Content Centric Networking in Tactical and Emergency MANETs

1. Content Centric Networking in Tactical and Emergency MANETs Soon Y. Oh, Davide Lau, and Mario Gerla Computer Science Department University of California, Los Angeles {soonoh, chiume, gerla}@cs.ucla.edu

2. Introduction • Infrastructureless nature and quick deployment  a MANET is ideally suited for emergency & tactical operation, but • Challenging environments • Lossy channel and high mobility • Limited resources • Hard to find necessary content • No search engine • Scalable & efficient content search and dissemination in MANETs  Content Centric Networking

3. Content Centric Networking (CCN) • Users are interested in WHAT content – not WHERE it is or WHO has it • Data is addressed by name or content – rather than by location or IP address • No overhead in binding name to location • Enabled by low storage prices and high speed links Can CCN be directly applied to MANET environment?

4. WiCCN = CCN in MANETs • Advantages • Group based mobility/operation • resource sharing within group • Hierarchical data structure • Information locality (via Cache) • Challenges • Lossy channel and resource shortage • Data Push and Pull is required while Internet CCN is only Pull • Must Push Critical information and operation messages • Security and content authentication • Critical data and wireless broadcast medium Content Centric Networking

5. WiCCN protocol design goals • Hierarchical storage/search architecture • Topic based data vs spatial/temporal contents • Cross-layer approach • Scalable and resource aware

6. Related Work • TRIAD (2000) • User-friendly, structured, with location-independent names and content addressing (has influenced later protocols) • Data-Oriented (and beyond) Network Architecture (DONA) (2007) • Flat, self-certifying names instead of IP addresses and DNS • Contents is published and registered with a tree of trusted Resolution Handlers (RH) • Routing on Flat Levels (ROFL) (2006) • Semantic-free flat labels; it creates a circular namespace, e.g., DHT • Content Centric Network (CCN) (2009) • Network wide content caching and user-friendly, hierarchical names for routing; Digital signature for security • Named Data Networks (NDN) (2010) • Future Internet Architecture

7. Airborne Network Wideband Network Soldier System WiCCN Network Model • Group based mobility • Hierarchical topology • Interconnection via gateways • Heterogeneous devices – different capacities

8. WiCCN Content Types • Topic based content • Data files, video and audio clips • Data is stored at publisher (originator) or near backbone nodes and travels anywhere in the network • PULLED by users • No location and time sensitivity • Spatial/temporal content • Situation awareness data; operational messages • Content value is time and location sensitive • Pushedby publisher towards command center or proper location

9. Local Storage • Content Repository • Intermediate nodes cache content • Maximize the probability of sharing • Meta-Data Registry • Hash table for efficient look up • It is used to forward Interest packet • Meta-Data includes content attributes, e.g., type, time, loc, etc • Interest Table • Stores Interest Query packets • To suppress duplicate Interest packets • To relay content to requestors Content Repository Meta-Data Registry Interest Table

10. WiCCN Routing • Content Pushing • Spatial/temporal content • Geo-routing to command center or other destination

11. WiCCN Routing (Cont.) • Content Pulling • Using an Interest packet and local storages 1. Check Content Repository and send data if it exists Content Repository 2. If there is no content, check Meta-Data Repository Interest 3. If Meta-Data entry exist, a node relays Interest toward data origin Meta-Data Registry Interest 4. Otherwise, Interest is passed to a Gateway toward upper level 5. Interest is relayed Interest Table

12. WiCCN Routing (Cont.) • Difference to Internet CCN (due to wireless common medium) • Interest aggregation • Time stagger re-broadcast Interest packets • Upon overhearing the same Interest, cancel the re-broadcast • Data Packet collision avoidance • If more than one neighbors tries to transmit • Exchange Request/Reply • Respond with Reply before transmitting data

13. Packet Collision Avoidance REPLY Content Interest REQUEST REPLY

14. Security and Authentication • Using PKI • A gateway has private key and members in the domain have public keys • A gateway adds digital signature using a private key • Members encrypt packets using the public key • The private and public keys are pre-assigned

15. Implementation • Implement WiCCNon Linux OS • A gateway and members • The gateway floods/updates meta-data • A node sends Interest • Request/Reply- exchange and data transmission • Run simple four node topology • Compare performance with peer-to-peer protocol, e.g., Pastry over OLSR

16. Pastry Overhead • Every 3s new data generated (no real data transmitted) • A gateway floods meta-data • Pastry 378B/s average overhead • Traffic suddenly increases to maintain a P2P ring structure • OLSR traffic in the background

17. WiCCN Overhead • Every 3s new data generated (no data transmission in this experiment) • A gateway floods meta-data • Pastry 72B/s average overhead • Only Meta-Data flooding

18. End-to-End Delay • From node A to node D in the 4 node chain topology • File size 1, 5, 10, 15, 20, 25, 100MB • Pastry and WiCCNexperience same delay in peer to peer transmissions

19. End-to-End Delay (Cont.) • From node A to all nodes in the previous 4 node topology • No broadcast; each node requests data at different time • WiCCN presents significant lower delay due to content caching • In Pastry, node A transmits 3 times, but WiCCNnode A transmits only once; cached data, at an intermediate node, is transmitted

20. Conclusion • WiCCN performs better than DHT based content sharing • Mainly due to caching • Future work: • Implement on smart phones • Experiment with mobility • Design cache strategies • Bigger testbed/emulator

21. Thanks!