Here’s a link with more explanation.

In versions after 12.4(6)T, the spoke-to-spoke traffic with NAT is supported. Take a look at this link for more information.

Here’s the important information from the link

In Cisco IOS Release 12.4(6)T or earlier, DMVPN spokes behind NAT will not participate in dynamic direct spoke-to-spoke tunnels. Any traffic to or from a spoke that is behind NAT will be forwarded using the DMVPN hub routers. DMVPN spokes that are not behind NAT in the same DMVPN network may create dynamic direct spoke-to-spoke tunnels between each other.

In Cisco IOS Release 12.4(6)T or later releases, DMVPN spokes behind NAT will participate in dynamic direct spoke-to-spoke tunnels. The spokes must be behind NAT boxes that are preforming NAT, not PAT. The NAT box must translate the spoke to the same outside NAT IP address for the spoke-spoke connections as the NAT box does for the spoke-hub connection. If there is more than one DMVPN spoke behind the same NAT box, then the NAT box must translate the DMVPN spokes to different outside NAT IP addresses. It is also likely that you may not be able to build a direct spoke-spoke tunnel between these spokes. If a spoke-spoke tunnel fails to form, then the spoke-spoke packets will continue to be forwarded via the spoke-hub-spoke path.

I tried this out in a Dynamips lab and it worked great.

Here is a diagram of the dynagen lab I created with the relevant config

Posted by Rob Chee

One response to “DMVPN with NAT

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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.