From 368652877fa85f3565276df8d3a27b0afa5fd8a6 Mon Sep 17 00:00:00 2001 From: Julian T Date: Thu, 8 Oct 2020 14:02:33 +0200 Subject: Added notes --- sem5/net/mm10/noter.md | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 sem5/net/mm10/noter.md diff --git a/sem5/net/mm10/noter.md b/sem5/net/mm10/noter.md new file mode 100644 index 0000000..ec50e8a --- /dev/null +++ b/sem5/net/mm10/noter.md @@ -0,0 +1,59 @@ +# 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. -- cgit v1.2.3