DMVPN
Dynamic Multipoint VPN (DMVPN) builds on-demand spoke-to-spoke IPsec tunnels using multipoint GRE and NHRP for scalable hub-and-spoke VPNs. ENARSI covers troubleshooting DMVPN under VPN technologies.
All 300-410 Terms
Administrative Distance
Administrative Distance (AD) is the trustworthiness ranking a router assigns to a routing source, lower being preferred, used to choose between protocols offering the same prefix.
Route Redistribution
Route Redistribution injects routes learned by one routing protocol into another, requiring care with metrics, tags, and loop prevention.
Route Map
A Route Map is an ordered set of match/set clauses used to filter and manipulate routes or implement policy-based routing.
PBR
Policy-Based Routing (PBR) forwards packets based on a route map's criteria rather than the destination-based routing table.
EIGRP
EIGRP is Cisco's advanced distance-vector protocol using DUAL for loop-free paths and composite metrics.
OSPF
OSPF is a link-state IGP that builds a topology database and runs SPF, organized into areas with LSAs.
BGP
Border Gateway Protocol (BGP) is the path-vector protocol that exchanges routing and reachability between autonomous systems using attributes for best-path selection.
VRF-Lite
VRF-Lite creates multiple isolated Layer 3 routing tables on a single router without MPLS, keeping customer traffic separated.
MPLS L3VPN
MPLS L3VPN (MPLS Layer 3 VPN) uses VRFs, MP-BGP, and label switching to carry isolated customer routes across a provider MPLS core.
DMVPN
Dynamic Multipoint VPN (DMVPN) builds on-demand spoke-to-spoke IPsec tunnels using multipoint GRE and NHRP for scalable hub-and-spoke VPNs.
IPsec
IPsec is the suite that authenticates and encrypts IP traffic, used for site-to-site and remote tunnels including within DMVPN.
Infrastructure ACL
An Infrastructure ACL is an access control list that protects the network's core devices and control plane from unwanted traffic.
CoPP
Control Plane Policing (CoPP) rate-limits traffic destined to the router's control plane to protect the CPU from attacks and overload.
uRPF
uRPF (Unicast Reverse Path Forwarding) drops packets whose source address fails a reverse-path check: strict mode requires the source to be reachable via the receiving interface, while loose mode only requires a route to the source via any interface.
IP SLA
IP SLA generates synthetic probes to measure network performance (latency, jitter, reachability) and can trigger object tracking.