Network Layer Characteristics and Protocols

IPv4 header contains crucial information for packet routing, includes details like source and destination addresses, and protocol used.

IPv4 uses a 4-bit field to indicate version 4, distinguishing it from the newer IPv6.

A layer 3 hop count field in the IPv4 header that decreases with each hop. The packet is discarded when it reaches zero.

The IP addresses used in the IPv4 header to identify the source and destination of the packet.

IPv6 was designed to address the shortcomings of IPv4, such as address depletion and limited connectivity.

The main challenge IPv4 faced was running out of available IP addresses.

NAT was introduced to extend the life of IPv4, but it came with drawbacks like increased network complexity and potential performance issues.

IPv6 was created by the Internet Engineering Task Force (IETF) to overcome the limitations of IPv4.

A special IP address (127.0.0.1 for IPv4, ::1 for IPv6) used by a host to refer to itself. It allows a host to send and receive data to its own local processes.

A process where a host decides the best route for a packet to reach a destination. This involves evaluating the destination's network and its own network configuration.

Traffic destined for a host on the same local area network (LAN) as the sending host.

Traffic that needs to be sent to a host on a different network than the sending host.

A router or Layer 3 switch that acts as a gateway for hosts on a local network to access other networks.

A route entry that defines the path to take for any destination network that is not explicitly specified in the routing table. This is the default path for traffic leaving the local network.

A list of network routes that a host uses to decide which network interface and path network traffic should be sent through to reach a destination.

The process of identifying and communicating with the default gateway. Hosts need to know the default gateway address to send traffic to remote networks.

IPv6 uses a 128-bit address space, significantly larger than IPv4's 32-bit address space. This abundance of addresses eliminates the need for NAT, which translates private addresses to shared public addresses.

The IPv6 header is simplified compared to IPv4, containing fewer fields and a fixed size of 40 bytes. This streamlined header improves packet handling performance.

IPv6 uses a "Flow Label" field to identify packets belonging to the same flow. This enables devices to handle similar flows more efficiently.

The "Next Header" field in IPv6 specifies the protocol used in the payload of the packet, such as TCP, UDP, or ICMP.

IPv6 uses a "Hop Limit" field that replaces the TTL field in IPv4. This field tracks how many network hops the packet has traversed.

IPv6 packets can optionally include extension headers that provide additional information. These headers can be used for fragmentation, security, or mobility support.

IPv6 uses a "Traffic Class" field for Quality of Service (QoS) purposes, equivalent to the DiffServ field in IPv4.

Unlike IPv4, routers do not perform fragmentation on IPv6 packets. This streamlines packet forwarding and reduces processing complexities.

The process of determining the best path to send data packets between devices on a network.

This device is responsible for making routing decisions based on the destination IP address in the packet.

The router examines the destination IP address in the packet and uses its routing table to determine the best path to send the packet.

The router learns about directly connected networks and the IP addresses within those networks. The router automatically adds these routes to its routing table.

These routes are manually configured by the network administrator, and tell the router how to reach networks that are not directly connected.

These routes are learned automatically by the router through communication with other routers using routing protocols.

This command allows network administrators to view the information stored in a router's routing table.

This type of route is important for situations where there is no specific match in the routing table. It sends all traffic to a specific destination.

IP is a best-effort protocol, meaning it does not guarantee packet delivery. It operates with minimal overhead, as it doesn't resend lost data or require acknowledgments.

IP doesn't care about the underlying physical transmission medium (like copper wires, fiber optic cables, or wireless). It handles the network layer functions regardless of how data is physically traveling.

For connection-oriented services, like reliable data transfer, IP relies on protocols like TCP (Transmission Control Protocol) at the transport layer to handle these features.

When a packet is too large for the network to handle, the Network layer can break it down into smaller units. It handles this process, ensuring data is delivered to the next destination in smaller pieces.

IPv4 packets have a header that contains crucial information. It guides the packet to its destination, helps process the data, and ensures all layer 3 devices understand the packet's contents.

IPv4 is the core communication protocol for networks. It handles addressing and routing, ultimately making sure data reaches its intended destination.

IPv4 packets can be divided into smaller units during transmission if necessary. This ensures smooth data flow across networks with varying bandwidths.

IPv6, the successor to IPv4, doesn't employ fragmentation. It's designed to handle large data packets without breaking them down, optimizing network efficiency.

The network layer is responsible for connecting end devices and allowing them to exchange data. It uses IP protocols, primarily IPv4 and IPv6, to achieve communication.

Addressing: Assigning unique addresses to each device on the network. Encapsulation: Wrapping data from higher layers in an IP packet. Routing: Determining the best path for data to travel through the network. De-encapsulation: Removing the IP packet header at the destination.

IP Encapsulation: The network layer wraps data from the transport layer (segment) in an IP packet. This packet can be either IPv4 or IPv6, depending on the network protocol used. The IP packet is then forwarded through the network, with all layer 3 devices examining its contents.

The IP address remains unchanged from the source to the destination. However, this is a simplified explanation, as techniques like NAT (Network Address Translation) can modify the address during transmission.

IP is connectionless: It doesn't establish a connection before sending data. It's a best effort protocol, meaning it tries to deliver data but doesn't guarantee success. IP is media independent: It can be used over various physical mediums, like Ethernet or fiber optics.

IP doesn't require a pre-established connection with the destination. Data packets are sent out without prior confirmation.

IP doesn't guarantee delivery of packets. It tries its best, but factors like network congestion or failures can hinder data transmission. Packets might be lost, delayed, or delivered out of order.

IP can function over different types of physical connections, such as copper cables, fiber optic cables, or wireless networks. The network layer doesn't care about the underlying physical medium.