Add acn

docs/lectures/acn/07_information_centric_networks.md

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+# Information Centric Networks
+
+#### Problems with today's Networks
+
+* URLs and IP addresses are overloaded with locator and identifier functionality.
+* No consistent way to keep track of *identical copies*.
+* Information dissemination is inefficient.
+  * Cannot benefit from existing copies
+  * Can lead to problems like Flash-Crowd effect and Denial of service
+* Can't trust a copy received from an un-trusted node
+  * Security is host-Centric
+  * Based on *securing channels* (encryption) and trusting servers (authentication)
+* Application and content providers are independent of each other
+  * CDNs focus on web content distributions for major players
+
+![img](/lectures/acn/img/i.png)
+
+**Important requirements for ICNs** (Information Centric Networks)
+
+1. Accessing named resources - not hosts
+2. Scalable distribution through replication and caching
+3. Good control of resolution / routing and access
+
+## Content-based Routing for ICNs
+
+Apart from routing protocols that use direct identifiers 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.
+* The goal is to provide a network infrastructure capable of providing services better suited to today's application requirements
+  * Content distribution and mobility
+  * More resilience to disruption and failures
+
+#### Network Evolution
+
+**Traditional networking**
+
+- Host-Centric communications, addressing and end-points
+
+**ICNs**
+
+- Data-Centric communications addressing information
+- Decoupling in space - neither sender nor receiver need to know their partner.
+- Decoupling in time - *answer* not necessarily directly triggered by a *question*. **asynchronous communication**.
+
+#### Approach
+
+* Named Data Objects (NDOs)
+* In-network caching/storage
+* Multi-party communication through replication
+* Senders decoupled from receivers
+
+### Dissemination Networking
+
+* Data is requested by name, using any and all means available (IP, VPN tunnels, multi-cast, 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)
+
+![ICN Stack](img/j.png)
+
+* Change of network abstraction from **named host** to **named content** (content chunks).
+* Security is built in - **secures content** and **not the hosts**.
+* **Mobility** is present by design.
+* Can handle **static** and **dynamic** content.
+
+#### Naming Data
+
+###### Solution 1 - Name the data
+
+- **Flat** - non human readable identifiers
+  - `1HJKRH535KJH252JLH3424JLBNL`
+- **Hierarchical** - meaningful structured names
+  - `/nytimes/sport/baseball/mets/game0224143`
+
+###### Solution 2 - Describe the data
+
+- With a set of tags
+  - `baseball, new york, mets`
+- With schema that defines attributes, values and relations among attributes
+
+##### Using Names in CCNs (Content Centric Networks)
+
+- The hierarchical structure is used to do *longest match look-ups* which guarantees $$log(n)$$ state scaling for globally accessible data.
+- Although CCN names are longer than IP identifiers, their **explicit structure** allows look-ups as efficient as IP's.
+
+### ICN Forwarding
+
+* Consumer *broadcasts* and *interest* over all available communication media
+* Interest identifies a *collection of data* whose name has the interest as a prefex.
+* Anything that hears the interest and has an element of the collection can respond with that data.
+
+### ICN Transport
+
+* Data that matches an interest, *consumes* it.
+* Interest must be re-expressed to get new data.
+  * Controlling re-expressions allows for traffic management and congestion control.
+* Multiple (distinct) interests in the same collection may be expressed 
+
+### ICN Caching
+
+* Storage and caching are integral part of the ICN service
+* All nodes potentially have caches. Requests for data can be satisfied by any node holding a copy in it's cache.
+* ICN combines caching at the network edge with in-network caching.