5.1 : why does the SG uses loopback between R5 and SW3 ? between R5 and SW2 ? they are directly connected, using loop0 seems unnecessary


5.2 : why does R6 re annoucne vlan 10 into BGP ? it is already in its bgp table, and already sent to BB1. It seems enough that R4 announces Vlan 10 into BGP.