CCIE Enterprise key terms

A logical grouping of OSPF-enabled interfaces that shares one link-state database. Areas limit LSA flooding and SPF recalculation, and every non-backbone area must connect to area 0.

A configuration container in Cisco EIGRP that groups global, address-family, and interface settings under one named process, supporting IPv4 and IPv6 with per-address-family authentication and timers.

A BGP speaker permitted to reflect routes learned from one iBGP peer to other iBGP peers, removing the need for a full mesh. Clients treat reflected routes as learned from the reflector.

Virtual Routing and Forwarding: a router feature that keeps multiple independent routing tables on one device, allowing overlapping address space and traffic separation without separate hardware.

Multiprotocol BGP extends BGP to carry reachability for multiple address families, such as IPv6, VPNv4, and EVPN, using address-family configuration and extended communities to identify each context.

A tunneling technology that encapsulates Layer 2 frames inside UDP/IP, using a 24-bit VNI to identify up to 16 million logical networks across a routed underlay.

Ethernet VPN: a BGP address family that distributes MAC and IP reachability for overlay networks, commonly used as the control plane for VXLAN fabrics and MPLS-based Ethernet services.

A multicast routing mode where traffic is delivered only to receivers that explicitly join a group. A rendezvous point builds shared trees, and routers switch to shortest-path source trees.

The ICMPv6-based protocol suite that replaces ARP in IPv6, handling address resolution, router discovery, duplicate address detection, and stateless address autoconfiguration.

Cisco's first-hop redundancy protocol in which routers share a virtual IP and MAC address; one router actively forwards, another stands by, and priorities plus tracking control failover.

Locator/ID Separation Protocol: an overlay control and data plane that separates endpoint identity (EID) from routing location (RLOC), letting a mapping system redirect traffic without changing endpoint addresses.

A Cisco campus architecture that combines VXLAN data encapsulation, a LISP-based control plane, and Cisco TrustSec segmentation to provide policy-driven, automated wired and wireless connectivity.

An SD-Access device that connects a fabric site to external networks or other fabric sites, handling VXLAN decapsulation and route redistribution between fabric and non-fabric domains.

An SD-Access node that runs the LISP map-server and map-resolver functions, answering endpoint location queries so fabric edge nodes know where to tunnel traffic.

A software-defined WAN solution with centralized controllers that manage overlay tunnels, policy, and application-aware routing across mixed transport links using OMP.

Overlay Management Protocol: the Cisco SD-WAN control protocol that exchanges routes, policies, and TLOC attributes between vSmart controllers and WAN edge routers over encrypted sessions.

The Cisco SD-WAN controller that runs OMP, computes and distributes overlay routing and policy to edge devices, and maintains the network's centralized control plane.

Label Distribution Protocol: an MPLS control protocol where routers exchange label bindings for IGP-learned prefixes, building label-switched paths hop by hop without traffic engineering.

An MPLS or IPv6 source-routing model where the ingress node encodes a path as an ordered list of segments (SIDs), eliminating per-hop signaling and simplifying traffic engineering.

Dynamic Multipoint VPN: a hub-and-spoke IPsec and GRE design using NHRP for tunnel address resolution, allowing spokes to build direct tunnels to each other on demand.

A Cisco IPsec/IKEv2 framework that uses virtual templates and authorization to build hub-and-spoke or point-to-point tunnels with per-peer policy and dynamic routing.

A suite of protocols that authenticates and encrypts IP packets using AH or ESP, with IKE negotiating security associations. It protects site-to-site and remote-access VPN traffic.

Bidirectional Forwarding Detection: a lightweight protocol that rapidly detects path failures between two routers using short-interval hello packets, triggering faster routing-protocol convergence than native timers.

The point in the network where packet markings are accepted and trusted; devices before it classify and mark traffic, while devices beyond it rely on existing DSCP or CoS values.

IEEE 802.1AE link-layer encryption that protects Ethernet frames between directly connected devices using per-hop keys, providing confidentiality and integrity without IPsec overhead.

An IEEE port-based access control standard where a supplicant authenticates through an authenticator to a RADIUS server before the switch port grants network access.

Cisco Identity Services Engine: a policy server providing RADIUS and TACACS+ authentication, authorization, posture assessment, and guest access for wired, wireless, and VPN users and devices.

Security Group Tag: a value inserted in a Cisco header that identifies the role of a source, enabling group-based policy enforcement without depending on IP addresses or subnets.

Control Plane Policing: a QoS feature that rate-limits traffic destined to the router's CPU, protecting routing and management protocols from floods and denial-of-service attacks.

Unicast Reverse Path Forwarding: an anti-spoofing check that drops packets whose source address is not reachable via the receiving interface; strict and loose modes vary the verification.

A Cisco IOS firewall configuration model where interfaces are assigned to zones and traffic between zones is inspected by class and policy, replacing interface-based ACL filtering.

Public Key Infrastructure: the framework of certificate authorities, certificates, and enrollment protocols that binds public keys to identities, enabling authentication for VPNs, ISE, and device management.

A network management protocol that uses SSH transport and XML-encoded RPCs to read, edit, and commit configuration on network devices, supporting candidate configurations and transactions.

A data modeling language that defines the structure, constraints, and hierarchy of network device configuration and state, used by NETCONF, RESTCONF, and model-driven telemetry.

An HTTP-based protocol that exposes YANG-modeled data through REST methods such as GET, POST, PUT, PATCH, and DELETE using XML or JSON, offering a simpler alternative to NETCONF.

gRPC Network Management Interface: a modern protocol for retrieving, setting, and subscribing to YANG-modeled device data, widely used for high-frequency streaming telemetry.

A push model where network devices periodically stream structured, YANG-defined operational data to a collector, replacing polling via SNMP or CLI and enabling near-real-time monitoring.

An agentless automation tool that runs YAML playbooks over SSH or API connections to configure and validate network devices, using idempotent modules and inventories.

Embedded Event Manager: a Cisco IOS feature that watches for syslog, SNMP, CLI, or timer events and triggers automated actions such as applets or Tcl scripts.