Proxy-assisted Content Sharing Using Content Centric Networking (CCN)
for Resource-limited Mobile Consumer Devices
Jihoon Lee, Dae Youb KimIEEE Transactions on Consumer Electronics, Vol. 57, No. 2, May 2011
Hongbo [email protected]
2013.1.10
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Research Background
• Rapid developments in mobile technology– Mobile Phones Personal multimedia devices
• Evolution of Communication pattern – Client-Server Peer-to-Peer, Cloud Computing
• Too more signaling overhead in current Internet content exchange– Especially in the case of mobile consumer devices
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CCN Introduction
• A new communication paradigm to substitute the Internet
• Communication Characteristics comparing with TCP/IP– Receiver-centric communication
• Receivers pull information by sending interest message
– Hierarchical content naming scheme• Host without address, but with content object itself• Content with hierarchical names similar to URLS• Forwarding Interest packets by longest-prefix matching at
forwarding decision phase
– Cache and forward architecture• Every CCN device can cache data, use them to serve future requests
• Provide mobility, security, multi-path support 3
CCN Contents Sharing
• CCN protocol is based on Interest Packet and Data Packet
• Interest Packet– carries a name that identifies the desired data,
acts as a query for content– similar to “HTTP GET”
• Data Packet– carries the actual content– similar to “HTTP response”
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CCN Messages
unique identifier
a set of parameters
random nonce value to prevent the packet from looping
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Content Name
‘/’ character represents delimiter between different components
provides the global routing information contains the organizational routing information
Describes the versioning and segmentation functionality
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CCN Content Sharing and Delivery
• Essential Functions for CCN content sharing and delivery: Content Store, PIT and FIB,
• Content Store (buffer memory)– Stores data packets to be used in future by other recipients– Looks like content cache– Cache with replacement policies: Least Recently Used (LRU) and
Least Frequently Used (LFU)• PIT (pending interest table)
– Keeps track of interests forwarded toward content sources– PIT entries are eliminated after forwarding matching data packet
• FIB (forwarding information base)– Used to forward interest packets toward potential content holders of
matching data– Similar to an FIG table of IP router
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CCN Delivery
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If the content data is found, then deliver data (jump to 10)
Check PIT: If there is another Received request for the same content
If found, add the face
Consume PIT entry :1) replicated 2) sent out on all faces in the corresponding PIT entry
Refer FIB:1) determine the outgoing face2) add entry to PIT
Send Interest
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a mobile device X sends interest to the original source Y
The route for sending the interest packet is the route for receiving the data packet
The CCN devices on the route stores their forwarded data packets
Hand Over: Send Interest again
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Hand Over Occurred
Unnecessary data packets are transmitted to the old location
Re-sent again a number of interest packets for retrieving the already-requested data packets
Can’t re-use the stored data packets without updating the routing table
= deliver data from the remote original content holder
Issues in CCN
• Repeated transmission of interest packets• High resource consumption• Long transmission latency
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Proposed Scheme: Proxy-Assisted CCN
• User devices ask the proxy to download the requested content – User proxies with CCN in overlay over IP– CCN proxy can be a mobile device or a PC
• Must be continuously active
• User devices send content query packet to proxy node instead of sending interest packet– Proxy nodes resolve and make connections with other content
holder devices for user devices• Mobile device can reduce the overhead for CCN routing
information configuration and content sharing
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Proxy-based CCN content sharing
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CCN Overlay Configuration• Secure association of CCN proxy node
– Content prefix announcement– Content sharing
• Each device carries a unique cryptographic identity in the form of a public key pair
• Proxy nodes establish face configuration to construct routing tables – Network association: creating face configuration between a mobile
consumer device and a proxy node• Once a secure association is created
– No further processing at other proxy nodes except for network association
– No more exchanging process for additional interest packets even when a mobile consumer device changes its IP address, or its serving proxy nodes
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Proxy-assisted CCN Content Sharing
Step1: Mobile device sends content request message to proxy nodeStep 2: Proxy node initiates a normal CCN content sharing procedure
• Assumes the content request as one request from its own application layer
• Delivers the metadata information of the requested content sent by the content holders to the mobile device
Metadata information – can be acquired when CCN is generated – piggybacked in the first segment data of the content
Step 3: Mobile device configures fake PIT entries for requesting content data without furthering interest packets in segment unit of the content data 15
Secure association in mobile CCN environments
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Movement Indication
• Physical architecture, subnet address are used for detecting the movement of a mobile device– Subnet change, proxy change are regarded as a handoff
• When Movement detected – Mobile device sends ‘Hold request’ message to current
proxy node– Proxy node receives ‘Hold request’, stops delivering
content data packets to mobile device, stores the content data• HO field of the relevant entry in PIT is set to 1
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Interest packet at proxy CCN device
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Modified content data at proxy CCN device during handover
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Content Migration Processing
• Subnet change– Mobile device notifies the new IP address of its proxy
node by using ‘Handover notification’ message piggybacking the finally received content sequence number at the old location
– CCN proxy node transmits the stored content data to the new location of mobile device
• Proxy change– Mobile device detects the existence of proxy node by
proxy advertisement message– Modified CCN interest includes the requested content
name and the last received content sequence number from the previous content proxy
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Mobile device waits subsequent content data segments without using additional CCN interest packets
New proxy utilizes the modified CCN interest to reducethe control overhead during the delivery of the cached content data
Two-path delivery in proxy change case
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Two simultaneous paths for receiving the requested content data1) indirect path, the previous proxy node2) direct path, the new proxy node
Performance Evaluations
• Simulation Environment– Moving speed of a mobile device is 1 m/s – 15m/s– Proxying group of size 10 with one content source– Content consumer sends interest packets at the rate of 4
packets per one round– The minimum and maximum route refresh intervals are set to
1.5 seconds and 60 seconds– The direction that a mobile device travels is random (0 – 360
degrees)– Wireless router has a capacity of 10Mbps, pause time is
random– The size of CCN content segment is 4KB
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Performance evaluation model
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Delivery Radio
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As speed increases, the routing effectiveness of basic CCN degrades rapidly compared to proxy CCN
Traffic overhead at mobile CCN device
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The measures for the basic CCN gradually increase with mobility speed
The number for proxy CCN remains relatively constant regardless of speed
Download complete time
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When node speed varies, the proposed scheme remains quite stableand always better than the basic CCN scheme
Impact of CCN proxy on energy consumption
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Proxy CCN shows less energy consumption than basic CCN
Conclusion
• This paper shows the frequent network change of a mobile consumer device causes bad performance in CCN
• The proposed proxy-based CCN scheme solved above issue– Prevent unnecessary packet transmission at the
previous location during handover of a mobile consumer device
– Save energy consumption by reducing repeated transmission of interest packets
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