Summary route for EIGRP

MrXpertMrXpert Member Posts: 586 ■■■□□□□□□□

I want to summarize the following networks for eigrp but think i maybe making a mess of it:

C is directly connected, Loopback50
C is directly connected, Loopback51
C is directly connected, Loopback52
C is directly connected, Loopback53
C is directly connected, Loopback54
C is directly connected, Loopback55
C is directly connected, Loopback56
C is directly connected, Loopback57

so far I have worked out that the wildcard mask would be and then I subtract to give me I then goto the interfaces its on and would need to type ip summary address eigrp 75
but i dont know if the actual summary is right?
can anyone tell me if what I have is right or wrong and how i can get it right please?
I'm an Xpert at nothing apart from remembering useless information that nobody else cares about.


  • advanex1advanex1 CASP, MCSA 2016, MCSA 2012, CCNA, Security+, Network+, Project+, Server+ Member Posts: 364 ■■■■□□□□□□
    You're right.

    Break it down into binary, it's much easier to look at it.

    50.0 00110010 00000000
    50.1 00110010 00000001
    50.2 00110010 00000010
    50.3 00110010 00000011
    50.4 00110010 00000100
    50.5 00110010 00000101
    50.6 00110010 00000110
    50.7 00110010 00000111

    What bits do every network have in common? It would be all of the first octet and the first 5 bits of the second octet. If you treat those as if they were "turned on" ,11111111 11111000, you would get a subnet mask of which would be a route summary of -

    So in summary, just go from left to right, identify the common bits and the common bits make up your subnet mask. Hope this helps.
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  • MrXpertMrXpert Member Posts: 586 ■■■□□□□□□□
    Hi Advanex1, thank you so much for your help! your explanation really helped clear up my doubts
    I'm an Xpert at nothing apart from remembering useless information that nobody else cares about.
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