Everything is going seamlessly regarding redistribution if we have only one point of redistribution, but when we add another router on the edge of 2 routing protocols, for instance in order to provide “high availability” by adding another point of failure to get redundancy, then our network is exposed to very inefficient sub-optimal routing.
If we are going to inject networks from one routing protocol into another, in order to do that we need to conduct redistribution process. There are a few ways to accomplish that. I would like to focus on 4 of them: simple redistribution, with Redistribution lists, with Prefix Lists and with Route Maps.
VTI – Virtual Tunnel Interface has been invented as a simple deployment of VPN in conjunction with IPSec. Easiness of implementation, multicasts and QoS support, makes VTI interesting alternative to GRE Tunnel.