From: Jian Gu (guxiaojian@gmail.com)
Date: Thu Nov 10 2005 - 02:34:44 GMT-3
Here is my understanding:
Think DMVPN as an overlay network on top of public network, you define your
"private" IP addresses on mGRE tunnel interfaces (and run your routing
protocol over it) while "public" IP network is so-called NBMA network which
will be your transport network. DMVPN sets up IPsec tunnel dynamically for
spoke to spoke traffic, when you have something to send to another spoke,
the next hop will be one of your "private" IP addresses, now how does the
router know the destination IP addresses of the IPsec tunnel the router
needs to setup? NHRP comes into play here, with NHRP the router can
on-the-fly figure out the IPsec tunnel destination "public" IP addresses.
Since each spoke has permenent IPsec tunnel to hub, it is fair to say that
NHRP is used for spoke-to-spoke communication.
HTH
Jian
On 11/9/05, Venkatesh Palani <kvpalani@gmail.com> wrote:
>
> HI Guys,
> Could any one help me with the concepts of NHRP and how does it work with
> DMVPN. I cant really understand how NHRP work with DMVPN, does it help to
> estbalish Spoke-epoke to VPN if so when both the spokes use public IP
> address why should we need NHRP. it just driving me crazy.
> Any hep will be appreciated,
> Thank you,
> Venkatesh
>
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