Add acn

docs/lectures/acn/08_content_centric_networks.md

@@ -0,0 +1,96 @@
+# Content Centric Networks
+
+A Brief History of Networking
+
+- Gen 1. The **phone system** (focus on the **wires**)
+  - The utility of the system depends on running wires to every home & office.
+  - Wires are the dominant cost.
+  - A *call* is not the conversation, its the **PATH** between two end-office line cards.
+  - A *phone number* is not the name/address of the caller, its a **program** for the end-office switch fabric to build a path to the destination line card.
+  - <img src="/lectures/acn/img/k.png" alt="switch board" style="zoom:50%;" />
+  - Path building is **non-local** and **encourages centralisation** and **monopoly**.
+  - Calls fail is any element in the path fails so reliability goes down exponentially as the system scales up.
+  - Data cannot flow until the path is set up so efficiency decreases with setup time.
+
+- Gen 2. The **Internet** (focus on the **endpoints**)
+  - Data sent in independent chunks and each chunk contains the name of the final destination.
+  - Nodes forward packets onward using routing tables.
+  - **ARPAnet** was built on top of the existing phone system.
+
+- Gen 3. **dissemination** (focus on the **data**)
+
+#### TCP/IP
+
+###### Pros
+
+- Adaptive routing lets system **repair failures**
+- **Reliability increases exponentially** with **system size**.
+- **No call setup** means **high efficiency** at any bandwidth and scale.
+- Distributed routing supports any topology and tends to spread load and avoid a hierarchy's hot spots.
+
+###### Cons
+
+- *Connected* is a binary attribute. 
+- Becoming part of the internet requires a globally unique, globally know IP address that's topologically stable on routing time scales.
+  - Connecting is a heavy weight operation
+  - The net struggles with moving nodes
+
+#### Conversation and Dissemination
+
+Acquiring chunks of data (web pages, emails, videos etc) is not a conversation, it's *dissemination*.
+
+In a dissemination **the data matters**, not the supplier.
+
+- Data is request by name.
+- Anything that hears the request, and has a valid copy can respond.
+- The return data is signed, so integrity and association can be validated.
+
+CCN can run over and be run over anything e.g. IP.
+
+#### CCN Packets
+
+![img](/lectures/acn/img/l.png)
+
+**Interest** - similar to HTTP `GET`
+
+**Data** - similar to HTTP response
+
+#### Content Based Security
+
+Data packets are authenticated with digital signatures.
+
+![img](/lectures/acn/img/m.png)
+
+#### CCN Forwarding
+
+Consumer *broadcasts* and *interest* over all available communication media
+
+- e.g. `get '/parc.com/van/presentation.pdf'`
+- response: `heres '/parc.com/van/presentation.pdf/p1' <data>`
+
+##### Names and Meaning
+
+* Like IP, CCN nodes imposes no semantics on names
+* Meaning comes from **application**, **institution** and **global conventions** reflected in prefix forwarding rules.
+* Globally meaningful name leveraging the DNS global naming structure
+  * `/parc.com/van/presentation.pdf`
+* Local and context sensitive, it refers to different objects depending on the room you're in.
+  * `/thisRoom/projector`
+
+#### Strategy Layer
+
+* When you do not care who you are talking to, you don't care if they change
+* When you are not having a conversation, there's no need to migrate conversation state.
+* Multi-point gives you multi-interface for free.
+* When all communication is locally flow balanced, your stack knows exactly whats working and how well.
+
+In the current Internet, Quality of Service (QoS) Problems are highly localised
+
+* Roughly half the problems are from serial dependencies created by queues
+* The other half are caused from a lack of receiver based control over bottle-necked links.
+
+Unlike IP, CCN is **local**, don't have queues and receivers have complete control
+
+![img](/lectures/acn/img/n.png)
+
+Tree serves as transport state