Comparing DMVPN Single Tier and Dual Tier Headend Architectures - IPSec VPN & mGRE Termination

This article explains the difference between DMVPN Single Tier and Dual Tier Headend setup. We examine each model and show how IPSec and GRE/mGRE tunnels terminate on the Hub Headend and Frontend router. Detailed diagrams show how protocol packets are encapsulated and decapsulated for each scenario.

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-services-tech/910-cisco-dmvpn-single-dual-tier.html

Configuring Cisco Dynamic Multipoint VPN (DMVPN) - Hub, Spokes, mGRE Protection and Routing

This article covers setup and configuration of Cisco DMVPN. Topics covered include: DMVPN operation, Configuring DMVPN Hub router, NHRP, mGRE, DMVPN Spoke routers, Protecting DMVPN with IPSec, enable routing between DMVPN tunnels and verifying DMVPN status and remote networks.

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/901-cisco-router-dmvpn-configuration.html

Understanding Cisco Dynamic Multipoint VPN - DMVPN, mGRE, NHRP

This article serves as an introduction to the Cisco Dynamic Multipoint VPN (DMVPN) service. Learn what DMVPN is, mechanisms used (NHRP, mGRE, IPSec) to achieve its flexibility and data confidentiality, plus the prerequisites for installation and setup. DMVPN Hub & Spoke, Spoke-to-Spoke concepts are also covered using our unique network diagrams.

To read our DMVPN article, click here.

Cisco GRE and IPSec - GRE over IPSec - Selecting and Configuring GRE IPSec Tunnel or Transport Mode

This article aims to explain the differences between GRE IPSec Tunnel and GRE IPSec Transport mode and how they can be configured and implemented in a Secure Cisco VPN Network. Packet Analysis of both modes with detailed diagrams and Cisco IOS configuration commands, ensures the reader will not be left with any unanswered questions on this topic!

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/872-cisco-router-gre-ipsec-tunnel-transport.html

Configuring Point-to-Point GRE VPN Tunnels - Unprotected GRE & Protected GRE over IPSec Tunnels

This article covers the configuration of Cisco GRE Tunnels, unprotected & IPSec protected. GRE Routing between networks, GRE over IPSec and verification commands are included to ensure the GRE IPSec tunnel is operating. Diagrams, commands, mtu, transport modes, isakmp, ipsec and more are analysed in great depth.

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/868-cisco-router-gre-ipsec.html