Content-Centric Networking (CCN)
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Content-Centric Networking (CCN) is a new approach that moves from addressing end systems to naming content directly. This allows content to be cached within the network close to consumers for improved performance and reduces traffic by satisfying multiple requests from the same cached copy. CCN uses hierarchical content names, in-network caching, and interest and data packet types to enable content retrieval and routing. The architecture has in-network caching, no routing loops, and built-in security features to authenticate content.
Content-Centric Networking (CCN)
- 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? 2
- 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 3
- 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 4
- 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 5
- 6. CCN Applications Content Delivery Networks (CDN) Streaming IPTV, Video on Demand (VoD) VoIP, teleconferencing Gathering sensor data & streaming Controlling actuators Light control 6
- 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 7
- 8. Architecture Bits are bits whether they are in routers, wires, or disks 8
- 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
- 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/ 11
- 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 12 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 13
- 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 15
- 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 16
Editor's Notes
- #6: NSP – Network access point
- #8: Motes without IP support IP routes are not symetric
- #9: Strategy layer define – forwarding preferences, which face to select based on performance, retransmission after loss, window size
- #11: Local names are also possible
- #13: PIT – suppress duplicate packets
- #14: A1 – less skewed A2 – More skewed
- #15: 1 circle – IP routers 2 circles – IP + CCN routers