1. Content-Centric
Networking (CCN)
CS4482 High Performance Networking
Dilum Bandara
Dilum.Bandara@uom.lk

2. Outline
 V. Jacobson, D. K. Smetters, J. D. Thornton, M.
Plass, N. Briggs, and R. Braynard, “Networking
Named Content,” In Proc ACM CoNext ‘09, Dec.
2009.
 What?
 Why?
 How?
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3. Motivation
 60’s & 70’s
 Internet was designed to
share resources
 2 end points talking to each
other
 Today
 Content is the key
 Location is irrelevant
 Content name  End point
 Use network to reach the
end point
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4. Motivation (Cont.)
 Issue – Traffic aggregation
 Scalability
 Availability
 Security
 Location dependent
 End is not the true end
 Solution is not wrong, problem
has changed
 CCN/NDN solution
 Hierarchy of warehouses
 Spatial & temporal locality
 Name & secure content
 Route using name
 Cache contents
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5. Incentives
 Content providers
 Lower traffic
 Better security, scalability,
performance
 Consumers
 Better QoS, QoE
 Free local access
 Edge & Tier 2/3 ISPs
 Reduce transit traffic
 Diminishing return from
caching at higher levels
 Tier 1 ISPs & routers close
to content providers
 Starve
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6. CCN Applications
 Content Delivery Networks (CDN)
 Streaming
 IPTV, Video on Demand (VoD)
 VoIP, teleconferencing
 Gathering sensor data & streaming
 Controlling actuators
 Light control
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7. CCN Features
 In-network caching
 Unicast, multicast, broadcast
 Flow control
 No routing loops – nonce
 Ability to name non-existing data
 Enable them to be routed to potential data sources
 Security
 Mobility
 Incremental deployment
 Route symmetry
 Performance measuring, security
 Fine grained control of FIB entries & policies
 No need for DNS
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8. Architecture
 Bits are bits whether they are in routers, wires,
or disks
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9. Packet Format
 Datagram packets
 XML-based packets
 Receiver driven communication
 An interest packet must be send to get a data packet
 Clocking, Window of interests, Flow control
 Use 1st interest packet to find segment names
 CCNx implementation 9

10. Naming Content
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11. Naming Content (Cont.)
 Unique names
 Binary or human readable
 Favor hierarchical names
 Large content is segmented
 Can invoke remote methods & pass data
 /seti.org/resources/update/check_status
 /seti.org/resources/update/node102/free_CPU_90
 Name unavailable contents
 /nws.org/radar9/data_x1_x2_y1_y2/
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12. Node Architecture
 All nodes have
same architecture
 Size of tables &
capabilities may vary
 Multiple faces
 CS – exact match
 4KB packets
 PIT – exact match
 4 sec timeout
 FIB – longest prefix
match
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PIT – downstream data path
FIB – upstream interest path
FIB – Forwarding information base

13. In-Network Caching
 ISPs
 Benefit from caching its transit traffic
 Can charge content providers to cache
 Different policies for content providers
 Varying cache sizes – static & dynamic
 Content provider can set cache validity
 Cache replacement policies
 IP routers – MRU replacement
 CCN routers – LRU or LFU replacement
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14. Routing & Policies
 IS-IS or OSPF can be used
to fill in FIB
 Control plane policies
 Prefix forwarding
 Multi-path routing
 Default route at edge routers
 Data plane policies
 Policies per FIB entry
 Advertise/block specific
prefixes
 Priorities for faces
 e.g., WiFi preferred
over 3G
 Cache access/sharing 14
Settlement-free peering
Consumer-provider
relationship

15. Security
 In current Internet we trust the server & not the content
 Content authentication – Digital signatures
 Content is secured, not its location
 Self-signing or hierarchical certificates
 Private content can be encrypted
 DoS/DDoS
 Hard to attack ends
 Don’t know where interest packet will be answered
 Interest /data flooding is limited to a link
 Drop packets without a matching PIT entry
 Routers can check whether interests are getting data
 Content provider can ask routers to block
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16. Issues
 Size of CS, PIT, & FIB
 CCN name not just a TV but its components
 Billions of domains, contents, & chunks
 State full routers
 Solutions – IP Tunneling, CCN interest tagged with IP
 Doesn’t support asynchronous communication
 1 message in IP  2/4 CCN messages
 Block m-to-1 communication
 No TTL  no constrained flooding
 Packets are not modified
 When should PIT time out?
 No clear boundaries
 Hard to separate issues in node architecture, naming, & security
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