You are troubleshooting an issue with the configuration of mGRE on the hub router in a hub-and-spoke configuration. Examine the output of the configuration of the tunnel interface on the hub router:

• 300-410 : All Parts

Explanation:
The tunnel mode gre multipoint command must be executed on the tunnel interface. An mGRE configuration is one in which the tunnel is allowed to have multiple destinations. The distinguishing feature between an mGRE interface and a point-to-point GRE interface is the tunnel destination. While it is specified on a point-to-point GRE interface, it is not on an mGRE interface. Instead the command tunnel mode gre multipoint is executed on the tunnel interface. This allows the interface to use the Next Hop Routing protocol (NHRP) to discover the IP addresses of the other tunnel endpoints.

The tunnel destination is not specified on the tunnel interface using mGRE. Instead the command tunnel mode gre multipoint is executed on the tunnel interface.

The tunnel mode gre multipoint command must be executed on the tunnel interface, not the physical interface.

The tunnel destination is neither specified on the tunnel interface nor on the physical interface when using mGRE.

Objective:
VPN Technologies
Sub-Objective:
Configure and verify GRE