The Ad Hoc network shown below including node Q is currently

The Ad Hoc network shown below (including node Q) is currently operating. The network is running the AODV routing protocol. Show the steps required to route a packet from node P to node G. In particular, show what state is maintained at relevant nodes in the network. What changes occur to the route, and how are these determined if node 0 drops out of the network?

Solution

Part 1

Aodv is one of the on demand routing.

Aodv routing first search for route in routing table.If no route found then do route discovery.

Initially, no routing table. So, P send RREQ(route request message) throught flooding.

RREQ msg contain Source id, Sequence number, destination id, sequence of route

Step 1.

P send RREQ to N, L,Q

Step 2.

N send RREQ to O,K,L,J,P

L send RREQ to N,J,P

Q send RREQ to I,P

Step 3.

O send RREQ to M,K,N

K send RREQ to M,O,N,J

L send RREQ to N,J,P

J send RREQ to E,K,N,L

P ignore this request because its send through P only (send by N)

N send RREQ to O,K,L,J,P

J send RREQ to E,K,N,L

P ignore this request because its send through P only (send by L)

I send RREQ to Q,F,H,G

P ignore this request because its send through P only (send by Q)

Step 4.

M send RREQ to O,K (P->N->o->M)

K send RREQ to M,O,N,J (P->N->O->K)

N ignore this message because msg go through it.

Like this it will flood in whole network.

Once the RREQ reaches to G that is destination id in RREQ. G will send unicast msg RREP(route replay msg ) to source node that is P

G->I->Q->P (RREP)

When P receive RREP then P send data msg throught the route (P->Q->I->G)

P save this route in routing table for future reference.

Part 2

When P want to send data to G.

Ist check route for node G in routing table. It will find route in route table that will go through Q node.

P send data msg to Q and wait for ACK. No ack come. Then send RREQ msg again.

Step 1

P send RREQ to N,L (P->N),(P->L)

Like this it will flood in whole network

Once it reach to G

This will be shortest path

Path (P->N->J->E->D->F->G)

Path (P->L->J->E->D->F->G)

Among this two path G will take one path that reaches G firstly for RREP.

When P receive RREP then P send data msg throught the route.

P save this route in routing table for future reference.