my question is that i am going to setup GRE/IPSEC between the 2 routers , but the 2 loopback interfaces of the lt2pv3 tunnel will be routable through the GRE/IPsec tunnel , is this optimum solution & will it work , or there is a nother solution to secure the l2tp " l2tp/ipsec)
There will not be any issue in configuring the loopback interfaces with GRE/IPSEC configuration. You can use the physical interface (or the loopback interface) IP addresses to identify Internet Key Exchange (IKE) peers.
The below URL illustrates an IP Security (IPSec) configuration using a generic routing encapsulation (GRE) tunnel between two routers. IPSec can be used to encrypt GRE tunnels to provide network layer security for non-IP traffic, such as Novell Internetwork Packet Exchange (IPX), AppleTalk, and so forth. The GRE tunnel in this example is purely used for transporting non-IP traffic. Hence, the tunnel does not have any IP address configured. Here are some configuration considerations:
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...