Content-based Routing for Information Centric Networks

1. Content-based Routing for Information Centric Networks D. Reininger ECE 544 Spring 2014

2. Introduction • Apart from routing protocols that use a direct identifier of nodes, networking can take place based directly on content. • Content can be collected from the network, processed in the network, and stored in the network • Goal is to provide a network infrastructure capable of providing services better suited to today’s application requirements: • content distribution & mobility • more resilience to disruption and failures • We look next at such content-based networking and data aggregation mechanisms.

3. Networking Evolution • Traditional networking • Host-centric communications addressing end-points • Information-centric networking • Data-centric communications addressing information (e.g., data in context). • Decoupling in space – neither sender nor receiver need to know their partner. • Decoupling in time – “answer” not necessarily directly triggered by “question”, asynchronous communication.

4. Information-centric Networking • Approach • Named Data Objects (NDOs) • in-network caching • multi-party communication through replication • decoupled senders from receivers • Architectural questions • How do we address information? • How do we obtain information? • How do we route information?

5. ICN Communication Model Chart notes describe the information exchange.

6.  Dissemination networking • Data is request by name, using any and all means available (IP, VPN tunnels, multicast, proxies, etc). • Anything that hears the request and has a valid copy of the data can respond. • The returned data is signed, and optionally secured, so its integrity & association with name can be validated (data centric security)

7. ICN Stack • Change of network abstraction from “named host” to “named content” • Security built-in: secures content and not the hosts • Mobility is present by design • Can handle static as well as dynamic content • Use of 2 messages: Interest and Data Objects Van Jacobson, et al, Networking Named Content, CoNEXT2009

8. Universal? • Any architecture that runs over anything is an overlay (IP is an overlay). • IP started as a phone system overlay; today much of the phone system is an IP overlay. System theorists would say ‘IP is universal’. • ICN has the same character: it can run over anything, including IP, and anything can run over ICN, including IP. • And ICN has a simpler, more general relationship with lower layers than IP.

9. Example: Content Distribution

10. Example: Content Distribution

11. Example: Content Distribution

12. Example: Content Distribution

13. Example • Content goes only where there’s interest. • It takes at most one trip across any link. • Average latency is minimized. • Total bandwidth is minimized. • There’s no routing or control traffic associated with the replicas.

14. Approaches • Content Centric Networks • Naming: Hierarchical naming, single address • Security: Signed content • Routing: Longest prefix matching • Caching: Local or network based • Content existence knowledge: Not part of the CCN core • Producer-consumer meeting: Propagation of interests • Network of Information • Naming: Flat naming • Security: Signed content • Routing: (1) Name resolution (2) Information transfer • Caching: Network based • Content existence knowledge: Through name resolution service • Producer-consumer meeting: Name resolution service provide locations

15. Approaches • Publish Subscribe Internet Routing Paradigm • Naming: Multi-level identifiers • Security: Signed content • Routing: (1) Name resolution (2) Information transfer • Caching: Network based • Content existence knowledge: Registrations in Rendezvous system • Producer-consumer meeting: Rendezvous system provides location • Data Oriented Networking Architecture • Naming: Flat naming • Security: Signed content • Routing: Queries are resolved to locations • Caching: Network based • Content existence knowledge: Through resolution infrastructure • Producer-consumer meeting: Resolution infrastructure provides location

16. Naming • Solution 1: Name the data • Flat, not human readable identifiers • 1DB76EB8DFD6B0b92A293AADC8421830BDE73CB6 • Hierarchical, meaningful structured names • /nytimes/sport/baseball/mets/game022414/ • Solution 2: Describe the data • With a set of tags • baseball, new york, mets • With a schema that defines attributes, values and relations among attributes

17. Using Names in CCN • The hierarchical structure is used to do ‘longest match’ lookups (similar to IP prefix lookups) which helps guarantee log(n) state scaling for globally accessible data. • Although CCN names are longer than IP identifiers, their explicit structure allows lookups as efficient as IP’s.(see hashing work by RasmusPagh and Martin Dietzfelbinger)

18. Routing • Three general approaches • Name Resolution Routing (NRR) • Content-based Routing (CBR) • Name-based routing (NBR) • Two phases • Routing of NDO requests • Routing of NDO back to the requester

19. Name-Based Routing • Client asks for a data object sending interest packets which are routed toward the publisher of the name prefix using longest-prefix matching in the forwarding information base (FIB) of each node. • The FIB is built using routing protocols of the Internet. • When a note receives multiple requests for the same NDO, only the first is forwarded to the source. • When a copy of the data object is encountered on the path, a data packet containing the requested object is sent on the reverse path back to the client and all nodes along the path cache a copy.

20. Content Centric Network (CCN) Chart notes describe numbered steps

21. CCN packets There are two CCN packet types: interest (similar to http “get”) and data (similar to http response). Both are encoded in an efficient binary XML.

22. CCN node model Get /parc.com/videos/WidgetA.mpg/v3/s2

23. Publish-Subscribe Internet Routing Paradigm (PSIRP) Chart notes describe numbered steps

24. Content-based Publish-Subscribe Routing

25. Content-based Pub/Sub Routing

26. Content-based Pub-Sub Routing

27. Forwarding on Bloomed link ids • The FI encodes the network links (rather than the nodes) on the path of interest between the producer and consumers • FI is encoded in a probabilistic data structure called a Bloom filter that routers use for selecting interfaces on which to forward an NDO. • Bloom filters encode source route-style forwarding information into packet headers, enabling forwarding without depending on end-to-end addressing. • Routers do not need to keep forwarding state. Forwarding decisions are simple and forwarding tables are small, potentially allowing faster, smaller, and more energy-efficient switches. • The use of Bloom filters result in a certain number of false positives; in this case this means forwarding on some interfaces where there are no receivers.

28. Pub/Sub Routing using Link ID and FI zFilter: FI Bloom Filter See chart notes for further description

29. Network of Information

30. Name Resolution Routing • Use a Name Resolution Service (NRS) that stores the bindings from object names to topology-based locators pointing to corresponding storage locations in the network. • Three conceptual routing phases: • Routing the request message to the responsible NRS node where the object name is translated into one or multiple source addresses • Routing the request message to the source address(es) • Routing the data from the source(s) to the requester. • All phases can potentially use different routing algorithms. • A name-based routing method might be used for the first phase. • The second and third phases might use a topology-based routing like IP. • There are multiple alternatives to loosely or tightly integrate the phases in an ICN architecture.

31. Summary of characteristics of the ICN approaches

32. Content-Based Security • Name-content mapping verification via per-data packet signature • Data packet is authenticated with digital signature ICN trust establishment by associating content namespaces w/ public keys

33. Basic ICN forwarding • Consumer ‘broadcasts’ an ‘interest’ over any & all available communications media: get ‘/rutgers/ECE544/Lecture06-14.pdf’ • Interest identifies a collection of data - all data items whose name has the interest as a prefix. • Anything that hears the interest and has an element of the collection can respond with that data: HereIs ‘/rutgers/ECE544/presentation.pdf/p1’ <data>

34. Basic ICN transport • Data that matches an interest ‘consumes’ it. • Interest must be re-expressed to get new data. (Controlling the re-expression allows for traffic management and environmental adaptation.) • Multiple (distinct) interests in same collection may be expressed (similar to TCP window).

35. Caching • Storage for caching NDOs is an integral part of the ICN service. • All nodes potentially have caches; requests for NDOs can be satisfied by any node holding a copy in the cache. • ICN combines caching at the network edge as in P2P and other overlay networks with in-network caching (e.g., transparent web caches)

36. Advantages of the ICN approach • Scalable and cost-efficient content distribution • IP traffic to quadruple from 2010 – 2015 • Mobile data traffic increased 26x • Mostly attributed to media traffic that continues to be 90% of global consumer traffic by 2015

37. Issues • Scalability • Privacy (interest subscription and content description) • Legal (caching NDOs) • Business case for deployment

38. References • A Survey of Information-Centric Networking, B. Ahlgren, et. al. IEEE Communications Magazine, July 2012, http://itec.hust.edu.cn/~jwchen/courses/compnet2013/references/A%20Survey%20of%20Information-Centric%20Networking-CommMag-ADI+12.pdf • A Survey of Information-Centric Networking Research, G. Xylomenos, et. al., Published in IEEE Communications Surveys and Tutorials • Is Information-Centric Multi-Tree Routing Feasible? ICN Workshop 2013, M. Papalini et. al. • LIPSIN: Line Speed Publish/Subscribe Inter-Networking, Petri Jokela, et.al. • Information-Centric Networking: Seeing the Forest for the Trees, Ali Ghodsi, Scott Shenker, et.al. • Bloom Filters • http://billmill.org/bloomfilter-tutorial/ • http://en.wikipedia.org/wiki/Bloom_filter#Examples • A Multi-Level DHT Routing Framework with Aggregation, H. Liu et. al, http://conferences.sigcomm.org/sigcomm/2012/paper/icn/p43.pdf