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Forum Replies

  1. Probably I’ve understood it, since I haven’t watched your video before asking the question. Let me try: There is no permanent problem between Router 1 and his neighbors, since this was just an example from you. Moreover there still could be a problem with a query between Router 3 and Router 2 (theres none in your example but it could happen). Nevertheless I barely unterstand the “congestion” part?!

  2. great explanation ,thank you.

  3. Hi Paul,
    You generally have it right. The short answer is after 90 seconds, an SIA-Query is sent.

    The longer answer:

    Each router manages its own SIA Query and SIA Query Response management. This means that as soon as each router has put a route in Active (regardless of whether the router in question was the actual first router to start the process) and has sent a Query to its neighbors, that router also starts a timer. At 90 seconds, for each neighbor from which it has not received a reply, it will send an SIA Query to check on the status of the original query. Any of those other routers that, themselves, are also waiting on a Reply from others will respond back to the router that gave the SIA-Query with an SIA-Reply. Any neighbor that does not respond to an SIA-Query by the time the original timer reaches 3 minutes will be considered stuck in active.

  4. Hi Lazaros, I got it. Thanks a lot for you reply.Its really helpful.

  5. If a route/neighbour fails, how can you recover from SIA? Recycle the interface facing the neighbour that’s down?

    I’m also curious how you can simulate this in GNS3. Surely the main cause of SIA is congestion? How did you replicate the replys from R2 not reaching R1? Use an ACL?

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