Question : GRE tunnel terminated on a PIX 506e running 6.3.5?

Is it possible to terminate a GRE tunnel, originating on a ISR 2811, on PIX 506e running 6.3.5?
If so, do you know where I can find an example of such a configuration for the ISR & the PIX?

Answer : GRE tunnel terminated on a PIX 506e running 6.3.5?

try this link.  it is 2 pix's. but you should be able to make the neccessary config modifications on the 2811

http://www.cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a00800a43f6.shtml