"The routers should be using the CISCO default layer 2 WAN protocol"
Which protocol is the default layer 2 WAN?
Now I am a bit puzzled. Does the above statement means I should use a default route between routers with known ip addresses?
I actually established connectivity by configuring PPP encapsulation on all 3 routers. And they are now able to communicate. However I am now second guessing myself. Should I have set a default route instead? Would this meet the requirements of using default layer 2 WAN protocol?