9. Glossary
AAA — Authentication, Authorization, and Accounting; centralized security framework for user access management. See section 6.8.
ACL — Access Control List; packet filter that permits or denies traffic based on header criteria. See section 6.6.
AD — Administrative Distance; trustworthiness rating (0-255) that determines route preference when multiple routing sources exist. See section 4.1.4.
ARP — Address Resolution Protocol; maps IP addresses to MAC addresses within a broadcast domain. See section 1.3.
BGP — Border Gateway Protocol; path-vector routing protocol used for internet routing between autonomous systems.
BPDU — Bridge Protocol Data Unit; STP control messages exchanged between switches to build a loop-free topology. See section 3.5.
CAPWAP — Control and Provisioning of Wireless Access Points; tunnel protocol connecting lightweight APs to WLCs. See section 3.6.3.
CDP — Cisco Discovery Protocol; proprietary Layer 2 neighbor discovery protocol. See section 3.3.1.
CIDR — Classless Inter-Domain Routing; IP addressing without traditional class boundaries, enabling flexible subnet sizes. See section 2.6.
CLI — Command Line Interface; text-based device management interface.
DHCP — Dynamic Host Configuration Protocol; automatically assigns IP configuration to clients using the DORA process. See section 5.3.
DNS — Domain Name System; hierarchical system that resolves domain names to IP addresses. See section 5.3.2.
DR — Designated Router; OSPF router elected to flood LSAs on multi-access networks, reducing adjacencies. See section 4.4.3.
DSCP — Differentiated Services Code Point; 6-bit QoS marking field in the IP header. See section 5.7.
EtherChannel — Link aggregation technology that bundles multiple physical links into one logical link for bandwidth and redundancy. See section 3.4.
FHRP — First Hop Redundancy Protocol; gateway redundancy protocols (HSRP, VRRP, GLBP) that provide backup default gateways. See section 4.5.
FTP — File Transfer Protocol; TCP-based file transfer with authentication on ports 20/21. See section 5.9.
GLBP — Gateway Load Balancing Protocol; Cisco FHRP that provides load balancing across multiple gateways. See section 4.5.
HSRP - Hot Standby Router Protocol; Cisco FHRP for gateway redundancy
ICMP - Internet Control Message Protocol; ping and error messages
IEEE - Institute of Electrical and Electronics Engineers; standards body
IOS - Internetwork Operating System; Cisco device operating system
IPsec - IP Security; VPN encryption and authentication protocol suite
JSON - JavaScript Object Notation; data encoding format for APIs
LACP - Link Aggregation Control Protocol; IEEE 802.3ad EtherChannel negotiation
LLDP - Link Layer Discovery Protocol; IEEE neighbor discovery
LSA - Link-State Advertisement; OSPF topology information
MAC - Media Access Control; Layer 2 hardware address
MIB - Management Information Base; SNMP database structure
NAT - Network Address Translation; private-to-public IP translation
NDP - Neighbor Discovery Protocol; IPv6 equivalent of ARP
NTP - Network Time Protocol; clock synchronization
OSPF - Open Shortest Path First; link-state routing protocol
PAT - Port Address Translation; many-to-one NAT using ports
PDU - Protocol Data Unit; data at each layer (frame, packet, segment)
PoE - Power over Ethernet; power delivery over data cables
PSK - Pre-Shared Key; shared password for wireless authentication
QoS - Quality of Service; traffic prioritization mechanisms
RADIUS - Remote Authentication Dial-In User Service; AAA protocol
REST - Representational State Transfer; API architecture style
RFC - Request for Comments; internet standards documents
RIP - Routing Information Protocol; distance-vector routing protocol
RSTP - Rapid Spanning Tree Protocol; fast-converging STP
SDN - Software-Defined Networking; controller-based network architecture
SNMP - Simple Network Management Protocol; device monitoring
STP - Spanning Tree Protocol; loop prevention
SSH - Secure Shell; encrypted remote access
SSID - Service Set Identifier; wireless network name
SVI - Switch Virtual Interface; Layer 3 VLAN interface
TACACS+ - Terminal Access Controller Access Control System Plus; Cisco AAA
TCP - Transmission Control Protocol; reliable Layer 4 transport
TFTP - Trivial File Transfer Protocol; simple UDP file transfer
TTL - Time to Live; packet hop limit
UDP - User Datagram Protocol; best-effort Layer 4 transport
VLAN - Virtual Local Area Network; Layer 2 broadcast domain segmentation
VPN - Virtual Private Network; encrypted tunnel over public network
VRF - Virtual Routing and Forwarding; routing table virtualization
VRRP - Virtual Router Redundancy Protocol; open standard FHRP
WLC - Wireless LAN Controller; centralized AP management
WPA - Wi-Fi Protected Access; wireless security standard
