Full Reachability after IGP redistribution

Hi folks,

I would like to understand the full reachability requirement after doing the IGP redistribution.  If a subnet or interface in the router that is not advertised into any routing protocol either by the initial config or by any task up to the IGP redistribution, does it require to have reachability to that subnet?  



  • Hi,

    In some cases, you may be asked to have only one way route redistribution but if you are required to have full reachability you need to have two way redistribution. If any subnet that is not advertised or you are not explicitly asked to advertise it, it doesn't matter at all. So, perform two way redistribution if you are asked to have full reachabilty, and ignore such a route which is not advertised by any routing protocol.


  • It's one of those funny things about which I had an argument during my first lab attempt. There was a loopback which was not redistributed or Advertised into IGP/BGP. And Lab manual says that by this time all of loopbacks should be reachable. Which of course goes against your config. I asked similar thing to proctor and he said lab manual should be right and you must have missed something.

    I drew L2/L3 diagrams and presented those to proctor but he kept saying same thing.

    I decided not to redistriburte that loopback or include in IGP/BGP in the end and still passed Config Section without loosing marks in IGP Section.

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