Routing Concepts – Vocabulary Flashcards

Vocabulary flashcards covering key routing concepts from the lecture notes, including routers, packets, BGP, routing tables, IP addressing, encapsulation, ARP, static/dynamic routing, and path selection.

Router

A device that connects different networks and forwards packets between them, acting as the traffic controller of the Internet.

Packet

A chunk of data broken from a larger message that travels across the network in hops to its destination.

Hop

One move of a packet from one router to the next on its journey to the destination.

BGP (Border Gateway Protocol)

The routing protocol used by Internet service providers to exchange reachability information and determine routes across the global Internet.

IP Routing Table

A router’s RAM-based database of networks, next-hop addresses, exit interfaces, and path metrics used to forward packets.

Network Address (Example: 192.168.1.0/24)

The destination network portion defined by the subnet mask; 192.168.1.0/24 represents the 192.168.1.0 network.

Next-Hop IP Address

The IP address of the next router toward the destination.

Exit Interface

The local router interface used to forward a packet toward its next hop.

Administrative Distance (AD)

A value that ranks how trustworthy the source of a routing entry is; lower AD is preferred.

Metric

A numeric cost used by a routing protocol to rate a path; lower is better. Different protocols compute it differently.

Route Source Codes

Indicators of how a route was learned: C = Connected, S = Static, D = EIGRP, O = OSPF.

Static Routing

Manually configured routes by an administrator; secure and predictable but not scalable.

Dynamic Routing

Routes learned automatically from other routers via protocols such as OSPF and EIGRP.

Encapsulation

Wrapping an IP packet inside a Layer 2 frame for transmission to the next hop.

De-Encapsulation

Removing the Layer 2 frame to read the Layer 3 IP header.

ARP (Address Resolution Protocol)

Protocol that maps IP addresses to MAC addresses on the local network.

IP Address

A unique numerical label assigned to a device for identification and routing on a network.

Subnet Mask

Defines the size of a network; e.g., /24 corresponds to 255.255.255.0.

ISP (Internet Service Provider)

A company that provides access to the Internet and connects you to the larger network.

Path Determination

The router process of selecting the best path to a destination using the routing table and metrics.

Best Path

The most efficient route, typically the one with the lowest metric as determined by the routing protocol.

Layer 2 vs Layer 3

Layer 2 is the data-link (Ethernet) layer; Layer 3 is the network (IP) layer; routers operate at Layer 3.

Packet Forwarding

The process of a router receiving a packet and sending it out on another interface toward its destination.

Next-Hop MAC Address

The MAC address of the next-hop router used to forward a frame toward the destination.

Re-Encapsulation

Encapsulating a packet again in a new Layer 2 frame for transmission on the next network.