Have many spokes that will connect to a hub site,and won't fit in a router if using one GRE tunnel for each remote. Won't have IPsec. Plan to use DMVPN to allow only one router to handle all the tunnels. Is it possible to use Dynamic Multipoint VPN using only multipoint GRE, without IPsec? In the documents I saw at Cisco's web site, they always tell about GRE and IPsec.
I think you should be able to configure DMVPN without IPSEC in which case its basically just a multipoint GRE tunnel with NHRP. To do that you can just use DMVPN configs and omit the IPSEC/tunnel protection part. For DMVPN configuration, have a look at:
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...