Re: Comparing two IP routing table

I can suggest you only a scripting way to find "partial" overlapping:

- implement the isSubnetOf() function, so that if x=10.0.1.0/24 and y=
10.0.0.0/16, x.isSubnetOf(y)=true. With perl, python,... you can do that in
few lines.
- Get the two lists of prefixes to compare. Instead of "show ip route", I
suggest "show ip cef" (output is simple to manage, sorted by prefix).
- Use isSubnetOf() inside a script loop; compare each prefix of Company A
with each prefix of Company B, and viceversa.
- When you get a "true", put comparing and compared prefixes in the
conflict-list.

If you prefer Excel, I think it is possible achieve this with excel and VBA.

If I use Exel, I will begin in splitting each prefix in five columns (byte1,
byte2, byte3, byte4, prefix-len), then using VBA to implement isSubnetOf
function and to do loop.

Is it easy? Depends on you.
-mirco.

On Sun, May 9, 2010 at 9:56 PM, <ocsic_at_hotmail.co.uk> wrote:

> both entities will continue to have HO and data centers in different
> locations, but will be consolidated under one VRF, so a routing conflict can
> pull traffic in the wrong direction..... therefore IP subnets must be unique
> and I want to stay away from NAT which will be messy.
>
> I also have to look for variable subnet conflicts, because if for example
> one company has a longer match compared to the other, it will pull traffic
> of other company in its direction, so although they are not identical
> routes, it is still a conflict. So don't think Diff program will do the
> whole job...
>
>
>
> --------------------------------------------------
> From: "Ccieyarub" <ccieyarub_at_gmail.com>
> Sent: Sunday, May 09, 2010 8:29 PM
> To: <ocsic_at_hotmail.co.uk>
> Cc: "Cisco certification" <ccielab_at_groupstudy.com>
> Subject: Re: Comparing two IP routing table
>
>
> Hi
>> If company B will be migrated into vrf than the overlapping of ip is not
>> an issue, what's the motivation for looking for ip address conflict in
>> that scenario??
>> Thanks
>> A-
>>
>> Sent from my iPhone
>>
>> On 2010-05-09, at 2:55 PM, <ocsic_at_hotmail.co.uk> wrote:
>>
>> Does anyone know if there is a easy way to compare two large IP routing
>>> tables
>>> for IP address conflict, each IP routing table has over 5000 routes. For
>>> example if company A acquires company B and wishes to migrate company B
>>> into
>>> its VRF. Company A would like a detailed report of the IP address
>>> conflicts
>>> between itself and company B.
>>>
>>> Can anyone suggest what is the easiest way to approach this. I have
>>> thought
>>> of
>>> importing the routing tables in Excel into each column and writing a
>>> Macro to
>>> compare the two columns. But this seems like a tedious task.
>>>
>>> Is this the best way or can anyone suggest a faster better way?
>>>
>>> Thanks in advance !
>>>
>>> IS
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>> _______________________________________________________________________
>>>
>>
>>
>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Mon May 10 2010 - 20:37:54 ART