I'm scratching my head over this one. After battling to get a working 3G configuration using the new 3.75G HSPA+ card, which is now working with no problem for Internet access, I'm struggling to bring up a DMVPN connection to our hub router (DMVPN NHS).
ISAKMP appears to be working fine, both agree ISAKMP SA's and enter state QM_IDLE. They also agree an ESP SA. The spoke sends packets encrypted down the tunnel though the hub end does not receive them and does not complete the NHRP registration and as such the tunnel never fully comes up. 'show DMVPN' on the spoke doesn't proceed past NHRP phase, and on the hub it is never seen. The debugs show NAT-T working as it would be expected to and also shows ISAKMP and IPSEC SA's agreeing on inbound/outbound session ID's
What could be going wrong here?
The DMVPN configuration should be fine as I have used an external 3G modem/gateway in the past and the tunnel can establish. So it's almost as if it is an interoperation between the DMVPN config and the 3G config on the 819.
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