NAT-QUESTION

[mmtantawi]

Thanks for your reply.

Please i want to understand if what i understood is correct or not :-

1- NAT is devided in to the 4follwoing Parts :-

Static - Dynamic- PAT - Overloading .

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Static Nat :-

is used only if you have one real IP Address and need this Real IP Address to be assign to one Internal User Only, and this User will always access internet with this real IP Address,and if the Users change the Internal IP Address, the Users will not be able to access internet, is that correct ?

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2- Dynamic NAT :-

i am confused here, whcih Part is correct ?

First Part :-

Dynamic NAT, is used if i have a gorup of internal IP Address and 1 real IP.

and all the users need to access internet through this real IP , is that correct ?

====

Second Part :-

Dynamic NAT, is only when i have a group of real IP Address and i have here a group of Internal IP , and i need each one of the Internal to access Internet through each one of the external Real IP. is that correct ?

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what is the PAT & Overload ? what is the diffrent between them ?

and if i have only 1 real IP Address and 200 users as internal, with which NAT should i go ? Dynamic, Static, PAT, or overload ?

Please Update me.

what is the PAT & Overloaded ?

[rajinikanth]

Hi,

NAT types are two

1.Static

2.Dynamic

Static NAT ? Mapping an unregistered IP address to a registered IP address on a one-to-one basis. Particularly useful when a device needs to be accessible from outside the network.

Dynamic NAT ? Maps an unregistered IP address to a registered IP address from a group of registered IP addresses. Dynamic NAT also establishes a one-to-one mapping between unregistered and registered IP address, but the mapping could vary depending on the registered address available in the pool, at the time of communication.

Overloading ? A form of dynamic NAT that maps multiple unregistered IP addresses to a single registered IP address by using different ports. Known also as PAT (Port Address Translation), single address NAT or port-level multiplexed NAT.

For 1 real IP Address and 200 users as internal use PAT i.e overload.

Hope this helps you,

Thanks,

Raj

[mmtantawi]

Thanks For your reply.

is what i understood is correct now ?

1- Static NAT = for ONLY ONE PRIVATE IP to ONE PUBLIC IP .

2- Dynamic NAT = for Only ONE Private IP to a group of Public IPS ?

is that correct .

Please Update me

[desai.jaideep]

Hi

Let me make things straight and square for you:

NAT was introduced to overcome the shortage of public IPs on internet.The basic function of NAT is private-to-public conversion.It has 4 parts:

(1) NAT overload : when you have 200 PCs in private network 192.168.1.0/24 and you have single public IP 203.94.227.1...then you do NAT ovrload so that all the 200 PCs can access internet and will go out through single IP which is 203.94.227.1.

(2)PAT : a NAT overload can direct packets from internal network to public (ext.)network, but if you have a web-server in ur lan which need to be accessed from outside, then u do PAT.i.e, you will map port 80 of 203.94.227.1 with your server 192.168.1.254 on port 80.So that whenever there is http request on 203.94.227.1, it will be forwarded to 192.168.1.254.

(3)Static NAT : when you have a multi-purpose server in ur LAn and you want any outside connection to be made to 192.168.1.254 on any port, then you define that in ur router and map 192.168.1.254 with 203.94.227.1.This is static NAT.

(4)Dynamic NAT : When u have a pool of 203.94.227.0/24 and ur internal network is 192.168.1.0/24.You can define that each and every PC in ur network will go out through different public Ip through the pool given to u.then u do dynamic NAT.hence this is a first-come-first-server basis, and to any inside IP initiating the connection will be a assigned an public ip.Hence all Pcs in ur network can be accessed from outside b'coz all have different public IPs.

Hope I am making myself clear.

Pls rate helpful posts.

Regards

JD

[mmtantawi]

Thanks For your reply.

what i understood is that :-

Dynamic NAT = is only have a group of real IPs & A group of Internal IPs / or Single Internal IP , and needs to access internet.

if i have for example 3 real IPs (192.168.1.5 - 192.168.1.6 - 192.168.1.7 ) & 5 IPs as Internal, so when the first internal IP needs to access internet , he will ask the router , where is the First Real IP that is available in the Real IP Pool so i can take it ?

the Router will check, and will find that , there is one ready ( 192.168.1.5 ), so he will give it to him .

so the rest of the real IPS is 4.

and so on , for that .

so was i am correct or not in that .

Please update me .

[desai.jaideep]

Hi

Yes

Regards

JD

[devang_etcom]

hi...

PAT and NAT with overload is the same thing...PAT, or NAT overloading, is a feature of Cisco IOS NAT and can be used to translate internal (inside local) private addresses to one or more outside (inside global?usually registered) IP addresses. Unique source port numbers on each translation are used to distinguish between the conversations.

With NAT overload, a translation table entry containing full address and source port information is created.

there is no different between PAT and OVERLOAD...

if you have single real ip and multiple LAN user then you have to go for the NAT with overload option...

rate this post if it helps

regards

Devang

[Ravilogin]

Hi Devang,

I'd like to give few inputs for u r Q.

1.There are 2 types of NAT.

i.STATIC

ii.Dynamic.

In the case of Dynamic NAT we can configure in two diffrent manners.

1.Defining pool of IPs

or

2.PAT

You can use pool of IPs if you have more no. of private IPs. As per your inputs u have 3 private IPs so configure PAT (Keep remaining two IPs as Reserved)

U can use PAT in case of u have only one Private IP.(In technical terms it called as Overload )

Note : - If u configure dynamic NAT there is

no possiblities of External (outside world)

to Internal Communication.

If you want futher inputs pls revert to this.

Regards

Ravi