revisiting resource pooling: the case for in …revisiting resource pooling: the case for in-network...
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Revisiting Resource Pooling: The Case for In-network Resource Sharing
Lorenzo Saino
Department of Electronic and Electrical Engineering University College London
Joint work with Ioannis Psaras and George Pavlou
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Outline
• Background – Resource pooling – Information Centric Networking
• In-network resource pooling – Main concepts – High level operation
• Early results • Summary
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Resource Pooling
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Resource Pooling
• Well known principle in systems design supporting efficient utilization of resources under variable user demands.
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Resource Pooling
• Well known principle in systems design supporting efficient utilization of resources under variable user demands.
• Resource pooling deeply routed in Internet architecture: – Packet switching enables pooling of link capacities and routers
processing power – Buffers enable pooling of link capacity at adjacent time periods – MPLS traffic engineering and ECMP enable pooling of multiple paths
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Resource Pooling
• Well known principle in systems design supporting efficient utilization of resources under variable user demands.
• Resource pooling deeply routed in Internet architecture: – Packet switching enables pooling of link capacities and routers
processing power – Buffers enable pooling of link capacity at adjacent time periods – MPLS traffic engineering and ECMP enable pooling of multiple paths
• Pooled resources: – Router processing power – Links – Buffers – Paths
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Efficiently Pooling End-to-end Paths
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Efficiently Pooling End-to-end Paths
• Multipath TCP has been recently proposed to efficiently pool end-to-end paths
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Efficiently Pooling End-to-end Paths
• Multipath TCP has been recently proposed to efficiently pool end-to-end paths
• Multiple simultaneous connections are opened between two communicating hosts over different paths
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Efficiently Pooling End-to-end Paths
• Multipath TCP has been recently proposed to efficiently pool end-to-end paths
• Multiple simultaneous connections are opened between two communicating hosts over different paths
• Load is dynamically shifted among each path based on available bandwidth
![Page 11: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/11.jpg)
Efficiently Pooling End-to-end Paths
• Multipath TCP has been recently proposed to efficiently pool end-to-end paths
• Multiple simultaneous connections are opened between two communicating hosts over different paths
• Load is dynamically shifted among each path based on available bandwidth
• Assumes that at least one host is multihomed
![Page 12: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/12.jpg)
Efficiently Pooling End-to-end Paths
• Multipath TCP has been recently proposed to efficiently pool end-to-end paths
• Multiple simultaneous connections are opened between two communicating hosts over different paths
• Load is dynamically shifted among each path based on available bandwidth
• Assumes that at least one host is multihomed • More reactive and fine-grained control than MPLS traffic
engineering and ECMP
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The long discussion on TCP
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The long discussion on TCP
• TCP addresses uncertainty using the packet conservation principle and by (proactively) suppressing demand
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The long discussion on TCP
• TCP addresses uncertainty using the packet conservation principle and by (proactively) suppressing demand
• TCP is moving traffic as fast as the path’s slowest link
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The long discussion on TCP
• TCP addresses uncertainty using the packet conservation principle and by (proactively) suppressing demand
• TCP is moving traffic as fast as the path’s slowest link • End-points have to speculate on the resources available along
the end-to-end path
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Information Centric Networking (ICN)
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Information Centric Networking (ICN)
• ICN paradigm aims at rethinking Internet architecture having in mind content distribution as the main use case
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Information Centric Networking (ICN)
• ICN paradigm aims at rethinking Internet architecture having in mind content distribution as the main use case
• CCN/NDN [CoNEXT’09] is the most prominent architecture
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Information Centric Networking (ICN)
• ICN paradigm aims at rethinking Internet architecture having in mind content distribution as the main use case
• CCN/NDN [CoNEXT’09] is the most prominent architecture
• Main principles: – Naming contents instead of hosts – Receiver-driven request-response mode of operation – Securing content, not channel – Ubiquitous packet caches on routers
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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ICN operation
R1
C S www.example.com
R1
www.example.com/video1.jpg/1
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Transport layer implications of ICN
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Transport layer implications of ICN
• Request and Data paths are symmetric • Instead of the “data-ACK” model of TCP, in ICN we have
a “request-data” model
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Transport layer implications of ICN
• Request and Data paths are symmetric • Instead of the “data-ACK” model of TCP, in ICN we have
a “request-data” model
• Receivers (instead of senders) regulate the traffic that is pushed in the network
• Based on requests forwarded, each forwarding entity knows how much traffic to expect within one RTT.
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In-network caches as resources
• Network caches have been used for resource optimization by storing popular contents, possibly for long time – Reduce latency, load on origin servers and bandwidth utilization
• Overlay caching: – Put caches in “strategic” places and redirect (HTTP) requests to those caches
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In-network caches as resources
• Network caches have been used for resource optimization by storing popular contents, possibly for long time – Reduce latency, load on origin servers and bandwidth utilization
• Overlay caching: – Put caches in “strategic” places and redirect (HTTP) requests to those caches
• Packet caching: – Individually named and self-identifiable packets/chunks allow for in-network
storage! – Put caches in every router and serve network-layer requests for named
chunks from caches on the path
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In-network caches as resources
• Network caches have been used for resource optimization by storing popular contents, possibly for long time – Reduce latency, load on origin servers and bandwidth utilization
• Overlay caching: – Put caches in “strategic” places and redirect (HTTP) requests to those caches
• Packet caching: – Individually named and self-identifiable packets/chunks allow for in-network
storage! – Put caches in every router and serve network-layer requests for named
chunks from caches on the path
• We use in-network caching for temporary storage
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Caches and resource pooling
• The presence of ubiquitous packet caches enables more efficient usage of resources by enabling pooling of sub-paths.
• More effective than buffers
A B C
A B C
Ti
Ti+1
X
X
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Pooled resources
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Pooled resources
Links
Switching devices
Buffers
Packet switching
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Pooled resources
Links
Switching devices
Buffers
Paths
Packet switching
ECMP, MPLS TE, MPTCP
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Pooled resources
Links
Switching devices
Buffers
Paths
Sub-paths
Packet caches
Packet switching
ECMP, MPLS TE, MPTCP
Our proposal
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Proposed solution
1. Push traffic as far in the path and as fast as possible 2. Once in front of the bottleneck, store traffic temporarily in
custodian nodes/routers and deal with congestion locally 3. Exploit all available (sub-)paths making decisions on a hop-by-
hop manner.
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Three-phase operation
• Push-data phase – Open-loop system – Receivers request for as much data as supported by their access link – Senders push data as far and as quickly as possible
• Cache & Detour phase – Every router monitors rate of incoming Requests – When demand is expected to exceed supply, the local router tries to find
alternative paths to detour – In the meantime traffic in excess (if any) is cached locally
• Backpressure phase – Closed-loop system – If alternative paths do not exist or are equally congested:
• Pace requests • Send notification upstream to slow down and enter closed-loop transmission
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Three-phase operation
A B C
E F
D
Push-data phase – open-loop system • Receivers request for as much data as supported by their access link • Senders push data as far and as quickly as possible
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Three-phase operation
A B C
E F
D
Push-data phase – open-loop system • Receivers request for as much data as supported by their access link • Senders push data as far and as quickly as possible
![Page 45: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/45.jpg)
Three-phase operation
A B C
E F
D
Push-data phase – open-loop system • Receivers request for as much data as supported by their access link • Senders push data as far and as quickly as possible
![Page 46: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/46.jpg)
Three-phase operation
A B C
E F
D
Cache & Detour phase • Every router monitors rate of incoming Requests • When demand is expected to exceed supply, the local router tries to find
alternative paths to detour • In the meantime traffic in excess (if any) is cached locally
![Page 47: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/47.jpg)
Three-phase operation
A B C
E F
D
Cache & Detour phase • Every router monitors rate of incoming Requests • When demand is expected to exceed supply, the local router tries to find
alternative paths to detour • In the meantime traffic in excess (if any) is cached locally
![Page 48: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/48.jpg)
Three-phase operation
A B C
E F
D
Cache & Detour phase • Every router monitors rate of incoming Requests • When demand is expected to exceed supply, the local router tries to find
alternative paths to detour • In the meantime traffic in excess (if any) is cached locally
![Page 49: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/49.jpg)
Three-phase operation
A B C
E F
D
Cache & Detour phase • Every router monitors rate of incoming Requests • When demand is expected to exceed supply, the local router tries to find
alternative paths to detour • In the meantime traffic in excess (if any) is cached locally
![Page 50: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/50.jpg)
Three-phase operation
A B C
E F
D
Backpressure phase – Closed-loop system If alternative paths do not exist or are equally congested: • Pace requests • Send notification upstream to slow down and enter closed-loop transmission
![Page 51: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/51.jpg)
Three-phase operation
A B C
E F
D
Backpressure phase – Closed-loop system If alternative paths do not exist or are equally congested: • Pace requests • Send notification upstream to slow down and enter closed-loop transmission
![Page 52: Revisiting Resource Pooling: The Case for In …Revisiting Resource Pooling: The Case for In-network Resource Sharing Lorenzo Saino Department of Electronic and Electrical Engineering](https://reader034.vdocuments.net/reader034/viewer/2022042218/5ec4b3a9d8ff1a5b1147f14d/html5/thumbnails/52.jpg)
Feasibility
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Feasibility
• Recent work [CuckooSwitch, CoNEXT’13], [MICA, NSDI’14], [Caesar, ANCS’14] shows the feasibility of per-packet read/write operations in DRAM at several 10s Gbps on off-the-shelf hardware.
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Feasibility
• Recent work [CuckooSwitch, CoNEXT’13], [MICA, NSDI’14], [Caesar, ANCS’14] shows the feasibility of per-packet read/write operations in DRAM at several 10s Gbps on off-the-shelf hardware.
• DRAM cost is steadily decreasing. We’ll soon have TBs of DRAM available on commodity servers.
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Feasibility
• Recent work [CuckooSwitch, CoNEXT’13], [MICA, NSDI’14], [Caesar, ANCS’14] shows the feasibility of per-packet read/write operations in DRAM at several 10s Gbps on off-the-shelf hardware.
• DRAM cost is steadily decreasing. We’ll soon have TBs of DRAM available on commodity servers.
• Ongoing work suggests also Flash-based packet caches could be a viable solution
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Availability of detour paths
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Some (very initial) results
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Summary and open issues
• Information-Centric Networking: – Lots of attention lately – Requires investment and effort – Worth doing, but need to get the full set of advantages
• There is an opportunity to deal with congestion control at the network layer
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Summary and open issues
• Information-Centric Networking: – Lots of attention lately – Requires investment and effort – Worth doing, but need to get the full set of advantages
• There is an opportunity to deal with congestion control at the network layer
• Open Issues: – How do you know detour paths are not congested – How will this co-exist with traditional TCP flows? – Out of order delivery – Flows swapping between original and detour paths