How are IP addresses assigned and used in different networks?

[CraigH]

I know the basics, every device connected to the internet has a unique IP address, and when I request something from another device connected to the internet my IP is sent with the request so that the data packets know where to come back to.

However I have problems with this; firstly, if I google "My IP" it tells me that my IP is an 11 digit number. I'm pretty certain there are more than 10^10 devices connected to the internet, so how are there enough IP's for every device?
I've heard of IPv6 which supposed to be the current form of IP's designated to devices, and these look like this 2001:0db8:85a3:0042:1000:8a2e:0370:7334
source http://en.wikipedia.org/wiki/IPv6
However my IP doesn't look like this, what's going on?

My second question is why does it say "Your public IP address is xxx.xx.xxx.xxx" when I google my IP? what is a public IP?
If I have multiple computers connected to the same wireless hub, or they are all connected to a Ethernet port in the same house/flat, then would there be any similarities in there IP address?
How about something like a university network? how would IP's be used there? for example at my uni all accommodation is connected to the university wireless network connection so we can access the internet.

I've downloaded a network analyser to try and work some of this stuff out. there seems to be about 3 packets every 3 seconds when my browsers closed but then loads when I request a webpage, but none of them have my IP as either the source or the destination, (well the last 3 digits are the same on allot of them)
Please help I'm very curious as to what's going on. Thanks!

 

[Old Wolf]

Yours is an IPv4 address. You're quite right that there aren't enough IPv4 addresses for every device to have one.

The answer to all your other questions is Network Address Translation.

Your entire house(/workplace/university/ISP/...) hides behind one address (the "public IP"). Your computers have their own address but those addresses are not visible to the outside (and are not unique addresses).

You have a network gateway device that rewrites all of the outbound messages originating from your network and puts the public IP into the packet headers; and then when the responses are received, undoes that rewrite and sends the response back to where the request came from.

 

[rcgldr]

If I have multiple computers connected to the same wireless hub, or they are all connected to a Ethernet port in the same house/flat, then would there be any similarities in there IP address?

Typically, multiple computers in a house will use a router or modem with router function, whch uses the same public IP but a different set of "ports" for each computer connected to the router.

However many ISP (internet service providers) also offer the (added cost) option of assiging a separate public IP for every computer (or device) connected to the cable / dsl modem. It's common for a cable modem to support up to 16 public IP's, but the cable company in my area currently has a max of 3 public IP's. DSL offers an 8 IP modem, but 3 of those are overhead, so you end up with 5 public IP's. Multiple IP's with DSL used to be signficantly more expensive than cable, but now the pricing is close.

In the case of shared web hosting, a single server will use multiple public IP's, one for each shared website on the server.

I'm not sure how all this will transition from IPv4 to IPv6, other than I assume IPv4 addresses will get "grandfathered" and remain the same.

 

[CraigH]

Ahh interesting, thanks guys!

 

[LudusRex]

I can provide a detailed explanation of how IP addresses are assigned and used in different networks. Firstly, IP addresses are unique numerical identifiers assigned to devices connected to a network. These addresses allow devices to communicate with each other and send and receive data packets.

There are two types of IP addresses: IPv4 and IPv6. IPv4 addresses are the traditional 32-bit addresses that are commonly used and look like the 11 digit number you mentioned. These addresses have a limited number of combinations, which is why there is a concern about running out of available addresses as more and more devices connect to the internet. This is where IPv6 comes in, as it uses a 128-bit address format and can provide a significantly larger number of unique combinations. However, not all devices and networks have transitioned to using IPv6 yet, which is why you may still see IPv4 addresses being used.

In terms of how IP addresses are assigned, there are two main methods: static and dynamic. Static IP addresses are manually assigned to a device and do not change, while dynamic IP addresses are automatically assigned by a network's DHCP (Dynamic Host Configuration Protocol) server and can change each time a device connects to the network.

Now, to address your questions about public and private IP addresses. A public IP address is the address that is assigned to your device by your internet service provider (ISP) and is used to communicate with other devices on the internet. This is the address that is shown when you google "My IP". A private IP address, on the other hand, is used within a local network (such as your home or university network) to allow devices to communicate with each other. These addresses are not visible to the outside internet.

In a network such as a university, there will be a range of private IP addresses assigned to different devices, but they will all have a common public IP address that is assigned to the university's network by the ISP. This allows all devices connected to the university's network to access the internet using the same public IP address.

As for the packets you saw in your network analyzer, it is normal to see a few packets being sent and received even when your browser is closed. These could be background processes or updates happening on your device. When you request a webpage, there will be a larger number of packets being sent and received as your device communicates with the server hosting the webpage. These packets may not have your IP address