Networking Routing Protocols and VLANs: Concepts and Configurations

Static Routing

Routes manually entered and maintained by the network administrator.

Dynamic Routing

Automatically updates routing tables to account for lost or changed routes.

router(config-if)#

The prompt indicating you are in the router's interface configuration mode.

Gateway

The networking device that enables data to enter and exit a LAN; the exit point for packets.

MAC Address

The physical address used by switches to forward data and map devices to specific ports.

Switch

A Layer 2 device used to interconnect hosts within a LAN.

network command

Used by dynamic routing protocols to advertise connected networks to other routers.

EIGRP

Enhanced Interior Gateway Routing Protocol; a Cisco-proprietary routing protocol.

Network Segment

Defines the physical link between two internetworking devices, like a router and a switch.

Next Hop Address

The IP address of the next router that a data packet must be sent to reach its destination.

Gateway Address

The IP address of the router interface connected to the local LAN.

? symbol

The Cisco command line interface symbol used to view help commands.

Switch OSI Layer

Operates at Layer 2 (Data Link Layer).

VLAN Security

Logically isolates users and contains broadcasts, providing better network security.

Gi0/0

Interface notation standing for Gigabit interface 0/0.

Static VLAN

A port-based VLAN created by manually assigning specific switch ports to a VLAN.

PoE (Power over Ethernet)

Provides electrical power over network cabling, eliminating the need for separate electrical outlets.

PoE Device Types

Power Sourcing Equipment (PSE) like switches, and Powered Devices (PD) like IP phones.

PoE Discovery

The process used to identify if a connected device requires power before supplying it.

ping

The command used to test network connectivity (e.g., ping 10.10.20.5).

OSPF Advantages

Rapid convergence, minimal bandwidth consumption, and support for VLSM.

VLSM (Variable Length Subnet Masking)

Allows efficient use of IP address space by creating different-sized subnets.

OSPF Areas

Used to partition large networks into smaller ones, minimizing route calculations.

OSPF Area 0

The reserved backbone area; all other OSPF areas must connect directly to it.

OSPF Hello Packets

Small packets used to verify that communication is established and active with neighbor routers.

OSPF Configuration Command

network [IP address] [wildcard mask] area [number] (e.g., network 10.10.0.0 0.0.255.255 area 0).

Hop Count

A metric representing the total number of routers a data packet crosses to reach its destination.

Routing Metric

A numeric ranking used by routers to find the best route; smaller numbers are better.

configure terminal (conf t)

The command used to enter global configuration mode from privileged EXEC mode.

Gateway of Last Resort

A default route (0.0.0.0) for forwarding data packets with unknown destination routes.

RIP (Routing Information Protocol)

Classified as a distance vector routing protocol.

Link-State Protocol Features

Uses Hello packets, establishes adjacencies, and sends updates only when route changes occur.

Link-State Convergence

Very fast because it sends updates only when the topology changes, not at fixed intervals.

OSPF Characteristics

An open standard protocol supported by many vendors, not just Cisco.

Three types of VLANs

Port-based, Tag-based, and Protocol-based.

VLAN Advantage

Allows grouping of computers logically by function rather than physical location.

Distance Vector vs. Link-State

Distance vector periodically sends the entire routing table (slow, high bandwidth). Link-state only sends updates on network changes (fast, low bandwidth).

Dynamic Routing Issues

Distance vector protocols can suffer from routing loops and consume excessive bandwidth.

Route Metrics Examples

Hop count, reliability, bandwidth, delay, cost, load, and ticks.