| 802.3 | Ethernet |
| AAA | Authentication Authorization Accounting |
| ABR | Area Border Router |
| ACL | Access Control List |
| AD | Advertised Distance |
| AD | Administrative Distance |
| AF | Assured Forwarding |
| API | Application Programming Interface |
| APIC | Cisco Application Policy Infrastructure Controller |
| APIC-EM | Application Policy Infrastructure Controller – Enterprise Module |
| ARP | Address Resolution Protocol |
| AS | Autonomous System |
| ASBR | Autonomouse System Boundary Router |
| ASN | Autonomous System Number |
| ATM | Asynchronous Transfer Mode |
| Auto-MDIX | Automatic Medium Dependent Interface Crossover |
| BDR | Backup Designated Router |
| BGP | Border Gateway Protocol |
| BID | Bridge ID |
| BPDU | Bridge Protocol Data Unit |
| CAC | Call Admission Control |
| CAPWAP | Control and Provisioning of Wireless Access Points |
| CBWFQ | Class-based Weighted Fair Queuing |
| CDPCP | Cisco Discovery Protocol Control Protocol |
| CE | Customer Edge |
| CHAP | Challenge Handshake Authentication Protocol |
| CIR | Committed Information Rate |
| Cisco AVC | Cisco Application Visibility and Control |
| Cisco TAC | Cisco Technical Assistence Center |
| Cisco WAAS | Cisco Wide Area Application Services |
| CLI | Command Language Interpreter |
| CO | Central Office |
| CoS | Class of Service |
| CPE | Customer Premises Equipment |
| CQ | Custom Queuing |
| CRC | Cyclic Redundancy Check |
| CS | Class Selector |
| CST | Commong Spanning Tree |
| CSU | Channel Service Unit (CSU/DSU) |
| DAD | Duplicate Address Detection |
| DAI | Dynamic ARP Inspection |
| DBD | Database Description |
| DCE | Data Communications Equipment |
| DDN | Dotted-decimal Numbers |
| DHCP | Dynamic Host Configuration Protocol |
| DMVPN | Dynamic Multipoint Virtual Private Network (Cisco proprietary) |
| DNS | Domain Name System |
| DR | Designated Router |
| DSCP | Differentiated Services Code Point |
| DSL | Digital Subscriber Line |
| DSLAM | DSL access multiplexer |
| DSU | Data Service Unit (CSU/DSU) |
| DTE | Data Terminal Equipment |
| DTP | Dynamic Trunking Protocol |
| DUAL | Diffusing Update Algorithm |
| E1 | European variant of T1 |
| EAPoL | EAP over LAN |
| EBGP | External Border Gateway Protocol |
| E-carrier | European digital transmission format |
| EF | Expedited Forwarding |
| EGP | Exterior Gateway Protocol |
| EIGRP | Enhanced Interior Gateway Routing Protocol |
| EoMPLS | Ethernet over MPLS |
| EUI-64 | Extended Unique Identifier |
| EVC | Ethernet Virtual Connection |
| EVC | Ethernet Virtual Circuit |
| FD | Feasible Distance |
| FHRP | First Hop Redundancy Protocol |
| FIFO | First-in, First-out |
| FTP | File Transfer Protocol |
| GGP | Gateway to Gateway Protocol |
| GLBP | Gateway Load Balancing Protocol |
| GRE | Generic Routing Encapsulation |
| HDLC | High-Level Data Link Control |
| HSRP | Hot Standy Router Protocol |
| HTTP | Hypertext Transfer Protocol |
| HWIC | High-speed WIC |
| IANA | Internet Assigned Numbers Authority |
| IBGP | Internal Border Gateway Protocol |
| ICANN | Internet Corporation for Assigned Names and Numbers |
| ICMP | Internet Control Message Protocol |
| IETF | Internet Engineering Task Force |
| IGP | Interior Gateway Protocol |
| IGRP | Interior Gateway Routing Protocol |
| IKE | Internet Key Exchange |
| ILMI | Integrated Local Management Interface |
| IoT | Internet of Things |
| IP | Internet Protocol |
| IPCP | IP Control Protocol |
| IPP | IP Precedence |
| IPsec | IP Security |
| IPsec AH | Authentication Header |
| IPsec ESP | Encapsulating Security Payload |
| IPsec VTI | Virtual Tunnel Interface (Cisco Proprietary) |
| IPv4 | IP version 4 |
| IPv6 | IP version 6 |
| IPX | Internetwork Packet Exchange |
| ISDN | Integrated Services Digital Network |
| IS-IS | Intermediate System-to-Intermediate System |
| ISP | Internet Service Provider |
| IVR | inter-VLAN routing |
| IWAN | Intelligent WAN |
| IXP | Internet Exchange Point |
| LACP | Link Aggregation Control Protocol |
| LAN | Local-area network |
| LCP | Link Control Protocol |
| LEC | Local Exchange Carrier |
| LED | Light Emitting Diode |
| LLC | Logical Link Control, sublayer, 802.2 standard Data Link Layer |
| LLQ | Low Latency Queuing |
| LSA | Link-state Advertisement |
| LSAck | Link-state Acknowledgment |
| LSDB | Link-state Database |
| LSR | Link-state Request |
| LSU | Link-state Update |
| LWAPP | Lightweight Access Point Protocol |
| MAC | Media Access Control, sublayer, 802.3 standard Data Link Layer |
| MAN | Metropolitan Area Network |
| MD5 | Message Digest 5 |
| MEC | Multichassis EtherChannel |
| mGRE | multipoint Generic Routing Encapsulation |
| MIB | Management Information Base |
| MISTP | Multi-Instance STP |
| MLP | Multilink PPP |
| MPLS | Multiprotocol Label Switching |
| MQC | Modular QoS CLI |
| MST | Multiple Spanning Tree |
| MSTP | Multiple Spanning Tree Protocol |
| MTU | Maximum Transmission Unit |
| NAT | Network Address Translation |
| NBAR | Network-Based Application Recognition |
| NBAR2 | Next-generation Network-Based Application Recognition |
| NBI | Northbound Interface |
| NCP | Network Control Protocol |
| NETCONF | Network Configuration Protocol |
| NFV | Network Functions Virtualization |
| NHRP | Next Hop Resolution Protocol |
| NIC | Network Interface Card |
| NIM | Network Interface Modules |
| NLRI | Network Layer Reachability Information |
| NMS | Network Management System |
| NTP | Network Time Protocol |
| ONF | Open Networking Foundation |
| OSI | Open Systems Interconnection |
| OSPF | Open Shortest Path First |
| OUI | Organizational Unique Identifier |
| P routers | Provider Router |
| PA | Path Attributes |
| PADI | PPPoE Active Discovery Initiation |
| PADO | PPPoE Active Discovery Offer |
| PADR | PPPoE Active Discovery Request |
| PADS | PPPoE Active Discovery Session-confirmation |
| PAgP | Port Aggregation Protocol |
| PAP | Password Authentication Protocol |
| PCP | Priority Code Point |
| PDLM | Packet Description Language Module |
| PDU | Protocol Data Unit |
| PE | Provider Edge |
| POP | Point Of Presence |
| PPP | Point-to-Point Protocol |
| PPPoE | PPP over Ethernet |
| PQ | Priority Queuing |
| PSK | Preshared Key |
| PSTN | Public Switched Telephone Network |
| PVST+ | Per VLAN Spanning Tree Plus |
| QoE | Quality of Experience |
| QoS | Quality of Service |
| RADIUS | Remote Authentication Dial-In User Service |
| Rapid PVST+ | Rapid Per VLAN Spanning Tree Plus |
| RD | Reported Distance |
| RD/AD | Reported Distance/Advertised Distance |
| RED | Random Early Detection |
| REST | Represented State Transfer |
| RID | Router ID |
| RIP | Routing Information Protocol |
| RIR | Regional Internet Registry |
| RPC | Remote Procedure Call |
| RSTP | Rapid Spanning Tree Protocol |
| RSTP+ | Rapid Spanning Tree Protocol Plus |
| RSVP | Resource Reservation Protocol |
| RTP | Reliable Transport Protocol |
| SBI | Southbound Interface |
| SDN | Software-defined Networking |
| SHA | Secure Hash Algorithm |
| SLA | Service Level Agreement |
| SLAAC | Stateless Address Autoconfiguration |
| SMTP | Simple Mail Transfer Protocol |
| SNMP | Simple Network Management Protocol |
| SPAN | Switched Port Analyzer |
| SPF | Shortest Path First |
| SRTT | Smoothed Round-trip Time |
| SSH | Secure Shell Protocol |
| SSL | Secure Socket Layer |
| STP | Spanning Tree Protocol |
| SVI | Switch Virtual Interface |
| SVI | switched virtual interface |
| syslog | System Logging |
| T1 | Digital WAN carrier facility |
| TACACS+ | Terminal Access Controller Access Controller System Plus |
| T-carrier | TDM transmission method |
| TCP | Transmission Control Protocol |
| TDM | Time-division multiplexing |
| TID | Traffic Identifier |
| ToS | Type of Service |
| TPID | Tag Protocol ID |
| TTL | Time to Live |
| UDP | User Datagram Protocol |
| UNI | User Network Interface |
| VID | VLAN ID |
| VLAN | Virtual LAN |
| VLSM | Variable-length Subnet Mask/masking |
| VoIP | Voice over IP |
| VPDN | Virtual Private Dial-up Networks |
| VPLS | Virtual Private LAN Service |
| VPN | Virtual Private Network |
| VPWS | Virtual Private Wire Services, also known as ETHoMPLS Ethernet over MPLS
or VLL Virtual Leased Line |
| VRRP | Virtual Router Redundancy Protocol |
| VTI | Virtual Tunnel Interface |
| VTP | VLAN Trunking Protocol |
| VTY | Virtual Type Terminal |
| WAN | Wide-area Network |
| WFQ | Weighted Fair Queuing |
| WIC | WAN Interface Card |
| WRED | Weighted Random Early Detection |