There are a lot ways to do this. We are going to talk about two of them.
First one is more for the Terminal/Console people and of course the fastest one. You need to open Terminal application (Applications -> Utilities -> Terminal) or other console type application like iTerm. Execute this line:
ifconfig | grep "inet " | grep -v "127.0.0.1" | cut -d" " -f 2
It is going to print IP address of your machine. Remember this IP address is going to be the one that gives your switch/router if you have one otherwise it is going to be your IP that ISP gave you.
The second way is for people who wants to use GUI approach. Open "System Preferences" on "internet & Wireless" section select "Network". Now in the left side select your active connection (should have a green indicator). Now near the "Status: Connected" is going to written your IP. If you don't see the IP press "Advanced" and choose "TCP/IP" tab in "IPv4 Address" field will be your IP.
If you are trying to find the Internal localaddress you can find it in your network settings in the System Preference/ Network.
If your trying to find your Outside internet IP address that your ISP gave you then you have to either look in your router or connect to the many free IP address finders, they will tell you what it is when you connect to them.
Open the Network section of System Preferences. Click the advanced button and then the TCP/IP tab to find the Router's IP address.
The Router only has one M.A.C Address and One IP Address But, the Router can have many Connections ( Devices using the network ) That may shoe up as their IP Addresses. But the Router only Has One IP Address
IP address remains the same. Mac address changes from router to router.
no a bridge does not use a IP address, it uses MAC address', rousters or layer 3 uses ip address.
Router can get your MAC address, IP address and computer name.
A MAC address is useful if you want the router to always provide the same IP address to the same network interface, or if you want to provide a service, such as a PXE boot image, to a specific computer regardless of its IP address.
A switch uses MAC address to forward frames while a router uses IP addresses.
the router is assigned an ip address.
Just search "My Ip Address". Its as easy as that!
If you have changed DHCP ip range, the ip address for your router has changed too. You can find your router ip address in your wireless adapter information.
the tcp/ip frame uses the ip address to send messages between devices (computers, printers, etc) on your network. This frame is inside an ethernet frame on the network layer. The ethernet layer does not use ip addresses at all, they use mac addresses. For an ethernet frame to travel through a router, it needs a mac address. Your router actually does not need an ip address. It will respond to broadcasts. In fact sometimes it won't answer to tcp/ip requests. Its job is to deliver the datagram to its destination more than it is to answer you (your computer that is). So sometimes a router will not answer a ping, but a computer on the other side of the router will answer even if there are several router in the path.
It is unclear what you mean by 'original address'. If you mean the "Real" IP address for the "Internet" then one place would be on the Router under "Status" or something similar, or on the network settings on the computer on a Windows machine, not sure if you can find it on a Mac with out the console.
It uses the MAC address, Media Access Control. Every packet sent from a computer contains its MAC address. The router stores this in its routing table. When it receives a packet with a destiation address of that MAC address, then it forwards it to that computer. This is called NAT, Network Address Translation. It uses the Destination IP address