4.1 - Aggregate-address

I've looked through the archives, and basically, it seems like the rationale given for adding the

aggregate-address summary-only

statement into R3 is to make sure that it's sent out to get full reachability from the backbone routers.


I understand in theory that we need to have full reachability in the lab in order to complete it, however, what I'm not clear about is why we wouldn't therefore have a similar aggregate for our Loopback address space sent out, or why this wouldn't be done by pushing an IGP into BGP somewhere.


I guess maybe I'm still struggling with keeping in mind that I will need to ensure full reachability once BGP is done to the backbone routers, and need to run more verifications once my BGP sections are done.


If we're not otherwise prevented from doing so, is it probably a good idea to simply shove in an aggregate somewhere in my BGP so that I can make sure full reachability exists to the backbone(s)?


Thanks in advance,




  • I see it has been awhile since Jeremy's post.  His question has been a big one in my mind as well.  It seems to be a judgement call to do what you have to to get reachability if the sum of the tasks do not accomplish that.   So I think we could first ask:

    1.) Am I missing something in the lab that I haven't completed that is keeping me from having full reachability?

    2.) If not, then what liberty do I have to add my own config to make it happen?  Can I assume that if the initial doc says "Upon completion, all devices should have full IP reachability to all networks in the routing domain, including any networks generated by the backbone routers unless excplicitly specified." I should just add whatever config I need to to complete this?  Since there are no points involved, does it mean I automatically fail the entire lab by not meeting this?

    I hope someone else can add some light to this.  Not just for this lab, but all them, especially the real one.

    Thanks jains

  • me too i got the same question, 6 months later.

    did you find any answer jains?

    in task 3.6 we had alredy summarized out address space to BB1 eigrp

    ip summary-address eigrp 10 5

    i though that maybe BB1 was redistributing this to its adjacent BB's.

    mumble mumble.

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