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NAT and pool of public addresses

From CCNA4 Lab manual, lab 1.1.5 :

((Step 7

Define the pool of usable public IP addresses

To define the pool of public addresses, use the ip nat pool command:

Gateway(config)#ip nat pool public-access 199.99.9.32 199.99.9.35

netmask 255.255.255.252)).

I believe there is a typo in the ip address above, because the 199.99.9.32 is network address and 199.99.9.35 is ip address.

8 REPLIES
New Member

Re: NAT and pool of public addresses

In the same lab above I was practicing the lab above (see attachment for details),,,I have got this NAT table (see attachment please)

1- I do not know form wher I have got this address:

10.70.82.16.

2- I have got heaps of ip addresses translation between these two ip addresses :

tcp 199.99.9.33:1886 10.10.10.3:1886

I do not why ?

I used ping once

Re: NAT and pool of public addresses

hi

The proper syntax for defining the pool is

ip nat pool name start-ip end-ip {netmask netmask | prefix-length prefix-length} [add-route] [type {match-host | rotary}] [accounting list-name]

in your case you got the whole subnet 199.99.9.32/30 to be used in the pool.

in this case you will have 2 usable ips which is 199.99.9.33 and 199.99.9.34 the other ips 199.99.9.31 will be ur network id and 199.99.9.35 ur broadcast id.

As per the syntax you need to mention the whole subnet from which you need to use the public ips for NAT purpose.

since you have mentioned the whole subnet (199.99.9.32/30)in the pool which is reqd it takes (199.99.9.33)the usable ip from the subnet for Natting purpose..

Thatsy you are seeing your 10.10.10.3 getting natted with 199.99.9.33..in addition to that you are seeing the port details of both the inside and out ips which it keeps to track the transaction which occurs at a particular time with particular application (like http,mail,ping).

regds

New Member

Re: NAT and pool of public addresses

"other ips 199.99.9.31 will be ur network id"

I did not get what did you mean here, this is a broadcast address for subnet 199.99.9.28/30!!!

What about this :

((1- I do not know form where I have got this address: 10.70.82.16))

Re: NAT and pool of public addresses

Hi

sorry about that it was a typo error i was referring 199.99.9.32 instead i have quoted 31..

There are some terminologies like inside local ,inside global and outside local,outside global.

Inside local address - The IP address assigned to a host on the inside network. This is the address configured as a parameter of the computer's OS or received via dynamic address allocation protocols such as DHCP. The address is likely not a legitimate IP address assigned by the Network Information Center (NIC) or service provider.

Inside global address - A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world.

Outside local address - The IP address of an outside host as it appears to the inside network. Not necessarily a legitimate address, it is allocated from an address space routable on the inside.

Outside global address - The IP address assigned to a host on the outside network by the host's owner. The address is allocated from a globally routable address or network space

do refer these links for more info on the same..

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094837.shtml

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094831.shtml

regds

New Member

Re: NAT and pool of public addresses

Sory for my late reply,,,but I do not know why have not I received email notification,,,this happend to me between time to time ,,no always,,,have you expeirenced same porblem ?

"There are some terminologies like inside local ,inside global and outside local,outside global."

I am familiar with these terminology.

But still I do not know from where I have got the address that I refered to, because I have not configured that address neither inside loacl, global nor outside local, global

New Member

Re: NAT and pool of public addresses

But still I do not know from where I have got the address that I refered to, because I have not configured that address neither inside loacl, global nor outside local, global

Re: NAT and pool of public addresses

Hi

Can you revert which ip you are trying to ping and also the config of taken out from u r lab router ?

regds

New Member

Re: NAT and pool of public addresses

((Can you revert which ip you are trying to ping and also the config of taken out from u r lab router ?))

I have to redo the lab again and I will post every things again

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