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ISDN stops Dialing after IPSec Crypto Map applied

Level 1
Level 1


Need Help! I hope this forum will help me solve this problem.

Problem Facing -

When IPSec Crypto Map applied on the ISDN Backup Dialer Interface of the Branch Router, ISDN Dialer interface stops making calls. Whereas it is tested before applying the Crypto Map - places calls successfully.

Network Setup in brief -

• Branch site Router (2801) connects to Aggregation Point Router (2821). Aggregation Point Router connects to DC Router (3845). Branch Site routers does not connect directly to the DC Router.

• Branch Site Router has a Leased Line connectivity and a ISDN backup connectivity to the Aggregation Point Router.

• Aggregation Point Router has a Leased Line connecting to one dedicated Router (3845) at DC and has a ISDN backup connectivity to another dedicated router (3845) at DC.

Network Diagram is attached for your kind ref!.

Customer Requirement -

Any traffic from Branch to the DC must be encrypted on both the Leased Line connection and ISDN Backup.

Network Diagram and configuration is attached for your kind ref!.

Applying Crypto Map on the Leased Line of the branch to establish the VPN tunnel between the DC routers is tested successfully.

This Test configuration attached, has just been performed between the ISDN Line of the Branch and Leased Line of Data Center - to check if the Crypto Map applied on the ISDN works fine.


Keshava Raju

1 Reply 1

Level 10
Level 10


AFAIK - you cannot apply a crypto list to a dialer interface and create a sucessful VPN tunnel.

You need to use loopback interfaces, I may be wrong, another netpro may have done it. But I think you should try using loopbacks.