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I was looking into Adhoc On-Demand Distance Vector Routing (AODV), in particular the following sources: https://www.cs.cornell.edu/people/egs/615/aodv.pdf

https://tools.ietf.org/html/rfc3561

Both refer to two different types integer identifier: nodes' sequence numbers (called "sequence numbers" in both sources) and RREQ IDs (called "Broadcast ID" in the first source). The first is used to make sure the network stores the most up-to-date information and to prevent nodes from broadcasting the same information twice. The second is used to "uniquely identify" (exact phrasing from both sources) a given RREQ event. This lets you ignore incoming RREQ's with the same source address and RREQ ID. My question is the following:

For RREQ packets, why send the RREQ ID at all? We already send the sequence number, and we increment it every time we send an RREQ, so it should be unique to a given RREQ.

To rephrase the question, why send both the RREQ ID and Sequence Number when, unless my logic above is wrong, you can achieve the same thing with only the sequence number?

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  • AODV is not something businesses use because it is too variable and unreliable. – Ron Maupin Dec 21 '20 at 15:37
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Dec 31 '20 at 20:46
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Since RREQs are rebroastcast to neighbors, a neighbor could possibly have already received the same RREQ on another path. It doesn't make sense for the routers to reprocess an already received and processed RREQ.

Both documents have aged considerably - nearly twenty years ago, many routers had very limited processing capabilities. Also, broadcasting isn't a very efficient propagation method.

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  • This doesn't really answer the question. The question was: why send two sequence numbers ("sequence number" and "RREQ ID"), when you can achieve the same functionality with one? – Joseph Myst Dec 21 '20 at 17:57

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