Posts Tagged ‘shortcut’
In this post we are going to speak mainly of NHRP. The other important part of DMVPN – IPsec – is relatively the same, and did not change with introduction of NHRP Phase 3. To begin with, let’s quickly recall the core features of NHRP Phase 1 & 2. For detailed overview, you may refer to DMVPN Explained
NHRP Phase 1:
No spoke-to-spoke tunnels but spokes dynamically register their NBMA addresses with the hub. Spokes use p2p tunnels and route all traffic across the hub. It is OK to summarize routes on the hub router and limit the amount of routing information received by the spokes.
NHRP Phase 2:
Uses a special CEF “trick” to implement spoke2spoke tunnels. All spokes need to receive full routing information with next-hop unchanged (e.g. using no next-hop-self eigrp or OSPF broadcast network type).
Look at the following topology: