These can be a real hurdle when setting up VoIP, help others by posting your configs, tips and tricks or simply ask others for help if you're stuck.
By kaiuk
#1495
I'm not sure what the Cisco answer would be, I'm sure it is something extremely in depth and technical so I'm just going to describe a real world application for it. On a typical local area network you will get a live public IP address from the ISP, but you don't want your local client machines to be exposed to the big bad internet (directly).

You firewall will have the public IP and then it will 'translate' the local IPs on the client machines to give them internet access. All the clients can see the internet, but the internet can only see 1 public IP - your firewall, not the client machines.
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By KenBrace
#1496
kaiuk wrote:I'm not sure what the Cisco answer would be, I'm sure it is something extremely in depth and technical so I'm just going to describe a real world application for it. On a typical local area network you will get a live public IP address from the ISP, but you don't want your local client machines to be exposed to the big bad internet (directly).

You firewall will have the public IP and then it will 'translate' the local IPs on the client machines to give them internet access. All the clients can see the internet, but the internet can only see 1 public IP - your firewall, not the client machines.
Ah yes I think I remember learning about this. About the difference between public and private IP addresses. I think originally they only had IPs with no public or private aspect. The only problem is that there weren't enough. You can't possibly give every single device on the planet its own IP address. The best thing to do is give each network its own IP and then give the individual devices their own private IPs within the system. The most common of these being 192.168.1.(something).
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By nytegeek
#2131
Network Address Translation allows one single device, like a router, to act as a translator between the Internet and your private network. This allows a single unique IP address to represent an entire group of computers. Your home network may have several devices but it only has one unique IP for the internet. NAT translates this data between the internet and your devices.

It is similar to when you call a company with a large telephone system. There may be only one phone number for people to call in on but NAT is like the receptionist that answers the calls and send them to the right extensions so that they ring the correct phone.

This is an incredibly simplified explanation but it is the base idea.
By kylerlittle
#2171
KenBrace wrote:
kaiuk wrote:I'm not sure what the Cisco answer would be, I'm sure it is something extremely in depth and technical so I'm just going to describe a real world application for it. On a typical local area network you will get a live public IP address from the ISP, but you don't want your local client machines to be exposed to the big bad internet (directly).

You firewall will have the public IP and then it will 'translate' the local IPs on the client machines to give them internet access. All the clients can see the internet, but the internet can only see 1 public IP - your firewall, not the client machines.
Ah yes I think I remember learning about this. About the difference between public and private IP addresses. I think originally they only had IPs with no public or private aspect. The only problem is that there weren't enough. You can't possibly give every single device on the planet its own IP address. The best thing to do is give each network its own IP and then give the individual devices their own private IPs within the system. The most common of these being 192.168.1.(something).
I think it also depends on the country and ISP.
By Se7ev
#2318
kylerlittle wrote:I think it also depends on the country and ISP.
No. NAT or Network Address Translation uses table to store WAN and LAN side (wide and local area network). Why is that usefull? So we reduce number of taken IP addresses. Instead having unique (wide) IP address on each device, you have unique IP for whole network. IPv4 is limited to 2^32 (4294967296) addresses and we wouldn't use NAT, we would ran out of those addresses much faster. On February 3rd 2011 we ran out of unassigned IPv4 addresses, now we are using IPv6, which has 2^128 addresses :)
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By Bonzer
#2587
Simply put, NAT or Network Address Translation allows multiple gadgets to connect to the internet or (any other network based on IP networking) through a single IP address. It's usually a firewall that does the job for you. You can google out for more details or follow the link below.

http://whatismyipaddress.com/nat
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By ericnail
#3142
Well, in order to understand NAT you should know why it exists. Basically with the ipv4 protocol we only have so many possible addresses and if we gave every single device a unique address (IP address) then we would quickly run out (at least until IPv6 becomes standard). ISP's have come up with a solution to this: NAT.

Think of NAT like a building number. Each street has buildings with a public address assigned to each. Within each building you have several apartments which are all assigned a private address specific to that building.

Essentially this is what NAT does. It takes the assigned address (your IP) and translates that into several private addresses (192.168.x.x) all under the one public address.
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