TechSpot

What makes an internal IP external?

By Jskid
Nov 21, 2012
Post New Reply
  1. For many home users when they connect to a home router there computer is assigned an IP address in class C (in the range 192.0.0.0 - 223.255.255.255) but there external IP (issued by the ISP) is different (e.g. 206.87.81.34). What device is responsible for this translation and how does it not which packet to send to which node on the network?
     
  2. Pan Wah

    Pan Wah TS Enthusiast Posts: 134   +27

    Jskid likes this.
  3. jobeard

    jobeard TS Ambassador Posts: 13,446   +324

    Pan Wah is correct. The router has the technology to perform NAT (Network Address Translation).
    The WAN side connection will have the public IP assigned by the ISP and all the LAN ports on the router will have the
    internal (ie: non-routable, private) addresses. In this case, the non-routable refer to the fact that 100million users have Class C
    addresses like 192.168.x.x so clearly they can't be routed beyond the subnet gateway (ie our personal routers).
     
    Jskid likes this.


Add New Comment

TechSpot Members
Login or sign up for free,
it takes about 30 seconds.
You may also...


Get complete access to the TechSpot community. Join thousands of technology enthusiasts that contribute and share knowledge in our forum. Get a private inbox, upload your own photo gallery and more.