From: Douglas M Todd, Jr (dtodd@PARTNERS.ORG)
Date: Thu Jun 28 2007 - 11:45:40 ART
Mike:
True, thanks for the clarification. Just was shedding some light, but
failed to point in the most direct location...
DMT
Mike Kraus (mikraus) wrote:
> Note, the internetwork expert guide would be for a wildcard mask. You
> would need to calculate the subnet mask for a summary address.
>
> As Sean said, "The best you can do is 10.1.0.0/18, which covers 0-63 in
> the third octet."
>
> To see this:
>
> convert them to binary (use calc if you need):
>
> 00010110 - 22
> 00100010 - 34
> 00100101 - 37
> 00101111 - 47
>
> Determine which bits are the same for all subnets:
>
> 00010110 - 22
> 00100010 - 34
> 00100101 - 37
> 00101111 - 47
> ^^
>
> In this case, the first two match. Converting 11000000 (matched bits)
> back into decimal you get 192. So, the best summarized space would be
> 10.1.0.0 255.255.192.0. This would cover all networks from 10.1.0.0 all
> the way up to 10.1.63.0 (and includes a lot of networks you don't really
> own).
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Douglas M Todd, Jr
> Sent: Thursday, June 28, 2007 9:23 AM
> To: Eric Dobyns
> Cc: ccielab@groupstudy.com
> Subject: Re: Is there a trick to this?
>
> Yip, there is a way to do this.
>
> Best to read up on access-lists and "and" "or" operations.
> You will need to find with the "and" operation the network.
> You will need to find with the "or" operation the ""mask""
>
> This will create a one line access-list which will cover the whole
> range.
> This may help you out.
>
> http://www.internetworkexpert.com/resources/01700370.htm
>
>
> Eric Dobyns wrote:
>> Take the following 4 loopback interfaces:
>>
>>
>>
>>
>>
>> 10.1.22.1 255.255.255.0
>>
>> 10.1.34.1 255.255.255.0
>>
>> 10.1.37.1 255.255.255.0
>>
>> 10.1.47.1 255.255.255.0
>>
>>
>>
>> Redistribute them into IGP as a single advertisement while wasting the
>
>> least amount of address space.
>>
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>
>
>
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