jang, donghyun 2011/4/4 dhjang@mmlab.snu.ac.kr
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The cache-and-forward network architecture for efficient mobile content delivery services
in the future internetSanjoy Paul, Roy Yates, Dipankar Raychaudhuri, Jim Kurose
Jang, Donghyun2011/4/4
dhjang@mmlab.snu.ac.kr
1/21
Introduction System overview CNF Protocol details Performance summary Conclusion
2/21
Table of contents
Representative Future Internet research project◦ NSF FIND and GENI in the U.S.◦ FP7 Future Networks and FIRE in Europe
This paper presents the initial results of an NSF FIND project
The initial results focus on designing a clean-slate network architecture for efficient delivery of media content to mobile users
3/21
Introduction
~2.5 billion cell phones vs. ~500 million wired PC
Smart phones and PDA proliferate rapidly The number of Internet transactions from
mobile devices may be expected to surpass those from wired network PC’s over the next 5-10 years◦ Shift of end-users from wired to mobile
4/21
Why should we focus onmobile contents?
VS
Internet usage pattern◦ Communication => contents service (delivery of
large file) Need next-generation Internet protocol
service optimized to support media content delivery to mobile user
5/21
Why should we focus onmobile contents?
Existing Internet protocols (e.g., TCP/IP) are not well-suited for mobile content services
TCP model assumes a contemporaneous source-to-destination path◦ Mobile users experience intermittent and
unreliable access over wireless channels TCP model was originally designed to
support point-to-point data services◦ It is not suitable for multipoint content
dissemination
6/21
Why do we need new architecture?
To solve the problems of TCP/IP architecture◦ Facilitate opportunistic transport on a hop-by-hop
basis rather than end-to-end streaming of data Hop-by-hop transport model implies large
in-network storage (cache) of content files This is basic idea of the cache-and-
forward (CNF) network architecture
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Main idea
Each node has a large storage cache CNF router may either be wired or wireless,
also mobile (especially, mobile CNF router refer to Cache and Carry (CNC) router)
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System overview –CNF and CNC router
CNC
Network serves two functions◦ Pull: Mobile end-user can request contents◦ Push: Content provider can push the content to
one or more end-users
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System overview –Pull & Push contents
When mobile end-user can request contents◦ Contents Discovery
copies of the same content can be cached in multiple CNF routers in the network
Discover the CNF router with the desired content that is “closest” to the requesting endpoint
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System overview –Pull contents
SContent
Content
• When content provider can push the content Post Office (PO)
Edge of the wired core network Holding and forwarding point for content to mobiles
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System overview –Push contents
PO
1. The sender contacts a name resolution service that resolves the name of the mobile host to a set of PO nodes
2. The sender will forward the file to one or more PO’s using conventional point-to-point routing
3. These PO’s will “hold” the file until contacted by the mobile host to arrange delivery
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System overview –The steps of pushing contents
Each query and content file is carried as a CNF packet data unit or package in a hop-by-hop fashion
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System overview –package
Implemented as overlay network on IP network
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CNF protocol details
A link in the CNF architecture is a logical link between two adjacent CNF nodes
Consists of two components◦ Link Session Protocol (LSP)◦ Link Transport Protocol (LTP)
The choice of LTP will depend on the characteristics of the link
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CNF protocol details –Link layer
Content discovery◦ Content-aware routing based on a content
identifier (CID) Routing content after content was
discovered◦ Conventional (IP) address-based routing
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CNF protocol details –Network layer
Fragment very large files (10’s of GB) into smaller chunks (~100MB-1GB) before transporting
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CNF protocol details –Transport layer
End-host
Name Resolution Service (NRS)◦ Map the name of an endpoint to its
corresponding POs File Name Resolution Service (FNRS)
◦ Map a CID (content identifier) to corresponding attributes of the content Attributes of the content
Content Hash, Content Creator, Content Access Rights, etc
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CNF protocol details –NRS & FNRS
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Conceptual Flow Diagram
Simulation by using ns2 Hop-by-hop vs. TCP performance
◦ TCP is better than hop-by-hop in low load◦ Hop-by-hop is better than TCP in high load
Wireless multi-hop performance◦ The results show that significant throughput gains
are possible with customized link layer protocols like CLAP instead of TCP
Content routing gains◦ Reduction of content retrieval time and traffic
load
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Performance summary
New approach to network design in response to growing needs for improved support for both mobility and content in the future internet
The design presented here is clearly preliminary and will be further refined
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Conclusion
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