2. About AODV:

a. The structure of RREQ sent by A (assuming that A doesn’t know the sequence number of D)

Destination ID Destination Sequence# Source ID Source Sequence# Hop Count
D 0 A 13 0

A increases sequence number before sending RREQ and destination sequence number of D is 0, because A doesn’t know the sequence number of D.

b. The backward routing table at F, C and D.

Backward routing table at F,
Destination ID Via Distance Sequence #
A B 2 13

Backward routing table at C,
Destination ID Via Distance Sequence #
A B 2 13

Backward routing table at D,
Destination ID Via Distance Sequence #
A C 3 13

c. Destination node is D, hence D will stop flooding RREQ and send RREP to A. So, E will not receive RREQ.
Meanwhile, H will receive RREQ from node G, as C will flood RREQ …show more content…
The forwarding routing table at A after receiving RREP from D,
Destination ID Via Distance Sequence #
D B 3 22

e. If node E moves away, will D detect it? Will D propagate this link break to other node? Why?

• Yes, D can detect link break between D and E, since the nodes periodically communicate with a “Hello” message in AODV. When E doesn’t respond to node D’s message, D will record it as a link break
• Link failure information is sent to active neighbors only and E is not active, because it is not involved in transferring data. So D will not propagate this link break to other nodes.

f. The link between A and B is broken, as A moves away from B. B detects it as it can’t receive “Hello” message from A now.
Now since the node A has moved from it’s place it will update it’s routing table
Destination ID Via Distance Sequence #
D B ∞ 23
It will also increment D’s sequence number.

Now node A will send the RREQ again to find a new route to destination cause A moved to a new place. Hence A will increment its own sequence number by 1. Now A has sequence number as 14. RREQ of A:
Destination ID Destination Sequence# Source ID Source Sequence# Hop Count
D 23 A 14