Add the rest of university notes
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@@ -26,7 +26,7 @@ They have two parts: physical part and a social part
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Social structures are vital for these networks - think covid tracking networks
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Clouds have multiple layers
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@@ -57,11 +57,11 @@ This can be used to exchange warning and beacon messages via V2V (vehicle to veh
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### Fully autonomous Vehicles
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Vehicles can connect to the cloud and share & request information to help other vehicles.
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An example of transient clouds - in this case vehicular clouds.
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@@ -15,7 +15,7 @@ One of the core features of a MANET node is the ability to autonomously connect
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* Typically routing is split into **route discovery** and **actual data transmission**.
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* Nodes have to self organise in order to route.
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(green boxes is route chosen)
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@@ -43,7 +43,7 @@ The source has a limited range of nodes it can detect, it cannot send it direct
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Table showing all different protocols of MANETs
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### Delay/Disconnection Tolerance
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@@ -77,7 +77,7 @@ Communication is made possible in the network when intermediate nodes become **c
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* They allow mobile nodes that pass by to collect and leave data on them.
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* They contribute to increasing the frequency of node contacts and improve **delivery ratio** and **delivery delay**.
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## Categories of VANETs
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@@ -10,7 +10,7 @@
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* **The focus phase allows** each node to forward a copy of its messages to other potential nodes until the messages gets to its destination.
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* The protocol uses a single-copy utility based routing scheme to forward a copy of the message further.
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* Forwarding decisions are made based on **timers** which record the times nodes come in communication range of each other.
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* Node $$A$$ forwards message with destination $$D$$ to node $$B$$ , **if and only if** $$B$$ has a higher potential of delivering the message to $$D$$.
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* Node $A$ forwards message with destination $D$ to node $B$ , **if and only if** $B$ has a higher potential of delivering the message to $D$.
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#### SimBet
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@@ -20,7 +20,7 @@ When deciding on the best carrier and the optimal number of messages, CAFREP dyn
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2. Predictive **node congestion** (node storage and in-network delays)
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3. Predictive **ego network congestion**
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Each layer you go up, the more information is exchanged between the nodes.
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@@ -34,7 +34,7 @@ $$
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Ret(X) = B_c(X) - \sum^N_{i=1} \space M^i_{size}(X)
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$$
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For a node $$X$$, it has buffer of size $$B_c(X)$$. When a message of size $$M^i_{size}$$ is sent to node $$X$$, it's buffer size is the total buffer minus the memory taken by the sum of all messages in the buffer.
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For a node $X$, it has buffer of size $B_c(X)$. When a message of size $M^i_{size}$ is sent to node $X$, it's buffer size is the total buffer minus the memory taken by the sum of all messages in the buffer.
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###### Node Receptiveness
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@@ -66,7 +66,7 @@ $$
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EN_{Ret}(X) = \frac{1}{N}\sum^N_{i=1}Ret(C_i(X))
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$$
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Gets the average of the retentiveness of node $$X$$ and it's neighbours $$c_i(X)$$
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Gets the average of the retentiveness of node $X$ and it's neighbours $c_i(X)$
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###### Ego Network Receptiveness
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@@ -88,9 +88,11 @@ $$
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#### Contents of CAFREP Node
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$$
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Replication\space rate = M \times \frac{TotalUtil(Y)}{TotalUtil(X) + TotalUtil(Y)}
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$$
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Total utility, changes constantly. The replication limit grows to take advantage of all available resources, and backs off when congestion increases.
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Social utility prevents replication at a high rate on free nodes that are not on the path to the destination.
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@@ -13,7 +13,7 @@
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* Application and content providers are independent of each other
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* CDNs focus on web content distributions for major players
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**Important requirements for ICNs** (Information Centric Networks)
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@@ -79,7 +79,7 @@ Apart from routing protocols that use direct identifiers of nodes, networking ca
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##### Using Names in CCNs (Content Centric Networks)
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- The hierarchical structure is used to do *longest match look-ups* which guarantees $$log(n)$$ state scaling for globally accessible data.
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- The hierarchical structure is used to do *longest match look-ups* which guarantees $log(n)$ state scaling for globally accessible data.
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- Although CCN names are longer than IP identifiers, their **explicit structure** allows look-ups as efficient as IP's.
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### ICN Forwarding
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@@ -7,7 +7,7 @@ A Brief History of Networking
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- Wires are the dominant cost.
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- A *call* is not the conversation, its the **PATH** between two end-office line cards.
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- 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.
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- <img src="/lectures/acn/img/k.png" alt="switch board" style="zoom:50%;" />
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- <img src="img/k.png" alt="switch board" style="zoom:50%;" />
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- Path building is **non-local** and **encourages centralisation** and **monopoly**.
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- Calls fail is any element in the path fails so reliability goes down exponentially as the system scales up.
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- Data cannot flow until the path is set up so efficiency decreases with setup time.
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@@ -49,7 +49,7 @@ CCN can run over and be run over anything e.g. IP.
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#### CCN Packets
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**Interest** - similar to HTTP `GET`
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@@ -59,7 +59,7 @@ CCN can run over and be run over anything e.g. IP.
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Data packets are authenticated with digital signatures.
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#### CCN Forwarding
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@@ -91,6 +91,6 @@ In the current Internet, Quality of Service (QoS) Problems are highly localised
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Unlike IP, CCN is **local**, don't have queues and receivers have complete control
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Tree serves as transport state
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@@ -4,7 +4,7 @@
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##### Interplanetary communication
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<img src="/lectures/acn/img/o.png" alt="DTN in space" style="zoom:50%;" />
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<img src="img/o.png" alt="DTN in space" style="zoom:50%;" />
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> **Characteristics**
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>
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@@ -52,7 +52,7 @@
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>- High propagation delay
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>- Asymmetric data rate
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>
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>
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>
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>
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>**Security**
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>
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@@ -127,7 +127,7 @@ Based on the *bundle* protocol
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* Access Control (only legit users with right permissions)
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* Limited protection from DoS attacks
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- Payload Security Header is computed once at the source bundle agent, carried unchanged, and checked at the destination bundle agent (and possibly also security boundary bundle agents)
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@@ -102,7 +102,7 @@ Precedence
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- 95% allocated already (440,000 netblocks)
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**IPv6** supports 128 bit address
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**IPv6** supports 128-bit address
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- Loads of addresses :white_check_mark:
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- Routing protocols need to ported :negative_squared_cross_mark:
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@@ -132,7 +132,6 @@ Because IPv6 did not magically solve address shortage problem and not all router
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###### Full Cone
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```
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ea:ep - NAT address : NAT port
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```
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@@ -141,17 +140,12 @@ When client receives packet from server 1 `da:dp`, the NAT translates the NAT ad
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###### Address Restricted Cone NAT
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In this case server 2 is not trusted and therefore any request will be dropped.
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###### Port Restricted Cone NAT
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If the router receives a packet from a bad IP or bad port, it will be dropped.
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###### Symmetric NAT
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Here the internal address is obfuscated from the external servers, same client can use different ports for different communications.
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@@ -41,7 +41,7 @@ DNS is a consistent namespace
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- Extract information from tree upon client requests
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- `gethostbyname()`
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###### Root
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@@ -121,7 +121,7 @@ What happens when the resolver queries a server that doesn't know the answer? tw
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1. **Recursive** (optional)
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- Server generates a new query to the next server
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#### Load Balancing
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@@ -14,7 +14,7 @@ Simplest possible paradigm
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- Wait for `ack(x)`
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- Transmit `seq(x+1)`
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This has really poor performance in high latency and uses high bandwidth (half the bandwidth is overhead (acknowledgements))
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@@ -88,12 +88,12 @@ RTT - round trip times
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- When the first `RTT` measurement is taken the sender sets the smoothed `RTT` (`SRTT`), `RTT` variance (`RTTVAR`) and `TIMEOUT` in the following way
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- `SRTT = RTT`
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- `RTTVAR = RTT/2`
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- `TIMEOUT = `$\Mu\cdot$`SRTT + 4*RTTVAR`
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- Where $\Mu$ is a constant, which in this implementation is 1.08 (obtained experimentally)
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- `TIMEOUT = `$\mu\cdot$`SRTT + 4*RTTVAR`
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- Where $\mu$ is a constant, which in this implementation is 1.08 (obtained experimentally)
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- When subsequent `RTT` measurements are made the sender sets the `RTTVAR`, `SRTT`, TIMEOUT
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- `RTTVAR`$= (1 - \frac{1}{4}) \times$`RTTVAR`$+ \frac14 \times |$`SRTT`$-$`RTT`$|$
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- `SRTT`$= (-\frac18)\times$`SRTT`$+\frac18\times$`RTT`
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- `TIMEOUT`$= \Mu\times$`SRTT`$+ 4\times$`RTTVAR`
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- `TIMEOUT`$= \mu\times$`SRTT`$+ 4\times$`RTTVAR`
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###### Packet loss rate calculation
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