Sign of the Times

Network Layer

The OSI layer responsible for addressing, encapsulation, routing, and de-encapsulation of packets to enable communication between networks.

IPv4 (Internet Protocol Version 4)

A network layer protocol that uses 32-bit addresses to identify devices and route packets across networks.

IPv6 (Internet Protocol Version 6)

A network layer protocol that uses 128-bit addresses and provides a larger address space, simplified headers, and improved packet handling.

IP Encapsulation

The process of enclosing a transport layer segment within an IP packet for transmission across a network.

Connectionless Communication

A communication method in which no connection is established between source and destination before data is sent.

Best-Effort Delivery

A delivery model in which packets are transmitted without guarantees of successful delivery, sequencing, or error recovery.

Media Independence

A characteristic of IP that allows packets to be transmitted over different physical media and data link technologies.

Maximum Transmission Unit (MTU)

The largest packet size that can be transmitted over a network medium without fragmentation.

Fragmentation

The process of dividing an IPv4 packet into smaller packets to accommodate a network segment with a smaller MTU.

Differentiated Services (DiffServ)

A quality-of-service mechanism used to classify and manage network traffic priorities.

Header Checksum

An IPv4 header field used to detect errors in the packet header.

Time to Live (TTL)

An IPv4 field that limits the number of router hops a packet can traverse before being discarded.

Protocol Field

An IP header field that identifies the encapsulated upper-layer protocol, such as TCP, UDP, or ICMP.

Traffic Class

An IPv6 header field used to prioritize and manage packet traffic for quality of service.

Flow Label

An IPv6 header field used to identify packets belonging to the same traffic flow for special handling.

Payload Length

An IPv6 header field that specifies the size of the data portion carried by the packet.

Hop Limit

An IPv6 field that limits the number of router hops a packet can traverse before being discarded.

Extension Header (EH)

An optional IPv6 header placed between the main IPv6 header and payload to provide additional network-layer information.

Routing Table

A data structure used by hosts and routers to determine the best path for forwarding packets.

Default Gateway

A router or Layer 3 device that forwards traffic from a local network to remote networks.

Host Routing Table

A routing table maintained by an end device that determines how packets are sent to local or remote destinations.

Router Routing Table

A routing table maintained by a router containing information used to forward packets between networks.

Directly Connected Route

A route automatically added to a router's routing table for networks attached to active interfaces.

Remote Route

A route to a network that is not directly connected and is learned either statically or dynamically.

Default Route

A route used when no more specific route exists in the routing table.

Static Route

A manually configured route that specifies a fixed path to a destination network.

Dynamic Routing

A routing method in which routers automatically discover, update, and maintain routes using routing protocols.

OSPF (Open Shortest Path First)

A dynamic routing protocol that exchanges routing information to determine optimal paths between networks.

EIGRP (Enhanced Interior Gateway Routing Protocol)

A dynamic routing protocol that uses metrics to select efficient routes between networks.