aTIFF (LZW) decompressor
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T=8T=8
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 14 (2,4) 1 1 15 (2,3) 1 1 25 (4,3) 16 (1,3) 0 1/0 /0 /06 (3,4) 0 /0 1/07 (4,2) 18 (3,2) 0 /0 1/0 /0
QuickTime™ and aTIFF (LZW) decompressor
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T=11T=11
node no. 1 node no. 2 node no. 3 node no. 4time link m1 N1(1) N1(2) p1 m2 N2(1) N2(2) N2(3) p2 m3 N3(1) N3(2) N3(3) p3 m4 N4(1) N4(2) p4
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 (1,2) 1 1 14 (2,4) 1 1 15 (2,3) 1 1 25 (4,3) 16 (1,3) 0 1/0 /0 /06 (3,4) 0 /0 1/07 (4,2) 18 (3,2) 0 /0 1/0 /0
11 (3,1) 111 (2,1) 0 1/0 /0 /0
QuickTime™ and aTIFF (LZW) decompressor
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Ex. 2Ex. 2
• Given the PIFD algorithm, which is similar to the PIF algorithm, albeit with a second (other than the source) unique node D which behaves differently from the other nodes. For each of the following claims, determine whether the claim is true or false:
The ClaimsThe Claims• All the nodes will receive the message after a
finite time period and all will have m=1 eventually.
• The algorithm ends. i.e. there is a finite time after which no more messages are transferred.
• The source node knows when the algorithm has finished
• When the source node finishes the algorithm, the algorithm has ended.
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PIFD
Algorithm For Node D:Init: Init: l N(l)0; m0; p0Upon receipt of MSGs(l)
N(l)1if m=0 then
p1send MSGs to all neighbours m1
The Claims RevisitedThe Claims Revisited• All the nodes will receive the message after a finite time
period and all will have m=1 eventually.• The algorithm ends. i.e. there is a finite time after which
no more messages are transferred.• The source node knows when the algorithm has finished• When the source node finishes the algorithm, the
algorithm has ended.
