please type the answers, having trouble reading the hand writing (15 points) In
ID: 2291680 • Letter: P
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please type the answers, having trouble reading the hand writing
(15 points) In DSDV routing algorithm, when a node sends its routing information to neighbors, it does not include the next hop of each route. For example, in the following figure, B only sends 2. neighbors. Why we c information about Next Hop in this process? (A, 1, A-550 (A, 1, A-550) (B, 0, B-102) (C 1, C-588) (B, 0, B-102) (C, 1, C-588) Dest. Next Metric Seq Dest. Next Metric SeqDest. Next Metric Seq A B 2 A-550 A | A | 0 A-550|| A | A | 1 A-550 B | B | 1 B-102|| B | B | 0 B-102 B | B C? B | 2 |C-588|[ C | C | 1 |C-588 0 C-588Explanation / Answer
In DSDV, each route is tagged with a sequence number which is originated by the destination, indicating how old the route is. Each node manages its own sequence number by assigning it two greater than the old one (call an even sequence number) every time. When a route update with a higher sequence number is received, the old route will be replaced.
In case of different routes with the same sequence number, the route with better metric is used. Updates are transmitted periodically or immediately when any significant topology change is detected.
There are two ways of performing routing update:
1. “full dump”, in which a node transmits the complete routing table, and
2. “incremental update”, in which a node sends only those entries that have changed since last update.
To avoid fluctuations in route updates, DSDV employs a "settling time" data, which is used to predict the time when route becomes stable. In DSDV, broken link may be detected by the layer-2 protocol, or it may instead be inferred if no broadcasts have been received for a while from a former neighbouring node.
Hence here the next hop can be skipped or omited since the broad casting metric didnt change
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