dmvpn

The video demonstrates another method of achieving redundancy in your DMVPN deployment using NHS cluster and recovery backup feature. We look at how routing and EIGRP neighbor adjacency changes when a spoke registers to one or more NHS at a time in the same cluster, and observe the failover behavior. This feature provides a good compromise between failover time and routing simplicity.

The first half of the video shows you how to specify an interesting traffic that will cause a DMVPN spoke-to-spoke tunnel to be initiated, and utilized. In the second half, we will look at an ability to configure per-tunnel QoS from hub to spokes using NHRP group.

The video shows you how to build a redundant DMVPN network with dual-hub dual-cloud design. The failover capability is provided by routing protocol. With EIGRP chosen for demonstration in this video, we show how to perform a simple tweak in the routing metric to solve potential asymmetrical routing. The video concludes with failover testing and shows that spoke-to-spoke traffic is not interrupted upon a Hub failure.

The video shows you how to build a redundant DMVPN network with dual-hub dual-cloud design. The failover capability is provided by routing protocol. With EIGRP chosen for demonstration in this video, we show how to perform a simple tweak in the routing metric to solve potential asymmetrical routing. The video concludes with failover testing and shows that spoke-to-spoke traffic is not interrupted upon a Hub failure.

The video demonstrates another benefit of DMVPN Phase 3. We look at how DMVPN operates when a large network is partitioned into hierarchical regions for scalability and still maintain the capability of creating spoke-to-spoke tunnels. The video also points out some configuration pitfalls with the NHRP network id and tunnel key.

The video extends our previous knowledge on NHRP (see videos RS0015, RS0016) by adding IPSec and form DMVPN. We walk through the crypto configuration and point out the specific to support dynamic IPSec tunnel creation for spoke-to-spoke communication. DMVPN is one of the most popular forms of WAN connectivity over internet due to the low configuration requirement and ability to allow additional sites to be brought up with minimal effort, without modifying the Hub configuration.

The video continues from "RS0015 - NHRP Phase 1" video into Phase 2 and 3 with dynamic Spoke-to-Spoke tunnels. We observes how a spoke router is able to construct a direct tunnel to other spokes through the process of Resolution request and reply. In the second half, the video demonstrates the benifit of route summarization allowed by NHRP Phase 3 configuration. Wireshark capture is reviewed throughout the video. 

The video looks at Next Hop Resolution Protocol (NHRP) Phase 1 with Hub-and-Spoke topology and explains the differences from point-to-point GRE tunnel. NHRP is the basis of widely-used DMVPN. Without the IPSec encryption in DMVPN, we are able see the actual NHRP packets in action, which helps to understand how the protocol operates (ie. Spoke Registration Request/Reply). We will analyze these packets in Wireshark.