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  1. Rene,

    When would we choose to use Phase 1, 2, or 3, and why? I understand the differences between the three, but do we gain any benefit from implementing one or the other that is noticeable to end users?

    It seems to me that perhaps allowing spoke routers to talk to each other may decrease latency in the real world, as they would not have to hop through the hub router, but other than that I'm not sure.



  2. Hi Patrick,

    The different versions are like an evolution of DMVPN. We don't really use phase 1 anymore unless you have a really good reason why you want to force all traffic through the hub (security perhaps?). Otherwise, it's more effective to allow spoke-to-spoke traffic.

    Both phase 2 and 3 allow spoke-to-spoke traffic, the advantage of phase 3 is that we use the "shortcuts" so you don't need specific entries anymore in the routing tables of the spoke routers. I can't think of any advantages right now that phase 2 has over phase 3 so if you implement this, you probably want to use phase 3.


  3. Hi Jevon,

    That's right, the hub only has one physical interface and there's only one tunnel interface. Both spoke routers will "land" on the same tunnel interface of the hub router.


  4. No problem Jevon :slight_smile:

    Take a look at the configuration here:

    DMVPN Phase 1 Basic Configuration

    The Gigabit interfaces are for the "underlay" network. These could be the interfaces that connect your router to the ISP, it's where you have your public IP address. Just like with "regular" routing, you can connect from many different sources to one IP address.

    The tunnel interface on the hub router uses the Gigabit Interface as its source and it can accept connections from many different spokes. All spoke routers connect to the same IP address and the hub will accept these connections.


  5. Jevon,
    They aren't sharing a physical interface. They are connected together through a logical inteface--the tunnel interface. Each device has its own physical interface that actually sends and receives the bits on the wire.

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