Proxy-assisted Content Sharing Using Content Centric Networking (CCN) for Resource-limited Mobile Consumer Devices Jihoon Lee, Dae Youb Kim IEEE Transactions on Consumer Electronics, Vol. 57, No. 2, May 2011 Hongbo Shi

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 2

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” 4

CCN Messages unique identifier a set of parameters random nonce value to prevent the packet from looping random nonce value to prevent the packet from looping 5

Content Name ‘/’ character represents delimiter between different components ‘/’ character represents delimiter between different components provides the global routing information contains the organizational routing information Describes the versioning and segmentation functionality 6

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 7

CCN Delivery 8 If the content data is found, then deliver data (jump to 10) Check PIT: If there is another Received request for the same content Check PIT: If there is another Received request for the same content If found, add the face If found, add the face Consume PIT entry : 1) replicated 2) sent out on all faces in the corresponding PIT entry Consume PIT entry : 1) replicated 2) sent out on all faces in the corresponding PIT entry Refer FIB: 1) determine the outgoing face 2) add entry to PIT Refer FIB: 1) determine the outgoing face 2) add entry to PIT

Send Interest 9 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 10 Hand Over Occurred Unnecessary data packets are transmitted to the old location 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 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 11

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 12

Proxy-based CCN content sharing 13

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 14

Proxy-assisted CCN Content Sharing Step1: Mobile device sends content request message to proxy node Step 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 16

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 17

Interest packet at proxy CCN device 18

Modified content data at proxy CCN device during handover 19

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 20 Mobile device waits subsequent content data segments without using additional CCN interest packets Mobile device waits subsequent content data segments without using additional CCN interest packets New proxy utilizes the modified CCN interest to reduce the control overhead during the delivery of the cached content data New proxy utilizes the modified CCN interest to reduce the control overhead during the delivery of the cached content data

Two-path delivery in proxy change case 21 Two simultaneous paths for receiving the requested content data 1) indirect path, the previous proxy node 2) direct path, the new proxy node Two simultaneous paths for receiving the requested content data 1) indirect path, the previous proxy node 2) 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 22

Performance evaluation model 23

Delivery Radio 24 As speed increases, the routing effectiveness of basic CCN degrades rapidly compared to proxy CCN As speed increases, the routing effectiveness of basic CCN degrades rapidly compared to proxy CCN

Traffic overhead at mobile CCN device 25 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 26 When node speed varies, the proposed scheme remains quite stable and always better than the basic CCN scheme When node speed varies, the proposed scheme remains quite stable and always better than the basic CCN scheme

Impact of CCN proxy on energy consumption 27 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 28