TCP/IP - [Part 4] - INTERNET LAYER PROTOCOLS

Internet Layer = Network Layer [OSI Model]

Internet Layer is similar to Network Layer of OSI Model:

Internet Layer

• Internet layer is responsible to manages device addressing and it tracks the location of devices on the network.
• Internet Layer is responsible for establishing data communication channel between multiple networks or nodes or devices or hosts.
• It determines the best path to move data, which means that the Internet layer must act as a transport traffic between devices that are not locally attached.
• Internet-Layer is used when a connection needs to establish between two or more different networks. If two or more nodes or devices are connected locally, then there is no any requirement of Internet layer.
• Router is a layer 3 devices, which is specified at the Internet layer and provide the routing services within an inter-network.

Below protocols come under the Internet Layer :- 

Internet Protocol (IP) 

• All hosts on a network have a logical ID, whic is known as software address, logical address or IP address. This address has valuable encoded information, which greatly simplifying the complex task of routing.
• IP is responsible to deliver the packet from the source host to the destination host based on their addresses. It is helpful to find the best path and to track and manage the devices
• IP receives segments from the Host to Host layer and break them into packets and then reassembles packet back into the segments on the receiving side. 
• Each packet is assigned the IP address of the sender and of the receiver. 
• Each router which is layer-3 device, receives a packet and makes routing decisions based on the destination IP address of packet.

Internet Control Message Protocol (ICMP)

• ICMP is an internet layer protocol used to diagnose network communication issues. So basically it is for error reporting and used by network devices like router
• ICMP ensure that data is reaching its intended destination or not , in a timely manner. So it can provide hosts with information about network problems.
• It is a management protocol and messaging service provider for IP. 
• The following are some common errors which are reported by ICMP:

-Destination Unreachable error

-Buffer Full/Source Quence

-Hops/Time Exceeded error

-Ping Packet Internet Groper (Ping) uses ICMP echo request and reply messages to check the physical and logical connectivity of machines on an inter-network.

-Trace-route using ICMP time-outs, basically Trace-route is used to discover the path of a packet, how -it is traverses on an inter-network.

Address Resolution Protocol (ARP)

• ARP resolve the Software Address/IP Address into a Hardware Address/Mac Address/Physical Address

Reverse Address Resolution Protocol (RARP)

• RARP resolves the Hardware Address/Mac Address/Physical Address into Software Address/IP Address.

Proxy Address Resolution Protocol (Proxy ARP)

• The Proxy ARP occurs, if one node will respond to an ARP request on behalf of another node.

To know more about Proxy ARP, go to PROXY ADDRESS RESOLUTION PROTOCOL (Proxy ARP)

Gratuitous Address Resolution Protocol (Gratuitous ARP)

• The Gratuitous ARP is sent as a broadcast message to a node to announce or update its IP to MAC mapping to the entire network.

To know more about Gratuitous ARP, go to GRATUITOUS ADDRESS RESOLUTION PROTOCOL (Proxy ARP)

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Anubhav Upadhyay

Hello and welcome to networktopic Blog. My name is Anubhav. I am a Senior Network Egineer. I have created this blog specially to serve interview questions and answer on Network Routing and Switching, I will try my best to serve correct and updated networking knowledge for you as per my corporate experience.

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