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Cisco Bug: CSCuj77430 - ISM-VPN drops deny crypto acl traffic instead of passing it in clear

Last Modified

Nov 27, 2020

Products (1)

  • Cisco 3900 Series Integrated Services Routers

Known Affected Releases

15.2(4)M 15.3(3)M

Description (partial)

When ISM-VPN module is Active, the deny ACL traffic gets blackholed, and dropped till the SAs come up for permit lines (which is a superset of deny ACEs).
Once the tunnel is up, the traffic that is supposed to have passed through in clear-text [the deny ACEs] gets encrypted by ISM.

This symtom is observed in ISR-G2 with ISM-VPN module in Active State. 
- Crypto Map is configured, where the Crypto ACL has Deny entries at the top.
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