Tidy up

docs/lectures/acn/11_connecting.md

@@ -7,7 +7,7 @@ This is about **resource management**
 - **Supply** - Available link capacity on path
 - **Demand** - Host transmitting and receiving traffic
 - **Elastic** - capacity reduces -> demand is scaled back
-  - Hosts stop sending / send less
+    - Hosts stop sending / send less
 - **Inelastic** - applications can’t handle this
 
 TCP manages resource usage based on observed loss and latency
@@ -19,8 +19,8 @@ If capacity > demand, there is no need for quality of service
 If capacity < demand, we need to keep queuing minimal
 
 - As queuing directly impacts latency, jitter and loss
-  - In stable networks
-  - **Jitter**: The difference in delays, a measure of stability
+    - In stable networks
+    - **Jitter**: The difference in delays, a measure of stability
 
 #### IP Type of Service
 
@@ -59,76 +59,76 @@ Precedence
 ### Differentiated Services (DiffServ)
 
 - Operates on *traffic aggregates*
-  - Label packets with desired class via ToS
-  - Routers apply different queuing as operator sees fit
+    - Label packets with desired class via ToS
+    - Routers apply different queuing as operator sees fit
 - Four service classes, or *per-hop behaviour*
-  - **Default**: best effort
-    - No QoL applied
-  - **Expedited Forwarding**: low delay, loss & jitter
-  - **Assured Forwarding**: low loss if within rate
-  - **Class Selector**: use ToS precedence bits
+    - **Default**: best effort
+        - No QoL applied
+    - **Expedited Forwarding**: low delay, loss & jitter
+    - **Assured Forwarding**: low loss if within rate
+    - **Class Selector**: use ToS precedence bits
 
 ##### Problems
 
-- End to end semantics
+- End-to-end semantics
 - Mapping to service level agreement
-  - If an internet company sells a network with a certain speed, this might have legal repercussions if QoS are enacted
+    - If an internet company sells a network with a certain speed, this might have legal repercussions if QoS is enacted
 - Mapping to application demands
 
 ### Integrated Services (IntServ)
 
 - Operates on explicitly signalled *flows*
-  - Think phone switchboards
-  - The network signals exactly what it can and can’t do to the destination nodes
+    - Think phone switchboards
+    - The network signals exactly what it can and can’t do to the destination nodes
 - Flow setup specifies some quality of service
 - Routers perform **C**onnection **A**dmission **C**ontrol
-  - CDA can accept and reject traffic based on whether or not the route/path is available
+    - CDA can accept and reject traffic based on whether or not the route/path is available
 
 ##### Problems
 
 - Complexity
-  - Hard to scale
+    - Hard to scale
 - Mapping requirements to parameters
-  - This was easier when ATM did it as they owned all the infrastructure
-  - Whereas now it is difficult to map across all different companies
+    - This was easier when ATM did it as they owned all the infrastructure
+    - Whereas now it is difficult to map across all different companies
 - Per-flow state
-  - Extremely difficult
+    - Extremely difficult
 
 ## NAT
 
 ### Address Shortages
 
-**IPv4** supports 32 bit addresses
+**IPv4** supports 32-bit addresses
 
 - 95% allocated already (440,000 netblocks)
 
-**IPv6** supports 128-bit address
+**IPv6** supports 128-bit addresses
 
 - Loads of addresses :white_check_mark:
-- Routing protocols need to ported :negative_squared_cross_mark:
+- Routing protocols need to be ported :negative_squared_cross_mark:
 - Associated services needing to move :negative_squared_cross_mark:
 
 ### Network Address Translation
 
-Because IPv6 did not magically solve address shortage problem and not all routers are ipv6 aware, we had to rely on NAT.
+Because IPv6 did not magically solve the address shortage problem and not all routers are IPv6-aware, we had to rely on NAT.
 
 - Private Addressing, `RFC1918`
-  - `172.16/12`, `192.168/16`, `10/8`
-  - Devices with these local IPs should never be externally routed
-  - Not for security reasons - just for getting more addresses
+    - `172.16/12`, `192.168/16`, `10/8`
+    - Devices with these local IPs should never be externally routed
+    - Not for security reasons - just for getting more addresses
 - Traditional NAT, `RFC3022` is the standard
-  - Use private addresses internally (within the local network)
-  - Map into a (small) set of routable addresses
-  - Use source ports to distinguish connections
-  - For large scale **carrier grade NAT** [`RFC6598`] on `100.64/10`
+    - Use private addresses internally (within the local network)
+    - Map into a (small) set of routable addresses
+    - Use source ports to distinguish connections
+    - For large-scale **carrier-grade NAT** [`RFC6598`] on `100.64/10`
 
 #### Implementation
 
 - Requires IP, TCP/UDP header rewriting
-  - Addresses, ports and checksums all need to be recalculated
+    - Addresses, ports and checksums all need to be recalculated
 - Behaviours
-  - Network Address Translation
-  - Network Address and Port Translation
+    - Network Address Translation
+    - Network Address and Port Translation
 
 ###### Full Cone
 
@@ -136,7 +136,7 @@ Because IPv6 did not magically solve address shortage problem and not all router
 ea:ep - NAT address : NAT port
 ```
 
-When client receives packet from server 1 `da:dp`, the NAT translates the NAT address `ea:ep` to the clients internet address and port `ia:ip`.
+When the client receives a packet from server 1 `da:dp`, the NAT translates the NAT address `ea:ep` to the client's internet address and port `ia:ip`.
 
 ###### Address Restricted Cone NAT
 
@@ -148,4 +148,4 @@ If the router receives a packet from a bad IP or bad port, it will be dropped.
 
 ###### Symmetric NAT
 
-Here the internal address is obfuscated from the external servers, same client can use different ports for different communications.
+Here, the internal address is obfuscated from the external servers. The same client can use different ports for different communications.