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I have just started learning about routers and switches and how they are used in designing a network.

Connecting multiple routers and making them self-configure, causes them to dynamically discover the distance between multiple hosts and destinations, in turn, enabling them to find the shortest path while delivering a packet to a destination. I also understand that public IP addresses are distributed to ISPs by IANA.

But what is stopping us from connecting multiple ISPs to a single router or a combination of routers and configuring a unique public IP address ourselves without referring to IANA? Will this setup work?.

Or is my understanding of this whole concept is wrong?

Sreram
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  • Related: [How to… Internet without ISP?](https://superuser.com/q/900021/53590) – user Jun 27 '17 at 11:48
  • Also, note that some mid-range NAT routers have *dual WAN* or even *multi WAN* (more than two) capability, typically with either load balancing or failover. This is often used to provide some degree of redundancy, but to be practically useful requires the uplinks to be physically separate. You can't really do something similar with a router that supports only a single uplink, because the software running on it would get confused. – user Jun 27 '17 at 11:50
  • So is this thing theoretically possible? But then, why do we have the IANA? – Sreram Jun 27 '17 at 11:56
  • Your question mentions "configuring a unique public IP address". IANA (and the RIR system) keep track of who uses which addresses to make sure that they are indeed unique. – Sander Steffann Jun 27 '17 at 13:19
  • So does that mean a router which configures its own IP address without permission will be flagged (or in a way, be considered illegal)? – Sreram Jun 27 '17 at 18:21
  • @Sander Steffann that was the main purpose of my question. Isn't it possible to configure our own IP addresses in our private network? So because the world wide web is also a connection of too many routers (or this is what I think it is), won't we have the ability to configure our own IP address if we buy services from too many ISPs (along with too many routers)? There must be a large number of unassigned IPs, so what's stopping us from guessing one that's not in use? – Sreram Jun 27 '17 at 18:24
  • You cannot just use any IP address. The main reason why is routing. In order for you to hit the internet you need to be able to talk to your ISP's gateway - you need to be on the same network to do that. You can technically use any IP on that network - but it isn't always going to work. Many ISPs have IPs assigned by circuit ID, or use DHCP, and in either case, if you randomly assign an address, you may conflict with another device and that will lead to a lot of traffic issues or the gateway may just refuse to talk to your router. – MaQleod Jun 27 '17 at 18:51
  • You can grab some unused addresses, and if you find a bad ISP you might even be able to route it for a while. Address hijacks happen all the time. A good ISP will reject you though, and many networks check route announcements against the RIR databases to filter out invalid ones. You might be liable for any damages caused though, because you *are* abusing someone else's space. – Sander Steffann Jun 27 '17 at 20:25

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