Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Distributed Algorithms for Content Allocation in Interconnected Content Distribution Networks Valentino Pacifici, Gy¨ orgy D´ an Laboratory for Communication Networks KTH Royal Institute of Technology Stockholm, Sweden Hong Kong, April 30, 2015 V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 1 / 16
❼ ❼ ❼ ❼ ❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Booming Content Delivery Market Content Distribution in the Internet ❼ 2009: P2P traffic → up to 70 % of Internet traffic ❼ 2013: Netflix + YouTube → 50 % fixed network traffic ❼ 2017: Video traffic → 80 % of IP traffic V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 2 / 16
❼ ❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Booming Content Delivery Market Content Distribution in the Internet ❼ 2009: P2P traffic → up to 70 % of Internet traffic ❼ 2013: Netflix + YouTube → 50 % fixed network traffic ❼ 2017: Video traffic → 80 % of IP traffic Over-the-top Content providers ❼ ↑ Quality of delivered content ❼ ↑ Revenue ❼ ↑ User demand for content V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 2 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Booming Content Delivery Market Content Distribution in the Internet ❼ 2009: P2P traffic → up to 70 % of Internet traffic ❼ 2013: Netflix + YouTube → 50 % fixed network traffic ❼ 2017: Video traffic → 80 % of IP traffic Over-the-top Content providers ❼ ↑ Quality of delivered content ❼ ↑ Revenue ❼ ↑ User demand for content Content Delivery Networks (CDNs) ❼ ↑ Delivered content on behalf of OTT providers ❼ ↑ Revenue ❼ ↑ 2017: delivery of 2 3 of total video traffic V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 2 / 16
❼ ❼ ❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Network Operator Managed CDNs Network operators ❼ Content distribution stresses network infrastructure (OTT, P2P) ❼ Network operators not part of revenue chain ↓ V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 3 / 16
❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Network Operator Managed CDNs Network operators ❼ Content distribution stresses network infrastructure (OTT, P2P) ❼ Network operators not part of revenue chain ↓ Network Operator Managed CDNs (nCDNs) ❼ Storage of content close to the customers ❼ Objectives: 1 Improve user’s QoE → decrease latency 2 Decrease traffic cost → decrease network traffic V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 3 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Network Operator Managed CDNs Network operators ❼ Content distribution stresses network infrastructure (OTT, P2P) ❼ Network operators not part of revenue chain ↓ Network Operator Managed CDNs (nCDNs) ❼ Storage of content close to the customers ❼ Objectives: 1 Improve user’s QoE → decrease latency 2 Decrease traffic cost → decrease network traffic Content Allocation Problem ❼ nCDNs periodically update content allocation based on predicted demands ❼ Pre-fetching : nCDN i decides on allocation A i ∈ O and fetches the content V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 3 / 16
❼ ❼ ❼ ❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Autonomous Content Delivery Networks O ISP 1 A 1 ½O o 2O ❼ nCDN optimized for local performance V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 4 / 16
❼ ❼ ❼ ❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Autonomous Content Delivery Networks O ISP 1 A 1 ❼ nCDN optimized for local performance V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 4 / 16
❼ ❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Autonomous Content Delivery Networks ISP 2 O ISP 1 A 2 ISP 3 A 1 A 3 ❼ nCDN optimized for local performance Interconnected nCDNs ❼ Maximize users’ QoE ❼ Retrieve items from connected nCDNs with lowest latency V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 4 / 16
❼ ❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Autonomous Content Delivery Networks ISP 2 O ISP 1 A 2 ISP 3 A 1 A 3 ❼ nCDN optimized for local performance Interconnected nCDNs ❼ Maximize users’ QoE ❼ Retrieve items from connected nCDNs with lowest latency Cost for serving one request (latency) ❼ α i from own nCDN i V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 4 / 16
❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Autonomous Content Delivery Networks ISP 2 O ISP 1 A 2 ISP 3 A 1 A 3 ❼ nCDN optimized for local performance Interconnected nCDNs ❼ Maximize users’ QoE ❼ Retrieve items from connected nCDNs with lowest latency Cost for serving one request (latency) ❼ α i from own nCDN i ❼ β j i from connected nCDN j V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 4 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Autonomous Content Delivery Networks ISP 2 O ISP 1 A 2 ISP 3 A 1 A 3 ❼ nCDN optimized for local performance Interconnected nCDNs ❼ Maximize users’ QoE ❼ Retrieve items from connected nCDNs with lowest latency Cost for serving one request (latency) ❼ α i from own nCDN i α i ≤ β j i < γ i ❼ β j i from connected nCDN j ❼ γ i from content provider V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 4 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Interconnected nCDNs - The Cost Model ❼ K i storage capacity of nCDN i ❼ w o i ∈ R + demand for item o ∈ O at nCDN i ❼ R i = � j ∈N ( i ) A j → content available from connected nCDNs i ( A − i ) � min j ∈N ( i ) { β j ❼ β o i | o ∈ A j } → lowest latency to retrieve item o V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 5 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Interconnected nCDNs - The Cost Model ❼ K i storage capacity of nCDN i ❼ w o i ∈ R + demand for item o ∈ O at nCDN i ❼ R i = � j ∈N ( i ) A j → content available from connected nCDNs i ( A − i ) � min j ∈N ( i ) { β j ❼ β o i | o ∈ A j } → lowest latency to retrieve item o Average latency experienced by customers of operator i : � w o C i ( A i , A − i ) = i α i A i V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 5 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Interconnected nCDNs - The Cost Model ❼ K i storage capacity of nCDN i ❼ w o i ∈ R + demand for item o ∈ O at nCDN i ❼ R i = � j ∈N ( i ) A j → content available from connected nCDNs i ( A − i ) � min j ∈N ( i ) { β j ❼ β o i | o ∈ A j } → lowest latency to retrieve item o Average latency experienced by customers of operator i : � w o � w o i β o C i ( A i , A − i ) = i α i + i ( A − i ) A i R i V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 5 / 16
Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Interconnected nCDNs - The Cost Model ❼ K i storage capacity of nCDN i ❼ w o i ∈ R + demand for item o ∈ O at nCDN i ❼ R i = � j ∈N ( i ) A j → content available from connected nCDNs i ( A − i ) � min j ∈N ( i ) { β j ❼ β o i | o ∈ A j } → lowest latency to retrieve item o Average latency experienced by customers of operator i : � w o � w o i β o � w o C i ( A i , A − i ) = i α i + i ( A − i ) + i γ i A i R i O � { A i ∪R i } V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 5 / 16
❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Objective Distributed algorithm - desiderata 1 nCDN i exchange information only with connected N ( i ) V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 6 / 16
❼ Problem Definition Failure of Distributed Greedy Bilateral Compensation-based Algorithms Conclusion Objective Distributed algorithm - desiderata 1 nCDN i exchange information only with connected N ( i ) 2 Reveals little information about w o i V. Pacifici, G. D´ an (EE,KTH) Replication in Interconnected nCDNs Apr 30, 2015 6 / 16
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