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Keynote IFIP/ACM Latin America Networking Conference 2012, Medellin, Colombia
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IFIP/ACM LANC 20127th Latin America Networking Conference
Information-Centric Networking in Wireless/Mobile Networks
Torsten Braun, Universität Bern, [email protected], cds.unibe.ch
Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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Overview
> Future Internet> Information-Centric Networking (ICN)
— ICN Approaches, e.g., CCN and PSI— Service-Centric Networking — ICN and Cloud Computing
> ICN in Wireless / Mobile Networks— Mobility— Delay/Disruption-Tolerant and Opportunistic Networks— Network Coding and Energy Efficiency
> Conclusions
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Future Internet
> The current Internet is based on principles of the 1960s with the main purpose to interconnect large computers.
> Today, Internet users are mainly interestedin retrieving content and accessing serviceswith increasing demand for mobility&security
> Increasing bandwidth demand due to— (personalized) multimedia data streams— Cloud computing and storage,
visualization on (mobile / high-resolution) end systems— Huge amounts of data from measurements and scientific
experiments— Internet of Things, Internet of Services, …
> New approaches, e.g., Information-Centric Networking, need more research, development, testing etc.
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Motivation for Information-Centric Networking
> Today’s network traffic is dominated by information retrieval rather than point-to-point communication between machines or humans.
> Circuit communication model is not considered as appropriate any more.
> Future communication architecture should focus on information objects instead of nodes.
> Today, wires and memories solve complimentary aspects of the same problem:— Wires move information in space.— Memories move information in time.
> Future communications architecture should unify both issues.> Flash crowds are difficult to avoid in IP-based networks.
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Traditional Web Retrieval / Web Services
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web server / web service
DNS server
search engine /service registry
user’s end system
Key Principles and Functions of ICN
> Naming of content rather than hosts/interfaces— Content independent of devices that store it— Naming is location independent (mobility support !)
> Receivers (subscribers) request content.> Senders (publishers) advertise and deliver content.> Receivers and senders do not have to be aware of each
other and are decoupled in time.> Functions needed
— Name resolution to match subscriptions and publications— Routing and path formation— Forwarding content from publisher to subscriber
[Pentikousis, K.; Chemouil, P.; Nichols, K.; Pavlou, G.; Massey, D.; "Information-centric networking [Guest editorial]", IEEE Communications Magazine, vol.50, no.7, pp.22-25, July 2012
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Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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Content Distribution with ICN
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/unibe.ch/braun/lecture/20120405
1
32
4 5 76
Naming Approaches
> Human-readable, hierarchical names— supports aggregation— needs coordination— Example: CCN
> Flat (self-certifying) names— Often based on hashing content name and/or owner’s public key— Aggregation more difficult but more flexible. — Examples: PSI, NetInf
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Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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Name Resolution and Data Transport
> Decoupled— Name resolution and data transport are independent of each
other, cf. DNS, with possibly different nodes for resolution and data transport
— allows different, possibly already existing transport mechanisms, also multi-path
— Examples: PSI, NetInf> Coupled
— Nodes for both name resolution and data transport with inverse data path compared to search path
— rather disruptive technology— Local routing procedures advantageous in case of short link
disruptions— Examples: CCN, NetInf
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Content-Centric Networking (CCN)
> Combination of content lookup and message routing> Idea: describe the user’s interests in the message header,
but not where to get it. > Messages (using XML encoding)
— Interest: content name, selector— Data: content name, signature (info), data
> Hierarchical content names— Example: /unibe.ch/braun/lecture/20120405
> Related Projects— NDN = Named Data Networking, www.named-data.net — CCNx = Open Source Core Software Project for
Content-Centric Networking, www.ccnx.orgVan Jacobson, Diana K. Smetters, James D. Thornton, Michael F. Plass, Nicholas H. Briggs, and Rebecca L. Braynard: Networking named content, 5th international conference on Emerging networking experiments and technologies (CoNEXT '09). ACM, New York, NY, USA, 1-12.
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IP Model
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FIB
FIB: Forwarding Information Base
SRC
DST
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Interest Message Processing in CCN
1. Longest prefix match on content name in Content Store: returning data and discarding Interest
2. Pending Interest Table match: adding request to PIT and discarding Interest
3. Forwarding Information Base match: forwarding of Interest towards data— FIB population by announcements of content availability
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Match in Content Store
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FIB
CS: Content StoreFIB: Forwarding Information BasePIT: Pending Interest Table
Name
CS
Name
Data
Data
Name
PIT
Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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Match in Forwarding Information Base
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FIBCS
Name
PIT
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Match in Pending Interest Table
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FIBCS
Name
PIT
x
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CCN Naming
> Hierarchical naming allowing aggregation> Examples
— /unibe.ch/braun/lecture/20120405— /unibe.ch/N10/R306/Projector
> Support for simple operations— %C1.org.ccnx.frobnicate~1~37— command in the namespace org.ccnx— operation is frobnicate, which takes 1 and 37 as arguments
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IP / CCN Hour-Glass Models
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WWW, email, VoiP
HTTP, SMTP, RTP
TCP, UDP
IP
Ethernet, WiFi
Fiber, radio, copper
browser, chat
file, stream
security
contentchunks
TCP, P2P, Broadcast
Fiber, radio, copper
Strategy
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CCN Routing
> Longest Prefix Match Routing (as in IP)> FIB entries should be populated proactively for known content.> Alternatively, searching for content, e.g., using flooding
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CCN Transport
> Stateless operation with receiver control> Reliability by local retransmissions in strategy layer> Hop-by-hop flow control> Sequence numbers in names
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CCN Security
> Signing of names and data in each packet> Denial-of-Service attacks are difficult:
Multiple Interests → only 1 data packet per Interest
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Torsten Braun: Information-Centric Networking in Wireless/Mobile Networks
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CCN Evaluation
> Advantages— Automatic content distribution— < 1 round-trip-time— Minimization of latency— Minimization of bandwidth— Local congestion control— Built-in security
> Challenges— Routing protocols— Hierarchical naming— Source mobility
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Publish-Subscribe Internet (PSI) Naming
> Information items = files, streams, services> Each information item has its own name. > Names are unique (SID,RID) pairs
— Rendezvous Identifier (RID)– Fixed-length, (flat) bit string– produced by application
specific function, e.g., hashing
— Scope Identifier (SID)– Containers for information
items– Basis for access control
> Scope hierarchy with information belonging to different scopes.> www.fp7-pursuit.eu
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SId1 SId2
SId1 SId1 SId2
SId3
RId1 RId2 RId3
RId1 RId2 RId3RId4
RId3
PSI Network Primitives
> Subscribe— used to express interest in information items— Users can subscribe to information items or scopes.
(SID/RID) must be known. > Publish
— used to announce information items— sent if information items have been requested
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PSI Operation
> Information producer publishes information item to rendezvous system consisting of rendezvous points.
> Rendezvous points are responsible for certain scopes.> Information consumer subscribes to information item.> Rendezvous system matches announcements and subscriptions
and triggers delivery from information producer to information consumer, e.g. using OpenFlow
> Various caching strategies: on-path, off-path, replication
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publication
subscription
path establishment
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Service-Centric Networking (SCN)
> ICN/CCN is content-centric and encodes a few operations on content as extensions of names.
> Proposal: Service-Centric Networking— Extension of content-centric networking to support services,
possibly operating on content. — Description of a service using content naming scheme,
e.g., /google.com/file-service— Service request (response) in Interest (Data) message
> Services— Infrastructure services, e.g., cloud computing services— Client-oriented services, e.g., web services— Continuous content retrieval and streaming services,
e.g., A/V conferencing, streaming— Event services, e.g., exceeding sensor data thresholds or stock data— In-network services, e.g., aggregation and filtering of sensor data
Braun, T.; Hilt, V.; Hofmann, M.; Rimac, I.; Steiner, M.; Varvello, M.: Service-Centric Networking, 2011 IEEE International Conference on Communications Workshops (ICC), pp.1-6, Kyoto, 5-9 June 2011Medellin, October 5, 2012
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Service-Centric Network
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Service request/response
SCN routerSCN network
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Advantages of SCN
> No service lookup and service registry
> Caching of service data
> Extended caching of multimedia data (transcoding)
> Location-based services
> Optimized service selection
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Uniform Naming for Services (Functions) and Content (Data)
> Services perform (data) processing and are represented by functions to be invoked. Content stores for data.
> Service-centric networking should support both data and functions.> Object-orientated programming paradigm integrates
both functions and data into objects. Method calls among objects to invoke functions.
> Proposal: Object names for both services (functions) and content (data), e.g., — /youtube.com/rendering — /unibe.ch/braun/lecture/20120405
> Advantages of object-oriented approach— Uniform naming— Services can be implemented as a set of cooperating objects
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SCN Object Types
contentdata
read
1: Content Object 2: Service Object
contentdata
read
3: Content/Service Object
function3function1
function2
function1
function2
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Example: Video Rendering
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render
video-file1
read
client
video-file2
read
video-file3
read writewritewrite
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Example: Real-time Audio Conferencing
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Echo cancellation
Trans-coding
Sent audio data
Received audio data
Mixing
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SCN Prototype Evaluation
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user1
ccnd1
client1
user2
ccnd2
client2 ccndrconversion service & repository
CCN router
ccndp
publisher
1/8
2/711/12
3
5
6
4
13/14
18/19
10
159
16
17/20
1-8 9-16 17-200
20406080
100120140160180200
186 31 4
time [s]
1-8: Client 1 retrieves bit map image (40 MB)9-16: Client 2 retrieves JPEG image17-20: Client 1 retrieves JPEG image
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ICN and Cloud Computing
> ICN might be used to— find/call cloud services (computation, storage)— deploy cloud services— support caching of cloud data
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Upcoming EU FP7 Integrated Project: Mobile Cloud Network
> Integration of— Radio Access Network— Mobile Core Network— Data Centre (computing, storage, applications)
into (decentralized) cloud computing infrastructure (management!)> Advantages: elasticity, costs, performance, e.g., by
exploitation of user location for service provisioning → Follow Me Cloud
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MobileCloudNetwork Architecture
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Benefits of ICN in Wireless/Mobile Networks
> Broadcast property of wireless medium → single Interest to many neighbor nodes
> No beaconing required to learn about neighbor nodes> Reduced delay and network load due to possible caching> Request/Response based routing in mobile ad-hoc networks
(MANETs) could be replaced by Interest/Data exchange, cf. Directed Diffusion
> Support of short mobile nodes’ encounters> ICN architectures inherently support receiver mobility !
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Source Mobility
> Problem— Finding a source’s location at the beginning of and when source is moving during
communication. > Solutions
— Routing-based approaches– (Proactive) updating of routing tables in case of moving sources
→ issues on scalability and convergence
— Indirection – (Home) agent forwards all Content Requests to mobile source, cf. Mobile IP.– This requires location-based identifiers, cf. location/identity separation.
— Resolution– Receiver requests location-based identifier for a content name specified in a Content Request. – Approach adds resolution phase and requires resolution entities in visited networks.
> Conclusions and Suggestions— Both content names and locators might be needed to efficiently support ICN source
mobility. — Flexible use of content names / locators — Possibly late binding of content names and locators
Vasilios Siris:, Torsten Braun: Content-Centric Networking Architectures for Moving Objects, COST Action IC0906, STSM Report, 2012, http://cost-winemo.org/ Medellin, October 5, 2012
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CCN in Delay/Disruption-Tolerant (DTN) and Opportunistic Networks
Name Origin of Interest
Data
/feeds.sf.tv/podcast/10vor10 me -
/youtube.com/movies/ DesperateHousewives
mydaughter -
… … …
/unibe.ch/braun/lecture/ OperatingSystems
me,mystudent
os.mpg
… … …
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Encounter
Possible message exchange at encounter1. Exchange of interests, possibly with priority of own / friends’ interests2. Exchange of relevant data
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Content-Centric Networks and DTN/Opportunistic Networks
> Content-Centric Networks and Delay/Disruption-Tolerant Networks seem to be a good match. — No needs for beacons and neighbour lists— Exploitation of wireless broadcast media— Efficient exchange of Interests and Data
> Publish / Subscribe approaches might be less beneficial here.
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Network Coding and CCN
> Regular case: — 4 Interests + 4 Data
messages> Network Coding:
— 3 Interests + 3 Data messages
> Problem: Naming> Proposal: Encapsulation
Alexander Striffeler: Network Coding in mobile CCN, Bachelor Thesis at Universität Bern
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Interest A
Interest B
Interest A B
Data A
Data B
Data A B
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Network Coding of CCN Data Messages
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Energy Efficiency and CCN
> ICN can reduce packet transmissions on links> This comes at the expense of additional memory needed in
caches. > Assumptions for power usage
— DRAM: 3 W/GB — Hard disk: 0.02 W/GB— SSD: 0.01 W/GB— Energy for transmission: 15 W/Gbps = 15 Joules/Gigabit
> Analytical evaluation in example scenarios, options— no CCN support at all — CCN support in CCN router
Tuan Anh Trinh, Torsten Braun: Energy Efficiency in Information-Centric Networking, COST Action IC0804, STSM Report, 2012, http://www.irit.fr/cost804/
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Example Scenario
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Energy Efficiency and CCN
> Required energy for serving K requests from original content source: Eread_from_source = K * N * link_energy * datasize.
> Required energy for serving request from cache:Eread_from_cache = K * M * link_energy * datasize + lifetime_in_cache * storage_power * datasize
> ICN can help to decrease energy costs, if Eread_from_cache < Eread_from_source
→ (N - M) * link_energy / storage_power > lifetime_in_cache / K— lifetime_in_cache: lifetime a content object is usually stored in the cache— storage_power: power required to store a certain amount of data— link_energy: energy to transport a certain amount of data across a link
> lifetime_in_cache / K = inter_access_time (avg. time between two content accesses)> access frequency f = 1/inter_access_time→ f > storage_power / ((N-M) * link_energy)
> Example— Link energy = 15 Joules / Gigabit = 120 Joules / GB— Storage power = 3 W/GB for storage in DRAM— M = 1, N = 11— ICN only reduces energy consumption if f > (3 W / GB) / ((11-1) * (120 Joules / GB)) = 1 / 400 sMedellin, October 5, 2012
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Conclusions
> Information-Centric Networking attracts huge research interest.
> ICN has potential to — save bandwidth— reduce delay— save energy— support receiver mobility— operate efficiently in wireless networks— support DTN and opportunistic networks
> Challenges— storage in routers— routing strategies— source mobility— more general services
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Thank You for Your Attention !
> [email protected] > http://cds.unibe.ch> http://www.slideshare.net/torstenbraun
Medellin, October 5, 2012