DMVPN Best Tutorial

DMVPN stands for Dynamic Multipoint VPN and it is an effective solution for dynamic secure overlay networks. In short, DMVPN is combination of the following technologies:

1) Multipoint GRE (mGRE)
2) Next-Hop Resolution Protocol (NHRP)
4) Dynamic Routing Protocol (EIGRP, RIP, OSPF, BGP)
3) Dynamic IPsec encryption
5) Cisco Express Forwarding (CEF)

Ref: -> http://blog.ine.com/2008/08/02/dmvpn-explained/

EIGRP Load balancing without using variance

First of all, the variance command assigns a multiplier that says when two routes are “close enough” to load balance. Normally, when presented with a route of metric 100 and one of metric 200, routing protocols will choose the former and ignore the latter. With “variance 2″, both routes will be considered equal and make it to the routing table. Depending on the setting of “traffic-share”, the routes will be used proportionally to their metrics. How Does Unequal Cost Path Load Balancing (Variance) Work in IGRP and EIGRP? describes it in detail.

http://ccnprecertification.com/2005/09/16/eigrp-load-balancing-without-using-variance