Re: Are you an IOS NAT expert?

Thanks Ahmed :)
As a matter of fact, I do teach from time to time.

On Tue, May 19, 2009 at 2:35 PM, Ahmed Ejaz <aahmedejaz_at_gmail.com> wrote:

> This is awesome, Pavel do u offer any boot camps or private lessons ? :)
>
> Thanks
>
>
>
> On Tue, May 19, 2009 at 5:26 PM, Pavel Bykov <slidersv_at_gmail.com> wrote:
>
>> Also, just use a structured approach, it's really not that hard.
>>
>> Here are a couple analogies, that might ease your pain coming together
>> with
>> Cisco's terms.
>>
>> Imagine "inside" and "outside" in terms of building and a chair. A chair
>> can
>> always be either inside the building or outside the building. It can never
>> be at the both places at once and it definitively has to be on one of the
>> sides. Same goes for physical location of hosts in the IP network.
>>
>> Now how you are looking at the chair? You can either be inside the
>> building
>> and look at the chair locally, or go outside the building and look at the
>> inside chair from outside with the global perspective. So local and global
>> defines a viewpoint - where do you look from.
>>
>> When you are oustside, and you are looking on the inside chair, you look
>> at
>> it through window with a global perspective - inside's chair image is
>> distorted by the window (read: it's IP adress is translated by the NAT),
>> but
>> when you are inside the building and looking at the chair locally, it's
>> image is not distorted (read: it's IP address is not translated).
>>
>> Same goes if the chair is outisde the building. If you're outside and the
>> chair is outside, you're looking at it with a global perspective, but if
>> you
>> go inside the building and look at the chair that is outside the building
>> -
>> the chair is distorted (translated). So your local view of outside (i.e.
>> outside local in Cisco's terms) is distorted by the Window/NAT.
>>
>> inside local , inside global, outside local and outside global are all
>> cisco
>> term's that adhere to these concepts
>>
>> Everything else is just adding to those concepts. NAT POOL are different
>> window colors, while ACLs define the types of chairs that can be seen...
>> But
>> i wouldn't go there with analogies.
>>
>> Main types of translations are therefore "inside source": how do we see
>> the
>> inside chair from outside the building (inside global), and "outside
>> source": how do we view the outside chair from inside the building
>> (outside
>> local).
>>
>>
>>
>>
>>
>>
>> On Mon, May 18, 2009 at 11:43 AM, Dale Shaw <dale.shaw_at_gmail.com> wrote:
>>
>> > Hi all,
>> >
>> > I really dislike IOS NAT. Reeeaaallly dislike it. I cut my teeth on
>> > NAT on Linux and BSD and it just seems to make so much more sense to
>> > me on those systems.
>> >
>> > The "inside local", "inside global", "outside local" and "outside
>> > global" concepts -- why, Cisco? Whhhhhy? And it's just as
>> > brain-destroying on PIX/ASA, if you ask me.
>> >
>> > Anyway, I could whinge and moan about Cisco's implementation all day
>> > long, but that's not going to help. Essentially, I'd like to become
>> > much better at identifying and applying solutions to NAT scenarios
>> > with IOS.
>> >
>> > I've been setting up NAT on routers for years, and in the end, I can
>> > always make it work. For trickier configurations, sure, it takes
>> > longer, but I get there. As we all know, though, there's no time for
>> > trial and error in the exam room. I want to be able to look at a NAT
>> > task and immediately know which interface(s) should be 'inside' and
>> > which interface(s) should be 'outside', which of the many NAT
>> > configuration options will get the job done, and what "gotchyas" each
>> > method comes packaged with (e.g. when static routes are required).
>> >
>> > Don't get me wrong, I understand how a packet can be transformed by a
>> > NAT, it's really just gaining a deeper understanding of Cisco's
>> > implementation.
>> >
>> > So, I guess I'm happy to hear what study material helped you really
>> > 'get' NAT - DocCD links, other Cisco.com articles, books, workbooks,
>> > whatever - but I'm more interested in the way you approach NAT tasks
>> > in terms of logic, strategy and troubleshooting. I personally haven't
>> > found a resource yet that gives me the background theory I require to
>> > get the most out of practice labs.
>> >
>> > cheers,
>> > Dale
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net
>> >
>> > _______________________________________________________________________
>> > Subscription information may be found at:
>> > http://www.groupstudy.com/list/CCIELab.html
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>>
>> --
>> Pavel Bykov
>> ----------------
>> Don't forget to help stopping the braindumps, use of which reduces value
>> of
>> your certifications. Sign the petition at http://www.stopbraindumps.com/
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>>
>>
>>
>>
>>
>>
>

-- 
Pavel Bykov
----------------
Don't forget to help stopping the braindumps, use of which reduces value of
your certifications. Sign the petition at http://www.stopbraindumps.com/
Blogs and organic groups at http://www.ccie.net