How to limit the EIGRP DUAL diffusion range in a large internetwork

Discussion in 'Cisco' started by James Harris, Jan 6, 2005.

  1. James Harris

    James Harris Guest

    Where do DUAL queries stop? I thought that the diffusing update queries
    would go out as far as the classful boundaries, by default, but the texts I
    have read recently seem to me to say the queries will go all the way out to
    the boundary of the internetwork before reducing back. Cisco's web site
    says, "If you run into a situation where it seems that the query range is
    the problem, it is always best to reduce the query range rather than
    increasing the SIA timer," but that document doesn't say how to reduce the

    We have a large internetwork with auto summarisation turned off in some
    cases. I had a 3.5min outage before a link recovered - possibly a
    stuck-in-active, though I don't believe there was an SIA reported in the

    So do the queries stop at the classful boundaries, at network summaries, or
    at the edge of the internetwork?
    James Harris, Jan 6, 2005
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  2. Andrey Tarasov, Jan 6, 2005
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  3. James Harris

    merv.hrabi Guest

    One EIGRP feature that is useful in addressing query boundaries and sIA
    event is the EIGRP stub routng feature
    merv.hrabi, Jan 7, 2005
  4. James Harris

    thrill Guest

    Queries stop at network summaries and on links that are connected to
    routers configured as stubs. All of your edge routers must be
    configured as stubs (if they support it), if they do not you should be
    sending them only a summary default route. Queries will not be sent
    out links where the queried route falls within the summary that you are
    sending, or if the link at the other end is configured as a stub.
    Configuring a router as a stub basically tells the router at the other
    end, not to send it queries for any routes that go active (which is the
    result as sending a summary default route). In large networks, it is
    extremely important not to be sending queries to low end routers
    because they do not have the horsepower to manage large numbers of
    queries in short periods of time. If you track down your SIA's you
    will find that it is your 2x00 series routes and lower that are the
    source of SIA's. In large networks it is important that your IP
    address space is allocated such that you can do as much network
    summarization as possible.

    thrill, Jan 9, 2005
  5. James Harris

    SysAdm Guest


    look at advertising a summary address....

    SysAdm, Jan 13, 2005
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