Also see IpSec
GRE Tunnel with VRF Configuration Example
http://www.ciscosystems.co.nz/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6660/ps6808/prod_white_paper0900aecd8055c34e_ps6658_Products_White_Paper.html
http://blog.internetworkexpert.com/2008/08/02/dmvpn-explained/
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CategoryCisco CategorySecurity