addressing of a network

[syeda amna]

hi
i want to know about addressing of network. i know there is physical address (MAC address) and there is a logical address(IP address). what is the need of two addresses? what is IPX?

 

[ckshivaram]

IPX (Internetwork Packet Exchange) is a networking protocol from Novell that interconnects networks that use Novell's NetWare clients and servers. IPX is a datagram or packet protocol. IPX works at the Network layer of communication protocols and is connectionless (that is, it doesn't require that a connection be maintained during an exchange of packets as, for example, a regular voice phone call does).

Packet acknowledgment is managed by another Novell protocol, the Sequenced Packet Exchange (SPX). Other related Novell NetWare protocols are: the Routing Information Protocol (RIP), the Service Advertising Protocol (SAP), and the NetWare Link Services Protocol (NLSP).

---------- Post added at 22:33 ---------- Previous post was at 22:28 ----------

1. IP address (network address) is just used for transferring information from one network to another network. Travelling of information among networks uses IP addresses. It is used to identity the network and host.

A MAC address (physical addresses) is used for distribution of information with in the network segment. The Ethernet uses MAC address to transfer data between hosts. When its used with IP network the IP address is resolved using ARP protocol to find the MAC address of the end device and the data is transmitted.

Port numbers are used by the TCP/UDP protocol to isolate the traffic which is multiplexed and sent by the user application. For example the user device can open multiple applications at the same time like multiple web browsers email and FTP. To identify the data individually the port number are used.

2. We need I.P address because when we work on LAN we can communicate without I.P address with the help of NETBIOS and WINS but in WAN we work on network layer and data frame becomes packet and packet need I.P address for routing

3. IP Address is at the "Software or Logical level and helps to establish communication between 2 or more Networks at the OSI (Network Level) whereas the MAC Address is at the OSI (Data Link Layer) which has the Physical Address of the actual node (machine). Final Data Distribution (Information Transfer) from the Network Segments (originally PAckets at the Transport Layer) to the Destination Client Node must work at he PHYSICAL LEVEL which starts at the DATA LINK LAYER.

The final Layer in the OSI model (Physical Layer) then translates the MAC ADDRESS to the actual WIRES (RJ45) etc. which work at the ELECTRONS LEVELS.

ONLY MAC ADDRESSES and NO IP ADDRESS will not work. Software at the TRANSPORT LAYER (TCP and IP) does not support physical addresses.

 

[syeda amna]

thanks Mr ckshivaram.
i am still confused because i dont know much about networking. you have mentioned

We need I.P address because when we work on LAN we can communicate without I.P address with the help of NETBIOS and WINS but in WAN we work on network layer and data frame becomes packet and packet need I.P address for routing

what is frame? what is the difference between frame and packet?

 

[lostinxlation]

what is the need of two addresses? ?

Pick any computer network textbook and read it. IP address and MAC address work in the different layer and you need to understand the protocol stack.

what is the difference between frame and packet?

Practically, they are the same, but we call it differently depending on which protocol layer we are talking about.

Read a textbook and understand the protocol stack.

 

[ckshivaram]

Frames is an OSI layer 2 (data link layer) Protocol Data Unit where as Packets is an OSI layer 3 Protocol Data Unit .

Data link layer of sending machine adds additional header and trailer to bits (PDU of OSI layer 1 i.e Physical Layer) and it becomes a frame then it is passed on to the upper layer which is the network layer that will then add other info and attach it to the frames which then becomes a packet (additional info added includes sending network ip address and receiving network ip address.
the receiving machines's corresponding layers decrypt the messages that will detect whether the packet belongs to it .

In other words
Packet: This term is considered by many to correctly refer to a message sent by protocols operating at the network layer of the OSI Reference Model. So you will commonly see people refer to IP Packets. However, this term is commonly also used to refer generically to any type of message.

Frame: This term is most commonly associated with messages that travel at low levels of the OSI Reference Model. In particular, it is most commonly seen used in reference to data link layer messages. It is occasionally also used to refer to physical layer messages, when message formatting is performed by a layer 1 technology.

 

[syeda amna]

thanks to Mr ckshivaram

Pick any computer network textbook and read it. IP address and MAC address work in the different layer and you need to understand the protocol stack.

I know MAC address is at the Data link layer while IP address is at the network layer. But i have a confusion why we need these two.

 

[lostinxlation]

thanks to Mr ckshivaram


I know MAC address is at the Data link layer while IP address is at the network layer. But i have a confusion why we need these two.

well, if you know they work in different layers, you would know that IP address cannot be used on data link layer. How can you deliver the data to the destination without having MAC address ?
like I said, read a book. You need to learn ARP too to see the clear picture.

 

[ckshivaram]

Think of it as the difference between your street number and your ZIP / pin code. The post office uses the zip code to get a letter to the right post office (network) but you need another address like 123 main street to get the letter to its final destination. Even if the street address was unique, say 1174badce7QQk# main street, that doesn’t help you get a letter to me. You’d have to have every post office and every mail carrier have a complete list of every unique person and place in the world available to them at all times in order to route the letters properly.

That’s why both addresses are used.

IP addresses are not really unique to computers. Your IP address is probably 192.168. something which thousands upon thousands of people probably also share. Even your internet address (IP) is something that if you don’t use it for a while (turn off the modem) it will be assigned to someone else. That’s why you have to pay extra to have a permanent static address. The supply is limited.

 

[saif haider]

MAC address is the physical address. it is pre assigned form manufacture. consider a server with built in LAN ports and Wifi. how would the hardware of server will know on which port the network is connect. Definitely it has different MAC address, Physical address which cant be change. while IP address is logical in a sense that when we connect to internet. The network assign our connection an IP address. DNS connection or manual configuration these are all logical configuration for ur network identification.

 

[srizbf]

the MAC address , which is the lan card address cannot change. it is the physical address.

the logical address is your ip , which is assigned depending on the network.

there is a mapping between the logical and physical , to identify the machine.

while you can move the pc to a new location and when you get the new ip , the mac is mapped to it.