Network Troubleshooting Notes: Optical Link Budget, Certificates, Licensing, BYOD, and Hardware Failures

Vocabulary flashcards covering key concepts from the lecture notes on optical link budgets, digital certificates and PKI, licensing, BYOD, and hardware failures.

Optical link budget

Total calculation of all anticipated losses along a fiber optic link to ensure the received signal is sufficient for proper operation.

Optimal link budget

Comprehensive calculation that considers all anticipated losses along the fiber path to guarantee adequate signal at the receiver.

dB/km

Decibels per kilometer; unit of attenuation used to express how much signal is lost per kilometer of fiber.

OTDR

Optical Time Domain Reflectometer; instrument that measures losses and reflections along a fiber and reports attenuation (often in dB/km).

Attenuation

Reduction in optical power as light travels through fiber, connectors, splices, and components.

Splice

Method of joining two fiber ends; can introduce additional signal loss if not done properly.

Patch panel

Panel that organizes and terminates connections; can contribute to insertion losses in a fiber run.

Multiplexing losses

Power loss incurred when combining multiple signals into a single fiber path.

Demultiplexing losses

Power loss incurred when separating multiple signals at the receiving end.

Receiver power budget

The amount of optical power that must arrive at the receiver for proper operation.

Link budget calculation

Process of subtracting all losses (distance, connectors, splices, mux/demux) from the transmitter power to determine the received level.

Receiver sensitivity range

The range of signal levels the receiver can detect, e.g., approximately -7 to -23 dB.

Digital certificate

Credential used to verify identities in TLS/HTTPS and other network authentication contexts.

Certificate Authority (CA)

Trusted entity that issues and signs digital certificates used in public key infrastructure.

SSL/TLS certificate

Certificate used to establish secure connections over HTTPS by enabling encryption and authentication.

Untrusted certificate

Certificate not signed by a trusted CA or with an invalid/unknown chain, causing security warnings.

Expired certificate

Certificate that is past its validity period and is considered invalid.

Root certificate

Top-level certificate in a trust chain; trusted root certificates anchor trust relationships.

802.1X with EAP

Network access control using certificates and the Extensible Authentication Protocol (EAP) to authenticate devices/users.

License feature issue

Error indicating a device reports a feature as not licensed or unlocked.

License key

Key used to unlock features on a device; can correspond to different license tiers.

Platinum license

Top-tier license that unlocks the full feature set required by advanced configurations.

Gold license

Mid- or lower-tier license that may omit some features needed for certain deployments.

Global Server Load Balancing (GSLB)

Feature to distribute user requests across geographically dispersed servers; requires appropriate licensing.

Clustering

Feature enabling coordinated operation of multiple devices; typically requires a higher license.

Feature not licensed error

Error indicating a requested feature isn’t available due to the current license.

BYOD

Bring Your Own Device policy; employees use personal devices on the corporate network.

MAC address registration

Process of registering device MAC addresses so they can be recognized or whitelisted on the network.

Screened subnet

A secured subnet that isolates BYOD devices behind a firewall or screening device before accessing the internal network.

Hardware failure

Failure of networking hardware components (routers, switches, firewalls) requiring troubleshooting and possible replacement.

Dual power supply

Redundant power supplies that keep a device running if one supply fails.

Emergency maintenance window

Scheduled time to perform urgent hardware replacements or maintenance to restore service.