EIGRP uses the BGP cost community during redistribution on the PE router of the CE routes and the idea of POI (point of insertion) and automaticlly creates the ‘super backbone’ for EIGRP to use the Provider link over the backdoor links

OSPF use the SHAM link inside the VRF to create ‘super backbone’ area 0 over the Provdier network to change the link over the Provider to an IntraArea link instead of and InterArea link… And the shamlink sets the cost to a value lower than the backdoor link cost


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