Re: Public IP assign to Lan interface

From the ISP's perspective (in most cases), all your IPs are public. If you
use some of these public address to perform NAT to private IPs is up to
you, and strictly a business decision. Some places use public IPs on the
LAN side and this is perfectly valid as well.

IP addresses are becoming scarce so many people use NAT to need fewer
public IPs, NAT can also provide some abstraction of your internal
addressing to increase security. On the other hand it can add complexity,
and obscure original source IPs in security logs etc so some places choose
to use all public IP addresses. Usually these are companies that have large
blocks of IPs already allocated to them.

You can even use a mix, and have both public and private IPs on the inside
LAN. I see this in companies that started with all public IPs and either
outgrew their block or for other reasons.

On Thu, Jul 17, 2014 at 10:28 AM, Amit Joshi <ccieamj_at_gmail.com> wrote:

> When we go for internet connection for specific organization, ISP provide
> the IP pool fro WAN and LAN as well.
>
> query is whey ISP give such pool for LAN and we have to assign one ip to
> our LAN interface and it is public ip address. What is the reason behind
> it? What I would like to understand the back end
>
> setup of ISP in such situation?
>
>
> On 7/17/2014 8:54 PM, marc abel wrote:
>
> I have no idea what you are trying to say.
>
>
> On Thu, Jul 17, 2014 at 10:06 AM, amit joshi <ccieamj_at_gmail.com> wrote:
>
>> Hi All,
>>
>> Quick question, why ISP ask the customer to assign the public IP address
>> to
>> his LAN interface?
>>
>> What is the reason behind it? What I would like to understand the back end
>> setup of ISP in such situation?
>> --
>> Regards,
>>
>> Amit
>>
>>
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>
>
> --
> Marc Abel
> CCIE #35470
> (Routing and Switching)
>
>
>

-- 
Marc Abel
CCIE #35470
(Routing and Switching)
Blogs and organic groups at http://www.ccie.net