Difference Between Ip Address and Mac Address

Mon, Jul 12, 2010, by KRTWORLDWIDE

Web Talk

This article explains about the difference of ip address and the mac address in the communication technology of internet.



  The term  IP address stands for “INTERNET PROTOCOL ADDRESS”. An IP address is a 32 bit decimal number that is normally written as four numbers between 1 and 255, each separated from the other by a decimal point. An example of IP address is


The above form of representing the IP address is called “dotted decimal notation.”

Deep understanding of IP Address concepts

An internet is made up of combination of physical networks(LAN or WAN) connected by routers. When a host communicates with another hosts, the packets may travel from one physical network to another using these routers. This suggests that communication at this level also needs some global identification system. A host must be able to communicate with any other host without worrying about which physical network must be passed through. This means that the hosts must be identified uniquely and globally at this layer also. N addition, for efficient and optimum routing, each router must also be identified uniquely and globally at this layer.

 The identifier that is used in the IP layer of the TCP/IP  protocol is called the INTERNET PROTOCOL ADDRESS OR THE IP ADDRESS.

It is a 32-bit binary address, implemented in software, that uniquely and universally defines a host or a router on the internet.

The IP addresses are unique. They are unique in the sense that each address defines one, and only one, device(host or router) on the internet. Two device on the internet can never have the same IP address.

Each IP address consists of four bytes(32 bits), defining two parts:  netid and host id

Where  net id     :  Identifies  a network
            Host id   :. Identifies host on that network.

For example in the IP address  (class b address), the first 2 bytes 127.255 defies the netid and the last 2 bytes 255.255 defines the host id.


 The hosts and routers are recognized at the network level by their logical address. Every protocol  that deals with interconnecting networks requires logical address (i.e  IP address).

However , packets must pass through physical networks to reach these hosts and routers. At the physical level, the hosts and routers are recognized by their physical address. A physical address is a local address. Its jurisdiction is a local network. It should be unique locally, but not necessary universally. It is called physical address because it is usually( not always) implemented in hardware. Examples of physical address are  48 bit MAC address in Ethernet and token ring protocols, which are implemented on the NIC installed in the host or router.

The physical and logical addresses are two different identifiers. We need both of them because a physical network, such as Ethernet can be used by two different protocols at the network layer such as  IP and  IPX(Novell) at the same time. Likewise , a packet at the network layer  such as IP may pass through different physical networks such as Ethernet and Local talk.

Therefor in order to deliver a packet to a host or router we need 2 kinds of addressing, one is logical and the other one is physical.. The logical address is IP address and the physical addresss is MAC address.

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