How does the internet know where to send a request for an IP like 8.8.8.8?

Question

Background (Hypothesis or assertion, framing, not the question(s) but important to what I'm trying to understand.)

I am familiar with IANA and use trace route regularly and I understand there is no self identified router that is "the internet." I understand that. I am also familiar at least in theory with the internet backbone.

I as a mere mortal "consumer" am limited by what my ISP allows over "their" network. They justify it because it's "their network and their bandwidth." They "own" it. They can control what IP I use and even shape my traffic or drop what they don't like.

I assume (yes I know that's dangerous) that powerful corporations like Google, Amazon, etc. don't have to deal with such ridiculous restrictions because they either have a "direct" connection to the internet or are simply so powerful or privileged that no-one would dare. If they own an IP address, say 8.8.8.8 they can set their IP address to that and everyone cooperates (generally.) OK say hypothetically tomorrow Google no longer exists and IANA gives me 8.8.8.8. I know crazy but bear with me. Where do I need to be physically on the internet so as not to be blocked from using it by my ISP. Assuming I'm not being NAT'd. And if Google has to use an ISP what is to stop them from just deciding Google can't use a particular IP anymore and they have to use one the ISP issues?

Question What I seek to understand from a technical point of view is how if I own an IP address I can set up shop with my IP address and how that works (yes I know my ISP wants me to believe they are my only option or I need their permission., but this doesn't explain why Google doesn't need permission from an ISP or doesn't have to just settle for what their ISP gives them.) Yes I know IANA assigns them, but how does one establish it, once it is allotted to you, and without arbitrary limitations imposed by individual networks along the way? Is there a protocol that publishes hey I'm this IP address that I say I am (assuming IANA agrees) so it can be seen across the internet. Say I have a static IP that I already "own" why can't I just use that and tell everyone that the IP my ISP gave me is not the final stop and that there is another IP further down? Do I have to call up on the telephone everyone with a router on the internet and get them to agree I am IP 8.8.8.8 or is this handled centrally? If it's not centrally managed whats to stop just anyone from saying they are 8.8.8.8?

Answer 1

I as a mere mortal "consumer" am limited by what my ISP allows over "their" network.

If by that, you mean you are a residential customer, then yes, and the question is off-topic here.

What I seek to understand from a technical point of view is how if I own an IP address I can set up shop with my IP address and how that works (yes I know my ISP wants me to believe they are my only option or I need their permission., but this doesn't explain why Google doesn't need permission from an ISP or doesn't have to just settle for what their ISP gives them.)

As a business customer, you negotiate a contract with your ISP(s). You can get addresses from your ISP(s), or you can get a contract that allows you to use provider-independent addressing. The RIRs have run out of IPv4 addresses to assign, so you would need to acquire those on the open market, but IPv6 addressing is plentiful, and you can get your own from your RIR.

For IPv4 addresses, the ISPs will not advertise any prefix longer than /24, so you could not get a single address and expect it to be advertised on the public Internet. As a business customer, the longest IPv6 prefix ISPs will advertise is /48, but that would be the longest prefix that you would get from an RIR.

Google, like any other business customer, contracts with the ISPs to which it connects.

And if Google has to use an ISP what is to stop them from just deciding Google can't use a particular IP anymore and they have to use one the ISP issues?

If an ISP peering with Google decides that Google must use addressing from the ISP, a foolish decision that will violate its contract with Google and cost it a fortune in revenue, then Google simply takes its business to other ISPs.

Say I have a static IP that I already "own" why can't I just use that and tell everyone that the IP my ISP gave me is not the final stop and that there is another IP further down? Do I have to call up on the telephone everyone with a router on the internet and get them to agree I am IP 8.8.8.8 or is this handled centrally? If it's not centrally managed whats to stop just anyone from saying they are 8.8.8.8?

The Internet is simply the collection of ISPs peering with each other. The Internet uses BGP as its routing protocol, and BGP advertises the networks about which an ISP knows to the other ISPs to which it connects.

As a business customer with provider-independent addressing, you will probably get your own AS number, and peer with your ISP(s) using BGP.

Answer 2

In addition to Ron's excellent answer, there are private links.

If any two organisations choose to do so, they can establish private links between them by buying some wire, fibre, radios, lasers, satellites etc and connecting them together, subject to whatever laws are required for digging up the road or launching rockets as appropriate. For this to be worthwhile, they'd have to be a) lots of traffic, or b) overwhelming control/privacy reasons, or c) very conveniently close together. You still might want to use your existing internet assigned numbers though, as they are conveniently maintained by internet agencies, or you could use your own bureaucracy for it.

It's easy to believe reason A for a private link between say Google and Amazon, reason B between say the government of a country and foreign embassies, or C between adjacent supplier-customer factories.

The following is intended playfully as a description of history:

• If they're not adjacent you might have to rent a leased line or similar from a registered telco, depending on your country's laws.
• You could do this with all of your suppliers and other partner organisations.
• It might get expensive so you might want to club together with other organisations and perhaps put a pile of leased line terminations next to a switch somewhere convenient like a big city.
• As the longer wires are very expensive you might want to do that it most of the big cities in the world.
• You might do favours for other local organisations and take traffic for them.
• Perhaps you could get others to join your club, as the more there are, the lower the amortised costs will be.
• If there's a lot of you, you'll need some kind of bureaucratic unit to manage the addressing. Perhaps you could give large players blocks of addresses, get some kind of automation to help propagate them.
• If there were enough of you, you could build a whole new internet!

If you want to connect to everybody in the world, however, your best bet is to use one of the established global networks: a) postal, b) telephony, c) internet. In which case you have to go along with the conventions of a) the UPU, b) the ITU, or ISOC.

It might well be true that yesterday's upstart is today's status quo and tomorrow's entrenched power. But the political questions about the collection of things which comprise the internet is for elsewhere.

PS. The only other thing to add is that in real life Google's DNS server 8.8.8.8 is a very unusual address as far as routing goes, in that it is anycast to some locally convenient actual DNS server.

Answer 3

Internet routing does not work on individual addresses, it works on address blocks. The status quo is that providers on the internet will only route /24 (256 addresses) or larger blocks of IPv4 addresses and /48 or larger blocks of IPv6 addresses.

The internet shares routes over a protocol called BGP. The big networks mostly trust each other to only advertise legitimate routes, but if you obtain a BGP connection as a little guy your BGP connection is likely to be filtered to only allow IP blocks which you have demonstrated you have permission to advertise. If your provider is small they may have to in turn talk to their upstreams and peers and demonstrate to their providers that they have permission from the owner of the IP block.

BGP has default rules for determining what it considers to be the "best" path, but these rules are often overidden based on the commercial considerations of the providers.

If you want to use your own address blocks and exchange routes over BGP, you will need to purchase a service that that allows this. Most "broadband" services will not. If you are in an area where broadband services support multiple ISPs you might find a boutique ISP who is prepared to do it, but then again you might not.

Once you start looking at connections with dedicated bandwidth (rather than the "best effort" of broadband connections), such as "leased lines" or "metro ethernet" you are more likely to find they offer BGP. You could also rent a point to point link to a datacenter and then buy IP transit service separately from a provider there.

Even though the providers offering these services are usually part of same companies as the "broadband" providers at large providers they are likely to be different departments. Talking to the "broadband" sales/support folks at a large provider about this stuff is unlikely to get you anywhere.

Alternatively you could choose to locate your equipment at a datacenter where "IP transit" providers offering BGP already have a presence, this is IMO likely to be one of the cheapest ways to get a connection with BGP.