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+# Adhoc routing
+
+Mobility or MANET requires other routing.
+
+## Versus wired routing
+
+Assymetric links
+:   Becuase of interference and different power levels, A might be able to send to B
+    but not the other way around.
+
+## Routing types
+
+Proactive
+:   Routes are known before send, using tables. 
+    But does not respond to network changed very vell.
+    Also requires lot of traffic to keep up to date.
+Reactive
+:   Routes are found on demand, so reduces overhead.
+    Delay because route must be found first.
+Hybrid
+:   Something in between.
+    Best of two worlds.
+
+## Flooding
+
+Every message is sent to everyone.
+Often used for control messages, but not for data as it requires alot of resources.
+
+Nice if nothing is known about network.
+
+**Not always reliable** can have hidden terminal in wifi situration
+(also called *Broadcast Storm Problem*).
+Can be solved by introducing random small delay when forwarding.
+
+Other solution could be to not forward if already seen *n* times.
+
+## Dynamic source routing
+
+1. **Route discovery**
+Using route request (RREQ) to find a route, often with flooding.
+2. **Sending data**
+3. **Route maintanance**
+Keeping the route up to date. This could be done continuesly or when sending new
+data.
+
+A reply to RREQ (RREPLY) can then be returned in the route collected with the RREQ.
+However if nodes are unidirectional it must be sent back using flooding.
+
+**A problem** with this is the overhead of having the whole route in the packet.
+
+### Route caching
+
+Each node can cache routes to other nodes.
+But how to check if a route is broken?
+
+Nodes can check if neighbour connections are broken using MAC ACK.
+This node can then signal to sender that the route is broken.
+
+If L2 does not have ACK, we can use control packages.