Content Centric Networking in Tactical and

Emergency MANETsSoon Y. Oh, Davide Lau, and Mario Gerla

Computer Science DepartmentUniversity of California, Los Angeles{soonoh, chiume, gerla}@cs.ucla.edu

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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

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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?

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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

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WiCCN protocol design goals

Hierarchical storage/search architecture

Topic based data vs spatial/temporal contents

Cross-layer approach

Scalable and resource aware

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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

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WiCCN Network Model Group based mobility Hierarchical topology Interconnection via gateways Heterogeneous devices – different capacities

Soldier System

Airborne Network

Wideband Network

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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 PUSHED by publisher towards command center or proper

location

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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

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WiCCN Routing Content Pushing

Spatial/temporal content Geo-routing to command center or other destination

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WiCCN Routing (Cont.) Content Pulling

Using an Interest packet and local storages

Content Repository

Meta-Data Registry

Interest Table

Interest

1. Check Content Repository and send data if it exists2. If there is no content, check Meta-Data Repository3. If Meta-Data entry exist, a node relays Interest toward data origin4. Otherwise, Interest is passed to a Gateway toward upper level

Interest

5. Interest is relayed

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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

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Packet Collision Avoidance

Interest

REPLY

REPLY

REQUEST

Content

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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

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Implementation Implement WiCCN on 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

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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

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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

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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 WiCCN experience same delay in peer to peer transmissions

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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 WiCCN node A transmits only once;

cached data, at an intermediate node, is transmitted

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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

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