how many VPN tunnels can a cisco 2921 support with ISM VPN module?

[Joe Santos]

I have an 50Mbps ethernet access internet connection.  I plan on using a Cisco 2921 as my headend IPSEC gateway.  How many tunnels will this device support?

[Richard Burts]

I do not believe that there is any limit on the "number" of tunnels. The limit would be on how much traffic those tunnels are processing. Here is what the Cisco data sheet for the ISM says about capacity

The Cisco 2900 Series Module (ISM-VPN-29) can provide hardware-based IPSec encryption services of 145 and 550 Mbps in the Cisco 2901, 150 and 600 Mbps in the Cisco 2911, 220 and 700 Mbps in the Cisco 2921, and 385 and 900 Mbps in the Cisco 2951 (IPSec IMIX and 1400-byte packets).

here is the link if you want further information

http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/vpn-internal-service-module-isr-g2/data_sheet_c78-682436.html

HTH

Rick