Every computer that connects to the Internet has to have an IP address assigned to it. IP addresses identify where the computer is located on the Internet so that Web servers and mail servers can send data to the correct computer. An IP address is a series of four numbers separated by dots:. There are two types of IP addresses — public and private. Private IP addresses are special IP addresses that are known only to a router and its home network. A Web server will not deliver Internet data to a private IP address.
It will deliver the data to the router which has a public IP address and then the router will deliver the data to the computer that has the private IP address. Routers are special because they have two IP addresses. This is the side of the router that faces the Internet and has a public IP address. A computer, connected to a router which will be called 'R1' , which is connected to another router which will be called 'R2' that also acts as the DHCP server of the LAN and has an external IP address.
So I can see why R2 has two IP addresses: As others have said -- ignoring misconfigurations, bugs, errors states and so on -- a router needs to be on multiple networks and so most naturally has multiple IP addresses. There are certain kinds of networks, most notably point-to-point links and virtual private networks links, which don't need addresses and are sometimes used unnumbered.
The router has routes which specify exit interfaces rather than the usual next-hop IP address; as the exit interface is point-to-point, the next router is implicit. A router which connected lots of unnumbered point-to-point links might conceivably therefore have no IP addresses at all, and still be useful.
Consider it a theoretical case only: no one would do it in real life because you'd want to have at least an IP address to connect to for configuration purposes.
And many network engineers prefer to number all the interfaces even if not strictly required, as it can help with monitoring and fault finding. R1 thinks it's silly to get a packet which could have and "should have" gone directly to R2, so tells PC with an ICMP redirect; which the PC can ignore or use at it pleases. You can switch off the ICMP Redirect messages on most routers, but many network engineers consider them useful as they usually show a misconfiguration.
One of the special interfaces a router can have is a "null" interface, which just throws away its packets. Normally this is used as a place to send packets which have been judged to be improper in some way, such as packets with an internal source address arriving on an external interface. A null interface doesn't have an address. So a router which was configured just to accept packets and throw them away might have just a single IP address or none if it is on the end of a point-to-point link , and send everything to the null interface.
You might do this for logging purposes; also, it can sometimes be more convenient to propagate routes to bad addresses rather than access lists. Welcome to Network Engineering! Routers route between networks, so they need interfaces in the networks they route to.
Otherwise, they're like a "bridge to nowhere. Usually though, it'll have two or more - a router's intention is to connect multiple networks and for that, it is required to have an interface in each network.
For instance, there are multiple gateways attached to a network, each leading to another network. There are simple nodes that can only use a default gateway and the stub router is the one with a complete routing table - knowing all the routes to the other networks.
So, it's used as the default gateway and then routes to the actual gateway through the same network. Also as jonathanjo has pointed out , a router may have "unnumbered links" that don't require a local IP address - simple serial interfaces, VPN connections or similar. You can have only one IP on the Router, but it will not be able to route packets to another network. In the list on the left side of the window, choose your network and then click "Advanced" at the bottom-right of the window.
Your router's IP address will be listed next to "Router. Unfortunately, Android phones typically have no built-in tool for finding your router's IP address. Some Android models running customized interfaces — like Samsung's One UI found in Galaxy phones — give you access to this information, but it's generally easier to find the router's IP address using another device, like your laptop or desktop computer.
Alternately, you can install an app like Wi-Fi Analyzer , which can also display this information. For you. World globe An icon of the world globe, indicating different international options. Get the Insider App. Click here to learn more. A leading-edge research firm focused on digital transformation.
Good Subscriber Account active since Shortcuts. Account icon An icon in the shape of a person's head and shoulders.
It often indicates a user profile.
0コメント