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What is structure/hiearchy of IP addresses?

I mean, is mandatory that IP address e.g. 216.9.10.0 is subnet of 216.9.0.0? Of course many times that is the case and IMO it would be logical, but I have heard that you can own IP address space. I think only way that can work is there is now structure like this and 216.9.10.0 can be under e.g. 216.9.9.0.

That bring another questions, how routing works? Of course regardless those exections usually routers can route hiearchy piece by piece starting from first number of the IP addr to last one, but not always. Is that the case? Normally routing is hiearchy process, but few of hops are with execptions. Autonomous systems need tell with BGB that there is hiearchy address space, but remember one execption inside that space. For example, space 216.1.0.0-216.1.255.255 and somepoint inside is IP 210.1.1.1.

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  • "I mean, is mandatory that IP address e.g. 216.9.10.0 is subnet of 216.9.0.0?" That depends on the network mask. All IPv4 network are subnets of 0.0.0.0/0, but not of 0.0.0.0/8.
    – Ron Maupin
    Nov 26, 2023 at 15:44
  • "I have heard that you can own IP address space." No, IANA owns the IP address space and can assign it out to the RIRs, which in turn can assign it to companies, but IANA still owns it and can revoke the assignment, as can the RIRs.
    – Ron Maupin
    Nov 26, 2023 at 15:46
  • Depends of network mask? With what mask 216.9.10.0 isn't subnet of 216.9.0.0? And the point of question is, can hiearchy of IP addresses be "broken"? E.g. 108.1.0.1/24 is subnet of 210.0.0.1/24? Technically routers could route this if many route mark this execption to their routering records, right?
    – worner
    Nov 26, 2023 at 20:15
  • Yeah, nobody can't "own IP", but IANA/RIRs can assign IPs to you. Now, what says location/position of IP space to you? If you at first want to use your IPs in NYC and then move London, what happens?
    – worner
    Nov 26, 2023 at 20:18
  • "E.g. 108.1.0.1/24 is subnet of 210.0.0.1/24?" No. "With what mask 216.9.10.0 isn't subnet of 216.9.0.0?" Any mask on 216.9.0.0 that is longer than /20 will not include 216.9.10.0. "If you at first want to use your IPs in NYC and then move London, what happens?" That depends on the other companies to which you want to connect. You may be able to make a business agreement to have them route any addresses you are assigned. The Internet is just agreements between connecting companies.
    – Ron Maupin
    Nov 26, 2023 at 20:21

1 Answer 1

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IP addresses are hierarchical for delegation only. You can add bits to a delegated prefix, breaking it into smaller subnets which can then be used or re-delegated.

You cannot use that information for routing however, e.g. x.0.0.0/24 and x.0.1.0/24 can be part of entirely different networks, located on different parts of the globe.

BGP is used to exchange the delegated prefixes with their respective gateways, organized within ASNs.

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  • Okay, what do you exactly mean by "hierarchial for delegation only" What is differences between delegation on assiging? And how x.0.0.0/24 and x.0.1.0/24 can be entirely different networks if delegation only? And as inportant, what this all mean for routing?
    – worner
    Nov 26, 2023 at 15:38
  • And another question: IP addresses contain network and host part, right? So is the case that network part is "hiearchial for delegation" and host not?
    – worner
    Nov 26, 2023 at 15:40

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