ppt - MMLab

puffyyaphankyonkersΔίκτυα και Επικοινωνίες

26 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

165 εμφανίσεις

Jang,
Donghyun

2011/4/4

dhjang@mmlab.snu.ac.kr

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Introduction


System overview


CNF Protocol details


Performance summary


Conclusion

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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


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~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


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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

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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


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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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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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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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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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S

Content

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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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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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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Implemented as overlay network on IP
network

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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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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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Fragment very large files (10’s of GB) into
smaller chunks (~100MB
-
1GB) before
transporting


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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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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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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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