advertisement

Throughput optimization … Max-flow optimization Zongpeng Li’s slides: 2-8 (copies comes next in these slides) Network coding Butterfly example (in these slides) Zongpeng’s slides: 14-15 (copies in these slides) 1 LP: Hello world … 2 LP: Hello world … 3 4 5 Without network coding … S T1 T2 Using unicast, how much can S send to T1 and T2? Without network coding … S T1 and T2 both get 50% of senders capacity T1 T2 Using unicast, how much can S send to T1 and T2? Without network coding … S T1 T2 Using multicast, how much can S send to T1 and T2? Without network coding … S A,B B C,D D T1 and T2 both B A,B D T1 D C,D B get ¾ streams (75% of senders capacity) T2 Optimization problem equal to “packing of Steiner trees” (NP-hard problem) With network coding … S A A T1 and T2 both get 2/2 streams (100% of senders capacity) Improvement by 33% A B B A+B A+B T1 B A+B T1 S A,B B D B D A,B D T1 C,D S A A C,D B A B A+B A+B T2 B T1 B A+B T1 11 Savings can also be in terms of “bandwidth” … 12 b1 b1 b2 b1 b2 b1 b2 b2 b1 b1 b2 b1 b2 b1 b2 b1+b2 b1+b2 b1+b2 b2 …or “time” … 14 Network Coding Example (animation) a b A technique to improve: 1. network throughput 2. efficiency 3. scalability … a 1 b a b 2 3 a ab a b Information is coded at potentially every node 1 2 3 4 5 abb 5 4 b a ab 6 Network Coding Example (without) a b A technique to improve: 1. network throughput 2. efficiency 3. scalability … a 1 b a 2 b 3 a b a Information is coded at potentially every node 1 2 3 4 5 b 5 4 b a 6 Network Coding Example (with) a b A technique to improve: 1. network throughput 2. efficiency 3. scalability … a 1 b a b 2 3 a ab a b Information is coded at potentially every node 1 2 3 4 ab 5 4 b ab 6 18 19 20